\Babduct\b To move away from the midline; \Babduction;\b; See also \Jadduct\j
\Baberrant\b 1: Not conforming to type. 2: An individual exhibiting unusual characters due to external environmental influences rather than to genetic factors; \Baberration.\b
\Babience\b An avoidance reaction; withdrawal or retraction from a stimulus; See also \Jadience\j
\Babiogenesis\b Spontaneous generation; the concept that life can arise spontaneously from non-living matter by natural processes without the intervention of supernatural powers; See also \Jbiogenesis\j
\Babioseston\b The non-living component of the total particulate matter suspended in water; See also \Jbioseston\j
\Babiotic\b Devoid of life; non-living; See also \Jbiotic\j
\Bablation\b The removal of a surface layer, as of ice by melting or evaporation.
\Baboospore\b A spore produced from an unfertilized female gamete.
\Baborigine\b The original or indigenous biota of a geographical region; \Baboriginal.\b
\Babort\b To arrest development; \Babortion.\b
\Babrasion\b The process of erosion by rubbing off or wearing away of surface material.
\BAbrocomidae\b Rat chinchillas; family containing 2 species of rat-like rodents (Hystricomorpha) that inhabit burrows and crevices in the Andes of South America; stiff hairs project over the nails of the 3 central digits of the hindfeet.
\Babscission\b The natural process by which two parts of an organism separate; \Babscise.\b
\Babsenteeism\b The behaviour shown by animals which nest away from their offspring but visit them from time to time with food, providing minimal parental care.
\Babsolute age\b The precise geological age of a fossil or rock, usually calculated by means of radiometric dating; See also \Jrelative age\j
\Babsolute dating\b A method of geological dating which involves measuring the amount of decay of a radioactive isotope and gives a direct measure of the amount of time that has elapsed since formation of the rocks; See also \Jrelative dating\j
\Babsolute humidity\b The actual amount of water vapour present in a mass of air; See also \Jrelative humidity\j
\Babsorption\b 1: The process by which one substance (the absorbate) is taken into and incorporated in another substance (the absorbent); \Babsorb.\b 2: In ecological energetics, that part of the total intake of food (consumption) not voided during regurgitation or as faeces.
\Babundance\b The total number of individuals of a species in an area, volume, population or community; often measured as cover in plants.
\Babyssal\b Pertaining to great depths within the Earth, or to zones of great depth in the oceans or lakes into which light does not penetrate; commonly used in oceanography of depths between 4000 and 6000 m; \Babyss;\b see marine depth zones.
\Babyssal plain\b The more or less flat ocean floor below 4000 m, excluding ocean trenches, having a slope of less than 1 in 1000; see marine depth zones.
\Babyssobenthic\b Living on or in the ocean floor in the abyssal zone; see marine depth zones.
\Babyssopelagic\b Living in the oceanic water column at depths between 4000 and 6000 m, away from the ocean floor; see marine depth zones.
\Bacacia\b \JMimosaceae\j
\BAcanthaceae\b Zebra plant, shrimp plant; family of Scrophulariales containing about 2500 species of often twining herbs or woody plants commonly accumulating orobanchin and iridoid compounds; mostly tropical in distribution; flowers frequently condensed in cymes; bracts and bracteoles often coloured and sometimes enclosing the flowers; individual flowers having a calyx with 4-5 clefts, 4-5 petals, 2, 4 or 5 stamens; producing a capsular fruit.
\BAcantharia\b Class of protozoans (\JActinopoda\j) possessing a skeleton made of radial spines which are joined in the centre, arranged regularly and composed of strontium sulphate; most float passively in surface waters of the open sea and reproduce by the formation of spores.
\BAcanthobdellida\b Monotypic subclass of hirudinoidean worms (Annelida) ectoparasitic on freshwater fishes in cold lakes of northern Europe and Alaska; morphology intermediate between oligochaetes and leeches; body with 30 segments each bearing 4 annuli, length 3-35 mm; possessing posterior sucker only.
\BAcanthocephala\b Thorny-headed worms, spiny-headed worms; phylum of exclusively parasitic, pseudocoelomate worms found mainly in vertebrate intestinal tracts and typically utilizing an arthropod intermediate host; body divided into retractable proboscis (typically armed with hooks), neck and trunk; lacking a digestive tract; comprising 3 classes, Archiacanthocephala, Eoacanthocephala and Palaeacanthocephala.
\BAcanthochitonida\b Small order of specialized chitons typically with the shell valves completely or partially covered by the peripheral girdle; surface of each valve usually divided into 4 distinct sections; includes the largest known chiton, the gumshoe.
\BAcanthodii\b Extinct class of primitive bony fishes (Osteichthyes) known from the Silurian to the Permian; tail fin heterocercal; ganoid scales present; stout spines present in front of fins.
\BAcanthopodina\b A suborder of \JAmoebida\j; also treated as a class of the protoctistan phylum Rhizopoda.
\Bacanthosoma\b Late zoeal larval stage of sergestoid shrimps (Decapoda).
\BAcanthuridae\b Surgeonfishes; family containing 7 species of tropical marine perciform teleosts most abundant in the Indo-Pacific; body compressed, up to 500 mm in length; dorsal and anal fins long, sometimes with filamentous rays; mostly herbivorous, feeding on algae scraped from coral.
\BAcari\b Mites and ticks; diverse order of small free-living and parasitic arthropods (Arachnida) comprising about 30,000 recognized species although this may represent only a small proportion of the world fauna; body mostly small (80\Fm\nm-20mm), compact; head and abdomen fused; mouthparts include chelicerae and subcapitulum; immense variety of form and habit in 3 suborders, Acariformes, Opilioacriformes and Parasitiformes.
\BAcariformes\b Diverse suborder of mites (Acari) comprising 3 subgroups, Astigmata, Oribatei, Prostigmata; includes phytophagous, fungivorous, predatory and parasitic forms; Actinotricha.
\Bacarology\b The study of mites and ticks; \Bacarological.\b
\Bacarophilous\b Thriving in association with mites; \Bacarophile, acarophily\b.
\Bacarophytism\b Symbiosis between plants and mites.
\BAcarpomyxa\b Class of rhizopod protozoans comprising small multinucleate plasmodial forms and similar uninucleate forms, usually branching and sometimes forming a network; a test is absent and there are no fruiting bodies or spores as in \JEumycetozoa\j; includes 2 classes, Leptomyxida and Stereomyxida.
\Baccessory chromosome\b Any chromosome differing from the normal A-chromosomes.
\Baccidental\b Not normally occurring in a particular community or habitat.
\Baccidental parasite\b A parasite found associated with an organism which is not its normal host.
\BAccipitridae\b Eagles, harriers, hawks, kites, Old World vultures; large and diverse family of raptors (Falconiformes) distributed worldwide except for polar regions; feeding mainly on small vertebrates captured using powerful feet, some feeding on carrion; solitary or gregarious in habits, monogamous, nesting in trees, cliffs or on the ground; contains about 215 species.
\Bacclimation\b The gradual and reversible adjustment of physiology or morphology as a result of changing environmental conditions; often used with reference to an individual organism in an artificial or experimentally manipulated environment; See also \Jacclimatization\j \Jaccommodation\j
\Bacclimatization\b The gradual and reversible adjustment of physiology and morphology to changing natural environmental conditions; often used to refer to the changes observed in a species over a number of generations; See also \Jacclimation\j \Jaccommodation\j
\Bacclivous\b Having a gentle upward slope.
\Baccommodation\b 1: The capacity of a plant to adapt to changes in the environment. 2: A decrease in response or sensation as a result of repeated stimulation; See also \Jacclimation\j \Jacclimatization\j
\Baccrescent\b Increasing in size with age; used of plants that continue to grow after flowering.
\Baccretion\b 1: Increase in size by the external addition of new material. 2: Deposition of material by sedimentation.
\Baccumulator\b Any organism that actively concentrates a particular element or compound in its tissues.
\Bacellular\b Not composed of cells; See also \Jcellular\j
\BAceraceae\b Maple; family of Sapindales containing over 100 species of trees and shrubs with mostly palmately lobed or veined leaves; flowers regular, pentamerous; fruit is a samara.
\BAchariaceae\b Small family of Violales containing only 3 species of climbing or stemless monoecious herbs without a latex system; confined to South America.
\BAchatocarpaceae\b Small family of Caryophyllales comprising 8 species of spiny shrubs or trees found from Texas to Argentina.
\Bachene\b A small, dry, indehiscent fruit developed from a single carpel containing a single seed.
\Bachromatic\b Without colour; unpigmented.
\BA-chromosome\b Any of the normal chromosomes of a eukaryotic organism.
\Bachroous\b Without colour, unpigmented.
\Bacid rain\b Rain with a high level of acidity (low pH) due to pollution by oxides of sulphur and nitrogen produced by oil and coal combustion.
\Bacidic habitat\b A habitat with a pH less than 7, typically poor in nutrients.
\Bacidophilic\b Thriving in an acidic environment; \Bacidophile\b, \Bacidophily\b; See also \Jacidophobic\j
\Bacidophobic\b Intolerant of acidic environments; \Bacidophobe\b, \Bacidophoby\b; See also \Jacidophilic\j
\Bacidotrophic\b Feeding on acidic food or acidic substrates.
\BAcipenseridae\b Sturgeons: family of large (1-5.5m) freshwater or anadromous fishes widespread in the northern hemisphere; body spindle-shaped bearing rows of large bony scutes; mouth protrusible; teeth absent in adult; swim bladder large; contains 25 species, some exploited commercially; eggs marketed as caviar.
\BAcipenseriformes\b Order of primitive bony fishes (Osteichthyes) comprising 2 families, Acipenseridae (sturgeons) and Polyodontidae (paddlefishes).
\Bacme\b A period of maximum vigour; the highest point attained in phylogenetic or ontogenetic development; \Bacmic\b; See also \Jepacme\j
\BAcochlidioidea\b An order of small, elongate opisthobranch molluscus found in sandy sediments of marine or sometimes brackish waters; commonly lacking a shell and a head shield; possessing a pair of tentacles; typically discarding their old radula teeth.
\BAcoela\b Order of primitive free-living turbellarians found abundantly in or on marine sediments but with a few brackish water or freshwater forms; characterized by their simple construction, the lack of a permanent gut cavity, the lack or weak development of a muscular pharynx, and the presence of a statocyst containing a single statolith.
\BAconchulinida\b Order of Filosa \Iq.v.;\i naked amoebae with true filose pseudopodia (filopodia), that feed on various other microorganisms and algae, either by ingestion or parasitic penetration.
\Bacorn barnacle\b \JThoracica\j
\Bacorn worm\b \JHemichordata\j
\Bacoustics\b The study of sound; \Bacoustic.\b
\Bacquired characters, inheritance of\b 1: Lamarckism; that changes in use or disuse of an organ result in changes in size and functional capacity and that these modified characters are transmitted to the offspring. 2: Neo-Lamarckism; that characters acquired by organisms as a response to environmental factors are assimilated into the genome and transmitted to the offspring.
\Bacquired trait\b A character or trait which is a result of direct environmental influences.
\BAcrania\b \JCephalochordata\j
\BAcrasea\b Cellular slime moulds \Iq.v.;\i treated as a class of rhizopod protozoans.
\BAcrasiomycetes\b Cellular slime moulds \Iq.v.;\i treated as a class of Myxomycota in the fungi.
\BAcrasiomycota\b Cellular slime moulds \Iq.v.;\i treated as a phylum of protoctistans.
\BAcrididae\b Large and diverse family of insects (order Orthoptera) comprising the locusts and true grasshoppers; contains about 7000 species in 1100 genera, including the majority of the economically important orthopterans.
\Bacridophagous\b Feeding on grasshoppers; \Bacridophage, acridophagy\b.
\BAcrochordidae\b Wart snakes; family of primitive snakes (Serpentes) found in India, Sri Lanka and some Indo-Australian Islands; ridged scales on body do not overlap; nasal openings on top of snout.
\Bacrodendrophilous\b Thriving in tree top habitats; \Bacrodendrophile\b, \Bacrodendrophily\b.
\Bacronurus\b Transparent larval stage of surgeonfish (Acanthuridae).
\Bacropleustophyte\b A large aquatic plant floating freely at the water surface.
\BAcrosiphoniales\b Order of marine and brackish water green algae with a simple or branched uniseriate filamentous body attached to the substrate by rhizoids; cells usually multinucleate with a perforated cylindrical chloroplast.
\BAcrothoracica\b Order of free-living, filter-feeding barnacles (Cirripedia) that inhabit burrows in mollusc shells, coral skeleton and limestone in tropical and temperate shallow marine habitats; characterized by reduced calcareous plates and by degenerate complemental males; contains about 50 species.
\BAcrotretida\b Order of small inarticulate brachiopods comprising about 25 extant species; pedicle typically short or absent; foramen present.
\Bacrotropism\b An orientation response resulting in the continued growth of a plant in the direction in which growth originally commenced; \Bacrotropic.\b
\Bactic\b Pertaining to rocky shores; often used of the zone between high and low tides; intertidal.
\BActinelida\b Order of protozoans (Actinopoda) forming a transitional group between the Acantharia and Heliozoa.
\BActiniaria\b Sea anemones; order of solitary zooantharians comprising about 800 species found in all the seas, from the intertidal zone to abyssal depths; typically lacking a hard exoskeleton; basal end may be an adherent pedal disk or a bulbous structure used for anchoring in soft substrates; oral disk typically circular with surrounding tentacles arranged with a six-fold symmetry.
\BActinidiaceae\b Chinese gooseberry; family of Theales containing about 300 species of tanniferous, woody plants, widely distributed in tropics, subtropics and mountains of Asia.
\Bactinobiology\b The study of the effects of radiation on living organisms; \Bactinology\b.
\BActinoceratida\b Extinct order of nautiloid cephalopod molluscs known from the Lower Ordovician to the Lower Carboniferous; predominantly orthozonic with large siphuncles.
\Bactinomorphy\b Radial symmetry in flowers.
\BActinomyxea\b Class of \JMyxozoa\j containing parasites of aquatic oligochaetes and sipunculans; characterized by an outer spore covering composed of 3 valves which may be drawn out into long processes, and by the presence of 3 polar capsules; treated as a class, Actinomyxida, of the protoctistan phylum Cnidosporida.
\BActinophryida\b Order of protozoans (\JHeliozoa\j) containing mostly free cells that lack a skeleton and a centroplast, found in both marine and fresh water.
\BActinopoda\b Superclass of the protozoan subphylum Sarcodina characterized by the possession of radial axopods (consisting of a rigid axial rod surrounded by cytoplasm) amongst the fine pseudopodia; food particles are trapped on the sticky axopods, pulled in towards the capsule and enclosed in a vacuole; most are marine and pelagic; comprising 4 classes, Acantharia, Heliozoa, Phaeodaria and Polycystina; also treated as a distinct phylum of Protoctista.
\BActinopterygii\b Ray-finned fishes; subclass of bony fishes (Osteichthyes) characterized by fins of membranous skin supported by spines or rays; includes the majority of living bony fishes.
\BActinotricha\b \JAcariformes\j
\Bactinotroch\b Planktonic larval stage in the phylum \JPhoronida\j
\Bactinula\b Free-swimming tentaculate larva of some hydrozoan cnidarians, formed from a ciliated planula.
\BActinulida\b Order of free-living Hydrozoa which are solitary and motile but not pelagic and occur in interstitial spaces in marine sands; typically small with a covering of cilia by which they move; exhibiting a general actinula larva-like organization.
\Bactive chamaephyte\b A type of \Jchamaephyte\j in which the horizontal vegetative shoots persist through unfavourable seasons in a procumbent position.
\Bactive process\b Any process requiring the expenditure of metabolic energy.
\Bactophilous\b Thriving on rocky seashores; \Bactophile\b, \Bactophily\b.
\Bactualism\b The theory that seeks to explain the evolution of the Earth in terms of relatively small scale natural fluctuations or events that have been operative throughout the entire geological history of the Earth and have thus produced changes of great magnitude; uniformitarianism: See also \Jcatastrophism\j
\BAculeata\b Bees, wasps, ants; diverse group of hymenopteran insects (suborder Apocrita) comprising about 60,000 species many of which are eusocial; ovipositor typically modified as sting for injection of venom, or spread of pheromones or allomones.
\Bacyclic parthenogenesis\b Reproduction by parthenogenesis alone, in which the sexual phase of an alternation of generations cycle has been lost; See also \Jparthenogenesis\j
\Badaptation\b 1: The process of adjustment of an individual organism to environmental conditions; adaptability. 2: Process of evolutionary modification which results in improved survival and reproductive efficiency. 3: Any morphological, physiological, developmental or behavioural character that enhances survival and reproductive success of an organism; \Badaption\b.
\Badaptiogenesis\bThe production of new adaptations.
\Badaption\b \JAdaptation\j
\Badaptive landscape\b The figurative representation of the fitness of organisms in the form of a topographical map, on which those fit genotypes (species) able to occupy particular ecological niches are depicted as adaptive peaks separated by adaptive valleys representing unfit gene combinations.
\Badaptive peak\b A peak on an \Jadaptive landscape\j
\Badaptive radiation\b The evolutionary diversification of a taxon (adaptive type) into a number of different ecological roles or modes of life (adaptive zones), usually over a relatively short period of time and leading to the appearance of a variety of new forms.
\Badaptive valley\b A valley in an \Jadaptive landscape\j
\Badduct\b To move towards the midline; \Badduction\b; See also \Jabduct\j
\Badeciduate\b Not falling off, or coming away.
\Badelphogamy\b Fertilization between two different individuals derived vegetatively from the same parent plant.
\Badelphoparasite\b An organism parasitic on a closely related host organism; See also \Jalloparasite\j
\Badelphophagy\b The fusion of two gametes of the same sex.
\Badelphotaxy\b The mutual attraction between spores after extrusion.
\BAdenophorea\b Class of nematodes including free-living aquatic and terrestrial forms, and parasites of plants and animals; characterized by the position of the head chemoreceptors (amphids) behind the lips and of the 16 cephalic sensory organs which are found on or behind the lips; external cuticle always 4-layered; comprising 2 subclasses, Chromadoria and Enoplia.
\BAdephaga\b Suborder of beetles (Coleoptera) comprising about 34,000 species including Carabidae (predaceous ground beetles), Dytiscidae (giant water beetles), Gyrinidae (whirligig beetles), the first containing the vast majority of species.
\Badichogamy\b Simultaneous maturation of male and female reproductive organs of a flower or hermaphroditic organism; \Badichogamous\b; See also \Jdichogamy\j
\Badience\b Movement towards a stimulus; an approaching reaction; See also \Jabience\j
\Badmiral butterfly\b \JNymphalidae\j
\Badnate\b Closely applied to; growing on; attached along the entire length.
\BAdoxaceae\b Family of Dipsacales containing a single species of delicate perennial herbs with a circumboreal distribution.
\BAdrianichthyidae\b Family of small (to 200 mm) beloniform teleost fishes comprising only 3 species, restricted to freshwater lakes of the Celebes; body elongate, compressed; head depressed with large jaws; pelvic fins small.
\Badsorption\b The adhesion of molecules as an ultra-thin layer on the surface of solids or fluids; \Badsorb\b.
\Badspersed\b Widely distributed; scattered.
\Badtidal\b Living immediately below low tide level.
\Badvection\b The process of transfer by virtue of motion; the transfer of heat or matter by horizontal movement of water masses.
\Badventitious\b Accidental; occurring at an unusual site; secondary.
\Badventive\b Not native; an organism transported into a new habitat.
\Badynamandrous\b Having non-functioning male reproductive organs; \Badynamandry\b.
\Badynamogynous\b Having non-functioning female reproductive organs; \Badynamogyny\b.
\BAegithalidae\b Long-tailed tits; family containing 7 species of small titmice (Passeriformes) found in America, Eurasia and Java; nest intricate, domed, built in trees and bushes.
\Baeolation\b Erosion of a land surface by windblown sand and dust; \Beolation\b.
\Baeolian\b Pertaining to the action or effect of the wind; \Beolian\b.
\Baeolian deposit\b Wind-borne soil deposit; See also \Jalluvial deposit\j \Jcolluvial deposit\j
\Baeon\b An indefinitely long period of time; \Beon\b.
\BAepyornithidae\b Elephant birds; extinct family of large, ratite birds standing up to 3 m tall; found in subforest habitats in Madagascar.
\Baerobic\b 1: Growing or occurring only in the presence of molecular oxygen; \Baerobe\b, \Baerobiosis\b; See also \Janaerobic\j. 2: Used of an environment in which the partial pressure of oxygen is similar to normal atmospheric levels.
\Baerobiology\b The study of airborne organisms.
\Baerochorous\b Disseminated by wind; \Baerochore\b, \Baerochory\b.
\Baerogenic\b Gas-producing; \Baerogenesis\b; See also \Janaerogenic\j
\Baerohygrophilous\b Thriving in high atmospheric humidity; \Baerohygrophile\b, \Baerohygrophily\b; See also \Jaerohygrophobous\j
\Baerohygrophobous\b Intolerant of high atmospheric humidity; \Baerohygrophobe\b, \Baerohygrophoby\b; See also \Jaerohygrophilous\j
\Baerophilous\b 1: Pollinated by wind; fertilized by airborne pollen. 2: Thriving in exposed windy habitats; \Baerophile\b, \Baerophily\b. 3: Disseminated by wind.
\Baerophyte\b An epiphyte growing on a terrestrial plant and lacking direct contact with soil or water.
\Baeroplankton\b Those organisms freely suspended in the air and dispersed by wind; aerial plankton.
\Baerotaxis\b The directed movement of a motile organism towards (positive) or away from (negative) an air-liquid interface, or a concentration gradient of dissolved oxygen; \Baerotactic\b.
\Baerotolerant\b Used of anaerobic organisms having the capacity to grow to a limited extent under aerobic conditions.
\Baerotropism\b An orientation response to a gaseous stimulus; \Baerotropic\b.
\BAeshnidae\b Widely distributed family of large, hawker dragonflies (Odonata) which are often marked with blue and green colours; eyes large, almost contiguous across top of head.
\Baestival\b Pertaining to the early summer season; See also \Jhibernal\j \Jhiemal\j \Jserotinal\j \Jvernal\j
\Baestivation\b 1: Passing the summer or dry season in a dormant or torpid state; \Bestivation\b, \Baestivate\b; See also \Jhibernation\j. 2: The manner in which plant structures are folded prior to expansion or opening.
\Baetiology\b 1: The branch of science dealing with the study of origins or causes. 2: The demonstrated cause of a disease or trait; causation; \Betiology\b, \Baetiological\b.
\BAetosauria\b Extinct group of thecodontian reptiles known from the Triassic; body rather crocodile-like, armoured with bony plates; up to 3 m long.
\BAextoxicaceae\b Family of \JCelastrales\j containing a single tree species native to Chile; flowers borne in axillary racemes, pentamerous; fruit is a drupe.
\Bafforestation\b The process of establishing a forest in a non-forested area; See also \Jreforestation\j
\BAfrenulata\b Class of pogonophoran marine worms comprising a single order, Vestimentifera; body devoid of setae; bridle absent from mesosoma.
\BAfrican subkingdom\b A subdivision of the Palaeotropical kingdom.
\BAfrican tulip tree\b \JBignoniaceae\j
\BAfrican violet\b \JGesneriaceae\j
\BAftonian interglacial\b An interglacial period of the Quaternary Ice \JAge\j in North America.
\Bagamandroecious\b Used of a plant having male and neuter flowers in the same inflorescence; See also \Jagamogynoecious\j \Jagamohermaphrodite\j
\Bagameon\b A species comprising only nonsexually reproducing individuals.
\Bagamete\b A mature reproductive cell which does not fuse with another to form a zygote; a noncopulating germ cell; See also \Jgamete\j
\Bagamic\b Without gametes; used of complexes of organisms in which all individuals reproduce asexually.
\BAgamidae\b Large, diverse family of arboreal and terrestrial lizards (Sauria) widespread in Oriental and Palaearctic regions from North Africa to Australia; contains about 320 species of diurnal, insectivorous or herbivorous lizards, characterized by a depressed or compressed body, a non-autotomic tail, and by oviparity.
\BAgamococcidiida\b Primitive order of coccidians comprising only 3 species found in marine annelids; typically without merogony or gamonts in the life cycle.
\Bagamodeme\b A local interbreeding population of predominantly asexually reproducing individuals; See also \Jdeme\j
\Bagamogenesis\b Asexual reproduction.
\Bagamogony\b Asexual reproduction by development of a new individual from a single cell, following binary or multiple fission, or budding.
\Bagamogynoecious\b Used of a plant having female and neuter flowers in the same inflorescene; See also \Jagamandroecious\j \Jagamohermaphrodite\j
\Bagamohermaphrodite\b Used of a plant having hermaphrodite and neuter flowers in the same inflorescence; See also \Jagamandroecious\j \Jagamogynoecious\j
\Bagamont\b The sexual individual or generation producing \Jagamete\j
\Bagamospecies\b A species or population comprising only asexually reproducing individuals.
\Bagamospermy\b Reproduction without fertilization in which embryos and seeds are formed asexually, but not including vegetative reproduction; \Bagamospermous\b.
\Bagamotropic\b Used of flowers that do not close again once they have opened; See also \Jgamotropic\j \Jhemigamotropic\j
\BAgaonidae\b Fig wasps; family of small phytophagous wasps (Hymenoptera) that live only in the flowers and fruits of figs, and upon which the host is dependent for pollination; adults are sexually dimorphic, the male lacking wings and eyes, and having feeble limbs; contains about 160 species.
\BAgaricaceae\b Edible mushrooms; family of typically umbrella-shaped fungi in which the cap breaks cleanly from the stalk, which usually bears a ring; spore masses on gills dark coloured when mature; found on the ground in grassland and open woodland.
\BAgaricales\b Large, diverse order of hymenomycete fungi which can be saprobic in a variety of habitats, parasitic on plants and other fungi, or mycorrhizal; produce fruiting bodies (basidiocarps) which are diverse in form but having basidia arranged in a fertile layer (hymenium) which is typically exposed at the time of basidiospore formation and discharge; includes fungus causing dry rot of wood, edible mushrooms, boletes, fly agarics and inkcap mushrooms.
\BAgaricogastrales\b Order of gasteromycete fungi in which the fertile layer (hymenium) persists after maturity; fruiting body typically resembling the edible mushroom.
\Bagaricolous\b Living on mushrooms and toadstools; \Bagaricole\b
\BAgavaceae\b Century plant, dragon tree, snake plant, yucca; family of Liliales comprising nearly 600 species of coarse herbaceous or arborescent plants with perennial leathery or fleshy leaves; native to warm, mostly arid regions.
\Bage\b 1: To become old; to attain maturity. 2: The period of time a group or organism has existed. 3: The length of geological time since the formation of a rock either by solidification from a molten state (igneous) or by sedimentation (sedimentary). 4: A period of geological history characterized by a dominant life form, such as the age of fishes. 5: A geological time unit shorter than an epoch.
\Bage of amphibians\b That period of the Earth's history dominated by amphibians; the Carboniferous and Permian periods.
\Bage of cycads\b That period of the Earth's history dominated by cycads; the Jurassic period.
\Bage of fishes\b That period of the Earth's history dominated by fishes; the Silurian and Devonian periods.
\Bage of gymnosperms\b That period of the Earth's history dominated by gymnosperms; the Mesozoic era.
\Bage of mammals\b That period of the Earth's history dominated by mammals; the Cenozoic era.
\Bage of man\b That period of the Earth's history dominated by man; the Quaternary period.
\Bage of marine invertebrates\b That period of the Earth's history dominated by marine invertebrates; the Ordovician and Cambrian periods.
\Bage of reptiles\b That period of the Earth's history dominated by reptiles; the Mesozoic era.
\Bage structure\b The number or percentage of individuals in each age class of population.
\Bageing\b The process of irreversible decline of bodily function and adaptability with time or increasing age.
\BAgelasida\b Small order of tetractinomorph sponges widely distributed in shallow tropical and warm temperate waters; having a skeletal reticulum of spongin fibres with protruding short, spined megascleres.
\BAgelenidae\b Sheet-web spiders, house spider; family of spiders (Araneae) that construct sheet webs with tubular retreats; body with a flattened thorax, legs long and thin, covered with long hairs; eyes arranged in two short rows.
\BAgeneiosidae\b Family of predatory tropical South American freshwater catfishes (Siluriformes) found mostly in slow-moving backwaters; body naked, dorsal fin with stout spine, barbels rudimentary; gas bladder enclosed in bony capsule; contains about 35 species, some important as food, others collected for aquaria.
\Bageotropism\b The absence of orientation movements in response to gravity; \Bageotropic\b.
\Baggregation\b A society or group of conspecific organisms which has a social structure and consists of repeated members or units but with a low level of coordination, integration or genotypic relatedness.
\Baggression\b A hostile act or threat made to protect territory, the family group or offspring, or to establish dominance.
\Baggressive mimicry\b \JMimicry\j in which a predator mimics a non-predatory model in order to deceive its prey.
\BAgnatha\b Jawless fishes; class or superclass of aquatic vertebrates lacking true jaws formed from modified gill arches; with poorly developed or absent paired fins; gills present on inner surfaces of gill arches; possess 2 pairs of semicircular canals; contains 2 extant orders, Myxiniformes and Petromyzoniformes, and several fossil groups.
\BAgnotozoic\b \JProterozoic\j
\BAgonidae\b Poachers; family containing 50 species of small (to 300 mm) bottom-dwelling marine scorpaeniform teleost fishes found on soft sediments from intertidal to 1200 m; body elongate, covered with rows of bony plates.
\Bagonistic behaviour\b Social interaction between members of a species, involving aggression or threat and conciliation or retreat.
\Bagonistic buffering\b The use of infants by adults to inhibit the aggressive behaviour of other adults.
\BAgonomycetales\b Small order of hyphomycete fungi characterized by the lack of propagative spores (conidia); reproduction and dispersal is by means of rounded compact masses of hyphae or groups of cells.
\Bagouti\b \JDasyproctidae\j
\Bagrarian\b Pertaining to cultivation or cultivated plants.
\Bagrestal\b Growing on arable land.
\BAgriochoeridae\b Extinct family of ruminants (Tylopoda) having a lightly built pig-like body with long tail and clawed feet; found from the Upper Eocene to the Miocene.
\Bagroclimatology\b The study of climate in relation to the productivity of plants and animals of agricultural importance.
\Bagrology\b The branch of agriculture dealing with the study of soils.
\Bagronomy\b The theory and practice of agricultural management, crop production and husbandry.
\Bagrophilous\b Thriving in cultivated soils; \Bagrophile, agrophily\b.
\Bagrostology\b The study of grasses; graminology.
\BAgulhas Current\b A warm surface ocean current that flows south off the coast of South Africa, derived in part as an extension of the Mozambique Current and Indian South Equatorial Current; see ocean currents.
\Bahermatypic\b Pertaining to a non-colonial assemblage, or an individual; used of a coral that lacks symbiotic algae; \Bahermatype\b.
\BA-horizon\b The dark coloured upper mineral horizon of a soil profile, immediately below the O-horizon and comprising some humified organic material as a result of biological activity or cultivation; see soil horizons.
\Baigialophilous\b Thriving in beach habitats; \Baigialophile, aigialophily.\b
\Baigicolous\b Living in beach habitats; \Baigicole.\b
\BAiluropodidae\b Giant panda; family containing single species of large bear-like mammals (Carnivora) restricted to a few mountain forest areas in the south west of China; feeding exclusively on bamboo but habits and biology little known.
\Baiphyllophilous\b Thriving in evergreen woodland; \Baiphyllophile, aiphyllophily.\b
\Baiphyllus\b Evergreen; \Baiophyllus.\b
\Bair capacity\b That volume of air remaining in a soil after saturation with water.
\Bair porosity\b The ratio of the volume of air in a given mass of soil to its total volume.
\Baithalophilous\b Thriving in evergreen thickets; \Baithalophile, aithalophily.\b
\Baitiogenic\b Used of a movement or reaction induced by an external stimulus.
\Baitionomic\b Used of growth patterns and other phenomena imposed by the environment.
\Baitiotropism\b Any tropism resulting from an exogenous stimulus; \Baitiotropic,\b
\BAizoaceae\b Fig marigold, stone plant, hottentot fig; large family of succulent herbs (Caryophyllales) mostly from South Africa and Australia; characterized by adaptations to arid conditions such as fleshy leaves covered with hairs, leaves buried in ground with only the tips showing, or having only 2 leaves; flowers often brightly coloured, with numerous petals.
\BAjacicyathida\b Extinct order of usually solitary archaeocyathids (Monocyathea) known from the Lower and Middle Cambrian.
\BAkaniaceae\b Family of Sapindales containing a single species of alkaloid-producing tree native to eastern Australia.
\Bakaryotic\b Lacking a discrete nucleus; non-nucleated; \Bakaryote\b; See also \Jeukaryotic\j \Jprokaryotic\j
\Bakinesis\b Absence or cessation of movement.
\Bakinete\b A highly resistant, thick-walled, resting spore formed by some blue-green algae during periods of unfavourable environmental conditions.
\Baktology\b The study of shallow inshore ecosystems.
\BAkysidae\b Family of small (to 20 mm) southeast Asian freshwater catfishes (Siluriformes); comprising 7 species each with a naked body, short dorsal fin with 1-2 spines and 3 pairs of barbels.
\BAlangiaceae\b Small family of Cornales containing about 20 species of sometimes thorny woody plants native to the Old World.
\Balarm call\b A sound produced by an animal when danger threatens but is still a significant distance away.
\Balarm pheromone\b A chemical substance, exchanged by members of a group, that induces a state of alarm or alertness.
\Balarm reaction\b The sum of all non-specific responses to sudden exposure to stimuli to which the organism is not adapted.
\BAlaska Current\b Aleutian \JCurrent\j
\BAlaudidae\b Larks; family containing about 80 species of small terrestrial passerine birds found worldwide in open barren areas and on shores; habits gregarious, migratory, feeding on invertebrates; nest solitary, on ground.
\Balbatross\b \JDiomedeidae\j
\Balbinism\b The absence of pigmentation in animals; partial albinism in plants is termed variegation.
\BAlbulidae\b Bonefishes; family containing 4 species of tropical marine teleosts found mainly in shallow coastal waters; body elongate, herring-like, snout produced; feed primarily on benthic molluscs and crustaceans.
\BAlcedinidae\b Kingfishers; family of small colourful woodland birds (Coraciiformes) that feed on fishes and other aquatic vertebrates by diving from flight, or on insects caught on the wing; habits solitary, monogamous, non-migratory; nesting in burrows in banks or in tree holes; contains about 90 species distributed worldwide but most diverse in Old World tropics.
\BAlcidae\b Auks, puffins; family containing 23 species of diving seabirds (Charadriiformes) found in the northern hemisphere; wings short and rounded offering poor flight but efficient underwater swimming; habits gregarious, migratory; feeding mostly on fishes and crustaceans.
\BAlcyonacea\b Soft corals; order of colonial octocorals distributed mainly in shallow waters of tropical seas but extending into polar seas; body form varying from encrusting to erect and branching; packing coenenchyme thick and filled with spicules; colony usually without polyps on basal portion.
\BAlcyonaria\b Octocorals; subclass of Anthozoa characterized by 8 hollow, marginal tentacles and 8 complete mesenteries dividing the gastrovascular cavity; found mainly fixed to hard substrates in shallow tropical waters but occasionally found anchored in soft sediment and in deep or cold water.
\Balder\b \JBetulaceae\j
\Balderfly\b \JSialidae\j (Neuroptera).
\BAlepisauridae\b Lancetfishes; family containing 3 species of large voracious myctophiform teleosts found in the deep sea; body slender, naked and with large sail-like dorsal fin; teeth dagger-like.
\BAlepocephalidae\b Slickheads; family containing about 35 species of benthic and pelagic deepsea salmoniform teleost fishes; body elongate, to 700 mm length; scales may be absent; adipose fin lacking; dorsal and anal fins positioned posteriorly.
\BAlestidae\b Tetras; family containing about 100 species of mostly small tropical African freshwater characiform teleost fishes included by some authorities in the Characidae; larger species are predatory, smaller forms usually omnivorous; often kept by aquarists.
\Baletophilous\b Thriving on roadside verges and beside railway tracks; \Baletophile\b, \Baletophily.\b
\BAleutian Current\b A warm surface ocean current that flows north and west off the coast of Alaska, derived as a deflection of the North Pacific Gyre; Alaska Current; see ocean currents.
\BAleyrodidae\b Whiteflies; family of small, actively flying insects (Homoptera) which have their forewings and bodies covered with a waxy, white powder; immature stages typically live on undersides of leaves, feeding on plant juices, and are commonly attended by ants as they produce honeydew; contains about 1200 species.
\Balfalfa\b \JFabaceae\j
\Balfonsino\b \JBerycidae\j
\Balgae\b Eukaryotic algae; an informal assemblage of photosynthetic non-vascular organisms which differ from more advanced plants in their lack of multicelluar sexual organs sheathed with sterile cells, and by their failure to retain the embryonic sporophyte within the female organ.
\Balgal bloom\b An explosive increase in the density of phytoplankton within an area.
\Balgal line\b The highest continuous line on the shore along which any particular algal species occurs; \I\Bcf.\b\i tang line.
\Balgophagous\b Feeding on algae; \Balgophage\b, \Balgophagy.\b
\BAlgophytic\b \JArchaeophytic\j
\Balien\b Non-native; a species occurring in an area to which it is not native.
\Balima\b Larval stage of stomatopods belonging to the genus, \BSquilla\b; a type of erichthus larva.
\Balimentation\b 1: Feeding, taking in nourishment. 2: Those processes, including precipitation, sublimation and refreezing, that serve to increase the mass of a glacier or snowfield.
\BAlismataceae\b Arrowhead, water plantain; cosmopolitan family containing about 75 species of perennial aquatic or marshinhabiting herbs.
\BAlismatales\b Order of Alismatidae, containing 3 families of perennial, aquatic or semiaquatic herbs with alternate leaves clustered near base; flowers usually with 3 green sepals and 3 white petals.
\BAlismatidae\b Archaic subclass of monocotyledons (Liliopsida) containing 4 orders of herbs, either aquatic, or of wet places, sometimes lacking chlorophyll and mycotrophic in habit; flowers with 3 sepals and 3 petals or reduced, producing seeds which usually lack endosperm.
\Balkaline\b Pertaining to habitats or substances having a pH greater than 7; basic.
\Balkalinity\b 1: The properties of an alkali. 2: A measure of the pH of sea water, calculated as the number of the number of milliequivalents of hydrogen ion that is neutralized by one litre of sea water at 20░C.
\Balkaliphilic\b Thriving in alkaline habitats; \Balkaliphile\b, \Balkaliphily\b; See also \Jalkaliphobic\j
\Balkaliphobic\b Intolerant of alkaline habitats or conditions; \Balkaliphobe\b, \Balkaliphoby\b; See also \Jalkaliphilic\j
\Balkaloduric\b Extremely tolerant of high pH (alkaline) conditions.
\Balkaloid\b A nitrogenous and often poisonous organic compound, produced especially by flowering plants; many alkaloids such as nicotine, caffeine, morphine. atropine, cocaine, quinine and strychnine have a pronounced physiological activity in animals.
\Ballele\b Any of the different forms of a gene occupying the same locus on homologous chromosomes, and which undergo pairing during meiosis, and can mutate one to another; allelomorph; \Ballelic\b, \Ballelism.\b
\Ballele frequency\b \JGene frequency\j
\Ballelochemic\b A secondary substance produced by an organism that has the effect of modifying the growth, behaviour or population dynamics of other species, often having an inhibitory or regulatory effect (allelopathic substance).
\Ballelogenic\b Producing offspring in broods that are entirely of one sex; \Ballelogeny\b; See also \Jamphogenic\j \Jarrhenogenic\j \Jmonogenic\j \Jthelygenic\j
\Ballelomorph\b \JAllele\j
\Ballelopathic substance\b An allelochemic; a waste product, excretory product or metabolite having an inhibitory or regulatory effect on other organisms.
\Ballelopathy\b The chemical inhibition of one organism by another.
\BAllen's Law\b The generalization that the extremities (ears and tails for example) of mammals tend to be relatively shorter in colder climates than in warmer ones.
\Balligator\b \JAlligatoridae\j
\BAlligatoridae\b Alligators, caiman; family containing 7 species of freshwater crocodilians with broad, flat snouts; fourth teeth of lower jaw fitting into pit in upper jaw; often included in the family Crocodylidae.
\Ballocryptic\b Used of organisms that conceal themselves under a covering of other material, living or non-living.
\Ballochthonous\b Exogenous; originating outside and transported into a given system or area; \Ballochthony\b; See also \Jautochthonous\j
\Ballochronic\b Not contemporary; existing at different times; used of populations or species living, growing or reproducing during different seasons of the year; See also \Jsynchronic\j
\Ballochroic\b Exhibiting colour variation, or having the ability to change colour.
\Ballochoric\b Occurring in two or more communities within a given geographical region; \Ballochore.\b
\Ballochemic\b Any secondary compound produced by plants as part of their defence mechanism against herbivores; acting either as a toxin or digestibility reducer.
\Ballobiosphere\b That part of the biosphere in which heterotrophic organisms occur but into which organic food material must be transported as primary production does not take place; See also \Jautobiosphere\j
\Ballogamy\b Cross fertilization; \Ballogamous.\b
\Ballogenetic plankton\b Planktonic organisms transported into an area by movement of the medium, but normally living and reproducing elsewhere.
\Ballogenic\b 1: Used of factors acting from outside the system, or of material transported into an area from outside. 2: Having different sets of genes; \Ballogenetic\b; See also \Jsyngenic\j
\Ballogrooming\b Grooming by one individual of another.
\Balloiogenesis\b Alternation of generations; an alternation between sexual and asexual phases in a life cycle.
\Ballokinesis\b Passive or involuntary movement; drifting; \Ballokinetic.\b
\Ballomaternal\b A female alloparent q.v.
\Ballometric growth\b Diferential growth of body parts resulting in a change of shape or proportion with increase in size; \Ballometry\b; See also \Jisometric growth\j
\Ballomone\b A chemical substance produced and released by one species in order to communicate with another species; See also \Jpheromone\j
\Balloparasite\b An organism parasitic on an unrelated host organism; See also \Jadelphoparasite\j
\Balloparent\b An individual that assists a parent in the care of its young, either male (allopaternal) or female (allomaternal).
\Ballopaternal\b A male \Jalloparent\j
\Ballopatric\b Used of populations, species or taxa occupying different and disjunct geographical areas; \Ballopatry\b; \Bcf.\b dichopatric, parapatric, sympatric.
\Ballopatric speciation\b The differentiation and reproductive isolation of populations that are geographically separated.
\Ballopelagic\b Used of organisms occurring at any depth in the pelagic zone; See also \Jautopelagic\j
\Ballophilous\b Used of a plant that lacks morphological adaptations for attracting and guiding pollinators; \Ballophily\b; \Bcf.\b euphilous.
\Ballopolyploid\b A polyploid hybrid having chromosome sets derived from two different species or genera; \Balloploid;\b See also \Jautopolyploid\j
\Ballosematic\b Pertaining to coloration or markings that imitate warning patterns of other typically noxious or dangerous organisms.
\Ballosome\b Any chromosome or chromosome fragment other than a normal A-chromosome.
\Ballotherm\b An organism having a body temperature determined largely by the ambient temperature; \Icf\i\B.\b autotherm.
\Ballotopic\b Used of populations or species that occupy different macrohabitats; \Ballotopy;\b See also \Jsyntopic\j
\Ballotrophic\b 1: Obtaining nourishment from another organism; \Jheterotrophic\j 2: Pertaining to the influx of nutrients into a water body or ecosystem from outside.
\Ballotrophic lake\b A lake receiving organic materials by drainage from the surrounding land; See also \Jautotrophic lake\j
\Ballotropism\b 1: The mutual attraction of cells, especially gametes; \Ballotropic.\b 2: The condition of a flower having a plentiful supply of readily available nectar.
\Ballotropous\b Used of unspecialized insect species that are able to feed on a variety of kinds of flowers; See also \Jeutropous\j
\Balluvial deposit\b A silty deposit transported by water; see also \Jaeolian deposit\j \Jcolluvial deposit\j
\BAlluvial soil\b An azonal soil formed from a relatively unmodified recent alluvial deposit in flood plains and deltas.
\Balluviation\b The deposition of sediment by a river at any point along its course.
\BAloeaceae\b Aloe, red-hot poker; family of Liliales comprising about 700 species of coarse plants with some secondary growth of the monocotyledonous type, native to Africa, Arabia and some nearby islands; plants from virtually stemless herbs to arborescent with clusters of succulent leaves crowning the branches or at ground level.
\BAlopiidae\b Thresher sharks; widespread family of large (to 6 m), active but inoffensive, pelagic lamniform elasmobranch fishes, comprising 3 species; upper lobe of caudal fin extremely long, used to manoeuvre and stun prey which includes pelagic fishes, cephalopods and crustaceans.
\Balpestrine\b Living at high altitude above the tree line, commonly used as synonymous with alpine; occasionally used of plants found below the tree line (subalpine plants).
\Balpine\b 1: Pertaining to the Alps. 2: Used of habitats and organisms found between the tree line and snow line in mountainous regions.
\BAlpine Meadow soil\b An intrazonal soil with a dark coloration, formed under meadow grass above the tree line in alpine regions; typically shallow and stony with thin litter and duff; A-horizon granular and strongly acidic, B-horizon absent, and C-horizon gleyed due to poor drainage.
\BAlpine Turf soil\b An intrazonal soil with a dark yellow-brown coloration formed under alpine turf; typically a well-drained soil with thin litter and duff; A-horizon stony and strongly acidic, B-horizon stony and moderately acidic.
\BAlseuosmiaceae\b Small family of Rosales containing about 12 species of shrubs native to New Caledonia and New Zealand.
\Balsocolous\b Living in woody groves; \Balsocole.\b
\Balsophilous\b Thriving in woody grove habitats; \Balsophile\b, \Balsophile.\b
\Balternation of generations\b The alternation of generations having different reproductive processes, typically of sexual (diploid) and asexual (haploid) phases, in the life cycle of an organism.
\BAltithermal period\b A postglacial interval (\Ic\i\B.\b 7500-4000 years B.P.) characterized by distinctly warmer conditions than at present; see also \JAnathermal period\j \JMedithermal period\j
\Baltitude\b The vertical distance between a given point and a datum surface, or chart datum; elevation.
\Baltricial\b Used of offspring or of species that show a marked delay in the attainment of independent self-maintenance; \Baltrices\b; See also \Jprecocial\j
\Baltruism\b The situation in which one individual acts to promote or enhance the fitness of an unrelated individual or of other members of a group at the same time reducing its own fitness; \Baltruistic.\b
\BAlucitidae\b Small family of moths (Lepidoptera) in which the wings are divided into 6 or more plumes; larvae burrow into plants and may induce formation of galls.
\BAmanitaceae\b Fly agarics; family of mushroom-like fungi (Agaricales) in which the cap can be broken cleanly from the stalk; gills not attached to stalk; includes many poisonous forms.
\BAmaranthaceae\b Amaranths, cockscomb; family of Caryophyllales containing about 900 species of mostly herbs, with a cosmopolitan distribution in warm regions; typically with regular flowers either solitary or in axillary cymes; flowers with 1 to 5 free stamens and a superior ovary.
\BAmaryllidaceae\b Family of monocotyledons usually included in the Liliaceae (\JLiliales\j); sometimes separated on the basis of their inferior ovary.
\Bamathophilous\b Thriving in sandy plains; \Bamathophile\b, \Bamathophily.\b
\Bamber snail\b \JStylommatophora\j
\Bambient\b Surrounding; background.
\Bambisexual\b 1: Having separate male and female flowers on the same plant. 2: Pertaining to both sexes.
\Bambivalence\b Behaviour resulting from two incompatible motivations, often taking the form of a mixture of the two motivational tendencies; displacement activity.
\Bambivorous\b Feeding on grasses and broadleaved plants; \Bambivore\b, \Bambivory. \b
\BAmblycipitidae\b Family of small freshwater catfishes (Siluriformes) found in fast-flowing rivers of India, Burma and Thailand; body slender, naked; dorsal fins short with weak spine; 4 pairs of barbels present; gas bladder partly enclosed by bony plates.
\BAmblyopsidae\b Cavefishes; family containing 6 species of small (to 100 mm) North American freshwater teleosts (Percopsiformes) found in cave systems or shallow coastal swamps; body slender, eyes and pigment absent in cave-dwelling forms; single dorsal fin present, pelvic fins reduced or absent; eggs brooded by female in spacious branchial chamber.
\BAmblypoda\b Order including a variety of large, primitive ungulates belonging to the suborders Pantodonta, Dinocerata, Xenungulata and Pyrotheria.
\BAmblypygi\b Tailless whip scorpions, whipspiders; order of predatory nocturnal terrestrial arthropods (Arachnida) found mainly in forest litter, in crevices, and beneath stones in tropical and subtropical regions; a few of the 70 species are cavernicolous; cephalothorax and abdomen joined by narrow waist; chelicerae with proximal fang, pedipalps spinose and raptorial, first pair of legs whip-like.
\BAmborellaceae\b Family of flowering plants containing a single species of evergreen shrub from New Caledonia; uniquely amongst the Laurales the wood has no vessels.
\Bambulatorial\b Adapted for walking.
\BAmbystomatidae\b Family containing about 30 species of mostly terrestrial, North American salamanders which have internal fertilization and lay eggs in ponds and streams; fore and hind limbs, and lungs present; larvae with long filamentous gills, sometimes neotenic; includes axolotl and mud salamanders.
\Bameiotic parthenogenesis\b \JParthenogenesis\j in which meiosis has been suppressed so that neither chromosome reduction nor any corresponding phenomenon occurs.
\Bamensalism\b An interspecific interaction in which one species population is inhibited, typically by toxin produced by the other, which is unaffected.
\Bametabolous\b Used of a pattern of development in which the offspring gradually assume adult characters through a series of moults; \Bametoecius\b; See also \Jmetoecious\j
\Bametoecious\b 1: Used of a parasite having only a single host during its life cycle. 2: Used of a parasite species that is highly host specific; \Bametoecius\b; See also \Jmetoecious\j
\Bamictic\b 1: Pertaining to females that produce unfertilized eggs that develop into offspring of one sex only. 2: Used of a lake that has no period of overturn because it is perennially frozen; See also \Jmictic\j
\BAmiidae\b Bowfin; primitive family of North American freshwater fishes found in still weedy backwaters; body with cycloid scales, mouth large with strong teeth; caudal fin heterocercal; gas bladder serves as accessory respiratory organ.
\BAmiiformes\b Order of primitive bony fishes (Osteichthyes) comprising a single extant family, the Amiidae.
\Bamino acid\b The basic structural component from which proteins are contructed; each comprising carboxylic acid and amino groups.
\Bamixis\b Absence or failure of interbreeding.
\Bammochthophilous\b Thriving on sand banks; \Bammochthophile\b, \Bammochthophily.\b
\Bammocoete\b Freshwater larval stage of a lamprey (Petromyzoniformes).
\Bammocolous\b Living or growing in sand; \Bammocole.\b
\BAmmodytidae\b Sand lances; family containing 12 species of bottom-dwelling marine teleost fishes (Perciformes) usually found in large schools over sandy sediments from low water to 150 m; body elongate, head pointed with lower jaw prolonged; teeth and pelvic fins absent.
\Bammonification\b The release of ammonia from nitrogenous organic material by the action of microorganisms.
\Bammonite\b \JAmmonoidea\j
\BAmmonoidea\b Ammonites; extinct subclass of cephalopod molluscs which typically possessed planispiral septate shells; siphuncle generally ventral; sutures often complex; comprised the largest subclass of cephalopods with over 160 families found extensively from the Devonian to the Upper Cretaceous.
\Bammophilous\b Thriving in sandy habitats; \Bammophile\b, \Bammophily.\b
\Bamnicolous\b Living on sandy river banks; \Bamnicole.\b
\BAmniota\b Vertebrate group comprising reptiles, birds and mammals characterized by the possession of extra embryonic membranes; See also \JAnamniota\j
\Bamoeba\b A single-celled eukaryotic organism that is naked and moves by means of pseudopodia; \JAmoebida\j
\BAmoebida\b Amoebae; order of protozoans (Gymnamoeba) which possess mitochondria but lack a flagellate phase; includes the amoeba and the entamoebae, which cause amoebic dysentry; subdivided into 5 suborders, Acanthopodina, Conopodina, Flabellina, Thecina and Tubulina, each of which is also treated as a class of the protoctistan phylum Rhizopoda.
\BAmoebidiales\b Order of trichomycete fungi containing two genera of freshwater symbiotic forms typically found in the rectum of crustaceans or larval insects but occasionally attached to external surface of host; once classified as protozoans as they lack both cellulose and chitin in their cell walls.
\Bamphiatlantic\b Occurring on both sides of the Atlantic Ocean.
\BAmphibia\b Class of quadruped vertebrates containing frogs, newts, salamanders, toads, caecilians and many fossil groups; skin glandular without epidermal scales, feathers or hairs; tail present primitively but lost in some groups; limbs or girdles reduced or absent in some forms; eggs anamniotic, primitively laid in water with external fertilization; tadpole larvae possess gills and open gill slits; ovoviviparity and viviparity exhibited by some species; contains a single extant subclass, Lissamphibia.
\Bamphibious\b Adapted to life on land as well as in water; \Bamphibian.\b
\Bamphiblastula\b Free-swimming larval stage of sponges, possessing some external flagellate cells.
\Bamphicarpogean\b Producing fruits above ground that are subsequently buried; \Bamphicarpogenous\b; See also \Jhypocarpogean\j
\Bamphichromatism\b The occurrence of different coloured flowers on individual plants in different seasons; \Bamphichromatic.\b
\Bamphicryptophyte\b A marsh plant with amphibious vegetative parts.
\BAmphidiscophora\b Subclass of hexactinellid sponges which are rooted to the substratum by a basal tuft of anchoring spicules.
\Bamphigamy\b Normal cross fertilization; the fusion of male and female gametes.
\Bamphigean\b Used of a plant having underground as well as aerial flowers.
\Bamphigenesis\b Sexual development; the fusion of two dissimilar gametes.
\Bamphigony\b Sexual reproduction involving cross fertilization.
\BAmphiliidae\b Family containing about 50 species of small freshwater catfishes (Siluriformes) found in fast-flowing streams of Africa; body flattened ventrally, sometimes with bony armature; mouth suctorial with 2-3 pairs of barbels.
\BAmphilinidea\b Order of cestodarian tapeworms found in turtles and fishes; typically with a flattened, elongate body and an indistinct anterior holdfast; uterine pore positioned near anterior end of body.
\Bamphimixis\b True sexual reproduction; the union of male and female gametes; may be either autogamy (inbreeding) or allogamy (outbreeding); \Bamphimict\b, \Bamphimictic.\b
\BAmphineura\b Class of elongate, bilaterally symmetrical molluscs that lack eyes and tentacles; shell, if present, consisting of 7 or 8 overlapping calcareous plates on the dorsal surface; head poorly differentiated; posterior mantle cavity contains anus and gills; comprises the subclasses Polyplacophora and Aplacophora, which are usually treated as separate classes.
\BAmphinomida\b Fireworms; order of errant polychaete worms containing about 165 species; pharynx cylindrical, eversible, unarmed; parapodia biramous with simple setae; cirri and branchiae present.
\Bamphioecious\b Used of a population or species showing broad variable tolerance of habitat and environmental conditions; see also \Jeuryoecious\j \Jstenoecious\j
\BAmphionidacea\b Order of eucaridan crustaceans comprising a single planktonic species found in open oceans to a depth of about 1700 m; body shrimp-like with a brood pouch, one pair of maxillipeds, and reduced thoracic legs and gills; feeding limbs and gut non-functional in the adult female.
\Bamphioxus\b \JCephalochordata\j
\Bamphiphyte\b A plant able to live either rooted in damp soil above the water level or completely submerged.
\BAmphipoda\b Sandhoppers; order of usually small peracaridan crustaceans found primarily free-living in aquatic habitats from freshwater to marine, although some are semiterrestrial or parasitic; body usually laterally compressed, occasionally linear or globular; comprises about 6000 species in 4 suborders: Gammaridea (sandhoppers, scuds, beach fleas), Hyperiidea (marine pelagic forms), Caprellidea (skeleton shrimps, whale lice) and Ingolfiellidea (hypogean forms).
\BAmphisbaenia\b Worm lizards; suborder of small, limbless, fossorial reptiles (Squamata) most widely distributed in Africa and South America; body annulated, eyes concealed, external ear openings absent; contains about 135 species in 2 families; may be oviparous or ovoviviparous.
\BAmphisbaenidae\b Family of burrowing worm lizards (Amphisbaenia) found mainly in tropical and subtropical America and Africa but also in southwestern Asia and the Iberian Peninsula; contains about 130 species, most feeding on soil arthropods; with small wedgeshaped head used for digging.
\Bamphistylic\b The condition in which both the hyomandibular and the palatoquadrate arch are involved in the suspension of the lower jaw in fishes; see also \Jautostylic\j, \Jholostylic\j, \Jhyostylic\j
\Bamphitoky\b Parthenogenesis in which both male and female offspring are produced.
\Bamphitopic\b Used of a population or species showing broad, variable tolerance of habitat and environmental conditions; see also \Jeurytopic\j \Jstenotopic\j
\Bamphitrophic\b Used of an organism that lives as a phototroph during daylight and as a chemotroph in darkness; \Bamphitroph.\b
\BAmphiumidae\b Family containing 3 species of eel-like salamanders (Caudata) from southeastern United States; fore- and hindlimbs greatly reduced, lungs and a single pair of gill slits (spiracles) present; fertilization internal; egg strings laid on mud, guarded by female.
\Bamphogenic\b Producing male and female offspring in approximately equal numbers; \Bamphogenous\b, \Bamphogeny\b; see also \Jallelogenic\j \Jarrhenogenic\j, \Jmonogenic\j, \Jthelygenic\j
\BAmphycyonidae\b Dog-bears; extinct family of large, heavily built dog-like carnivores found in northern hemisphere during the Oligocene.
\Bamplectant\b Clasping or twining for support.
\Bamplexus\b Precopulation pairing; the grasping of the female by the male prior to copulation.
\Bamplitude\b The range of tolerance to environmental conditions of an organism or species; ecological amplitude.
\BAmpulicidae\b Digger wasps; family containing about 160 species of primitive hunting wasps found mainly in the tropics; antennae inserted low on face; females hunt and paralyse cockroaches with their stings, using them to provision their nests.
\BAmynodontidae\b Extinct family of rhinoceroslike mammals (Ceratomorpha) known from the Eocene to the Miocene; similar to the hippopotamus in size and shape and probably also lived in rivers.
\BAnabantidae\b Climbing gouramis; family containing 40 species of freshwater perciform teleost fishes found in Africa, India and Indonesia which can walk on land using the spiny margins of gill opercula; able to utilize atmospheric oxygen through an accessory respiratory structure, the suprabranchial organ.
\BAnabantoidei\b Gouramis; suborder of freshwater perciform teleosts comprising about 70 species in 4 families found in Africa, India and southeast Asia.
\Banabiosis\b A state of greatly reduced metabolic activity assumed during unfavourable environmental conditions; \Banabiotic.\b
\BAnablepidae\b Four-eyed fishes; family containing 3 species of surface-living insectivorous nocturnal fresh and brackish water cyprinodontiform teleosts from Central and South America; anal fin of male modified as gonopodium for sperm transfer; eyes highly specialized for simultaneous aerial and aquatic vision with 2 pupils and a divided retina.
\Banabolism\b That part of metabolism involving the manufacture of complex substances from simpler substrates with the consequent utilization of energy; \Banabolic\b; See also \Jcatabolism\j
\BAnacanthobatidae\b Family of deep-water rajiform fishes containing about 15 species; body shape subcircular to rhomboidal; snout long and pointed; tail slender; dorsal fins absent.
\BAnacardiaceae\b Poison ivy, poison oak, sumach, smoke tree, mango, pistachio and cashew nut; family of Sapindales containing about 600 species of woody plants often producing allergenic reactions, or poisonous to the touch; often producing waxy or oily seeds; widespread in tropical regions; flowers small and regular, with 3-5 sepals and petals, 3-10 stamens; the fruit is commonly a drupe.
\Banachoric\b Living in fissures, holes and crevices; \Banachoresis.\b
\Banaclinotropism\b A tropism resulting in growth or movement in a horizontal plane; \Banaclinotropic.\b
\Banaconda\b \JBoidae\j
\Banadromous\b Migrating from salt to fresh water, as in the case of a fish moving from the sea into a river to spawn; \Banadromy\b; see also \Jcatadromous\j \Joceanodromous\j, \Jpotamodromous\j
\Banaerobic\b 1: Growing or occurring in the absence of molecular oxygen; \Banaerobe\b, \Banaerobiosis\b; See also \Jaerobic\j. 2: Used of an environment in which the partial pressure of oxygen is significantly below normal atmospheric levels; deoxygenated.
\Banaerobiotic\b Used of habitats devoid of, or significantly depleted in, molecular oxygen; \Banaerobiosis.\b
\Banaerogenic\b Not producing gas; used of microorganisms that do not produce visible gas during the breakdown of carbohydrate; See also \Jaerogenic\j
\Banalogous\b 1: Pertaining to similarity of function, structure or behaviour due to convergent evolution rather than to common ancestry; \Banalogue\b, \Banalogy\b; See also \Jhomologous\j. 2: Used of organisms having similar habitats or distributions.
\BAnamniota\b Vertebrate group comprising the lower classes (fishes and amphibians) that lack complex extraembryonic membranes and have only a trilaminate yolk sac; See also \JAmniota\j
\BAnamorpha\b Subclass of chilopods in which young hatch from egg with only 7 pairs of legs and pass through several moult stages at which trunk segments and limbs are added; adult with 19 trunk segments and 15 pairs of legs; eggs laid singly and not brooded; comprises 2 orders, Scutigerida and Lithobiida.
\Banaplasia\b 1: The progressive phase in the development of an organism, prior to attaining maturity. 2: An evolutionary state characterized by increasing vigour and diversification of organisms; \Banaplasis\b; see also \Jcataplasia\j \Jmetaplasia\j
\BAnapsida\b Subclass of Reptilia containing a single living order, Testudines (turtles and tortoises); characterized by a skull which lacks apertures in the temple regions behind the eyes.
\BAnaptomorphidae\b Extinct family of tarsier-like primates (Prosimii) with large eyes and a short face; olfactory regions of brain better developed than modern tarsiers; found in Europe and America from the Palaeocene to the Oligocene.
\BAnarhichatidae\b Wolffishes; family containing 7 species of bottom-living marine blennioid teleosts (Perciformes), found at moderate depths in the North Pacific and Atlantic; body elongate, to 2.5 m, scales present or absent; dorsal fin spinose, pelvics absent, pectorals well developed.
\BAnaspidacea\b Order containing about 15 species of freshwater syncaridan crustaceans found in surface and subterranean waters of the southern hemisphere (Australia, New Zealand and southern Africa).
\BAnaspidea\b Sea hares; order of herbivorous opisthobranch molluscs typically found on seaweed in shallow waters; with a small, more or less internal shell and ear-shaped rhinophores on the head; sometimes producing coloured ink which can be expelled from the mantle cavity.
\BAnaspidiformes\b Extinct order of jawless, fishlike vertebrates (Cephalaspidimorphi); body fusiform, with hypocercal tail and up to 15 pairs of external gill openings; known from the Silurian and Devonian.
\Banastomosis\b The union of branches to form a network.
\Banathermal\b Pertaining to a period of rising temperature; See also \Jcatathermal\j
\BAnathermal period\b A postglacial interval (\Ic.\i 10000-7500 years B.P.) characterized by rising temperatures following the last glaciation; see also \JAltithermal period\j \JMedithermal period\j
\BAnatidae\b Ducks, geese, swans; diverse family containing about 145 species of small to large water birds (Anseriformes), cosmopolitan in freshwater and coastal marine habitats; feed on wide variety of plants and animals; most are monogamous and solitary during breeding; nest on ground or in trees; some important as game or domesticated birds.
\Banatomical\b Pertaining to the structure of organisms, especially as revealed by dissection; \Banatomy.\b
\Banatropism\b The inversion of a seed or ovule so that the micropyle is bent downwards; \Banatropic.\b
\Banautogenous\b Used of a female insect that must feed before it can produce mature eggs; See also \Jautogenous\j
\Bancestor\b A progenitor of a more recent descendent taxon, group or individual; any preceding member of a lineage; \Bancestral.\b
\Bancestrula\b Primary zooid from which a bryozoan colony is formed by budding.
\Banchialine\b Maritime; used of coastal salt-water habitats having no surface connection to the sea.
\Banchor plant\b \JRhamnaceae\j
\Banchovy\b \JEngraulidae\j
\Banchusa\b \JBoraginaceae\j
\BAncistrocladaceae\b Small family of Violales containing about 20 species of shrubs climbing by hooked or twining branch tips, native to tropical Africa and Asia.
\Bancocolous\b Living in canyons; \Bancocole.\b
\Bancophilous\b Thriving in canyon forests; \Bancophil\b, \Bancophily.\b
\BAncylopoda\b Chalicotheres; extinct suborder of Holarctic horse-like mammals (Perissodactyla) known from the Eocene to Pleistocene; possessed 3 toes which probably bore claws rather than hooves; long forelimbs possibly used for digging up roots.
\BAndreaeopsida\b Granite mosses; small class of ancient bryophytes distributed worldwide but most abundant on rocky substrates in polar or cold temperate regions; characterized by the dehiscence of the spore capsule along longitudinal slits and by the small dark coloured, epilithic, tufted or cushion-like growth form of the gametophyte.
\BAndrenidae\b Family containing over 4000 species of generalized, soil- nesting bees (Hymenoptera) which produce a wax-like lining to nest cells; feeding on nectar and pollen as both adults and larvae.
\Bandric\b Male; See also \Jgynic\j
\Bandrochorous\b Dispersed by the agency of man; \Bandrochore\b, \Bandrochory.\b
\Bandrocyclic parthenogenesis\b Reproduction in which a series of parthenogenetic generations is followed by the production, by a portion of the population only, of males as a sexual generation See also \Jparthenogenesis\j
\Bandrodioecious\b Used of plant species having male and hermaphrodite flowers on separate plants; \Bandrodioecy\b; See also \Jgynodioecious\j
\Bandroecious\b Used of a plant having male flowers only; See also \Jgynoecious\j
\Bandroecium\b The male component of the flower, typically comprising a whorl of stamens surrounding the female component (gynoecium).
\Bandrogamy\b The impregnation of the male gamete by the female gamete.
\Bandrogenesis\b Male parthenogenesis; the development of an egg carrying paternal chromosomes only (patrogenesis) or the production of a haploid plant by the germination of a pollen grain within an anther; \Bandrogenetic\b; See also \Jgynogenesis\j
\Bandrogynous\b Producing male offspring only; See also \Jgynogenous\j
\Bandrogynous\b Having both male and female reproductive organs; hermaphrodite; \Bandrogyne\b, \Bandrogynism.\b
\Bandromonoecious\b Having male and hermaphrodite flowers on the same plant; See also \Jgynomonoecious\j
\Bandromorphic\b Having a morphological resemblance to males; \Bandromorphy\b; See also \Jgynomorphic\j
\Bandrophilous\b Thriving in proximity to man; \Bandrophile\b, \Bandrogynism.\b
\Bandrosome\b Any chromosome found only in a male nucleus.
\Bandrospore\b 1: A male spore; pollen grain. 2: An asexual zoospore giving rise to a dwarf male plant.
\Banebous\b Prepubertal; immature.
\Banecdysis\b The absence of moulting, or a prolonged intermoult period.
\Banemochorous\b Having seeds, spores or other propagules dispersed by wind; \Banemochore\b, \Bamenochory.\b
\Banemone\b \JRanunculaceae\j
\Banemoneuston\b Terrigenous organic and inorganic material transported by wind to the surface of water bodies.
\Banemophilous\b 1: Dispersed by wind. 2: Pollinated by wind-blown pollen; \Banemophile\b, \Banemophoby.\b 3: Thriving in sand draws.
\Banemophobic\b Intolerant of exposure to wind; \Banemophobe\b, \Banemophoby.\b
\Banemophyte\b 1: A plant occurring in windswept situations. 2: A plant fertilized by wind-blown pollen.
\Banemotaxis\b A directed reaction of a motile organism towards (positive) or away from (negative) wind or air currents; \Banemotactic.\b
\Banemotropism\b Orientation response to an air current; \Banemotropic.\b
\Baneuploid\b Having a chromosome number that is more or less than, but not an exact multiple of (euploid), the basic chromosome number.
\BAngara\b A continental landmass comprising most of central and northern Asia, formed from \JEurasia\jafter the break up of \JPangaea\j; see also \JCathaysia\j \JEuramerica\j
\Bangel shark\b \JSquatinidae\j
\Bangelfish\b \JChaetodontidae\j
\BAngiospermae\b Flowering plants; the major division of seed plants (Spermatophyta); characterized by the production of seeds fully enclosed within fruits; commonly known as the \JMagnoliophyta\j
\BAnglian glaciation\b A glaciation of the Quaternary Ice \JAge\j in the British Isles with an estimated duration of 90 thousand years; Lowestoft glaciation.
\Bangonekton\b Short-lived organisms inhabiting temporary pools on rocks, in tree stumps and similar sites.
\BAnguidae\b Slow worms; family containing about 75 species of terrestrial and arboreal lizards (Sauria) widely distributed in the Americas, Europe, North Africa and southern Asia; limbs well developed to absent; feeding on invertebrates and small vertebrates; tongue forked; eyelids mobile; tail autotomous; reproduction either oviparous or ovoviviparous.
\BAnguillidae\b Freshwater eels; family containing 16 species of small (to 1 m) anguilliform teleost fishes found in North Atlantic, Indian and western Pacific Oceans and adjoining freshwater systems; body cylindrical; dorsal, caudal and anal fins continuous, pectorals well developed; most species migrating to sea to spawn, the leptocephalus larval stage lasting up to 3 years; important in commercial fisheries.
\BAnguilliformes\b Order of mostly marine, eellike, teleost fishes in which the pelvic fins and girdle are absent; body smooth or bearing simple cycloid scales; development includes leptocephalus larval stage; contains 2 suborders, Anguilloidei (freshwater, spaghetti, snipe, moray, conger, cutthroat, arrowtooth, pike conger, duckbill, snake, worm, and longneck eels) and Saccopharyngoidei (deep-sea gulper eels).
\Banheliophilous\b Thriving in diffuse sunlight; \Banheliophile\b, \Banheliophily.\b
\BAnhimidae\b Screamers; family containing 3 species of South American water birds (Anseriformes) found in marshes or wet grasslands; long-legged, short-necked; wings broad with a spur on leading edge; feed on plants; nest on ground near water.
\BAnhingidae\b Anhingas, darters; small family of fish-eating aquatic birds (Pelecaniformes), cosmopolitan in tropical and warm temperate wooded lakes, swamps and rivers; feeding by diving from water surface, spearing fishes with long bill; nest in colonies in trees.
\Banholocyclic parthenogenesis\b Reproduction by parthenogenesis alone, as when the sexual reproduction phase has been lost from an alternation of generations cycle; See also \Jparthenogenesis\j
\Banhydrobiosis\b Dormancy induced by low humidity or by desiccation; \Banhydrobiose.\b
\BAniliidae\b Pipe snakes; family containing 10 species of subterranean snakes (Serpentes) from South America and southeast Asia; eyes small, not covered by scales; belly scales enlarged; often treated as part of the Typhlopidae \Iq.v\i.
\Banimal\b Any member of the kingdom Animalia.
\Banimalcule\b An archaic term for any microscopic organism.
\Banimalculism\b The belief that the embryo was contained within the sperm cell.
\BAnimalia\b Kingdom comprising all multicellular eukaryotic organisms exhibiting holozoic nutrition and having capacity for spontaneous movement and rapid motor response to stimulation.
\Banise\b \JApiaceae\j
\Banisogametic\b Producing gametes of dissimilar size, shape or behaviour; See also \Jisogametic\j
\Banisogamy\b The fusion of gametes of dissimilar size, shape or behaviour; See also \Jisogamy\j
\Banisomorphic\b Differing in shape or size; \Banisomorphy.\b
\BAnisophylleaceae\b Small family of Rosales containing about 40 species of trees or shrubs from tropical forests.
\Banisoploidy\b The condition of having an odd number of chromosome sets in somatic cells; \Banisoploid.\b
\BAnisoptera\b Dragonflies; suborder of active predatory insects (Odonata) in which the long slender wings are held horizontal at rest; larvae aquatic, body typically broad with depressed abdomen and rectal gills.
\BAnisozygoptera\b Small suborder of paleopterous insects (Odonata), comprising a single family and genus, exhibiting transitional characters between damselflies (Zygoptera) and dragonflies (Anisoptera).
\BAnkylosauria\b Ankylosaurs; a group of dinosaurs having body heavily armoured with bony plates; head small, teeth reduced and sometimes absent; known from the Cretaceous.
\Banlage\b A rudiment or primordium from which a given organ or structure develops during ontogeny.
\BAnnelida\b Ringed worms; phylum of bilaterally symmetrical coelomate worms comprising 3 classes, Polychaeta (bristleworms), Oligochaeta (earthworms, pot worms, sludge worms) and Hirudinoidea (leeches); body divided into cylindrical rings (segments) with serially arranged organs; segments may have lateral lobes (parapodia) bearing variety of chaetae and bristles.
\BAnniellidae\b Small family of limbless, burrowing lizards (Sauria) from California, containing 2 species; body length 250 mm; reproduction viviparous.
\BAnnonaceae\b Pawpaw, custard apple; largest family of the order Magnoliales, containing about 2300 species found mostly in the tropics; flowers often fragrant, each with 3 sepals, 6 petals and many stamens, carpels superior; fruits typically fleshy.
\Bannotinous\b Used of growth added during the previous year; one year old.
\Bannual\b Having a yearly periodicity; living for one year; see also \Jbiennial\j \Jperennial\j
\Bannual turnover\b The total biomass produced in one year.
\BAnobiidae\b Furniture beetles, death-watch beetle, woodworm; family of small brown beetles (Coleoptera) in which the head is hooded by the pronotum; typically feeding on dead wood; contains about 1600 species distributed worldwide; larvae C-shaped, white and fleshy with tiny legs; bore into wood and bark; adults emerge from wood leaving typical woodworm holes.
\BAnocheta\b Superorder of helminthomorphan diplopods (millipedes) comprising a single order, Spirobolida.
\Banoestrus\b A non-breeding period; \Banoestrous\b; see also \Jdioestrus\j \Jmonoestrous\j, \Jpolyoestrous\j
\BAnomalepidae\b Family containing 20 species of small (to 300 mm) worm-like, insectivorous, burrowing snakes (Serpentes) from tropical American rainforests.
\BAnomalodesmata\b Subclass of marine bivalve molluscs comprising about 500 species, which may be infaunal, burrowing, nestling or attached in habit; commonly found in the deep sea.
\BAnomalopidae\b Lanterneye; family of small (to 250 mm) pelagic beryciform teleost fishes, containing 4 species characterized by a well developed light organ associated with the orbit of each eye, apparently used for communication.
\BAnomaluridae\b Scaly-tailed squirrels; family containing 7 species of small arboreal mammals (Rodentia) found in tropical and subtropical forests of Ethiopian Region; tail long, hairy with characteristic patch of scales near its base; gliding membranes present between fore- and hindlimbs; feed on fruit, seeds and other plant material.
\BAnomura\b Hermit crabs, squat lobsters; infraorder of pleocyematan decapod crustacens; body crab-like or lobster-like, abdomen extended, bent upon itself or flexed beneath thorax; last thoracic sternite free; some species utilize empty gastropod shells as portable refuges.
\BAnopla\b Class of nemerteans characterized by the possession of a separate mouth and proboscis pore; comprising 2 orders, Heteronemertea and Palaeonemertea.
\BAnoplogastridae\b Fangtooth; family of small mesopelagic beryciform teleost fishes with a deep body which is robust anteriorly, compressed posteriorly; teeth very large and fang-like.
\BAnoplopomatidae\b Sablefish, skilfish; family containing 2 species of bottom-living temperate North Pacific marine scorpaeniform teleosts widespread from shallow water to 1500 m.
\BAnoplura\b Sucking lice; order of small (0.5-4.0 mm) wingless hemipterodean insects that live exclusively as ectoparasites of placental mammals; mouthparts specialized for piercing and sucking; abdomen distensible; legs robust, modified for attachment; eggs usually cemented to body hair; contains about 500 species, including the human body louse, \IPediculus\i.
\BAnostomidae\b Leporins, headstanders; family of small colourful South and Central American freshwater characiform teleost fishes; body elongate; dorsal fin anterior to mid-body; contains about 100 species, some of which adopt an oblique, head down posture (headstanders); popular amongst aquarists.
\BAnostraca\b Fairy shrimps; order of sarsostracan crustaceans containing about 180 species of suspension feeders distributed worldwide in ephemeral inland saline or freshwater bodies; characterized by an elongate body with up to 19 pairs of foliaceous limbs; includes the brine shrimp, \IArtemia salina\i.
\BAnotopteridae\b Daggertooth, javelinfish; monotypic family of large (to 1 m) predatory myctophiform teleost fishes found in temperate and subtropical seas to 300 m depth; body very long and slender, naked; jaws strong, bearing large dagger-like teeth; dorsal fin and photophores absent.
\Banoxic\b Used of a habitat devoid of molecular oxygen; \Banoxicity\b; see also \Jnormoxic\j \Joligoxic\j
\BAnseriformes\b Diverse order of water birds comprising 2 families, Anhimidae (screamers) and Anatidae (ducks, geese and swans).
\Bant\b \JFormicidae\j (Apocrita, Aculeata).
\Bant lion\b \JMyrmeleontidae\j (Neuroptera).
\BAntarctic Circumpolar Current\b A major cold surface current that flows eastwards through the Southern Ocean producing a circumglobal antarctic circulation; West Wind Drift; see ocean currents.
\Bantarctic cod\b \JNototheniidae\j
\BAntarctic convergence\b That region of the oceans of the southern hemisphere (at about 50░to 60░S) where cold antarctic surface water moving northeast meets and sinks below warmer water moving southeast.
\BAntarctic divergence\b The region of extensive upwelling close to Antarctica where water from intermediate depths replaces surface water drifting northeast in the Antarctic Circumpolar Current.
\BAntarctic kingdom\b One of the six major phytogeographical areas characterized by floristic composition; comprising New Zealand region, Patagonian region and South Temperate Oceanic island region.
\BAntarctogaea\b The Australian zoogeographical region, excluding New Zealand and Polynesia.
\Bantbird\b \JFormicariidae\j
\Banteater\b \JMyrmecophagidae\j
\Bantelope\b \JBovidae\j
\Bantenatal\b Before birth; during gestation.
\BAntennariidae\b Frogfishes; family containing about 60 species of voracious piscivorous anglerfishes (Lophiiformes) found on rocky substrates or amongst floating weed in shallow tropical and subtropical waters; body swollen, naked or warty, length to 350 mm; mouth oblique to vertical, teeth villiform, pectoral fin robust with elbow-like joint.
\Bantennation\b The act of touching or probing with antennae.
\Bantepisematic\b Pertaining to a character or trait aiding recognition and which implies a threat; See also \Jepisematic\j
\Banthecology\b The study of pollination and the relationships between insects and flowers.
\Banther\b The apical part of a stamen which produces the pollen or microspores.
\Bantheridium\b The male sex organ of the lower plants, usually producing numerous motile, flagellate gametes (antherozoids).
\Banthesis\b The period of flowering; the time at which flower buds open; the period of maximum physiological activity in plants.
\Banthesmotaxis\b The organization and arrangement of the parts of a flower.
\BAnthocerotales\b \JAnthocerotopsida\j; the hornworts treated as an order of the class Hepaticae.
\BAnthocerotopsida\b Hornworts; a class of bryophytes containing a single family of prostrate thalloid plants which may have lobate or membranous margins but lack leaves and ventral scales; rhizoids smooth; sporophyte consists of a bulbous foot, a persistent meristematic zone and a capsule which releases spores by dehiscence.
\BAnthocyathea\b Irregulares; extinct class of mostly solitary invertebrates (Archaeocyatha) known from the Cambrian; conical cup often irregular in outline, commonly with 2 porous walls.
\Banthogenesis\b The production of male and female offspring by asexual forms.
\BAnthomedusae\b Suborder of predominantly marine cnidarians (Hydroida) in which the polyps are typically colonial with a horny rather than calcareous exoskeleton; free medusae tall and bell-shaped with gonads usually on the stomach.
\Banthophilous\b Attracted to, or feeding on, flowers; \Banthophile\b, \Banthophily. \b
\BAnthophoridae\b Carpenter bees; large, diverse family containing over 4000 species of long-lived bees (Hymenoptera) which exhibit solitary, communal and primitive social behaviour; typically nesting in hollow stems or wood; producing unlined nest cells.
\BAnthophyta\b Magnoliophyta; flowering plants.
\Banthoptosis\b The fall of flowers.
\Banthotaxis\b The arrangement of the parts of a flower; \Banthotaxy.\b
\Banthotropism\b An orientation response of a flower to a stimulus; \Banthotropic\b
\BAnthozoa\b Class of marine Cnidaria in which the medusa stage is absent and the polyp reproduces sexually as well as asexually; polyp solitary or colonial and typically benthic; polyp usually cylindrical containing a gastrovascular cavity divided longitudinally by radially arranged mesenteries; dispersal is commonly by means of planula larvae; comprises 3 subclasses, Alcyonaria, Ceriantipatharia and Zoantharia.
\Banthracobiontic\b Living or growing on a burned or scorched substratum.
\BAnthracotheriidae\b Extinct family of large pig-like mammals (Artiodactyla) known from the Eocene to the Pleistocene; possibly amphibious in habit; may have been ancestral to the hippopotamuses.
\Banthrageny\b The decomposition of plant material to form peat.
\BAnthribidae\b Coffee-bean weevil; family of beetles (Coleoptera) which are usually covered in a pattern of dark-coloured or white scales or flattened hairs; contains about 2600 species feeding on seeds, fungi, as predators or on crops of economic importance.
\Banthropic\b Pertaining to the influence of man; \Banthropical.\b
\Banthropocentric\b Interpreting the activities of other organisms in relation to human values; \Banthropocentrism.\b
\Banthropochorous\b Having propagules dispersed by the agency of man; \Banthropochore\b, \Banthropochoric\b, \Banthropochory.\b
\Banthropogenesis\b The descent of man; the origin (phylogeny) and the development (ontogeny) of man.
\Banthropogenic\b Caused or produced through the agency of man; \Banthropogenous.\b
\BAnthropoidea\b Anthropoid apes; suborder of primates comprising the monkeys, apes and man; brain large; face mobile with forward-facing eyes, external ears small, lower incisors vertical; one pair of pectoral mammae present; digits usually with nails rather than claws; social behaviour often highly developed.
\Banthropology\b The study of man; \Banthropological.\b
\Banthropophilous\b 1: Thriving in close proximity to man; \Banthropophile\b, \Banthropophily.\b 2: Used of biting or blood-sucking insects that feed on man; \Banthropophilic. \b
\BAnthropozoic\b Geological time since the appearance of man.
\BAnthuridea\b Small order of isopod crustaceans with slender, elongate bodies.
\Bantibiosis\b The antagonistic association between two organisms in which one species adversely affects the other, often by production of a toxin; \Bantibiotic.\b
\Bantibody\b An immunoglobulin serum protein that binds to a specific antigen.
\Bantiboreal\b Pertaining to cool or cold temperate regions of the southern hemisphere; See also \Jboreal\j
\Banticryptic\b Used of protective coloration facilitating attack or capture of prey; See also \Jprocryptic\j
\Banticyclonic\b Used of a region of high atmospheric pressure at sea level; also used of a wind system around such a high pressure centre that has a clockwise rotation in the northern hemisphere or an anticlockwise motion in the southern hemisphere; \Banticyclone\b; See also \Jcyclonic\j
\Bantigen\b A substance which induces formation of antibodies.
\Bantigenic\b 1: Having the properties of an antigen; \Bantigenicity.\b 2: Exhibiting sexual dimorphism.
\BAntilles Current\b A warm surface ocean current that flows north in the western North Atlantic forming the westerly limb of the North Atlantic Gyre; see ocean currents.
\BAntilocapridae\b Pronghorn; monotypic family of antelopes (Artiodactyla: Ruminantia) found in open arid habitats of the western Nearctic region; characterized by an unbranched, permanent horn core with the horn sheath branched and shed annually.
\BAntipatharia\b Black corals, thorny corals; order of colonial ceriantipatharians found mainly in deeper waters in the tropics and subtropics; characterized by an erect branching form with a dark coloured, horny axial skeleton and small, hardly contractile polyps typically possessing 6 tentacles.
\Bantiphyte\b That generation of a plant showing alternation of generations in which the gametes are produced.
\Bantirrhinum\b \JScrophulariaceae\j
\Bantithetic\b Used of a life cycle exhibiting either an alternation of haploid and diploid generations or an alternation of morphologically dissimilar generations.
\Bantitropism\b The orientation of growth in a plant so that it twines in the opposite direction from that followed by the sun across the sky; \Bantitropic\b; See also \Jeutropism\j
\Bantizoea\b Early free-swimming larval stage of some stomatopods, possessing uniramous antennules and 5 pairs of biramous thoracic limbs, but lacking pleopods.
\BAnura\b Frogs and toads; large and diverse order of Amphibia comprising almost 3000 species in 23 families; body length to 400 mm, tail absent, hind-limbs enlarged for jumping; habitats terrestrial and aquatic, including arboreal and fossorial forms; eggs and larvae (tadpoles) typically aquatic, but reproductive strategies variable, including ovoviviparity and viviparity.
\Bapandrous\b Lacking, or having non-functional, male reproductive organs; \Bapandry.\b
\Bapatetic coloration\b A misleading coloration pattern, such as coloration resembling physical features of the habitat; camouflage.
\Bape\b \JPongidae\j
\Baperiodicity\b The irregular occurrence of a phenomenon; \Baperiodic.\b
\BAphaniptera\b Older name for the Siphonaptera (fleas).
\Baphaptotropic\b Not influenced by, or responsive to, a touch or contact stimulus; \Baphaptotropism.\b
\BAphelenchida\b Order of diplogasterian nematodes containing a variety of predators, fungal feeders, and parasites of higher plants and insects; often classified as a suborder of the Tylenchida.
\Bapheliotropism\b An orientation response away from sunlight; negative heliotropism; \Bapheliotropic.\b
\Baphercotropism\b An orientation response resulting in a turning away from an obstruction; \Baphercotropic.\b
\Baphid\b \JAphididae\j
\Baphidicolous\b Living amongst aggregations of aphids; \Baphidicole.\b
\BAphididae\b Aphids, blackflies, greenflies; family of over 3500 species of pear-shaped, soft-bodied insects (Homoptera) which move slowly over their host plants sucking juices and injecting toxic saliva; typically excreting honeydew or secreting wax for protection; life cycles complex, commonly involving both parthenogenetic and bisexual reproduction; includes many pests of agricultural plants.
\Baphidivorous\b Feeding on aphids; \Baphidivore\b, \Baphidivory.\b
\Baphotic\b Used of an environment or habitat having no sunlight of biologically significant intensity.
\Baphototaxis\b 1: The absence of a directed response to a light stimulus in a motile organism; \Baphototactic.\b 2: Negative \Jphototaxis\j
\Baphototropism\b 1: An orientation response away from light; negative phototropism; \Baphototrophic.\b 2: The absence of an orientation response to light.
\BAphragmophora\b Cosmopolitan order of pelagic chaetognaths characterized by the absence of ventral musculature; contains about 45 species in 3 families.
\BAphredoderidae\b Pirate perch; family of small (to 130 mm), nocturnal, eastern North American freshwater teleost fishes (Percopsiformes) inhabiting well vegetated lowland lakes and ponds; body compressed with single tall dorsal fin and rounded caudal fin; vent located near the throat in adults.
\Baphydrotaxis\b 1: The directed reaction of a motile organism away from moisture; \Baphydrotactic.\b 2: The absence of a directed response to moisture in a motile organism.
\BAphytic\b The period of geological time before the appearance of plant life; see also \JArchaeophytic\j \JCaenophytic\j, \JEophytic\j, \JMesophytic\j, \JPalaeophytic\j
\BApiaceae\b Umbels, anise, dill, celery, caraway, carrot, coriander, fennel, parsley, hemlock, parsnip, sea holly, samphire; large, nearly cosmopolitan family containing 3000 species of aromatic, often poisonous herbs, shrubs and trees with flowers typically small and borne in compound umbels; individual flowers are regular and bisexual, and commonly have 5 very small sepals, 5 petals and stamens and an inferior ovary; formerly known as the Umbelliferae.
\BApiales\b Order of Rosidae containing 2 families, Apiaceae and Araliaceae, of woody plants and herbs; Umbellales.
\BApicomplexa\b Phylum of parasitic protozoans characterized by the presence, at one end, of a complex of microtubules, club-shaped rhoptries, polar rings and other structures; parasitic in invertebrates and vertebrates, often intracellular, causing various diseases including malaria; only the male gametes are flagellate; consists of 2 classes, Perkinsea and Sporozoa; also classified as a phylum of Protoctista.
\BApidae\b Cosmopolitan family of hymenopteran insects containing the majority of eusocial bees in 3 well circumscribed subfamilies, Bombinae (orchid bees, bumblebees), Meliponinae (stingless bees), Apinae (honeybees); all construct nests with wax or resin cells, mostly within naturally occurring cavities; none excavates burrows; contains almost 1000 species, many extremely important as pollinators of crop plants.
\Bapivorous\b Feeding on bees; \Bapivore\b, \Bapivory.\b
\BAplacophora\b Alternative name for the \JSolenogastres\j and Caudofoucata (\JMollusca\j), treated as subclass of the class Amphineura.
\Baplanogamete\b A non-motile gamete; See also \Jplanogamete\j
\Baplanetic\b Having non-motile spores; \Baplanetism.\b
\BAploactinidae\b Velvetfishes; family containing 30 species of mostly small western Pacific coastal marine scorpaeniform teleosts; body compressed, covered with spines or prickles; head bearing large blunt spines or papillae.
\BAplochitonidae\b Family containing 4 species of small (to 300 mm), mostly anadromous, fresh-and brackish-water salmoniform teleost fishes from southern South America and southeastern Australia; body elongate, terete, scales sometimes absent; jaw teeth small or absent; adipose fin present.
\BAplodactylidae\b Family containing 5 species of shallow marine perciform teleost fishes, resembling hawkfishes and morwongs, found primarily in the southern hemisphere around Australia and New Zealand; jaw teeth flattened and recurved for feeding on algae.
\BAplodontidae\b Mountain beaver; monotypic family of burrowing rodents (Sciuromorpha) found in the Rocky Mountains; body heavy, limbs and tail short, claws large.
\BAplousobranchia\b Order of colonial tunicates (Ascidiacea) having a simple branchial sac lacking internal longitudinal folding, and goinad located in loop of intestine; individual zooids small, 1-25 mm in length; colonies formed by various types of budding; zooids may have separate tunics or a common tunic may envelop entire colony.
\BApocrita\b Bees, wasps, ants; suborder containing about 125 000 species of hymenopteran insects, which have a narrow waist between first and second abdominal segments; ovipositor modified as sting in some species; the larvae are grub-like; habits diverse, including free-living, parasitic, parasitoid, solitary and social; 2 divisions recognized, Parasitica (gall wasps, fig wasps, chalcid wasps, and other parasitic wasps), feeding mainly on body fluids of arthropod prey, and Aculeata (bees, wasps, ants) feeding mainly on nectar or honeydew; Clistogastra.
\BApocynaceae\b Oleander, periwinkle, golden trumpet, Chilean jasmine, corkscrew flower; family of Gentianales containing 2000 species of trees, shrubs, herbs or vines producing iridoid compounds and cardiotonic glycosides mostly from warm regions; flowers regular with 4 or 5 joined sepals, 4 or 5 joined petals forming a funnel supporting 5 stamens, and often 2 ovaries containing many seeds.
\BApoda\b \JGymnophiona\j
\BApodacea\b Subclass of holothurians (sea cucumbers) comprising 2 orders, Apodida and Molpadiida, in which the tube feet are greatly reduced or absent.
\BApodida\b Order of littoral to abyssal holothurians (Apodacea) comprising about 215 species typically found under rocks or buried in soft sediment; test worm-like, 50 mm to 2 m in length, smooth or rugose, tentacles simple or pinnate, tube-feet and respiratory trees absent.
\BApodidae\b Swifts; cosmopolitan family containing about 80 species of small aerial birds (Apodiformes) characterized by very fast acrobatic flight; head large, bill small with broad gape; wings elongated, curved; habits gregarious, monogamous, often crepuscular and migratory; usually nest on vertical surface of rock or tree; feed on insects caught on the wing.
\BApodiformes\b Order of mostly small neognathous birds specialized for fast and highly manoeuvrable flight; comprising 2 suborders Apodi (swifts) and Trochili (hummingbirds).
\Bapogamy\b Reproduction without fertilization; direct production of a plant from the gametophyte by budding, without the formation of gametes; \Bapogamous.\b
\Bapogenic\b Sterile.
\Bapogeotropism\b An orientation movement against gravity; negative geotropism; \Bapogeotropic.\b
\BApogonidae\b Cardinalfishes; family containing 170 species of small (to 200 mm) primarily tropical, shallow marine, reef-dwelling teleosts (Perciformes), including also some brackish, freshwater and deep-sea species; body elongate, colourful, with large eyes and 2 dorsal fins; many species are mouth brooders.
\Bapogynous\b Lacking, or having non-functional, female reproductive organs; \Bapogyny.\b
\Bapomixis\b Reproduction without fertilization, in which meiosis and fusion of gametes are partially or totally suppressed; \Bapomict\b, \Bapomictic.\b
\Bapomorphic\b Derived from and differing from an ancestral condition; \Bapomorph\b, \Bapomorphy\b; See also \Jplesiomorphic\j
\BAponogetonaceae\b Cape pondweed; family of Najadales containing about 40 species of perennial freshwater herbs with secretory canals containing oil or latex; leaves basal and usually with a long petiole and a floating blade; native to the tropics of the Old World and South Africa; flowers borne on spikes, bisexual, with 1-3 perianth segments, usually 6 stamens and 3 carpels.
\Bapophyte\b A native weed which appears after cultivation.
\BAporidea\b Small order of tapeworms found in the gizzard of ducks, swans and geese; scolex typically consisting of an armed rostellum and simple suckers, external segmentation lacking; mostly protandrous hermaphrodites.
\BApororhynchida\b Order of archiacanthocephalan thorny-headed worms found as parasites in the digestive tract of birds; typically with a large, globular proboscis which has an infolded anterior wall covered with spirally arranged, spine-like hooks.
\Baposematic coloration\b Coloration having a protective function; sometimes used in a restricted sense for warning coloration only; \Baposematism\b; \Baposeme\b; see also \Jproaposematic coloration\j \Jpseudaposematic coloration\j, \Jsynaposematic coloration\j
\Bapospory\b The production of a diploid gametophyte from a sporophyte without spore formation; \Baposporous.\b
\BApostomatida\b Order of hypostomatan ciliates found predominantly as parasites or symbionts on marine invertebrates; typically with an inconspicuous cytostome which is sometimes absent.
\Bapotypic\b Diverging from the basic or typical form.
\Bappeasement display\b A display that serves to prevent attack by reducing the opponent's attack drive and by releasing other non-aggressive behaviour.
\BAppendicularia\b Class of small (to 5 mm) paedomorphic planktonic tunicates, comprising about 70 species, that retain the larval tail and notochord in the adult; body enveloped within a complex transparent house that serves for food collection; water is forced through the house by movements of the tail, large particles are removed on coarse outer filter and only fine nanoplankton reaches the main inner filter; the houses are frequently discarded and new ones secreted; development is direct; Larvacea.
\Bappetitive behaviour\b 1: A variable introductory phase of an instinctive behaviour pattern or sequence; See also \Jconsummatory act\j. 2: Behaviour aiding in the satisfaction of a need in response to an internal condition.
\Bapple\b \JRosaceae\j
\Bapple canker\b \JHypocreales\j
\Bapricot\b \JRosaceae\j
\BApteronotidae\b Small family of freshwater catfishes (Siluriformes) from South America; body tapering posteriorly, anal fin well developed.
\BApterygidae\b Kiwis; family of small forest-dwelling ratite birds (Palaeognathae) from New Zealand comprising 3 species; height up to 0.3 m; legs stout, wings inconspicuous, feathers hair-like, eyes reduced; long sensitive bill used to probe for earthworms and insects; habits nocturnal, cursorial.
\BApterygiformes\b Order of small ratite birds containing a single family, Apterygidae (kiwis).
\BApterygota\b Subclass of primitively wingless insects, most of which are free-living, elongate forms with a direct larval development; formerly included the orders Collembola, Diplura, Protura and Thysanura; now often restricted to the Thysanura with the other groups treated as distinct classes of Hexapoda.
\Baptosochromatosis\b Change of colour in birds, without moulting.
\Baquaculture\b The cultivation of aquatic organisms.
\Baquatic\b Living in or near water; used of plants adapted for a partially or completely submerged life.
\Baquaticolous\b Living in water or aquatic vegetation; \Baquaticole.\b
\Baquatosere\b An ecological succession commencing in a wet habitat, leading to an aquatic climax.
\Baqueous desert\b An area of the sea floor or the bed of a lake more or less devoid of macroscopic organisms, typically with unstable sediment.
\Baquifer\b Permeable underground rock stratum which holds water.
\BAquifoliaceae\b Holly; family of Celastrales containing about 400 species of shrubs and trees, widely distributed but most abundant in the New World; flowers borne in small cymes; petals and stamens usually free; fruit is a small drupe containing 3 or more stones.
\BAquilonian region\b A biogeographical region comprising Europe, Asia north of the Himalayas, Africa north of the Tropic of Cancer and America north of latitude 45░N.
\Barable\b Used of land that is cultivated or fit for cultivation.
\BAracaceae\b Aroids; arum, dumb cane, philodendron, skunk cabbage, Swiss cheese plant, jack-in-the-pulpit; family of Arales containing about 1800 species of herbs, scrambling shrubs, climbing vines with aerial roots or free-floating aquatics, often producing latex or mucilage, with numerous tiny, malodorous flowers borne in a spadix; fruit usually a berry.
\Barachnactis\b Free-swimming tentaculate larva of some anemone-like cerianthids (Cnidaria).
\BArachnida\b Large and diverse class of mainly terrestrial arthropods (Chelicerata) comprising about 65 000 species in 11 extant orders, Scorpiones (scorpions), Uropygi (whip scorpions), Schizomida, Amblypygi (tailless whip scorpions), Palpigradi (micro whip scorpions), Araneae (spiders), Ricinulei Pseudoscorpiones (pseudoscorpions), Solpugida (wind scorpions), Opiliones (harvestmen), Acari (mites); antennae, wing and compound eyes absent; body divided into prosoma (cephalothorax) and opisthosoma (abdomen); 4 pairs of legs present, abdomen segmented or unsegmented, only rarely bearing appendages; respiration by means of tracheae and/or book lungs.
\BAraeolaimida\b Order of chromadorian nematodes found mostly in marine or brackish habitats; characterized by simple annulation of the body, lacking punctations and by the simple spiral form of the chemosensory amphids.
\BArales\b Aroids and duckweeds; order of Arecidae comprising two families of herbs, shrubs or vines, sometimes thalloid and free-floating; the family Lemnaceae is probably derived from the Aracaceae.
\BAraliaceae\b Ginseng, ivy; family of Apiales containing about 700 species of mostly woody, sometimes prickly, plants, with small flowers mainly borne in umbels and heads; widespread in warm regions; individual flowers normally with 5 sepals, petals and stamens, an inferior ovary, and producing drupe fruits.
\BAraneae\b Spiders; order of terrestrial arthropods comprising about 35 000 recognized species in 3 suborders, Mesothelae, Orthognatha, Lapidognatha; cephalothorax and abdomen joined by slender waist, chelicerae possessing distal fang; pedipalps leg-like, modified in male for sperm transfer; abdomen bearing book lungs and tracheae; usually 3 pairs of spinnerets, the silk serving many functions - used for traps, draglines, ballooning, wrapping prey, construction of domiciles, and defence.
\BAraneidae\b Orb-web spiders; family containing about 2500 species of spiders (Araneae) which spin typical orb webs with viscid spirals and many radii; prey caught in web are cut out and wrapped in silk; legs armed with many long spines, chelicerae with many teeth.
\Baraneophagic\b Feeding on spiders; \Baraneophage\b, \Baraneophagy.\b
\BAraphideae\b Order of pennate diatoms (Pennales) lacking a true raphe; (slit-like suture in valve); also treated as a suborder, Araphidineae.
\BAraucariaceae\b Family of conifers (Pinatae) containing the Monkey Puzzle tree, native to southern hemisphere excluding Africa; leaves broad to lanceolate; male cone is a catkin, female cone globose, often massive.
\BArbacioida\b Order of littoral to abyssal echinoids (Echinacea) comprising about 25 extant species; test sculptured, dentition stirodont, anus at aboral pole; includes the genus \IArbacia\i used widely in laboratory studies of embryology and biochemistry.
\Barboreal\b Living in trees; adapted for life in trees.
\Barboreous desert\b An area of sparsely scattered trees with little or no vegetation between; desert forest.
\Barboretum\b A botanic garden or parkland dominated by trees.
\Barboricide\b A chemical that kills trees.
\Barboricolous\b Living predominantly in trees or large woody shrubs; \Barboricole.\b
\Barboriculture\b The cultivation of trees.
\Barborvirus\b An arthropod-borne virus; \Barbovirus.\b
\Barbusticolous\b Living predominantly on scattered shrubs and perennial herbs with shrub-like habit; \Barbusticole.\b
\BArcellinida\b Testate amoebae; lobose amoebae having a test with a single opening, found predominantly in freshwater habitats although some occur in soil, litter and salt-water habitats.
\BArchaean\b A geological period (\Ic.\i 4500-2400 million years B.P.); a subdivision of the Precambrian; \BArchean\b; see geological time scale.
\BArchaebacteria\b One of the three primary kingdoms (\Jurkingdoms\j) of living organisms\j, comprising all methanogenic bacteria; see also \JEubacteria\j, \JUrkaryota\j.
\BArchaeoceti\b Extinct suborder of whales (Cetacea) containing the most ancient whales, known from the Eocene; porpoise-sized, with an elongate snout and nostrils on top of the skull; hind legs reduced to vestiges not visible externally; fed on fishes.
\BArchaeocyatha\b Extinct phylum of reef-forming organisms known from the Cambrian; resembling both sponges and corals in some features but possibly representing a higher grade of organization than the sponges.
\BArchaeocyathida\b Order of solitary or colonial Archaeocyatha (Anthocyathea); cup-shaped often irregular in outline; known from Lower and Middle Cambrian.
\BArchaeogastropoda\b An order of primitive prosobranch snails comprising about 3000 species of mostly marine and herbivorous species, as well as a few freshwater and terrestrial forms; includes the abalones, limpets, pheasant shells and top shells; shell variably shaped, often with mother-of-pearl internally; anterior mantle cavity typically containing 2 gills; usually with external fertilization.
\BArchaeognatha\b Order of primitively wingless insects (Apterygota); comprises about 250 species of fusiform insects which run fast and jump by abdominal flexion; body covered with pigmented scales; compound eyes large; abdomen with ventral styles on somites 2 to 9; free-living and nocturnal in habit, feeding on plant material.
\Barchaeophyte\b A plant taken into cultivation in prehistoric times.
\BArchaeophytic\b The period of geological time during the evolution of the earliest plants, the algae; Algophytic; see also \JAphytic\j \JCaenophytic\j, \JEophytic\j, \JMesophytic\j, \JPalaeophytic\j
\BArchaeopulmonata\b A small order of primitive pulmonate molluscs found at the edge of the sea; characterized by the type of reproductive system and by the separation of the genital pores.
\BArchaeornithes\b Subclass of fossil birds characterized by a long tail, 3 clawed digits on the forelimbs, small sternum and teeth on both jaws; includes \IArchaeopteryx\i from the Jurassic period.
\BArchaeozoic\b A geological period preceding the Cryptozoic, within the early Precambrian era; sometimes used for the whole of the early Precambrian period; \BArcheozoic\b; see geological time scale.
\Barchaeozoology\b The study of animal remains from archaeological sites.
\Barchegonium\b The female sex organ of many lower plants, bryophytes, pteridophytes and most gymnosperms, which typically comprises a distal neck and a swollen base containing the female gamete.
\BArcheobatrachia\b Suborder of primitive frogs (Anura) containing about 80 species in 6 families; eggs and larvae typically aquatic.
\Barcherfish\b \JToxotidae\j
\Barchetype\b The hypothetical ancestral type; the earliest common ancestor; \Barchetypal\b, \Barchetypic.\b
\BArchiacanthocephala\b Class of parasitic thorny-headed worms found as adults mainly in predatory birds and mammal hosts, and using insects and myriapods as intermediate hosts; characterized by a usually retractable proboscis with hooks arranged in concentric circles.
\BArchiannelida\b Group of archaic aquatic annelid worms with narrow bodies, primitive nervous systems and, sometimes, parapodia; formerly treated as a distinct class of Annelida.
\Barchibenthal zone\b The continental slope; the sea floor from the edge of the continental shelf to the continental rise; \Barchibenthic zone\b; see marine depth zones.
\Barchicleistogamic\b Having reduced reproductive organs within permanently closed flowers; See also \Jarchocleistogamic\j
\BArchidiales\b Small but widely distributed order of mosses (Bryidea); plants delicate, growing on bare sandy soil; characterized by their unique sporophyte development.
\BArchigregarinida\b Primitive order of gregarines found in the intestine of marine invertebrates and lower chordates, multiplying by multiple fission (merogony), gamete formation (gamogony) and sporozoite formation (sporogony).
\BArchinacelloidea\b Extinct order of monoplacophoran molluscs known from the Upper Cambrian to the Lower Silurian; shells variable in shape but with a single pair of muscle scars.
\Barchocleistogamic\b Having mature reproductive organs within permanently closed flowers; See also \Jarchicleistogamic\j
\BArchoophora\b Subclass of exclusively marine flatworms (Turbellaria) comprising the Acoela and Polycladida.
\BArchosauria\b Large group of advanced diapsid reptiles including the crocodiles, dinosaurs, pterosaurs and the codonts; the birds may be descended from archosaurs as their single temporal opening may be derived by fusion from the 2 apertures in the diapsid skull.
\BArchostemata\b Small suborder of beetles (Coleoptera) comprising about 30 species in 3 families.
\BArcoida\b Ark shells; an order comprising about 250 species of mainly marine, sedentary pteriomorphian bivalves; characterized by their shell structure.
\BArctic brown soil\b A soil having a shallow profile; acidic crumb-structured yellow-brown A-horizon, B-horizon absent, C-horizon more or less neutral.
\BArctic period\b The earliest period of the Blytt-Sernander classification (\Ic\i. 14 000-10 000 years ) characterized by primarily tundra vegetation and cold late-glacial conditions.
\BArctiidae\b Tiger moths; family of medium-sized colourful nocturnal moths (Lepidoptera) containing about 2000 species of widespread distribution but most abundant in the New World tropics; many produce sounds using a stridulatory organ on the side of the body; the characteristically hairy larvae are known as woolly bears; the larvae of some species are economically important pests causing damage to the foliage of broad-leaved trees.
\BArctocyonidae\b Extinct family of generalized primitive mammals (Condylarthra) known from the Cretaceous to the Eocene; slim bodied with slender limbs, clawed feet, small brain and primitive teeth; included omnivorous and herbivorous forms.
\BArctogaea\b The biogeographical area comprising the Palaearctic, Nearctic, Ethiopian and Oriental regions; see also \JMegagaea\j \JNeogaea\j, \JNotogaea\j, \JPalaeogaea\j
\BArdeidae\b Herons bitterns, egrets; family of medium to large wading birds (Ciconiiformes) characterized by long legs, long neck, long broad wings and a strong pointed bill; feed on fishes and other aquatic organisms; solitary or colonial breeders that nest on or off the ground; contains 62 species with cosmopolitan distribution in fresh to marine waters.
\BArecaceae\b The palms; formerly known as the Palmae; the only family of the order, \JArecales\j
\BArecales\b Palms; order of Arecidae comprising a single family of nearly 3000 species of mostly slender trees with an unbranched trunk and a terminal crown of large evergreen leaves; flowers generally small and insect-pollinated; mainly occurring in tropical and warm temperate regions; includes betel palm, coconut palm and date palm.
\BArecidae\b Diverse subclass of monocotyledons (Liliopsida) comprising about 5700 species in 4 orders; includes herbs, shrubs and trees with alternate leaves and small crowded flowers.
\Barena\b An area used for communal courtship display; lek.
\Barenaceous\b Derived from or containing sand; having the properties of sand; growing in sand; sandy.
\BArenicolidae\b Lugworm; family of capitellidan polychaete worms found burrowing in soft estuarine and inshore sediments; widely used as fishing bait by anglers.
\Barenicolous\b Living in sand; \Barenicole.\b
\Bareogeography\b Study of the distributions of plants and animals.
\Barescent\b Becoming dry or arid.
\BArgentinidae\b Herring smelts, argentines; family containing about 12 species of mesopelagic salmoniform teleost fishes found on outer shelf and upper continental slope; body elongate, to about 500 mm length, adipose fin present.
\BArgentinoidei\b Suborder of mostly deep-sea salmoniform teleosts comprising about 110 species in 5 families; including herring smelts, deep-sea smelts, barreleyes, slickheads, and tubeshoulders.
\Bargillaceous\b Comprising clay-sized particles; having the properties of clay.
\Bargillicolous\b Living on or in clay; \Bargillicole.\b
\Bargillophilous\b Thriving in clay or mud; \Bargillophile\b, \Bargillophily.\b
\Bargodromilic\b Pertaining to slow-flowing streams.
\Bargotaxis\b Passive movement due to surface tension; \Bargotactic.\b
\BArguloida\b Only order of \JBranchiura\j
\Barheic region\b An area in which no rivers arise; see also \Jendorheic region\j \Jexorheic region\j
\BArhynchobatidae\b Monotypic family of rajiform fishes from New Zealand; single dorsal fin present.
\BArhynchobdellae\b Order of freshwater, amphibious and terrestrial leeches parasitic or predacious on wide range of hosts; proboscis absent, jaws or piercing stylets present; contains about 200 species in 9 families; commonly blood feeders.
\Barid\b Used of a climate or habitat having a low annual rainfall of less than 250 mm, with evaporation exceeding precipitation and a sparse vegetation.
\BAriidae\b Family of marine catfishes (Siluriformes) cosmopolitan in tropical and subtropical seas; body naked, dorsal and pectoral fins with stout venomous spine; some forms migrate into estuaries or streams to spawn; eggs brooded orally; some species utilized as food-fish; referred to by some authorities as Tachysuridae.
\BAristolochiales\b Order of aromatic woody vines (Magnoliidae) comprising a single family of about 600 species; flowers often malodorous and lacking petals.
\Bark shell\b \JArcoida\j
\Barmadillo\b \JDasypodidae\j
\Barmyworms\b Larvae of noctuid moths (Lepidoptera) that migrate in huge numbers and cause extensive damage to crops.
\Baroids\b \JAracaceae\j
\Barrhenogenic\b Producing offspring that are entirely, or predominantly male; \Barrhenogeny;\b see also \Jallelogenic\j \Jamphogenic\j, \Jmonogenic\j, \Jthelygenic\j
\Barrhenotoky\b Parthenogenesis in which unfertilized eggs produce haploid males and fertilized eggs produce diploid females; \Barrhenotokous;\b See also \Jthelytoky\j
\BArripidae\b Australian salmon; family of primarily coastal marine teleost fishes (Perciformes) containing 2 species confined to Australia and New Zealand; body elongate, cylindrical, to 1 m length; important as sport and as food-fishes.
\Barrow worm\b \JChaetognatha\j
\Barrowhead\b \JAlismataceae\j
\Barrowroot\b \JTaccaceae\j
\Barrowtooth eel\b \JDyssomidae\j
\BArtamidae\b Wood swallows; family containing 13 species of small passerine birds found in open countryside and forest habitats of southeast Asia and Australian regions; bill pointed with broad gape; wings long and pointed; habits gregarious, aerial, some species migratory; feed on insects caught on wing.
\BArthracanthida\b Order of acantharians with pyramidal bases on the 20 radial spines and a capsule membrane separating the endoplasm from the ectoplasm.
\BArthrochirotida\b Extinct order of sea cucumbers (Holothuroidea) characterized by an axial skeleton of stout sclerites in the tentacles; known from the Devonian.
\BArthrodira\b Group of primitive fossil fishes (Placodermi); body covered with bony plates and a head shield; known from the Devonian.
\BArthropoda\b Very large phylum of invertebrates that includes the insects, arachnids, crustaceans and many smaller groups, totalling several million species and far outnumbering all other phyla added together; body metamerically segmented, most segments carrying a pair of jointed appendages; at least one pair of limbs specialized as jaws, the others variously modified for locomotion, feeding, respiration or reproduction; body enclosed in chitinous exoskeleton (cuticle) that is periodically moulted to permit growth; size range 80\Fm\nm to 3.6 m. Four subphyla recognized, Crustacea, Chelicerata, Uniramia, Pentastomida; classification and status of the Arthropoda is still controversial, component groups are sometimes regarded as distinct phyla retaining the term arthropod as a grade of organization.
\BArticulata\b 1: Class of epifaunal brachiopods (lamp shells) in which the valves are hinged by ventral valve teeth and dorsal valve sockets; lophophore usually with skeletal support; gut blind ending, without functional anus; contains about 280 species in 2 orders, Rhynchonellida and Terebratulida, found from the intertidal zone to depth of 5000 m. 2: Sole extant subclass of the echinoderm class Crinoidea comprising the stalked Millericrinida, Cyrtocrinida, Bourgueticrinida, Isocrinida and the free-living Comatulida.
\Bartificial selection\b Selection by man; domestication; selective breeding.
\BArtiodactyla\b Even-toed ungulates: diverse order of mostly large herbivorous or omnivorous terrestrial mammals characterized by possession of a cloven hoof in which digits 3 and 4 are dominant and carry most of the weight (paraxonic); bony horns often present; stomach simple to complex; contains 3 suborders, Suiformes (pigs, peccaries, hippopotamuses), Tylopoda (camels, llamas), Ruminantia (deer, giraffe, cattle, sheep, goats).
\Barum\b \JAracaceae\j
\Barundineous\b Having an abundance of reeds; reedy.
\Basaccharolytic\b Used of microorganisms that are unable to break down carbohydrates, alcohols or polysaccharides.
\BAscalaphidae\b Owl-flies; family of large, often strikingly coloured, neuropteran insects which fly mostly at dusk and at night, catching prey insects whilst on the wing; predacious larvae found on soil and in vegetation, feeding by ambushing prey; contains about 400 species.
\BAscaridida\b Order of exclusively parasitic rhabditian nematodes found in vertebrate hosts; generally possessing 3 or 6 lips with an outer circle of 8 sensilla and paired pore-like amphids; 2 spinules usually present in the male and 2 ovaries in the female.
\BAscetospora\b Phylum of spore-producing protozoans which are parasitic mostly in marine invertebrates; spores are multicellular but lack polar capsules; comprising 2 classes, Paramyxea and Stellatosporea.
\BAschelminthes\b A loose grouping of invertebrate groups characterized by the possession of a pseudocoelom; formerly treated as a phylum comprising the Rotifera, Gastrotricha, Kinorhyncha, Nemata and Nematomorpha but now regarded as a level of organization and each of its constituent groups is now classified as a phylum.
\BAscidiacea\b Sea squirts; class of solitary or colonial, sessile tunicates typically attached posteriorly, with branchial (inhalent) and atrial (exhalent) apertures at anterior end; gonads situated in loop of intestine or in body wall, heart ventral, direction of blood flow periodically reversed; many species accumulate heavy metals such as vanadium and iron; 3 orders recognized, Aplousobranchia, Phlebobranchia, and Stolidobranchia.
\BAsclepiadaceae\b Milkweed, butterfly weed, wax flower; large family of Gentianales containing about 2000 species of vines or erect herbs commonly producing various cardiotonic glycosides and alkaloids, mostly from warm regions; flowers typically in cymose inflorescences; each flower pentamerous, petals contorted; fruit consists of paired follicles.
\BAscoceratida\b Extinct order of cephalopods (Nautiloidea) which have a narrow juvenile portion and inflated adult portion to the test; siphuncle about central in position; known from the Middle Ordovician to the Silurian.
\BAscomycota\b \JAscomycotina\j; treated as a separate phylum of the kingdom Fungi.
\BAscomycotina\b Sac fungi, Ascomycetes; group of fungi possessing a minute reproductive structure (ascus) formed after plasmogamy, between an ascogonium and another cell, produces ascogenous hyphae containing nuclei which fuse only after binucleate cells are walled off within the ascogenous hyphae; meiosis and mitosis usually results in the formation of 8 haploid ascospores inside a saclike ascus; asexual reproduction by the production of conidiospores is also widespread; classified as a subdivision of true fungi, Eumycota, or as a phylum of the kingdom Fungi under the name Ascomycota; comprises 5 classes, Hemiascomycetes, Discomycetes, Loculoascomycetes, Plectomycetes and Pyrenomycetes.
\BAscoseirales\b Small order of brown algae found only in antarctic and subantarctic waters.
\BAscosphaerales\b Order of plectomycete fungi in which the ascogonium is a multinucleate swollen cell that arose as a lateral branch and the asci are evanescent; ascospores sometimes forming a membrane-enclosed spore ball; contains soil-living and root nodule species as well as parasites of bees.
\BAscothoracica\b Order of ectoparasitic and endoparasitic barnacles (Cirripedia) found on echinoderms and cnidarians from shallow coastal to abyssal waters; characterized by mouthparts modified for piercing and sucking; contains about 75 species; sometimes treated as a distinct subclass.
\Bascus\b The specialized cell in Ascomycote fungi in which the haploid ascospores develop.
\BA-selection\b Selection operating in a consistently and predictably adverse or resource limited environment and characterized by low population density, low species richness and little interspecific competition.
\BAsellariales\b Order of trichomycete fungi which are obligate gut symbionts of marine, freshwater and terrestrial isopods, and of terrestrial insects.
\BAsellota\b Water lice; suborder of isopod crustaceans containing about 2000 species widely distributed in freshwater and marine benthic habitats; especially diverse in the deep sea.
\Basexual\b 1: Lacking functional sex organs. 2: Used or reproduction not involving the fusion of gametes, including budding, fission, gemmation, parthenogenesis, spore formation and vegetative propagation.
\Basexual reproduction\b Reproduction without the formation of gametes and in the absence of any sexual process.
\Bash\b \JOleaceae\j
\BAsilidae\b Robber flies; cosmopolitan family containing about 5000 species of active predatory flies (Diptera) found commonly in open sunny habitats; anterior legs robust, bearing strong hairs, for gripping prey which are caught in flight; many mimic bees or wasps.
\Basparagus\b \JLiliaceae\j
\Baspect\b 1: The degree of exposure of a site to environmental factors. 2: The seasonal changes in the appearance of vegetation.
\Baspection\b The periodic changes in the appearance of vegetation within an area or community; the periods are usually recognized as seasons; \Baspectation.\b
\Baspidistra\b \JLiliaceae\j
\BAspidochirotacea\b Subclass of holothurians (sea cucumbers) in which the test has a marked bilateral symmetry, the tentacles are nonretractile, tube-feet are present, and respiratory trees are present or absent; some species have a toxin (holothurin) in the body wall; 2 orders recognized, Elasipodida and Aspidochirotida.
\BAspidochirotida\b Order of mainly shallow water, tropical, holothurians (Aspidochirotacea) comprising about 300 species which have a thick test, 15-30 tentacles, and in which respiratory trees are present; the dried body wall of some species is considered a gastronomic delicacy in Oriental regions (trepang, blêeche-de-mer).
\BAspidogastrea\b Subclass of trematodes comprising about 32 species endoparasitic in molluscs, fishes and turtles; characterized by their cylindrical, non-spinous body with a flattened ventral holdfast (haptor); development may involve an intermediate host or may be direct.
\Basporogenic\b Not producing, or developing from, spores; \Basporogenous.\b
\BAspredinidae\b Banjo catfishes; family of tropica nocturnal fresh- and brackish-water teleosts (Siluriformes) from South America; body depressed, tuberose, broad anteriorly, narrow posteriorly; head armoured with bony plates 3 pairs of barbels; large species important locally as food-fish; small forms popular amongst aquarists.
\Bass\b \JEquidae\j
\Bassassin bug\b \JReduviidae\j
\Bassemblage\b A group of fossils occurring together in the same stratigraphic level (an assemblage zone).
\Bassociation\b 1: A climax plant community characterized by two or more dominant species which have the life \Jform\j typical of the formation to which the association belongs. 2: Sometimes used in general to indicate a large assemblage of organisms in a particular area, with one or two dominant species, or to refer to any group of plants growing together and forming a small unit of natural vegetation.
\Bassortment\b The distribution of chromosomes to the germ cells during meiosis.
\BAstacidea\b Crayfishes, Norway lobster, lobster; infraorder of pleocyematan decapod crustaceans; first 3 pairs of thoracic legs chelate, uropods well developed.
\BAsterales\b Composites; cosmopolitan order of Asteridae containing a single enormous family, Asteraceae, of over 20 000 species of mostly herbs producing various repellent chemicals and latex or resin; flowers borne in centripetally flowering heads and may be perfect, pistillate, staminate or neutral; pollen is released into a tube and pushed out by growth of the style; includes many familiar species, aster, chamomile, chrysanthemum, cineraria, cocklebur, coneflower, dahlia, daisy, dandelion, goldenrod, hawkweed, lettuce, marigold, ragweed, sagebrush, sunflower, star thistle, thistle, tickseed; family formerly known as Compositae.
\BAsteridae\b The most advanced subclass of dicotyledonous (Magnoliopsida) plants with various sorts of repellents, which can be distinguished from the majority of other dicotyledons by their sympetalous flowers in which the stamens are equal to the number of, and alternate to, the corolla lobes, or, in which there are fewer stamens than corolla lobes.
\BAsterinales\b Order of mostly tropical loculoparenchemycetid fungi which are typically epiphytes or external parasites of plants.
\BAsteroidea\b Starfish, sea stars; subclass of intertidal to deep-sea asterozoan echinoderms comprising about 1500 species in 5 extant orders, Platyasterida, Paxillosida, Valvatida, Spinulosida and Forcipulata; arms typically merging gradually with central disk, 5 to multi-radiate; sexes usually separate, fertilization external, asexual reproduction by disk fission occurring in some species; development may be direct but commonly includes planktonic bipinnaria and brachiolaria larvae; feed as omnivorous scavengers or opportunistic predators, large prey may be digested externally.
\BAsterozoa\b Subphylum of echinoderms comprising a single class, Stelleroidea, and 3 subclasses, Somasteroidea, Asteroidea (sea stars) and Ophiuroidea (brittle stars); body flattened with radiating arms, mouth central and downward facing, anus absent or central aboral.
\Basthenobiosis\b A period of reduced metabolic activity.
\BAstigmata\b Diverse subgroup of acariform mites (Acari) typically found on or in association with arthropods, vertebrates and other animals, only rarely free-living throughout the life cycle; common on carrion, dung, in nests, and as pests of stored products.
\Bastilbes\b \JSaxifragaceae\j
\Bastogeny\b 1: The development of a colony by budding. 2: The developmental history of a colonial organism.
\BAstomatida\b Order of hymenostome ciliates characterized by their total lack of a mouth (cytostome), found mostly as endosymbionts in the digestive tract of terrestrial or aquatic oligochaetes.
\BAstrapotheria\b Order of extinct South American ungulates (Protoungulata) known from the Eocene to Miocene; anterior body robust, hindlimbs slender; possessed elephant-like proboscis.
\BAstroblepidae\b Family containing about 35 species of freshwater catfishes (Siluriformes) typically found in fast-flowing montane streams of tropical South and Central America; body depressed, naked, head broad; dorsal and adipose fin often with stout spine; single pair of barbels.
\BAstronesthidae\b Snaggletooths, star-eaters; family containing 27 species of small (to 150 mm) luminescent deep-sea stomiiform teleost fishes; body bearing 2 rows of photophores; front teeth fang-like.
\BAstrophorida\b Order of tetractinomorph sponges characterized by a radial skeletal architecture and generally coarse texture.
\Basyngamy\b Reproductive isolation by virtue of different breeding or flowering seasons; \Basyngamic.\b
\Batavism\b A reversion to an ancestral character state not evident in recent generations, possibly due to a recessive gene or to complementary genes; the aberrant individual is sometimes referred to as a throwback; \Batavistic.\b
\BAteleopodidae\b Family containing about 10 species of bottom-living lampridiform teleost fishes widespread in tropical and warm temperate seas; body elongate, to 600 mm length, anal fin long and continuous with small caudal; pelvics comprising only 2 filamentous fin rays.
\Bateliosis\b Dwarfism; reduced size but with normal proportions.
\BAtelopodidae\b Family containing about 30 species of small brightly coloured tree frogs (Anura) found in Central and South America; many are poisonous; most walk rather than hop.
\BAtelostomata\b Superorder of irregular euechinoidean echinoids that burrow in soft sediments; anus displaced from aboral pole posterior interambulacrum, dental apparatus absent in adult, gills lacking; aboral tube-feet serve respiratory function; 2 orders recognized, Cassiduloida and Spatangoida.
\BAthalamida\b Order of naked Granuloreticulos protozoans, lacking any test or shell.
\BAthalamida\b Used of waters or water bodies that have not had any connection to the sea in geologically Recent times, all ions in solution are thus derived from the substratum or atmosphere.
\BAthecanephria\b Order of pogonophoran marine worms possessing a sac-like anterior body cavity in the tentacular region and lateral ciliated ducts opening to the exterior; spermatophores cylindrical or spindle-shape.
\BAtherinidae\b Silversides, sand-smelts; family containing about 150 species of primarily marine atheriniform teleost fishes widespread in tropical and temperate coastal waters; body fusiform, to 600 mm length, typically almost transparent with silvery lateral stripe.
\BAtheriniformes\b Order of small marine, brackish and freshwater teleost fishes widespread in tropical and temperate region contains about 180 species in 4 families; including silversides, sand-smelts, rainbowfishes.
\Bathermobiosis\b Dormancy induced by relatively low temperatures; \Bathermobiose.\b
\BAtlantic Equatorial Countercurrent\b A warm surface ocean current that flows east in the tropical Atlantic, forming the northerly part of the equatorial circulation; see ocean currents.
\BAtlantic Equatorial Undercurrent\b A strong subsurface ocean current that flows eastwards across the Atlantic at the equator.
\BAtlantic North Equatorial Current\b A warm surface ocean current that flows westwads in the equatorial Atlantic and forms the southerly limb of North Atlantic Gyre; see ocean currents.
\BAtlantic period\b A period of the Blytt-Sernander \Jclassification\j (\Ic\i. 7500-4500 years B.P. ) characterized by oak, elm, linden and ivy vegetation and by the driest and warmest postglacial conditions.
\BAtlantic South Equatorial Current\b A warm surface ocean current that flows westwards in the equatorial Atlantic and forms the northerly limb of the South Atlantic Gyre; see ocean currents.
\Batlas moth\b \JSaturniidae\j
\Batmobios\b Organisms living in the air; aerial organisms.
\Batmophyte\b An epiphyte that obtains water by aerial assimilation over its entire surface.
\Batokous\b Without offspring; non-reproductive; vegetative; See also \Jepitokous\j
\Batrophic\b Used of organisms or life cycle stages that do not feed.
\Batrophy\b Marked reduction in size and functional significance.
\Battenuation\b 1: A reduction in strength or intensity; weakening. 2: The loss of virulence of a pathogenic microorganism.
\Baubergine\b \JSolanaceae\j
\BAuchenipteridae\b Family containing about 50 species of small (to 250 mm) tropical South American freshwater catfishes (Siluriformes); body naked, lateral line often zig-zagged; dorsal fin with single spine; 3 pairs of barbels.
\Baucuparious\b Attractive to birds.
\Baufwuchs\b A community of aquatic organisms and associated detritus adhering to and forming a surface coating on submerged stones, plants and other objects; fouling organisms.
\Baugur\b \JNeogastropoda\j
\Bauk\b \JAlcidae\j
\Baulophyte\b A non-parasitic plant living within a hollow cavity in another plant.
\BAulopidae\b Family of primitive bottom-living myctophiform teleost fishes containing 8 species found in warm coastal waters of the North Atlantic and Pacific to 1000 m depth; body slender, to 600 mm length, dorsal fin high and anteriorly placed; photophores absent.
\BAulorhynchidae\b Tubesnouts, tubenose; family containing 2 species of shallow marine gasterosteiform teleost fishes of the North Pacific that inhabit a variety of rocky, sandy, eelgrass- or algae-covered substrata; body very slender, to 160 mm length, cylindrical, bearing armour of lateral bony scutes; snout elongate, upper jaw protractile.
\BAulostomidae\b Trumpetfishes; family containing 3 species of tropical and subtropical shallow marine gasterosteiform teleost fishes often found around reefs in association with gorgonian corals; body slender, compressed, to 800 mm length; snout tubular; dorsal fin comprising 8-13 separated spines.
\Bauricularia\b A free-swimming, planktonic larval stage of sea cucumbers characterized by a single, continuous band of cilia looping around the paired lobes of the body.
\BAuriculariales\b Order of fungi (Phragmobasidiomycetes) now mostly included in the order \JEutremellales\j
\Bauroral\b Pertaining to the dawn.
\Baustral\b Southerly; pertaining to cool or cold temperate regions of the southern hemisphere; antiboreal; See also \Jboreal\j
\BAustralian chat\b \JEphthianuridae\j
\BAustralian kingdom\b One of the six major phytogeographical areas characterized by floristic composition; comprising Central, North & East, and South & West Australian regions.
\BAustralian laurel\b \JPittosporaceae\j
\BAustralian region\b A zoogeographical region comprising Australia, Maluku (the Moluccas), Sulawesi, Papua-New Guinea, Tasmania, New Zealand and the oceanic islands of the South Pacific; subdivided into Australian, Austro-Malayan, New Zealand and Polynesian subregions; Hawaii and Polynesia are sometimes excluded and regarded as distinct regions.
\BAustralian salmon\b \JArripidae\j
\Baustralopithecines\b Extinct group of homonoid apes that lived about 5-1.5 million years B.P., known from fossil remains found in Africa, in particular along the East African Rift Valley; they are thought to have walked upright on two legs; facial and skeletal characteristics link the group closely to chimpanzees and gorillas as well as to man; the best known of the australopithecines is Lucy, found at Hadar (Ethiopia) in 1974.
\BAustrobaileyaceae\b Family of archaic flowering plants (Magnoliales) comprising a single species of evergreen woody vine, native to northeast Australia; flowers are foul smelling and have poorly differentiated sepals and petals.
\Bautamphinereid\b An autotrophic amphibious plant.
\Bautecology\b The ecology of individual organisms or species; \Bautoecology\b; See also \Jsynecology\j
\Bautephaptomenon\b Autotrophic organisms which live attached to a surface; \Bauthigenic\b Derived from sea water and precipitated directly onto the sediment rather than settling through the water column.
\Bautoallogamy\b The condition of a species in which some individuals are adapted to cross fertilization and others to self-fertilization; \Bautallogamy.\b
\Bautobiosphere\b That part of the biosphere in which energy is fixed by photosynthesis in green plants; See also \Jallobiosphere\j
\Bautochorous\b Having motile spores or propagules disseminated by the action of the parent plant; \Bautochore\b, \Bautochory.\b
\Bautochthonous\b Endogenous; produced within a given habitat, community or system; indigenous; endemic; native; \Bautochthony\b; See also \Jallochthonous\j
\Bautocoprophagous\b Used of an organism that consumes its own faeces; \Bautocoprophage\b, \Bautocoprophagy.\b
\Bautodeme\b A \Jdeme\j composed predominantly of self-fertilizing individuals.
\Bautoecious\b Used of a parasite that passes through the different stages of its life cycle within the same host individual; \Bautoecius.\b
\Bautogamy\b 1: The process of self-fertilization or self-pollination. 2: The fusion of two reproductive nuclei within a single cell, derived from a single parent. 3: Reproduction in which a single cell undergoes reduction division producing two autogametes which subsequently fuse. 4: In protistans, the division of the micronuclei to produce eight or more nuclei, of which two fuse and give rise to a new macronucleus.
\Bautogenic\b Occurring within a given system; produced by the activities of living organisms within a system and acting upon that system.
\Bautogenous\b Used of a female insect that does not have to feed in order to facilitate maturation of her eggs; See also \Janautogenous\j
\Bautoicous\b Having male and female inflorescences on the same plant; monoecious.
\Bautoinfection\b The direct reinfection of a host individual by larval offspring of an existing parasite.
\Bautolysis\b The breakdown of a cell by its own enzymes; \Bautolytic.\b
\Bautomictic parthenogenesis\b \JParthenogenesis\j in which meiosis is preserved and diploidy reinstated either by the fusion of haploid nuclei within a single gamete or by the formation of a restitution nucleus.
\Bautomimicry\b Mimicry in which a palatable morph (the mimic) resembles a non-palatable morph (the model) of the same species; the polymorphism with respect to palatability can arise from a choice of different food plants by model and mimic.
\Bautonastic\b Pertaining to growth curvature promoted by endogenous factors; \Bautonastism\b, \Bautophagy.\b
\Bautoparthenogenesis\b The development of an unfertilized egg that has been activated by a chemical or physical stimulus.
\Bautopelagic\b Epipelagic; used of planktonic organisms living continually at the sea surface; See also \Jallopelagic\j
\Bautophagous\b Used of precocious offspring capable of locating and securing their own food; \Bautophage, autophagy.\b
\Bautophilous\b Self-pollinated; \Bautophily.\b
\Bautophyte\b A plant capable of synthesizing complex organic substances from simple inorganic substrates, typically by photosynthesis; \Bautophytic.\b
\Bautoploid\b Used of an organism with the characteristic chromosome set of its species.
\Bautopolyploid\b A polyploid variety resulting from the multiplication of the chromosome set of a single species; See also \Jallopolyploid\j
\Bautopotamic\b Pertaining to organisms adapted to stream environments and which complete their life cycles in streams; see also \Jeupotamic\j \Jtychopotamic\j
\Bautoradiography\b A photographic technique for determining the location of a chemical previously labelled with a radioactive isotope, which has been incorporated into a cell or organism.
\Bautosome\b Any chromosome other than sex chromosomes.
\Bautostylic\b The condition in which the hyomandibular plays no part in the suspension of the lower jaw in fishes, since the palatoquadrate arch articulates directly with the skull; see also \Jamphistylic\j \Jhyostylic\j, \Jholostylic\j
\Bautotherm\b An organism that regulates its body temperature independent of ambient temperature changes; See also \Jallotherm\j
\Bautotomy\b Self-amputation of an appendage or other part of the body.
\Bautotoxin\b Any substance produced by an organism that is toxic to itself.
\Bautotrophic\b 1: Capable of synthesizing complex organic substances from simple inorganic substrates; including both chemoautotrophic and photoautotrophic organisms. 2: Used of any organism for which environmental carbon dioxide is the only or main source of carbon in the synthesis of organic compounds by photosynthesis; \Bautotroph\b, \Bautotrophy\b; See also \Jheterotrophic\j
\Bautotrophic lake\b A lake in which all or most of the organic matter present is derived from within the lake and not from drainage off the surrounding land; See also \Jallotrophic lake\j
\Bautotropism\b The tendency to grow in a straight line unaffected by external factors; \Bautotropic.\b
\Bautoxenous\b Used of a parasite that passes through the different stages of its life cycle in the same host individual.
\Bauxanometer\b A simple apparatus for measuring growth (in length) of plant organs.
\Bauxin\b A plant hormone promoting or regulating growth.
\Bauxotrophic\b Used of a microorganism having a biochemical deficiency and requiring supplementary growth factors not needed by the wild type; \Bauxotroph\b, \Bauxotrophy.\b
\BAves\b Birds; class of feathered, bipedal, warm-blooded tetrapods; forelimbs specialized as wings for flight; stout keeled sternum present, pelvic girdle fused to synsacrum; neck elongate; teeth absent; right aortic arch only; reproduction oviparous, fertilization internal; eggs large, yolked, amniotic, shelled; contains 9000 Recent species in a single subclass, Neornithes.
\Baviculture\b The practice of keeping birds in captivity for scientific study.
\Bavifauna\b The bird fauna of an area or period.
\Bavocado pear\b \JLauraceae\j
\Bavocet\b \JRecurvirostridae\j
\Baxenic\b Used of a pure culture free from contaminant organisms; see also \Jdixenic\j \Jmonaxenic\j
\BAxinellida\b Order of tetractinomorph sponges found mainly in shallow tidal and sublittoral waters; typically branching form with the spicule-enclosing spongin fibres condensed axially or basally.
\Baxolotl\b \JAmbystomatidae\j
\Baye aye\b \JDaubentoniidae\j
\Bayu\b \JPlecoglossidae\j
\Bazalea\b \JEricaceae\j
\Bazara\b \JFlacourtiaceae\j
\Bazoic\b Without life.
\BAzoic\b The earliest geological period; the subdivision of the Precambrian era preceding the Archaeozoic; see geological time scale.
\Bazonal soil\b A soil lacking a well defined profile; a soil maintained in a permanently immature state by persistent deposition, truncation or erosion; see also \Jintrazonal soil\j \Jzonal soil\j
\Bazotification\b Nitrogen fixation.
\BAzygiida\b Order of digenetic trematodes in which the miracidium larva possesses a single pair of flame cells (excretory organs); the body of the cercaria is retracted into the tail.
\Bazygospore\b A spore produced from an unfertilized female gamete.
\Bazygote\b An organism produced by haploid parthenogenesis.
\Bbabbler\b \JTimaliidae\j
\Bbaboon\b \JCercopithecidae\j
\BBacillariophyceae\b Diatoms; large class of microscopic, unicellular chromophycote algae common in marine and freshwater habitats but also found in soil and damp moss; possessing an often ornate siliceous test (frustule) comprising 2 valves; chlorophylls \Ia\i and \Ic\i present with various xanthin pigments; reproduce by binary fission but sexual processes involving the production of haploid gametes are also found; comprises 2 orders, Centrales and Pennales; also treated as a distinct phylum of Protoctista under the name Bacillariophyta.
\BBacillariophyta\b The diatoms classified as a phylum of Protoctista; \JBacillariophyceae\j
\Bbackground radiation\b Natural radiation, comprising cosmic radiation (elementary particles from outer space) and terrestrial radiation (derived from the decay of naturally occurring isotopes).
\Bbackshore\b The zone of a beach above mean high water; also used for the zone covered only in exceptionally severe storms.
\BBacteria\b A division of moneran microorganisms with rigid or semi-rigid external walls containing peptidoglycans, except in the Mollicutes; divided into 19 groups identified by trivial names with no taxonomic significance, such as Mollicutes, Spirochaetes and Rickettsias; cell division usually occurs by binary fission, mitosis never occurs.
\Bbactericide\b An agent that destroys bacteria; \Bbactericidal.\b
\Bbacteriochlorophyll\b A form of chlorophyll found in photosynthetic bacteria.
\Bbacteriology\b The study of bacteria; \Bbacteriological.\b
\Bbacterioneuston\b The bacteria at the sea surface; the bacterial component of the neuston.
\Bbacteriophage\b 1: A virus infesting and usually lysing bacteria; often abbreviated to phage. 2: An organism that feeds on bacteria.
\Bbacteriophagous\b Feeding on bacteria; \Bbacteriophage\b, \Bbacteriophagy.\b
\Bbacteriostatic\b An agent inhibiting the growth of bacteria but not destroying them.
\Bbadger\b \JMustelidae\j
\Bbadland\b An arid or semi-arid area with scanty vegetation and marked surface erosion.
\BBagridae\b Family of primitive Old World catfishes (Siluriformes) found in fresh waters from Africa to southeast Asia; body naked, to 1 m length, dorsal fin short with strong spine; adipose fin usually large; 3 pairs of barbels present; larger species often utilized as foodfish, some small forms popular amongst aquarists.
\BBalaenidae\b Right whales; family of large (6-20 m) marine mammals (Mysticeta) comprising 3 species; baleen plates elongate; widespread except for tropical and south polar waters.
\BBalaenopteridae\b Rorquals; family of large (9-30 m) baleen whales (Mysticeta) found in northern and southern hemispheres; typically spending summers in high latitudes, migrating to warmer waters for winters; throat and chest region bearing numerous parallel grooves; contains 5 species including blue, humpback and minke whales.
\BBalanopaceae\b Small family of Fagales containing about 10 species of dioecious evergreen trees found in the southwestern Pacific region; male flowers borne in catkins, female flowers solitary with scale-like perianths; fruit an acorn-like drupe.
\BBalanophoraceae\b Family of Santalales containing about 60 species of fleshy root parasites, lacking chlorophyll and often fungus-like in appearance, widespread in tropical and subtropical regions.
\Bbald\b An elevated treeless area within a region of forest vegetation, usually grassy.
\Bbaleen whales\b \JMysticeta\j
\BBalistidae\b Triggerfishes, filefishes; family containing about 120 species of tropical marine tetraodontiform teleosts; body compressed with 2-3 dorsal fin spines; in triggerfishes the second spine locks against the first as a trigger, used to wedge the body in crevices.
\Bballistic\b Used of dehiscence in which the seeds are catapulted from the fruit.
\Bbalm\b \JLamiaceae\j
\Bbalsa\b \JBombacaceae\j
\BBalsaminaceae\b Touch-me-not, impatiens, busy Lizzie; family of Geraniales containing about 450 species of mostly glabrous herbs, mainly from the tropical Old World; flowers bisexual, commonly with 3 or 5 sepals, one forming a spur, 5 petals and stamens, and a superior ovary.
\Bbamboo\b \JBambusaceae\j
\Bbamboo rat\b \JRhizomyidae\j
\Bbamboo worm\b \JCapitellida\j
\BBambusaceae\b Bamboos; family of grass-like plants (Liliopsida) most of which have woody stems; may reach heights of 40 m; usually grow in clumps with a large underground rhizome; commonly treated as a subfamily of the \JPoaceae\j
\Bbanana\b \JMusaceae\j
\Bbandfish\b \JCepolidae\j
\Bbandicoot\b \JPeramelina\j
\BBangiales\b 1: Order of marine and freshwater red algae, of filamentous or parenchymatous body form. 2: \JBangiophycideae\j treated as a class of the phylum Rhodophyta.
\BBangiophycideae\b Subclass of red algae with thalli that are unicellular or consist of aggregations of cells that are filamentous or parenchymatous but of minimal complexity and in which cell division is predominantly intercalary; cells mostly uninucleate and with a single chloroplast; containing 4 orders Porphyridiales, Bangiales, Compsopogonales and Rhodochaetales; also treated as a class of the phylum Rhodophyta, under the name Bangiales.
\Bbanjo catfish\b \JAspredinidae\j
\Bbaobab\b \JBombacaceae\j
\Bbarachorous\b Having propagules dispersed by their own weight; \Bbarachore\b, \Bbarachory.\b
\Bbarb\b \JCyprinidae\j
\BBarbados cherry\b \JMalpighiaceae\j
\Bbarberry\b \JBerberidaceae\j
\Bbarbet\b \JCapitonidae\j
\BBarbeyaceae\b Family of Urticales containing a single species of small, dioecious tree native to northeast Africa and Arabia.
\BBarbourisiidae\b Whalefishes; monotypic cosmopolitan family of small (to 250 mm) bathypelagic beryciform teleosts; body stout and microscopically spinose; mouth very large, teeth minute; small pelvic fins present.
\BBarclayaceae\b Small family of water lilies (Nymphaeales) native to region from southeast Asia to New Guinea.
\Bbarokinesis\b A change of linear or angular velocity in response to a change in pressure; \Bbarokinetic.\b
\Bbarophilic\b Thriving under conditions of high hydrostatic or atmospheric pressure; \Bbarophile\b, \Bbarophily.\b
\Bbarotaxis\b A directed reaction of a motile organism to a pressure stimulus; \Bbarotactic.\b
\Bbarotropism\b An orientation response to a pressure stimulus; \Bbarotropic.\b
\Bbarracuda\b \JSphyraenidae\j
\Bbarracudina\b \JParalepididae\j
\BBarrandeoceratida\b Extinct order of cephalopod molluscs (Nautiloidea) known from the Middle Ordovician to the Middle Silurian; lacking cameral and siphuncular deposits.
\Bbarreleyes\b \JOpisthoproctidae\j
\Bbarren\b 1: Incapable of producing offspring; unproductive; infertile; incapable of producing seeds or fruit. 2: Devoid of vegetation, or of fossils.
\Bbarrial\b A mud flat.
\Bbarrier\b Any obstruction to the spread of an organism or to gene flow between populations; an unfavourable biological, climatic, geographical or other factor which prevents successful dispersal and establishment of a species.
\Bbarymorphosis\b Those structural changes in organisms that result from the effect of pressure or weight; \Bbarymorphic.\b
\Bbasal area\b 1: A cross-sectional area of a tree determined from the diameter of the trunk at breast height, 1.4m above ground. 2: The total area of ground covered by trees measured at breast height. 3: The actual surface area of soil covered or occupied by a plant measured close to the ground; ground cover.
\BBasellaceae\b Ulluco, Madeira vine; small family of tropical or subtropical herbs with twining or scrambling stems and thickened or tube-bearing rhizomes.
\Bbasic\b Rich in alkaline minerals and typically rich in nutrients as well; alkaline.
\Bbasic number\b The number of chromosomes in a basic chromosome set representing the lowest monoploid number in a polyploid series.
\BBasidiomycotina\b Basidiomycetes; subdivision of true fungi (Eumycota); characterized by sexual reproduction involving the formation of connections between hyphal cells so that each contains 2 compatible nuclei which fuse to form a basidium; meiotic division of the basidium produces 4 haploid basidiospores attached to the outside of the basidium; the basidia are arranged on a fruiting body (basidiocarp); comprises 4 classes, Teliomycetes, Phragmobasidiomycetes, Hymenomycetes and Gasteromycetes.
\Bbasidium\b The specialized spore-producing structure of Basidiomycote fungi on the surface of which are borne the haploid basidiospores.
\Bbasifuge\b A plant unable to tolerate basic soils.
\Bbasket shell\b \JNeogastropoda\j
\Bbasket star\b \JOphiuroidea\j
\Bbasking range\b The temperature range within which a reptile basking in direct sunlight remains inactive although alert.
\Bbasking shark\b \JCetorhinidae\j
\BBasommatophora\b Pond snails, ramshorn snails, freshwater limpets; order of pulmonate molluscs found in fresh water or along the margins of the sea; with unstalked eyes situated at the base of the tentacles and nearly contiguous genital pores.
\Bbasophilous\b Thriving in alkaline habitats; \Bbasophile\b, \Bbasophily.\b
\BBassleroceratida\b Extinct order of straight or curved cephalopod molluscs (Nautiloidea) in which the siphuncle is typically ventral and sutures often lobate; known from the Ordovician.
\BBataceae\b Small family containing 2 species of tropical maritime shrubs.
\BBatales\b Small order of Dilleniidae comprising 2 families of trees and shrubs producing mustard oil.
\BBatesian mimicry\b The close resemblance of a palatable or harmless species (the mimic) to an unpalatable or venomous species (the model) in order to deceive a predator; See also \Jmimicry\j
\Bbatfish\b \JOgcocephalidae\j
\Bbathophilous\b Thriving in deep-water habitats; \Bbathophile\b, \Bbathophily.\b
\Bbathyal\b 1: Pertaining to the sea floor between 200 m and 4000 m; see marine depth zones. 2: Pertaining to the deep sea.
\BBathydraconidae\b Family containing 15 species of antarctic perciform teleost fishes related to the Nototheniidae; body slender, to 160 mm length, depressed anteriorly with prolonged snout; single long dorsal fin present.
\BBathyergidae\b Mole rats; family containing 9 species of small fossorial hystricomorph rodents widespread in the Ethiopian region; body fusiform, limbs short and strong; eyes and ears vestigial; feeding mainly on roots and bulbs.
\BBathylagidae\b Black smelts; family containing 35 species of small (to 250 mm) deep-sea salmoniform teleost fishes resembling herring smelts (Argentinidae); body slender to deep; mouth small; eyes very large.
\Bbathylimnetic\b Pertaining to the deep-water regions of a lake.
\Bbathylittoral\b That part of the marine sublittoral zone that is devoid of algae.
\BBathymasteridae\b Ronquils; family containing 7 species of North Pacific, bottom-dwelling, coastal marine teleost fishes (Perciformes); body slender, to 300 mm length, single long dorsal fin present; dorsal and anal fins lacking spines.
\Bbathymetry\b The measurement of ocean or lake depth and the study of floor topography; \Bbathymetric.\b
\BBathynellacea\b Order of very small (0.5-3.5 mm) blind syncaridan crustaceans containing about 130 species found mostly in subterranean freshwater habitats but occasionally in saline waters; body vermiform, with reduced appendages as an adaptation to interstitial groundwater habitats; distributed worldwide.
\Bbathypelagic\b Living in deep water below the level of light penetration but above the abyssal zone, between 1000 m and 4000 m.
\Bbathyphilous\b 1: Thriving in lowlands. 2: Thriving in the deep sea; \Bbathyphile\b, \Bbathyphily.\b
\Bbathyplankton\b Planktonic organisms which undergo diurnal vertical migration, moving up towards the surface at dusk and down away from the surface at dawn; \Bbathyplanktonic\b; See also \Jepiplankton\j
\BBathypteroidae\b Tripod fishes; family containing 8 species of bottom-living deep-sea myctophiform teleosts; body cylindrical, becoming compressed posteriorly, snout depressed; eyes very small, teeth minute; photophores absent; some pelvic, pectoral and caudal fin rays elongate.
\BBathysauridae\b Family of bottom-living deep-sea lizard fishes (Myctophiformes) comprising 3 species which are widespread below about 900 m; body compressed, to 600 mm length, head depressed; teeth recurved, barbed, needle-like; photophores absent.
\Bbathyscaphe\b A free-moving manned vehicle for deep ocean exploration.
\Bbathysphere\b A spherical manned chamber suspended from a mother ship and lowered into the deep sea for underwater exploration.
\BBatoidea\b Superorder of mainly benthic marine elasmobranch fishes comprising about 450 species in 5 orders, Rhinobatiformes (guitarfishes), Rajiformes (skates and rays), Pristiformes (sawfishes), Torpediniformes (electric rays), Myliobatiformes (eagle, sting, devil rays); a few species epipelagic or freshwater; body more or less flattened dorsoventrally; pectoral and pelvic fins may be greatly expanded, anal absent, dorsal and caudal present or absent.
\Bbatology\b The study of brambles (Rosaceae).
\BBatrachoididae\b Toadfishes; family containing about 55 species of mostly marine bottom-dwelling teleosts; body naked or with tiny scales, length to 600 mm; head large, depressed, bearing barbels or flaps; dorsal fin spines may be venomous; photophores present in some species.
\BBatrachoidiformes\b Order of bottom-living predatory marine and freshwater teleost fishes comprising a single family, Batrachoididae (toadfishes).
\BBaventian glaciation\b An early glaciation of the Quaternary Ice \JAge\j in the British Isles.
\Bbay laurel\b \JLauraceae\j
\BB-chromosome\b A supernumary or accessory chromosome differing from normal A-chromosomes in morphology, genetic effectiveness and pairing behaviour.
\BBdelloida\b The sole order of the \JBdelloidea\j
\BBdelloidea\b Digonota; class of bottom-living aquatic rotifers found commonly in fresh water but also in damp moss and soil; body typically vermiform, covered with a glycoprotein cuticle; differentiated into a foot, trunk and head which bears a ciliated retractable corona with 2 trochal disks used for swimming and feeding; reproduction probably parthenogenetic; comprising a single order, Bdelloida.
\BBdellonemertea\b Small order of enoplan nemerteans found as commensals in marine bivalve molluscs; body dorsoventrally compressed, with an unarmed proboscis and a single posterior sucker.
\Bbeach\b The gently sloping strip of land along the margin of a body of water that is washed by waves or tides sufficiently to inhibit all or most plant growth.
\Bbeach flea\b Semiterrestrial amphipod crustacean capable of athletic jumping activity and often abundant along the strandline of the sea shore; sandhopper.
\Bbead tree\b \JElaeocarpaceae\j
\Bbeaked whale\b \JZiphiidae\j
\Bbean\b \JFabaceae\j
\Bbean weevil\b \JBruchidae\j
\Bbean wilt\b \JHypocreales\j
\Bbear\b \JUrsidae\j
\Bbeard worm\b \JPogonophora\j
\Bbeardfish\b \JPolymixiidae\j
\Bbeaver\b \JCastoridae\j
\Bbed\b A unit layer in a sequence of rock strata.
\Bbed load\b The quantity of rock and debris moved along a stream or river by the flow of water; See also \Jsilt load\j
\Bbedbug\b \JCimicidae\j
\Bbedding plane\b The division plane that separates individual beds or strata of a sedimentary or stratified rock.
\Bbee\b \JApidae\j (Apocrita, Aculeata).
\Bbee eater\b \JMeropidae\j
\Bbee fly\b \JBombyliidae\j
\Bbeech\b \JFagaceae\j
\BBeestonian glaciation\b A glaciation of the Quaternary Ice \JAge\j in the British Isles, with an estimated duration of 100 000 years.
\Bbeet\b \JChenopodiaceae\j
\Bbeetle\b \JColeoptera\j
\BBegoniaceae\b Begonia; large family of Violales containing about 1000 species of glabrous or often shaggy haired herbs to soft shrubs, largely tropical in distribution and including many garden ornamentals; leaves usually asymmetrical, flower stems in leaf axils often with branched inflorescences arranged with male flowers proximally and female flowers distally.
\Bbehaviour\b Any observable action or response of an organism.
\BBelemnoidea\b Belemnites; extinct order of cephalopod molluscs (Coleoidea) with an internal shell comprising phragmacone, rostrum and pro-ostracum; known from the Upper Carboniferous to the Eocene.
\Bbelladonna\b \JSolanaceae\j
\Bbellflower\b \JCampanulaceae\j
\BBelonidae\b Needlefishes, garfishes; family containing 25 species of surface-living piscivorous beloniform teleosts widespread in tropical and temperate seas; body elongate, to 2 m length; jaws prolonged bearing sharp teeth; pectoral fins short.
\BBeloniformes\b Order of primarily surface-living marine and freshwater teleost fishes comprising about 140 species in 5 families; including flying fishes, half-beaks, needlefishes, sauries.
\BBelontiidae\b Gouramis; family containing about 30 species of mostly small (to 150 mm) freshwater perciform teleost fishes from west Africa, India and southeast Asia; upper jaw protractile; utilize atmospheric oxygen through accessory respiratory structure, the suprabranchial organ; eggs laid in bubble nest at water surface.
\Bbelt\b A narrow strip or area of vegetation.
\Bbelt transect\b A narrow belt of predetermined width set out across a study area, and within which the occurrence or distribution of plants and animals is recorded.
\Bbeluga\b \JMonodontidae\j, white whale.
\BBenguela Current\b A cold surface ocean current that flows northwards off the east coast of Africa and forms the easterly limb of the South Atlantic Gyre; see ocean currents.
\BBennettitales\b Order of gymnosperms resembling the cycads, known only as fossils from the Mesozoic era; reproductive structures resembled flowers rather than cones.
\Bbenthic\b Pertaining to the sea bed, river bed or lake floor; benthonic; See also \Jpelagic\j
\Bbenthogenic\b Derived from the \Jbenthos\j
\Bbenthonic\b \JBenthic\j
\Bbenthophyte\b A plant living at the bottom of a water body or on the bed of a river.
\Bbenthopleustophyte\b Any large plant resting freely on the floor of a lake but capable of drifting slowly with the currents.
\Bbenthopotamous\b Living on the bed of a river or stream.
\Bbenthos\b Those organisms attached to, living on, in or near the sea bed, river bed or lake floor; see also \Jendobenthos\j \Jepibenthos\j, \Jhaptobenthos\j, \Jherpobenthos\j, \Jpsammon\j, \Jrhizobenthos\j.
\BBerberidaceae\b Barberry; large family of often spiny shrubs or herbs belonging to the Ranunculales; containing about 650 species widespread in the temperate northern hemisphere; flowers composed of free parts in 2-7 whorls which vary in morphology; ovary consists of a single carpel; fruit a berry or capsule.
\BBergmann's rule\b The generalization that geographically variable species of warm-blooded vertebrates tend to be represented by larger races in the colder parts of their range than in the warmer parts.
\Bberm\b The large deposits of dry loose sediment above the high tide line on a beach.
\BBeroida\b Small order of pelagic ctenophores with a worldwide distribution; body strongly flattened in the tentacular plane, lacking tentacles and tentacle bulbs.
\Bberry\b A fleshy indehiscent fruit containing many seeds and surrounded by a tough outer skin derived from the outer fruit wall (epicarp); includes the grape and tomato.
\BBerycidae\b Alfonsinos; cosmopolitan family containing 10 species of mainly deep-sea beryciform teleost fishes; body oval, compressed, length to 600 mm, scales ctenoid or cycloid; eyes and mouth large, teeth small; dorsal and anal fins robustly spinose.
\BBeryciformes\b Diverse order of marine teleost fishes comprising about 160 species in 13 families widespread in benthic and pelagic habitats of coastal waters and continental slopes to about 1300 m depth; body typically oblong, compressed, with relatively large head, mouth and eyes; includes pricklefishes, slimeheads, fangtooth, alfonsinos, lanterneyes, squirrelfishes and whalefishes.
\Bbetel nut\b \JPiperaceae\j
\BBetulaceae\b Birch, alder; family of Fagales containing about 120 species of trees or shrubs widely distributed in the temperate and cold temperate regions of northern hemisphere; flowers arranged in unisexual catkins; fruit is a samara.
\BB-horizon\b The upper subsoil horizon with an accumulation of clay, humus, iron and sesquioxides as a result of leaching and translocation from upper layers; see soil horizons.
\Bbibulous\b Highly absorbent; capable of absorbing water.
\Bbichir\b \JPolypteridae\j
\Bbiennial\b Lasting for 2 years; occurring every 2 years; requiring 2 years to complete the life cycle; see also \Jannual\j \Jperennial\j
\Bbiferous\b Producing fruit twice a year, or producing two crops per season.
\Bbiflorous\b Flowering in both spring and autumn.
\Bbight\b A large indentation in the coastline or continental shelf margin (seabight).
\BBignoniaceae\b Flame tree, empress tree, African tulip tree, calabash tree, trumpet creepers; family of Scrophulariales containing about 800 species of mostly woody plants, often vines, with large showy flowers; mainly tropical in distribution, especially tropical America; flowers usually borne in cymose clusters; petals and sepals fused, ovary superior; fruit commonly a capsule containing small winged seeds.
\Bbillfish\b \JIstiophoridae\j
\Bbillion\b A thousand million, 10\U9\u; this United States value has been adopted internationally; formerly a value of 10\U12\u (a million million) was widely used.
\Bbinary fission\b Division into two parts; the commonest form of asexual reproduction in protistans.
\Bbindweed\b \JConvolvulaceae\j
\Bbioassay\b Biological assay; the use of an organism for assay purposes.
\Bbiocenosis\b \JBiocoenosis\j
\Bbiochemical oxygen demand (BOD)\b The amount of oxygen required to degrade the organic material and to oxidize reduced substances in a water sample; used as a measure of the oxygen requirement of bacterial populations and serving as an index of water pollution; biological oxygen demand.
\Bbiochronology\b The dating of biological events using biostratigraphic or palaeontological methods.
\Bbiocide\b A chemical toxic or lethal to living organisms.
\Bbioclast\b A single fossil fragment.
\Bbioclastic sediment\b A sediment composed of broken fragments of organic skeletal material.
\Bbioclimatic law\b Any \Jclimatic rule\j
\Bbioclimatology\b The study of climate in relation to fauna and flora.
\Bbiocoenology\b The qualitative and quantitative study of communities of organisms.
\Bbiocoenosis\b A community or natural assemblage of organisms; often used as an alternative to ecosystem but strictly it is the fauna/flora associations themselves, excluding physical aspects of the environment; biocenosis; See also \Jthanatocoenosis\j
\Bbiodegradable\b Capable of being decomposed by natural processes.
\Bbioenergetics\b The study of energy flow through ecosystems; ecological energetics.
\Bbioerosion\b Erosion resulting from the direct action of living organisms.
\Bbiofacies\b A subdivision of a sedimentary unit based on a distinctive assemblage of fossils.
\Bbiogenesis\b The principle that all living organisms have derived from previously existing living organisms; \Bbiogenetic\b; See also \Jabiogenesis\j
\Bbiogenetic\b Produced by the activity of living organisms; \Bbiogenic.\b
\Bbiogenetic law\b The theory that an individual during its development passes through stages that resemble adult forms of its successive ancestors so that the ontogeny of an individual recapitulates the phylogeny of its group; recapitulation.
\Bbiogenic meromixis\b The mixing of a lake caused by an accumulation in the monimolimnion of salts liberated from the sediment by biological activity; see also \Jcrenogenic meromixis\j \Jectogenic meromixis\j
\Bbiogenous\b Living on or in other organisms; symbiotic.
\Bbiogeochemical cycle\b The cyclical system through which a given chemical element is transferred between biotic and abiotic parts of the biosphere, as for example in the carbon and nitrogen cycles.
\Bbiogeochemistry\b The study of mineral cycling and of organism-substrate relationships.
\Bbiogeographical region\b Any geographical area characterized by distinctive flora and/or fauna.
\Bbiogeography\b The study of the geographical distributions of organisms, their habitats (ecological biogeography) and the historical and biological factors which produced them (historical biogeography).
\Bbiogeosphere\b That part of the \Jlithosphere\j within which living organisms can occur; eubiosphere.
\Bbioglyph\b A trace fossil.
\Bbioherm\b 1: Any organism contributing to the formation of a coral reef. 2: A mound-like accumulation of fossil remains on the site where the organisms lived; \Bbiohermal.\b
\Bbiolith\b A rock of organic origin.
\Bbiological\b Pertaining to living organisms or life processes.
\Bbiological amplification\b The concentration of a given persistent substance by the organisms in a food chain so that the amount of the substance present in the body increases at each successive trophic level.
\Bbiological clock\b An inherent physiological mechanism for measuring time or maintaining endogenous rhythms.
\Bbiological control\b The control of a pest by the introduction, preservation or facilitation of natural predators, parasites or other enemies, by sterilization techniques, by the use of inhibitory hormones or by other biological means.
\Bbiological mineralization\b The biological decomposition of organic compounds and liberation of inorganic minerals; See also \Jimmobilization\j
\Bbiological races\b The sympatric populations of a species which differ biologically but not morphologically and in which interbreeding is inhibited by different food or host preferences or behaviour cycles.
\Bbiological rhythm\b A regular periodicity exhibited by biological processes.
\Bbiological species\b Groups of actually or potentially interbreeding natural populations genetically isolated from other such groups by one or more reproductive isolating mechanisms; biospecies.
\Bbiological weathering\b Changes in soil structure and composition resulting from biotic activity, as part of the soil-forming process.
\Bbiology\b The science of life; the study of living organisms and systems; \Bbiological.\b
\Bbioluminescence\b Light produced by living organisms and the emission of such biologically produced light; \Bbioluminescent\b; See also \Jphosphorescence\j
\Bbiolysis\b Death and subsequent tissue degradation of an organism.
\Bbiomass\b Any quantitative estimate of the total mass of organisms comprising all or part of a population or any other specified unit, or within a given area at a given time; measured as volume, mass (live, dead dry or ash-free weight) or energy (calories); standing crop.
\Bbiome\b A biogeographical region or formation; a major regional ecological community characterized by distinctive life forms and principal plant (terrestrial biomes) or animal (marine biomes) species; see map on page 48.
\Bbiometeorology\b Study of the effects of atmospheric conditions on living organisms.
\Bbiometrics\b The application of statistical methods to biological problems and the mathematical analysis of biological data.
\Bbiomineralization\b The process by which organisms produce skeletal structures containing crystalline or amorphous inorganic substances.
\Bbionomics\b Ecology; the study of organisms in relation to environment.
\Bbiont\b An individual organism.
\Bbiophagous\b Consuming or destroying other living organisms; \Bbiophage\b, \Bbiophagy\b; See also \Jsaprophagous\j
\Bbiophilous\b Thriving on other living organisms, often used specifically of plant parasites; \Bbiophile\b, \Bbiophily.\b
\Bbiophysics\b The application of physics to the study of living organisms and systems.
\Bbiophyte\b A plant that feeds on other living organisms; a parasitic or predatory plant.
\Bbiopoiesis\b The origin of life, including the abiotic synthesis of macromolecular systems and the transformation (eobiogenesis) of these systems into the first living organisms (eobionts).
\Bbioseston\b Plankton, nekton and suspended organic particulate matter derived from living organisms; the biological component of seston.
\Bbiospecies\b 1: A biological \Jspecies\j 2: A species defined primarily on biological characters.
\Bbiospeleology\b The study of subterranean life.
\Bbiosphere\b The global ecosystem; that part of the Earth and atmosphere capable of supporting living organisms.
\Bbiostratigraphy\b The study and classification of rock strata based on their fossil content; stratigraphic palaeontology; \Bbiostratigraphic.\b
\Bbiostratinomy\b The study of the relationship between fossils and their environments.
\Bbiostrome\b An accumulation of fossils that are distinctly bedded but do not form a mound-like or reef-like structure (bioherm); a fossil bed having no pronounced topographical relief.
\Bbiosynthesis\b The production of organic compounds by living organisms.
\Bbiota\b The total flora and fauna of a given area.
\Bbiotaxis\b The directed reaction of a motile organism towards (positive) or away from (negative) a biological stimulus; \Bbiotactic.\b
\Bbiotelemetry\b Study of the behaviour and activity of organisms using remote detection and transmission equipment; radio tracking.
\Bbiothermal\b Pertaining to the interrelationship of temperature and living organisms.
\Bbiotic\b Pertaining to life or living organisms; caused by, produced by, or comprising living organisms; See also \Jabiotic\j
\Bbiotic climax\b A plant community maintained at climax by some biotic factor such as grazing.
\Bbiotic community\b 1: A group of interacting species coexisting in a particular habitat; community. 2: In palaeontology, a group of species frequently found together.
\Bbiotic potential\b The maximum potential rate of increase of an organism or population under ideal conditions; reproductive potential.
\Bbiotic pyramid\b A diagrammatic representation of the successive trophic levels of a food chain in the form of a pyramid of numbers, with primary producers at the base and the sequence of consumers leading to the apex.
\Bbiotope\b 1: The smallest geographical unit of the biosphere or of a habitat that can be delimited by convenient boundaries and is characterized by its biota. 2: The location of a parasite within the host's body.
\Bbiotrophic\b Used of a parasite deriving nutrients from the tissues of a living host; \Bbiotroph\b, \Bbiotrophy.\b
\Bbioturbation\b The mixing of a sediment by the burrowing, feeding or other activity of living organisms.
\Bbiparous\b 1: Producing two offspring in a single brood; \Bbiparity\b; see also \Juniparous\j \Jmultiparous. 2: Having produced only one previous brood\j
\Bbipinnaria\b A free-swimming, planktonic larval stage of starfishes, possessing two separate bands of cilia looping around paired lobes on the body.
\Bbipolarity\b The occurrence of species or forms in both northern and southern hemispheres but not in the intervening equatorial belt; \Bbipolar.\b
\BBiraphideae\b Order of pennate diatoms (Pennales) possessing a fully differentiated raphe on each valve; also treated as a suborder, Biraphidineae.
\Bbirch\b \JBetulaceae\j
\Bbird of paradise\b \JParadisaeidae\j
\Bbird-of-paradise flower\b \JStrelitziaceae\j
\Bbird\b \JAves\j
\Bbird's-nest fungus\b \JNidulariales\j
\Bbirdwing butterfly\b \JPapilionidae\j
\Bbirth rate\b The number of offspring produced per head of population per unit time; natality.
\Bbisect\b A profile of vegetation and soil showing the natural distribution of growth above and below ground; a cross-section of vegetation and soil as revealed by a trench extending down to the deepest plant roots.
\Bbisexual\b 1: Used of a population or generation composed of functional males and females; gonochoristic. 2: Used of an individual possessing both male and female functional reproductive organs; hermaphrodite. 3: Used of a flower possessing both male and female reproductive organs; perfect; See also \Junisexual\j
\Bbiting midge\b \JCeratopongonidae\j
\Bbittern\b \JArdeidae\j
\Bbitterroot\b \JPortulaceae\j
\BBivalvia\b Bivalves; a large class of marine, estuarine a and freshwater molluscs which are ciliary or filter feeders on small particles; characterized by a shell of two calcareous valves joined by a flexible ligament alon a hinge line; head not differentiated; gills large, ciliated and involved in feeding; also known as Pelecypoda or Lamellibranchia; comprising 5 extant subclasses, Anomalodesmata, Heterodonta, Paleoheterodonta, Protobranchia and Pteriomorpha.
\BBivalvulida\b Order of \JMyxosporea\j characterized by having a spore with 2 shell valves.
\Bbivoltine\b Having two generations or broods per year; See also \Jvoltine\j
\BBixaceae\b Lipstick tree; small family of Violales containing about 20 species of tropical trees or shrubs which produce a red or orange secretion inside specialized cells or canals.
\Bblack coral\b \JAntipatharia\j
\Bblack earth\b \JChernozem\j
\Bblack fly\b \JSimuliidae\j
\Bblack mildew\b \JMeliolales\j
\Bblack mud\b A terrigenous marine sediment, black in colour, rich in hydrogen sulphide and having a high organic content; typical of poorly ventilated anaerobic basins.
\Bblack smelt\b \JBathylagidae\j
\Bblackberry\b \JRosaceae\j
\Bblackbird\b 1: \JIcteridae\j 2: \JTurdidae\j
\Bblackfly\b \JAphididae\j
\Bblackwater\b Water rich in humic acids and with low nutrient concentrations.
\Bbladdernut\b \JStaphyleaceae\j
\Bbladderwort\b \JLentibulariaceae\j
\Bblastochorous\b Pertaining to a plant that is dispersed by means of offshoots; \Bblastochore.\b
\BBlastocladiales\b Order of chytridiomycete fungi comprising about 50 species of saprophages or microscopic parasites with a fungal thallus differentiated into root-like filaments and reproductive structures, sometimes with incomplete cross walls (pseudosepta): also treated as a class of the protoctistan phylum Chytridiomycota, under the name Blastocladia.
\BBlastodiniales\b Small order of ectoparasitic marine dinoflagellates found on invertebrate and fish hosts.
\Bblastogenesis\b Asexual reproduction by budding or gemmation.
\BBlastoidea\b Extinct class of sessile, bud-like echinoderms (Pelmatozoa); with well developed pentamerous symmetry and biserial brachioles; theca composed of 17 major plates arranged in 3 circlets; known from the Silurian to the Lower Permian.
\BBlattaria\b Cockroaches; order of active orthopterodean insects with a depressed body and long cursorial legs; forewings hard or leathery, hindwings membranous, but may be reduced or absent; typically live on the ground under stones, in litter and wood debris, in nests, or in caves; contains about 3700 species, a few of which are household pests.
\BBlenniidae\b Combtooth blennies; family containing about 275 species of tropical to temperate, shallow marine, brackish and freshwater, perciform teleost fishes; body length to 600 mm, but usually much smaller; scales absent or vestigial.
\BBlennioidei\b Blennies; suborder of perciform teleost fishes comprising about 650 species in 15 families; pelvic fins when present in jugular position; total number of dorsal and anal fin rays equal to number of vertebrae.
\Bbletting\b The change in consistency, without putrefaction, of some fruits.
\Bblight\b A non-specific name for a variety of plant diseases, typically caused by a fungus.
\Bblind shark\b \JBrachaeluridae\j
\Bblister beetle\b \JMeloidae\j
\Bbloom\b An explosive increase in the density of phytoplankton within an area.
\Bblow off\b The loss of humus and loose top soil by wind action.
\Bblowfly\b \JCalliphoridae\j
\Bblowout\b A small area of land from which all of most of the soil has been removed by wind erosion; an excavation in sandy ground produced by wind action.
\Bblue\b \JLycaenidae\j
\Bblue mud\b A terrigenous marine sediment, blue in colour, formed under mildly reducing conditions, similar to a green mud.
\Bblue shark\b \JCarcharhinidae\j
\Bblue whale\b \JBalaenopteridae\j
\Bbluebell\b \JLiliaceae\j
\Bblueberry\b \JEricaceae\j
\Bbluebird\b \JTurdidae\j
\Bbluebottle\b \JCalliphoridae\j
\Bbluefish\b \JPomatomidae\j
\Bbluegrass\b \JPoaceae\j
\Bblue-green algae\b \JCyanophycota\j
\Bblue-green bacteria\b \JCyanobacteria\j
\BBlytt-Sernander climatic classification\b A classification of late glacial and postglacial climate based on stratigraphic evidence from plant remains; comprising the Arctic, Preboreal, Boreal, Atlantic, Subboreal and Subatlantic periods.
\Bboarfish\b \JCaproidae\j
\Bbobcat\b \JFelidae\j
\Bbody louse\b \JAnoplura\j
\Bbog\b An area of wet peaty substrate rich in organic debris but low in mineral nutrients, with a vegetation of ericaceous shrubs, sedges and mosses.
\BBog soil\b An intrazonal soil with a muck or peat surface layer and an underlying peat horizon over an impervious grey-blue clay, formed in boggy or swampy conditions; typical of glaciated basins.
\BBoidae\b Pythons, anacondas, boas; family of small to very large (to 10 m) non-venomous constrictor snakes (Serpentes); left lung and vestige of pelvic girdle present; habits terrestrial, fossorial, arboreal or semiaquatic; feeding on variety of birds and mammals; reproduction oviparous or viviparous; containing about 60 species with pantropical distribution.
\BBoletaceae\b Boletes; family of fungi (Agaricales) which produce typical mushroom-shaped fruiting bodies; fertile spore-producing layer present lining tubes on underside of the cap, replacing the gills; often found in mycorrhizal association with trees.
\Bbolete\b \JBoletaceae\j
\Bbolochorous\b Having propagules dispersed by propulsive mechanisms; \Bbolochore\b, \Bbolochory.\b
\BBombacaceae\b Balsa, baobab, kapok tree, silkcotton tree; small family of Malvales containing about 200 species of trees, commonly with light and soft wood and large showy flowers which are typically asymmetrical with 5 sepals, 5 or many stamens and a superior ovary; fruit is a large woody capsule.
\Bbombadier beetle\b \JCarabidae\j
\BBombay duck\b \JHarpadontidae\j
\BBombycidae\b Family of broad robust moths (Lepidoptera) from Asia that comprises about 100 species, including the domesticated silkworm that no longer exists in the wild; commercial silk is derived from the pupal cocoon.
\BBombycillidae\b Waxwings, silky flycatchers; family containing 9 species of passerine birds found in forest and open grassland habitats in the northern hemisphere; bill short and stout, with wide gape; feeds on insects and fruit; typically gregarious and monogamous; construct cup-shaped nests in trees.
\BBombyliidae\b Bee flies; cosmopolitan family containing about 4000 species of nectar-feeding flies (Diptera) with robust hairy bodies; commonly found hovering over flowers in sunny habitats; larvae parasitic on eggs or larvae of other insects.
\Bbonding\b The formation of a close relationship between two or more individuals; \Bbond.\b
\Bbone bed\b A stratum rich in fragments of fossil vertebrates.
\Bbonefish\b \JAlbulidae\j
\Bbonytongue\b \JOsteoglossidae\j
\Bbooby\b \JSulidae\j
\BBooidea\b Superfamily of primitive nonvenomous snakes (Serpentes) retaining a moderately developed left lung and vestige of pelvic girdle; contains about 135 species including the large constrictors (boas and pythons).
\Bbook louse\b \JLiposcelidae\j (Psocoptera).
\BBoraginaceae\b Anchusa, lungwort, forget-me-not; widely distributed family of Lamiales containing about 2000 species of herbs or woody plants commonly provided with unicellular hairs often with mineralized walls; flowers bisexual, usually regular and with 5 sepals, 5 petals forming a tube or funnel, 5 stamens and a superior ovary.
\BBordeaux mixture\b A common fungicide, containing copper sulphate and calcium hydroxide.
\Bboreal\b Pertaining to cool or cold temperate regions of the northern hemisphere: See also \Jantiboreal\j
\BBoreal kingdom\b One of the six major phytogeographical areas characterized by floristic composition; comprising Atlantic North American, Arctic and Subarctic, Euro-Siberian, Macaronesian, Mediterranean, Pacific North American, Sino-Japanese and Western and Central Asiatic regions.
\BBoreal period\b A period of the Blytt-Sernander classification (\Ic.\i 9000-7500 years B.P. ), characterized by pine and hazel vegetation and by relatively warm and dry conditions
\Bborer\b \JBostrichidae\j
\BBorhyaenoidea\b Extinct superfamily of carnivorous marsupials (Metatheria) known from the Palaeocene to the Pliocene in South America; the largest attained the size of a wolf.
\BBoston ivy\b \JVitaceae\j
\BBostrichidae\b Borers; family of small, dark beetles (Coleoptera); head tucked under rounded thorax; curved larvae are fleshy with tiny head; bore into dead or dying trees, grain, bamboo and other plant material.
\Bbotany\b The study of plants; \Bbotanical.\b
\Bbotfly\b 1: \JCuterebridae\j. 2: \JOestridae\j
\BBothidae\b Cosmopolitan family containing about 210 species of pleuronectoid flatfishes in which the eyes are on the left side of the head; body length to 1.5 m.
\BBothriocidaroida\b Extinct order of sea urchins (Echinoidea) known from the Middle Ordovician to the Upper Silurian; test with 2 columns of perforate plates and 1 of imperforate plates.
\Bbottle urchin\b \JSpatangoida\j
\Bbottleneck\b A sudden decrease in population density with a corresponding reduction of total genetic variability.
\Bbottletree\b \JSterculiaceae\j
\Bbottom water\b The dense, deep oceanic water mass formed by the cooling and sinking of surface waters at high latitudes.
\Bbougainvillea\b \JNyctaginaceae\j
\Bboulder\b A large sediment particle greater than 256 mm in diameter and too big to be handled easily; see sediment particle size.
\Bboundary layer\b The layer of fluid adjacent to a physical boundary in which the fluid motion is significantly affected by the boundary and has a mean velocity less than the free stream value.
\BBourgueticrinida\b Order of articulate crinoids in which the stalk is typically slender, cirri are absent, and attachment is by a terminal plate or root-like branches; about 40 extant species in 3 families, found from shelf to 9500 m depth.
\BBovidae\b Cattle, antelopes, gazelles, goats, sheep; diverse family of herbivorous terrestrial ungulates (Artiodactyla: Ruminantia); comprising about 110 species found in wide range of habitats from tundra to tropical forest in Holarctic, Ethiopian and Oriental Regions; now cosmopolitan through domestication; unbranched horns present in males and females of many species; horn core permanent - not shed annually as in deer.
\BBovoidea\b Superfamily of artiodactyls (Pecora) comprising the pronghorn (Antilocapridae) and the cattle, sheep, antelopes and gazelles (Bovidae); horns are present and covered with keratin (horn) rather than skin.
\Bbowerbird\b \JPtilonorhynchidae\j
\Bbowfin\b \JAmiidae\j
\Bboxfish\b \JOstraciontidae\j
\Bboxwood\b \JBuxaceae\j
\BBrachaeluridae\b Blind sharks; family containing 2 species of small (to 1 m) bottom-dwelling orectolobiform elasmobranch fishes found on rocky reefs of eastern Australia; body cylindrical, head broad and depressed, nostrils with long barbels; caudal fin lacking ventral lobe.
\Bbrachiation\b Progression in trees by swinging from branch to branch using the forelimbs; \Bbrachiating.\b
\Bbrachiolaria\b Late larval stage of some starfish possessing conspicuous larval arms and a glandular adhesive sucker.
\BBrachionichthyidae\b Family of little-known Australian anglerfishes (Lophiiformes) resembling the frogfishes (Antennariidae); body small, globose and denticulate.
\BBrachiopoda\b Lamp shells; phylum of solitary, unsegmented marine coelomates possessing a bivalve shell and typically attached to the substratum by a stalk (pedicle); a few species are unattached or cemented directly to substratum; ventral value usually larger than dorsal; body with looped or spiral array of tentacles (lophophore); gut simple. Brachiopods range from intertidal to 7500 m in cool-temperate or cold regions; 350 species in 2 living classes, Inarticulata, Articulata; abundant in Palaeozoic seas with 12 000 fossil species described.
\BBrachiopterygii\b Group of bony fishes (Osteichthyes) possessing spinous dorsal finlets, ganoid scales, lobate pectoral fins, a spiracle, and a pair of lung-like air bladders; includes the bichir and reedfishes (\JPolypteridae\j)
\BBrachycephalidae\b Small family of terrestrial toads (Anura) from southeastern Brazil comprising 2 species; body length to only 15 mm; forelimbs with only 2 functional digits, hindlimbs with 3; development thought to be direct, with terrestrial eggs.
\BBrachycera\b Suborder of flies (Diptera) comprising about 69 000 species including soldier flies, horseflies, clegs, robberflies, bee flies, hoverflies, fruitflies, vinegarflies, shore flies, botflies, houseflies, blowflies, fleshflies, warble flies and tsetse flies.
\BBrachydiniales\b Small order of marine unicellular dinoflagellates.
\BBrachypoda\b \JCephalocarida\j
\BBrachyura\b Crabs; largest infraorder of pleocyematan decapod crustaceans containing all true crabs; abdomen permanently flexed beneath carapace.
\Bbrackish\b Pertaining to water of salinity intermediate between fresh water and sea water; brackish water may be classified according to salinity as mesohaline, oligohaline or polyhaline.
\BBraconidae\b Braconid wasps; family of small, parasitic wasps (Apocrita) related to the ichneumons; eggs laid on larvae of other insects which are then parasitized and consumed before pupation.
\BBradypodidae\b Tree sloths; family containing 5 species of arboreal herbivorous Neotropical mammals (Edentata); teeth simple, peg-like; limbs elongate, bearing 2-3 strong claws, used for hanging from branches and clinging to trunks; tail vestigial; feed mainly on leaves.
\Bbramble shark\b \JEchinorhinidae\j
\BBramidae\b Pomfrets; cosmopolitan family containing 20 species of mostly mid-water oceanic teleost fishes (Perciformes); body deep, compressed, to 800 mm length; body scales spiny or ridged; single long dorsal fin present.
\Bbranchicolous\b Living on the gills of fishes or other aquatic organisms; \Bbranchicole. \b
\BBranchiobdellida\b Subclass of minute (3-10 mm) hirudinoidean worms (Annelida) ectoparasitic on freshwater crayfish; body with 15 segments each bearing 2 annuli; pharynx with strong jaws; anterior and posterior sucker present; comprises a single family containing 10 genera, formerly classified with oligochaetes.
\BBranchiopoda\b Class of small aquatic crustaceans inhabiting mostly inland waters ranging from fresh to hypersaline, occasionally marine; contains about 820 extant species in 4 orders, Notostraca (tadpole shrimps), Anostraca (fairy shrimps), Conchostraca (clam shrimps), Cladocera (water fleas).
\BBranchiostegidae\b Tilefishes; family containing 25 species of bottom-living, tropical and warm-temperate, marine teleosts (Perciformes); body elongate, compressed, to 1 m length; head rather square, often with high dorsal crest; single dorsal fin present.
\BBranchiura\b Fish lice; class of ectoparasitic crustaceans found on freshwater and coastal marine fishes, or rarely on amphibians; capable of swimming but typically attaching to host by paired suckers, feeding on host's blood and mucus by means of a sucking tubular mouth; contains about 150 species in a single order, Arguloida.
\BBrandenburg glaciation\b A subdivision of the Weichselian \Jglaciation\j
\BBrassicaceae\b Crucifers; cabbage family; turnip, honesty, watercress, horse radish, swede, rape, stocks, pepper root, radish, wallflower, candytuft; large family of Capparales containing about 3000 species of mostly herbs found mainly in temperate regions; many are cultivated for food or ornament; flowers typically with 4 sepals, 4 petals arranged in a cross, 6 stamens and a superior ovary; many are rich in sulphur.
\BBraun-Blanquet cover scale\b A scale for estimating cover of a plant species, comprising 6 categories: + (under 1%), 1 (1-5%), 2 (6-25%), 3 (26-50%), 4 (51-75%), and 5 (76-100%).
\BBrazil Current\b A weak, warm surface current that flows south off the coast of Brazil and forms the westerly limb of the South Atlantic Gyre; see ocean currents.
\BBrazil nut tree\b \JLecythidales\j
\Bbread mould\b \JMucorales\j
\Bbreadfruit\b \JMoraceae\j
\Bbreed\b 1: To reproduce. 2: To propagate organisms under controlled conditions. 3: A group of organisms related by descent; an artificial mating group having a common ancestor; used especially in genetic studies of domesticated species.
\Bbreeding system\b The mode, pattern and extent to which individuals interbreed with others from the same or different taxa.
\BBregmacerotidae\b Codlets; family containing 7 species of aberrant pelagic warm-water gadiform teleost fishes cosmopolitan in tropical and subtropical seas; first dorsal fin represented by solitary fin ray on top of head; second dorsal fin and anal fin elongate; pelvic fin rays markedly prolonged.
\Bbrephic stage\b A pre-adult stage; a larval stage.
\BBretschneideraceae\b Family of Sapindales containing a single species of deciduous tree producing mustard oil, native to the mountains of western China.
\Bbridal wreath\b \JRosaceae\j
\Bbrill\b \JScophthalmidae\j
\Bbrimstone butterfly\b \JPieridae\j
\Bbrine fly\b \JEphydridae\j
\Bbrine shrimp\b \JAnostraca\j
\Bbristlemouth\b \JGonostomatidae\j
\Bbristletail\b \JThysanura\j
\Bbristleworm\b \JPolychaeta\j
\Bbrittle star\b \JOphiuroidea\j
\Bbroadbill\b \JEurylaimidae\j
\BBromeliales\b Bromeliads, Spanish moss, pineapple, puya; order of Zingiberidae comprising a single family, Bromeliaceae, of mostly short-stemmed epiphytic herbs containing silica bodies, with firm, succulent leaves which are narrow, parallel-veined and often spiny-margined, arranged so that rainwater is channelled into a reservoir formed by the sheathing leaf bases; the 2000 species are widely distributed in America, mostly in the tropics.
\BBrontotheriidae\b Extinct suborder of large, rhinoceros-like mammals (Perissodactyla) which flourished during the Eocene and the Oligocene; limbs short and massive, teeth primitive, skull long and low with small braincase; includes brontotheres and titanotheres.
\BBronze Age\b An archaeological period dating from about 5000 years in Europe; a period of human history characterized by the use of bronze tools.
\Bbronze leaf\b \JSaxifragaceae\j
\Bbrood\b 1: The offspring of a single birth or clutch of eggs; any group of young animals that are being cared for together by an adult. 2: To incubate eggs.
\Bbrood parasitism\b The use of a host species to brood the young of another species (the parasite).
\BBrooksellida\b The sole order of the class \JProtomedusae\j
\Bbroom\b \JFabaceae\j
\Bbroticolous\b Living in close proximity to man, in dwelling houses or other buildings; \Bbroticole.\b
\Bbrotochorous\b Having propagules dispersed by the agency of man; \Bbrotochore\b, \Bbrotochory.\b
\Bbrotula\b \JOphidiidae\j
\BBrotulidae\b \JOphidiidae\j
\Bbrown algae\b \JPhaeophyceae\j
\Bbrown clay\b A pelagic sediment comprising an accumulation of volcanic and aeolian dust with less than 30% biogenic material.
\BBrown Earth\b Brown Forest \Jsoil\j
\BBrown Forest soil\b An intrazonal soil with a mull horizon but no pronounced illuvial layer, derived from calcium-rich parent material under deciduous forest in temperate conditions; typically with negligible litter, dark brown friable A-horizon and lighter coloured B-horizon; Brown Earth.
\BBrown Podzolic soil\b A zonal soil similar to Podzol \Jsoil\j but lacking the highly leached intermediate horizon; typically with moderate layer of litter and duff, dark greyish brown A-horizon and a granular light brown acidic B-horizon.
\BBrown soil\b A zonal soil with dark brown to greyish brown, slightly alkaline A-horizon and lighter coloured B-horizon over calcareous material, formed in temperate to cool arid climates.
\Bbrown water\b Fresh water rich in suspended organic matter but having a low nutrient content.
\Bbrowse\b 1: To feed on parts of plants; \Bbrowser.\b 2: The edible plant material within reach of browsing animals.
\Bbrowse line\b A line marking the height to which browsing animals have been feeding.
\BBruchidae\b Bean weevils, pea weevils; widespread family of beetles (Coleoptera) with the head usually constricted behind the eyes to form a neck; all feed on seeds, especially of leguminous plants, and several are pests of stored products; contains about 1500 species.
\BBrunelliaceae\b Small family of Rosales containing about 50 species of evergreen trees native to tropical America.
\BBruniaceae\b Small family of Rosales containing about 75 species of shrubs native to South Africa.
\BBrunizem\b Prairie \Jsoil\j
\BBrunoniaceae\b Family of Campanulales containing a single species of perennial herbs storing carbohydrates as inulin and having a special type of surface hair; native to Australia; flowers borne terminally on long heads; 5 sepals united into lobed tube, 5 petals and a superior ovary; fruit is a small nut.
\BBryales\b Large, cosmopolitan order of mosses (Bryidae); mat-forming annual or perennial plants occurring mainly on logs, soil or humus in both stable and disturbed habitats; stems usually erect, simple or sparsely branched, sometimes frondose; spore capsule inclined or pendulous on long stalk.
\BBryidae\b Large subclass of mosses (Bryopsida); terrestrial or freshwater green plants arising from a filamentous branched protonema; stems creeping or erect, simple or variously branched and with a poorly developed conducting system; contains between 8000 and 12000 species.
\Bbryochore\b That area of the Earth's surface covered by tundra.
\Bbryocolous\b Living on or in moss; \Bbryocole.\b
\Bbryology\b The study of mosses and liverworts; \Bbryological.\b
\Bbryophilous\b Thriving in habitats rich in mosses and liverworts; \Bbryophile\b, \Bbryophily.\b
\BBryophyta\b Division of plants exhibiting regular alternation of generations between a haploid, thallose or leafy gametophyte which produces male (antheridia) and female (archegonia) reproductive organs and gametes, and small diploid sporophyte which typically comprises a stalked, spore-bearing capsule and an absorptive basal portion; spores produced by meiosis, germinate either directly or via a protonematal stage into the gametophyte; contains 5 classes, liverworts (Hepaticopsida), hornworts (Anthocerotopsida), true mosses (Bryopsida), granite mosses (Andreaeopsida) and peat mosses (Sphagnopsida).
\BBryopsida\b True mosses; large class of bryophytes characterized by having sporophytes that remain attached to the gametophytes; leafy gametophyte rarely has dimorphous leaves and branching is of various non-dichotomous types; leaves have single growing point and are never bilobed; capsule produced on long-lived, unbranched stalk (seta), and typically opening by an apical operculum; capsule often with basal stomates (epidermal openings controlled by guard cells); spore dispersal often aided by a peristome of one or more rows of teeth; comprises 3 subclasses distinguished mainly by peristome characters, Polytrichidae, Bryidae and Tetraphidae.
\BBryopsidales\b Order of mainly marine green algae which are most diverse and abundant in warm waters; possessing a thallus consisting of branched tubes (siphons) which are rarely septate; photosynthetic pigments include the distinctive siphonein and siphonaxanthin; Siphonales; Codiales; also treated as a class of the protoctistan phylum Chlorophyta under the name Bryopsidophyceae.
\BBryozoa\b Moss animals; diverse phylum of small sessile aquatic coelomates that typically form colonies containing from a few to a million individuals (zooids); each zooid has a ciliated tentaculate lophophore around the mouth; skeleton cuticular, calcareous or gelatinous; gut U-shaped with anus opening outside lophophore; colonies formed by budding from primary zooid (ancestrula). Most bryozoans are marine, some brackish and freshwater, attached to hard substrates or algae, rarely on soft sediments; contains about 4000 extant species in 3 classes, Phylactolaemata, Stenolaemata and Gymnolaemata, and abundant fossil forms; formerly known as Polyzoa or Ectoprocta.
\Bbubble shell\b \JCephalaspidea\j
\BBucconidae\b Puffbirds; family containing about 30 species of small insectivorous Neotropical forest birds (Piciformes) found from Mexico to Paraguay; bill strong, straight or hooked, used to catch insects on the wing; habits solitary, sedentary, monogamous, non-migratory; nest in burrow in bank.
\BBucephalus larva\b Cercaria of the digenean fish parasite \IGasterostomum\i possessing a forked tail.
\BBucerotidae\b Hornbills; family of large arboreal birds (Coraciiformes) characterized by long massive bill bearing casque on upper margin; plumage loose, tail and wings elongate, legs short and strong; habits solitary or weakly gregarious, non-migratory, monogamous; feed mostly on fruit; nest in tree hole; contains 45 species in the Old World tropics from Africa to New Guinea.
\Bbuckbean\b \JMenyanthaceae\j
\Bbuckeye\b \JHippocastanaceae\j
\Bbuckthorn\b \JRhamnaceae\j
\Bbuckwheat\b \JPolygonales\j
\Bbudding\b 1: A type of asexual reproduction in which a new individual develops as a direct growth from the body of the parent, and may subsequently become detached. 2: The division of insect colonies; colony fission.
\BBuddlejaceae\b Butterfly bush; family of Scrophulariales containing about 150 species of shrubs or trees often with hairs of various sorts; mainly tropical and subtropical in distribution; flowers typically with 4 sepals, petals and stamens, and a superior ovary; sometimes included in the Loganiaceae.
\Bbudworm\b \JTortricidae\j
\Bbuffalo fly\b \JSimuliidae\j
\Bbuffer\b 1: A substance which stabilizes the pH of a solution against the addition of acidic or alkaline material. 2: To protect a system from change by external factors; \Bbuffering.\b
\Bbuffer species\b A plant or animal acting as an alternative food supply for another organism and thereby buffering the effect of the predator on its normal prey.
\Bbuffering\b The amelioration of environmental conditions by vegetation or topographic features; \Bbuffer.\b
\BBufonidae\b Toads; cosmopolitan family containing about 280 species of terrestrial or fossorial amphibians (Anura) typically with a thick, glandular and often warty skin; limbs short, body up to 240 mm length; reproductive habits range from fully aquatic eggs and larvae to terrestrial eggs and direct development.
\Bbug\b \JHemiptera\j
\Bbulb\b An underground shoot specialized as a perennating organ formed mainly from fleshy, colourless leaves containing food reserves surrounding the central apical bud and all enclosed in protective scales.
\Bbulbifery\b Asexual reproduction by the formation of bulbils in the axils of leaves, or in the floral branches.
\Bbulbil\b A small bulb formed from an aerial bud.
\Bbulbul\b \JPycnonotidae\j
\Bbullhead\b \JCottidae\j
\Bbullhead shark\b \JHeterodontiformes\j
\Bbumblebee\b \JApidae\j
\Bbumblebee bat\b \JCraseonycteridae\j
\Bbunt order\b A social hierarchy or order of dominance established by butting.
\Bbunting\b \JEmberizidae\j
\BBuprestidae\b Jewel beetles; family of metallic coloured, wood-boring beetles (Coleoptera) containing about 15 000 species; adults feeding on nectar, larvae on wood or as leaf miners.
\Bbur reed\b \JSparganiaceae\j
\Bburden\b The total number or biomass of parasites infecting a given host individual.
\BBurhinidae\b Stone curlews; family containing 9 species of medium-sized, long-legged, thick-kneed charadriiform shore birds widespread in dry, open, sandy and stony habitats; habits terrestrial, crepuscular or nocturnal, monogamous, often migratory; feeding on invertebrates and small vertebrates; nesting in scrape on ground.
\BBurmanniaceae\b Small family of Orchidales comprising about 130 mostly tropical species of small mycotrophic herbs, sometimes with reduced leaves lacking chlorophyll, otherwise leaves green and clustered at base of stem; fruit a capsule with numerous tiny seeds.
\BBurramyidae\b Pygmy phalangers; family containing 9 species of small (to about 250 mm) arboreal marsupials found in Australia, Tasmania and New Guinea; marsupium opens anteriorly; tail somewhat prehensile; habits nocturnal or crepuscular, mainly insectivorous but also feeding on a variety of plant material and eggs.
\Bburrfish\b \JDiodontidae\j
\BBurseraceae\b Gumbo-limbo; pantropical family of Sapindales containing about 600 species of trees and shrubs with prominent resin ducts; flowers small, unisexual; fruit is a drupe or a capsule.
\BBursovaginoidea\b One of 2 orders of gnathostomulids found in marine sands worldwide; characterized by the presence of a female bursa-vagina system, an injectory penis and paired sensory organs on the rostrum; the sperm are not filiform.
\Bbushbaby\b \JGalagidae\j
\Bbush hopper\b \JCaelifera\j
\Bbush rat\b \JOctodontidae\j
\Bbustard\b \JOtididae\j
\Bbusy Lizzie\b \JBalsaminaceae\j
\Bbutcherbird\b \JCracticidae\j
\BButomaceae\b Flowering rush; family of Alismatales containing a single species of perennial, emergent aquatic herbs native to temperate Eurasia; inflorescence is a many-flowered umbel; each flower has 6 perianth segments, 9 anthers and 6 follicles containing seeds.
\BBuxaceae\b Boxwood; cosmopolitan family of Euphorbiales containing about 60 species of mostly evergreen woody plants; flowers typically very small, each with 4-6 perianth segments and stamens, but often arranged in showy inflorescences, forming shiny black seeds in a fleshy drupe or capsule.
\BBuxbaumiales\b Small order of mosses (Bryidae) growing individually or in mats on soil, rotting wood or on rock surfaces; stems short or absent, sporophytes terminal.
\BByblidaceae\b Small family of Rosales containing only 4 species of insectivorous perennial herbs or half shrubs bearing long oily or mucilaginous glands for trapping insects; sometimes included in the \JDroseraceae\j
\BByrrhidae\b Pill beetles; family of small beetles (Coleoptera) containing about 300 species found primarily in temperate regions; larvae occurring in soil, feeding on mosses, liverworts and lichens.
\BC\B\D3\d plant\b\b A plant employing the pentose phosphate pathway of carbon dioxide assimilation during photosynthesis; most green plants belong to this category.
\BC\B\D4\d plant\b\b A plant employing the dicarboxylic acid pathway for carbon dioxide assimilation during photosynthesis and capable of utilizing lower carbon dioxide concentrations than C\D3\d plants.
\Bcabbage\b \JBrassicaceae\j
\BCabombaceae\b Small family of aquatic herbs (Nymphaeales) with creeping rhizomes and floating leafy stems; contains 7 species mostly from warm temperate to tropical regions of the New World.
\Bcacao\b \JSterculiaceae\j
\Bcacogenesis\b The condition of being unable to hybridize.
\BCactaceae\b Cacti; large family of Caryophyllales containing up to 2000 species of mostly spiny, stem-succulents with poorly developed leaves; native to the New World, especially in desert regions; often having large, showy flowers with many petals and stamens and an inferior ovary.
\Bcadavericolous\b Inhabiting dead bodies; also used of organisms feeding on dead bodies or carrion; \Bcadavericole.\b
\Bcaddisfly\b \JTrichoptera\j
\Bcaducous\b Used of structures shed or falling off early.
\Bcaecilian\b \JGymnophiona\j
\BCaeciliidae\b Diverse family containing about 85 species of terrestrial caecilians (Gymnophiona) widely distributed in the Neotropical region, Africa, India and the Seychelles; body length to 1.2 m; tail absent; scales often present; mostly viviparous but some are oviparous with aquatic larvae.
\BCaelifera\b Locusts, short-horned grasshoppers, monkey hoppers, bush hoppers, ground hoppers; suborder of typically diurnal phytophagous orthopteran insects comprising about 11 000 species common in grassland and other vegetation, although some are arboreal or arbusticolous; many engage in swarming and mass migration and some are serious crop pests.
\BCaenogaea\b A zoogeographical region incorporating the Nearctic, Oriental and Palaearctic; Cainogaea; Kainogaea; See also \JEogaea\j
\Bcaenogenetic\b 1: Of recent origin. 2: Used of transitory adaptations developed in the early ontogenetic stages of an organism; \Bcaenogenesis.\b
\BCaenolestidae\b Rat opossums; family of small shrew-like insectivorous marsupials found in forests of western South America; marsupium absent; lower first incisors large.
\BCaenophytic\b The period of geological time since the development of the angiosperms in the mid to late Cretaceous; Cenophytic; see also \JAphytic\j \JArchaeophytic\j, \JEophytic\j, \JMesophytic, Palaeophytic\j
\BCaenozoic\b \JCenozoic\j
\BCaesalpiniaceae\b Senna, royal poinciana, red bud, honey locust, Kentucky coffee tree; large family of Fabales containing about 2200 species of mostly woody leguminous plants widespread in tropical and subtropical regions; flowers usually irregular with 10 or fewer stamens; formerly known as the subfamily Caesalpinioideae of the family Leguminosae.
\Bcaespiticolous\b Living in grassy turf or pastures; \Bcaespiticole.\b
\Bcaiman\b \JAlligatoridae\j
\BCainogaea\b \JCaenogaea\j
\BCainotheriidae\b Extinct family of small, rabbit-like artiodactyls known from the late Eocene and Oligocene of Europe; without gnawing incisors; hindlegs elongate.
\BCainozoic\b \JCenozoic\j
\Bcalabash tree\b \JBignoniaceae\j
\BCalanoida\b Order of free-living, mainly planktonic copepod crustaceans found at all depths in the sea and in fresh water and inland saline waters; body divided into prosome and urosome behind segment bearing fifth swimming legs; contains about 2500 species, some extremely abundant in surface waters where they can be the main consumers of phytoplankton.
\BCalcarea\b Class of sponges characterized by a skeleton formed from calcium carbonate spicules laid down as calcite; the spicules may be free or fused; largely restricted to marine waters shallower than 1000 m; comprising 4 subclasses, Calcaronia, Calcinia, Pharetronidia and Sphinctozoa.
\Bcalcareous\b Rich in calcium salts; pertaining to limestone or chalk; growing on or having an affinity for chalky soil.
\BCalcaronia\b Subclass of calcareous sponges possessing choanocytes with an apical nucleus associated with the flagellum; producing an amphiblastula larva; comprises 2 orders, Leucosoleniida and Sycettida.
\Bcalceolaria\b \JScrophulariaceae\j
\Bcalcicole\b A plant growing in soils rich in calcium salts; calcipete; \Bcalcicolous\b; See also \Jcalcifuge\j
\Bcalcification\b 1: The deposition of calcium salts in living tissue. 2: The replacement of organic material by calcium salts during fossilization.
\Bcalcifuge\b A plant which is intolerant of soils rich in calcium salts; calciphobe; \Bcalcifugous\b; See also \Jcalcicole\j
\BCalcinia\b Subclass of calcareous sponges possessing choanocytes in which the flagellum arises independently of the basal nucleus; releasing larvae at the hollow blastula stage of development; comprises 2 orders, Clathrinida and Leucettida.
\Bcalcipete\b \JCalcicole\j
\Bcalciphilic\b Thriving in environments rich in calcium salts; boring into calcareous shells; \Bcalciphile\b, \Bcalciphily.\b
\Bcalciphobe\b \JCalcifuge\j
\Bcalciphyte\b A plant of soils rich in calcium salts
\Bcalcivorous\b Used of plants living on limestone or in soils rich in calcium salts; \Bcalcivore\b, \Bcalcivory.\b
\BCalifornia Current\b A cold surface ocean current that flows southwards along the coast of California, forming the easterly limb of the North Pacific Gyre; see ocean currents.
\BCalifornian bluebell\b \JHydrophyllaceae\j
\Bcaliology\b The study of burrows, nests, hives, tubes and other domiciles constructed by animals.
\BCallichthyidae\b Family containing about 130 species of mostly small (to 200 mm) freshwater South American catfishes (Siluriformes); body deep and heavily armoured with bony plates; dorsal and adipose fin with stout spine; 3 pairs of barbels; gas bladder enclosed in bony capsule; aerial respiration may occur through vascularized hindgut.
\BCallionymidae\b Dragonets; family containing about 40 species of bottom-dwelling marine teleost fishes (Perciformes); body depressed, to 200 mm length; scales and gas bladder absent; gill openings confined to single aperture on each side of head; sexual dimorphism pronounced; typically live buried in substratum feeding on invertebrates.
\BCalliphoridae\b Bluebottles, blowflies, greenbottles, cluster flies; large family of small to large flies (Diptera) many of which have a metallic body sheen; the maggot-like larvae feed on decaying organic or faecal matter, although some are parasitic; several species are serious pests of livestock or vectors of disease.
\BCallipodida\b Order of active carnivorous helminthomorphan diplopods (millipedes) found mostly in dry rocky habitats of the eastern Mediterranean and southern North America, several forms are troglophilic; body elongate, cylindrical, setose; sternal sclerites free, pleural and tergal sclerites fused.
\BCallitrichaceae\b Widely distributed family comprising about 35 species of typically aquatic many-branched herbs with small unisexual flowers; each flower without perianth, with a single stamen and a 4-celled ovary.
\BCallitrichales\b Order of Asteridae containing 3 small families of aquatic or semiaquatic herbs with reduced flowers.
\BCallitrichidae\b Marmosets, tamarins; family containing 14 species of small arboreal insectivorous primates (infraorder Platyrrhini) found in the Neotropical region; body long and slender, squirrel-like, limbs short, tail non-prehensile; locomotion scansorial.
\BCallorhinchidae\b Family containing 5 species of medium-sized (to 1 m) holocephalan fishes, restricted to shallow waters in temperate regions of the southern hemisphere; body compressed, snout rounded and bearing leaf-like proboscis.
\BCalmanostraca\b Subclass of branchiopodan Crustacea comprising the tadpole shrimps (Notostraca).
\Bcalobiosis\b The interrelationship between two species of social insect, in which one lives in the nest of, and at the expense of, the other.
\BCalobryales\b Small order of liverworts (Hepaticopsida), widely distributed but individual species typically restricted in range; plants green but lacking secondary pigments; organized into prostrate leafless stolons lacking rhizoids and erect leafy branches with hairs or slime papillae that secrete copious mucilage; female sex organs massive, scattered on stem or sometimes aggregated.
\BCalycanthaceae\b Small family of aromatic shrubs or small trees (Laurales) comprising 5 species restricted to North America and China; typically with solitary flowers and ribbon-like stamens; embryo with 2 spirally twisted cotyledons.
\BCalycerales\b Order of Asteridae comprising a single family, Calyceraceae, containing about 60 species of herbs with a specialized pollen presentation mechanism; native to Central and South America.
\Bcalyptopis\b Early zoeal larval stage of euphausiacean crustaceans.
\BCalyptoptomatida\b Extinct class of marine molluscs known from the Lower Cambrian to the Middle Permian; shell bilaterally symmetrical; aperture usually protected by an operculum possessing paired muscle scars.
\Bcalyx\b The outer whorl of a flower, comprising the sepals.
\BCAM plant\b A plant, typically a succulent, which employs the crassulacean acid metabolism for carbon dioxide fixation.
\BCamallanida\b Order of spirurian nematodes all of which are parasites utilizing copepod crustaceans as intermediate hosts and various terrestrial and aquatic vertebrates as definitive hosts; possessing simple, uninucleate oesophageal glands.
\BCamaroidea\b Extinct order of encrusting graptolites known from the Lower Ordovician; built of autothecae and indistinct stolothecae.
\BCambrian\b The earliest geological period of the Palaeozoic era (\Ic.\i 570-504 million years B.P); see geological time scale.
\BCamelidae\b Camels, llamas; family containing 4 species of herbivorous, terrestrial ungulates (Artiodactyla) native to the Palaearctic and Neotropical regions but now more widespread through domestication; feet with only 2 digits, hooves vestigial; stomach 3-chambered.
\Bcamellia\b \JTheaceae\j
\BCamerata\b Extinct subclass of crinoids known from the Lower Ordovician to Upper Permian; thecal plates typically united by fused, rigid polygonal platelets.
\BCamerothecida\b Extinct order of calyptoptomatid molluscs known from the Cambrian; operculum lacking.
\BCampanula\b \JCampanulaceae\j
\BCampanulaceae\b Campanula, lobelia, bellflower, throatwort, Canterbury bell; large cosmopolitan family containing about 2000 species of mostly herbaceous plants producing latex and storing carbohydrate as inulin; fruit is commonly a capsule or berry; flowers variable but typically with 5 separate sepals, 5 petals, 5 stamens and an inferior ovary bearing 2, 3 or 5 stigmas and carpels.
\BCampanulales\b Order of Asteridae containing 7 families, distinguished by a combination of alternate leaves, an inferior ovary and stamens that are either free or attached at the base of the corolla tube; mostly herbaceous but with some woody species.
\BCampephagidae\b Cuckoo shrikes; family containing about 70 species of Old World passerine birds found in forests and bushland habitats from Africa, through Asia to Australia; plumage soft; bill strong and hooked; wings long and pointed; habits arboreal, non-migratory, nesting in trees; feed on fruit and ground insects.
\BCampo\b A habitat comprising grassy plains with scattered bush and small trees, characteristic of parts of South America.
\Bcamptotropism\b The tendency to return to the natural position if forcibly displaced from it; \Bcamptotropic.\b
\BCanaceidae\b Surf flies; cosmopolitan family of flies (Diptera) comprising about 60 species found mostly around the seashore; larvae aquatic, often inhabiting intertidal rock pools.
\BCanaries Current\b A cold surface ocean current that flows south in the eastern North Atlantic, forming the easterly limb of the North Atlantic Gyre; see ocean currents.
\Bcandytuft\b \JBrassicaceae\j
\BCanellaceae\b Small family of primitive flowering plants (Magnoliales) found in the tropics; mostly aromatic trees, including wild cinnamon.
\BCanidae\b Dogs, foxes; cosmopolitan family of primarily carnivorous terrestrial mammals (Carnivora); habits range from solitary to formation of well-structured social groups; face long; canine teeth large, cheek teeth mostly adapted for crushing, some for cutting (the carnassials); claws blunt, non-retractile; contains about 35 species including dingos, jackals and wolves.
\BCannabaceae\b Cannabis, hops; small family of Urticales containing 4 species of erect or twining herbs, cultivated for fibre (hemp) or psychotrophic drugs (marijuana); small wind-pollinated flowers with pentamerous perianth, 5 stamens and a unilocular ovary.
\BCannaceae\b Cannas; small family of Zingiberales comprising about 50 species of often coarse, leafy-stemmed perennial herbs with silica cells; native to tropical and subtropical regions of the New World; flowers with a single functional stamen bearing a single pollen sac.
\Bcannonball fungi\b \JNidulariales\j
\BCanoidea\b Superfamily of carnivores (Ferae) comprising the dogs (Canidae), bears (Ursidae), raccoons (Procyonidae) and weasels (Mustelidae).
\Bcanopy\b The uppermost continuous stratum of foliage in forest vegetation formed by the crowns of the trees; subdivided into 2 or 3 canopy levels in energy-rich rainforests.
\BCanterbury bell\b \JCampanulaceae\j
\BCantharidae\b Soldier beetles; family of clongate, parallel-sided beetles (Coleoptera) typically found on flowers and in vegetation, feeding on nectar and pollen; larvae found in soil and litter, primarily predatory; contains about 5000 species distributed worldwide.
\Bcantharophilous\b Used of plants pollinated by beetles; \Bcantharophile, cantharophily \b
\BCape Horn Current\b The Antarctic Circumpolar Current in the region of Cape Horn; see ocean currents.
\BCape pondweed\b \JAponogetonaceae\j
\Bcaper\b \JCapparaceae\j
\Bcapillary water\b The water held in soil pore spaces and readily available to plants and soil organisms.
\BCapitellida\b Order of deposit-feeding polychaete worms comprising about 370 species; body long and cylindrical,; prostomium and peristomium unarmed; pharynx eversible, unarmed; parapodia biramous; includes bamboo worms.
\BCapitonidae\b Barbets; family containing about 80 species of pantropical forest birds (Piciformes); body compact, bill short and strong; habits solitary or gregarious, non-migratory, monogamous; feeding mostly on fruit; nest in tree hole or bank burrow.
\Bcapitulum\b A racemose inflorescence in which the flowering shoot is flattened and bears many stalkless flowers (florets) surrounded by a ring (involucre) of bracts; typically found in the composites (Asteraceae).
\BCapparaceae\b Caper; large family of mostly shrubs widespread in warm regions; flowers usually in racemes, with 2 plus 2 sepals, 4 diagonal petals, 4, 6 or more stamens and 2 carpels; capers are the pickled buds of \ICapparis spinosa\i; Capparidaceae.
\BCapparales\b Large order of Dilleniidae consisting of 5 families of herbs to woody plants typically producing mustard oils; including Brassicaceae.
\BCapparidaceae\b \JCapparaceae\j
\BCaprellidea\b Suborder of marine amphipod crustaceans comprising the skeleton shrimps (Caprellidae) and whale lice (Cyamidae); caprellids are mostly littoral climbers on algae and hydroids; cyamids are exclusively ectoparasitic on whales and dolphins; Laemodipodea.
\Bcaprification\b The pollination of fig flowers by fig insects (caprifers).
\BCaprifoliaceae\b Viburnum, honeysuckle, elderberry, snowberry; family of Dipsacales containing about 400 species of mostly woody plants mainly from north temperate and boreal regions, and tropical mountains; flowers bisexual and usually in cymose inflorescences; individual flowers usually with 4 or 5 sepals, petals and stamens, and an inferior ovary with many seeds.
\BCaprimulgidae\b Nightjars, goatsuckers; family containing about 75 species of small to medium-sized woodland birds (Caprimulgiformes) with cryptic coloration; head large, bill weak with large gape, mouth bearing bristles; habits solitary, largely terrestrial, monogamous, sometimes migratory; feeding on insects caught on the wing.
\BCaprimulgiformes\b Small, diverse order of crepuscular or nocturnal, neognathous birds containing 5 families including the frogmouths and nightjars; bill typically weak with a large gape, used to catch insects in flight.
\BCaproidae\b Boarfishes; family containing 6 species of small (to 300 mm) strongly compressed, deep-bodied marine zeiform teleost fishes widespread in coastal waters to 600 m depth; body typically reddish, scales ctenoid.
\BCapromyidae\b Hutias; family containing 10 species of medium-sized terrestrial and arboreal hystricomorph rodents confined to islands of the West Indies.
\Bcapsicum\b \JSolanaceae\j
\Bcapsule\b A dry dehiscent fruit developed from 2 or more many-seeded, fused carpels.
\Bcapuchin monkey\b \JCebidae\j
\Bcapybara\b \JHydrochoeridae\j
\BCarabidae\b Predacious ground beetles; tiger beetles, bombadier beetles; family of beetles (Coleoptera) containing over 30 000 species in 1500 genera; mostly active predators found in litter or vegetation; larvae ectoparasitic or predatory, feeding on predigested prey.
\BCaracanthidae\b Velvetfishes; family of tiny (to 50 mm) Indo-Pacific marine scorpaeniform teleosts containing only 3 species; body deep, compressed, naked; skin often papillose.
\Bcaracaras\b \JFalconidae\j
\Bcarambola\b \JOxalidaceae\j
\BCarangidae\b Jacks, pompanos, scads; family of predatory, tropical and temperate, pelagic marine teleost fishes (Perciformes); body variable, compressed to fusiform, length to 1.3 m; 2 dorsal fins present; possessing pair of small spines in front of anal fin; contains about 200 species some popular as game and food-fishes.
\BCarapidae\b Pearlfishes; family of tropical and subtropical marine and freshwater gadiform teleost fishes; body eel-like, to 300 mm, tail tapering to point; contains 28 species, some inhabiting internal cavities of benthic invertebrates; life cycle can include pelagic vexillifer and benthic tenuis larval stages.
\BCarapodidae\b \JCarapidae\j
\Bcaraway\b \JApiaceae\j
\Bcarbamate\b A biodegradable organic herbicide.
\Bcarbohydrate\b Any of a group of ketone or polyhydroxy aldehyde compounds including simple sugars (monosaccharides), and the more complex oligosaccharides (such as sucrose) and polysaccharides (such as cellulose and starch) which often serve as energy storage molecules.
\Bcarbon-14\b A radioactive isotope of carbon having a half-life of 5700 years; used in radiometric dating.
\Bcarbon assimilation\b The incorporation of inorganic carbon from carbon dioxide into organic compounds by photosynthesis.
\Bcarbon cycle\b The biogeochemical cycle of carbon, incorporating the fixation of inorganic carbon dioxide by photosynthesis to form organic complexes and its ultimate return to the atmosphere by processes of respiration and decomposition.
\Bcarbon dating\b A method of estimating the age of archaeological material and subrecent fossils by measuring levels of carbon-14.
\Bcarbon dioxide compensation point\b The concentration of carbon dioxide below which, in a non-limiting light intensity, photosynthesis just compensates for respiration and the value of net photosynthesis is zero.
\Bcarbonate compensation depth\b The oceanic depth at which the rate of solution of carbonate equals the rate of input at that level, typically a depth of about 5000 m.
\Bcarbonate dissolution depth\b The oceanic depth below which the solubility of calcium carbonate increases to the point that dissolution of calcareous shells begins; typically a depth of about 4000 m.
\Bcarbonicolous\b Living on burnt or scorched substrates; \Bcarbonicole.\b
\BCarboniferous\b A geological period within the Palaeozoic (\Ic.\i 365-290 million years B.P), divided into Pennsylvanian and Mississippian; see geological time scale.
\Bcarbonization\b An unusual type of fossilization in which organic material has been reduced to a carbon film residue.
\Bcarboxyphilic\b Thriving in carbon dioxide-rich habitats; \Bcarboxyphile\b, \Bcarboxyphily.\b
\BCarcharhinidae\b Requiem sharks; diverse cosmopolitan family of small to large (0.5-7.5 m), mainly pelagic, carcharhiniform clasmobranch fishes found in shallow water to 400 m; mostly marine but also penetrating tropical rivers and lakes; feed on variety of fishes, marine mammals, reptiles and invertebrates; reproduction typically viviparous with yolk sac placenta; contains about 50 species including tiger, sharp-nosed, grey, lemon and blue sharks; most species reported in shark attacks on people belong to this family.
\BCarcharhiniformes\b Large order of mainly marine, benthic or pelagic, coastal to oceanic, littoral to abyssal, galeomorph sharks; snout typically rather elongate, flattened, mouth subterminal; dorsal fins without fin spines; reproduction oviparous or ovoviviparous, to fully viviparous with yolk sac placenta; feed on variety of marine vertebrates and invertebrates; contains about 200 species in 8 families, including cat, hound, weasel, hammerhead, and requiem sharks.
\Bcarcinogenic\b Cancer-producing.
\Bcarcinology\b The study of crustaceans; \Bcarcinological.\b
\Bcardinal\b \JCardinalidae\j
\BCardiopteridaceae\b Family of Celastrales containing only 3 species of glabrous twining herbs producing a milky juice; native from southeast Asia to Australia.
\Bcardinalfish\b \JApogonidae\j
\BCardinalidae\b Cardinals; family of finches (Passeriformes) with large conical bills, found in woodland in the New World; males often highly coloured; commonly classified in the \JEmberizidae\j
\BCarettochelyidae\b Monotypic family of large (to 750 mm) predatory freshwater turtles (Testudines: Cryptodira) found in rivers of New Guinea and northern Australia; carapace covered with leathery skin, snout forming proboscis; feet webbed.
\BCariamidae\b Seriemas; family of large terrestrial gruiform birds found in forests and grasslands of central South America; legs strong for fast running, wings short, flight weak; feeding on variety of invertebrates and small vertebrates, including snakes; nest in trees.
\BCaribbean Current\b A warm surface ocean current that flows northwest in the Caribbean Sea, derived in part from the Atlantic South Equatorial Current and giving rise to the Florida Current through the Gulf of Mexico; see ocean currents.
\Bcaribou\b \JCervidae\j
\BCaricaceae\b Papaya; small family of Violales containing about 30 species of mostly soft-stemmed shrubs or trees typically with an unbranched trunk and terminal cluster of leaves; found in America and Africa; flowers regular, mostly unisexual; fruit is a berry.
\BCaridea\b Infraorder of pleocyematan decapod crustaceans including many commercially exploited species of prawns and shrimps; pleura of second abdominal segment overlap those of first and third segments; third thoracic legs not chelate; Eucyphidea.
\Bcarnation\b \JCaryophyllaceae\j
\BCarnivora\b Diverse order of terrestrial and aquatic carnivorous mammals comprising 10 families grouped in 2 suborders, Caniformia including Canidae (dogs, foxes), Ursidae (bears), Otariidae (sealions), Ailuropodidae (giant panda), Procyonidae (racoons), Mustelidae (weasels, otters), Phocidae (hair seals), and Feliformia including Felidae (cats), Viverridae (civets), Hyaenidae (hyaenas).
\Bcarnosaur\b Carnivorous saurischian dinosaur, typically bipedal and powerful, with dagger-like teeth; includes \ITyrannosaurus rex\i.
\Bcarotene\b A type of hydrocarbon, yellow to red pigment found as an accessory photosynthetic pigment in many plant cells.
\Bcarp\b \JCyprinidae\j
\Bcarpel\b The female reproductive structure in flowering plants, that bears and encloses the ovules; typically consisting of a basal ovary, elongate style and terminal, receptive stigma; commonly fused in advanced forms.
\Bcarpelotaxis\b The arrangement of carpels in a flower or fruit.
\Bcarpenter bee\b \JAnthophoridae\j
\Bcarpet beetle\b \JDermestidae\j
\Bcarpet moth\b \JGeometridae\j
\Bcarpet shark\b \JOrectolobiformes\j
\Bcarpogenous\b Growing on or in fruit.
\BCarpolestidae\b Extinct family of shrew-sized primates known from the Palaeocene and Eocene; probably herbivorous forms found on forest floors; digits with claws.
\Bcarpophagous\b Feeding on fruit or seeds; \Bcarpophage\b, \Bcarpophagy.\b
\Bcarr\b A mire containing scrub vegetation; fen woodland.
\Bcarrier\b An organism carrying a disease or infectious agent without showing typical symptoms and which is capable of passing the infection to another individual; See also \Jvector\j
\Bcarrion\b Dead putrefying flesh.
\Bcarrion beetle\b \JSilphidae\j
\Bcarrot\b \JApiaceae\j
\Bcarrying capacity\b The maximum number of organisms that can be sustained within a given area or habitat.
\Bcartilaginous fishes\b \JChondrichthyes\j
\BCarybdeida\b The sole order of \JCubozoa\j
\BCaryoblastea\b Phylum of protoctistans comprising one species, \IPelomyxa palustris\i, known from the muddy bottoms of freshwater ponds; characterized by the possession of membrane-bound nuclei and by the lack of the other cytoplasmic organelles characteristic of eukaryotes, except for the 9 + 2 flagellum, which is intracellular; nuclear division is apparently direct, not involving mitosis.
\BCaryocaraceae\b Souari nut; small family of evergreen trees or shrubs confined to tropical America.
\BCaryophyllaceae\b Chickweed, pink, carnation, moss campion, sweet William; large family of 2000 species of temperate and warm temperate, northern hemisphere herbs with stems commonly swollen at nodes; flowers typically with 5 sepals, 5 or more petals, 5 or 10 stamens and a superior ovary; producing a capsular fruit with many seeds.
\BCaryophyllales\b Large well defined order of Caryophyllidae; herbs or woody plants, often succulent and showing C\D4\d photosynthesis, sometimes with leaves reduced to spines; contains about 10 000 species in 12 families.
\BCaryophyllidae\b Subclass of dicotyledons (Magnoliopsida) with a fossil record dating back only to the beginning of the Palaeocene; characterized by their production of betalains but not anthocyanins or by the position of the ovule attachment in their compound ovary; contains 3 orders, Caryophyllales, Polygonales and Plumbaginales.
\BCaryophyllidea\b Order of tapeworms in which the posterior part of the body, the strobila, is unsegmented and contains only a single set of reproductive organs and in which the scolex is weakly developed; the life cycle involves freshwater oligochaete worms as intermediate hosts and freshwater teleost fishes as definitive hosts.
\Bcaryopsis\b A dry indehiscent fruit containing a single seed and derived from a single carpel the wall of which fuses with the seed wall during development; typical of members of the Poaceae, including the cereal crops.
\Bcashew nut\b \JAnacardiaceae\j
\BCassiduloida\b Order of irregular, littoral to upper continental slope, tropical to temperate, sea urchins (atelostomata) comprising only about 25 extant species; test rounded, mouth central, aboral ambulacra petal-like.
\Bcassowary\b \JCasuariidae\j
\Bcast\b A rock formed within a cavity, as in the replacement of a fossil by mineral infiltration.
\Bcaste\b Individuals within a colony belonging to a particular morphological type or age group, or that share a particular behaviour pattern and perform the same specialized function.
\Bcasting\b An object that has been cast off or voided by an organism, such as a faecal pellet or worm casting.
\Bcastor bean\b \JEuphorbiaceae\j
\BCastoridae\b Beavers; family containing 1 Nearctic and 1 Palaearctic species of semiaquatic mammals (Rodentia) that construct elaborate dams in small streams to form deep ponds; hindlimbs larger than forelimbs, feet webbed; tail broad and spatulate; feed on bark of trees.
\Bcastration\b The removal of, or interference with the function of, the testes (geld, emasculation) or ovaries (spey).
\Bcasual\b 1: A plant growing in a community with which it is not normally associated. 2: An alien species that survives for only a short period in the habitat to which it was introduced.
\BCasuariidae\b Cassowaries; family containing 3 species of large (to 1.5 m tall) ratite birds (Palaeognathae) found in rain forests of New Guinea and northern Australia; legs stout, powerful, bearing 3 digits; body black, feathers hair-like; upper neck and head naked, coloured blue and red; habits cursorial, polygamous; feed mainly on fruit.
\BCasuariiformes\b Order of ratite birds comprising 2 families, Casuariidae (cassowaries) and Dromaiidae (emus).
\BCasuarinales\b Casuarinas, she-oaks; order of Hamamelidae comprising a single family, Casuarinaceae, of about 50 species of evergreen trees bearing slender green branches with minute whorled leaves; native to Australia and adjacent areas.
\Bcat\b \JFelidae\j
\Bcat shark\b \JScyliorhinidae\j
\Bcatabatic\b Used of winds blowing down a slope, may be warm (foehn wind) or cold (fall wind).
\Bcatabolism\b That part of metabolism involving the degradation of complex substances with the resultant liberation of energy; See also \Janabolism\j
\Bcatadromous\b Migrating from fresh water to sea water, as in the case of fishes moving into the sea to spawn; \Bcatadromy\b; see also \Janadromous\j \Joceanodromous\j, \Jpotamodromous\j
\Bcatamenial\b Monthly; menstrual; \Bcatamenia.\b
\Bcataplasia\b An evolutionary state characterized by decreasing vigour; \Bcataplasis\b; see also \Janaplasia\j \Jmetaplasia\j
\Bcatarobic\b Used of an aquatic habitat in which slow decomposition of organic matter is taking place but in which conditions have not yet become anaerobic.
\BCatarrhini\b Infraorder of primates (suborder Haplorhini) comprising 4 families, Cercopithecidae (Old World monkeys), Hylobatidae (gibbons), Pongidae (great apes), Hominidae (humans).
\Bcatastrophism\b The doctrine that fossil faunas were the result of catastrophic changes which had periodically exterminated large numbers of species, so that past cataclysmic geological or climatic events have had a major impact on the course of evolution; See also \Juniformitarianism\j
\Bcatathermal\b Pertaining to a period of decreasing temperature; See also \Janathermal\j
\Bcatch crop\b A quick-growing crop which is cultivated between the rows of a main crop, between the main crops of an ordinary crop rotation or in place of a main crop which has failed.
\Bcatchment\b A natural drainage basin which channels rainfall into a single outflow.
\BCatenulida\b Cosmopolitan order of free-living aquatic turbellarians containing about 75 species of slow-moving, elongate and delicate worms; characterized by a simple pharynx and a straight gut, and by sperm lacking flagella.
\Bcaterpillar\b Soft-bodied larva of Lepidoptera (butterflies and moths) and Symphyta (sawflies) possessing 2 types of legs, true segmented thoracic legs, and unsegmented sucker-like false legs (prolegs) typically on the third to sixth and on the terminal abdominal segment.
\Bcatfish\b \JSiluriformes\j
\Bcatfish eel\b \JPlotosidae\j
\BCathartidae\b New World vultures, condors; family containing 7 species of large carrion-feeding birds found in North and South America; head naked, often coloured; wings broad, up to 3.5 m span; habits solitary or gregarious, monogamous; nesting on ground or in tree hollows.
\BCathaysia\b A continental landmass comprising most of China and southeast Asia, formed from the supercontinent \JEurasia\j after the break-up of Pangaea; see also \JAngara\j \JEuramerica\j
\Bcatkin\b A racemose inflorescence in which the main axis is typically elongate bearing many small stalkless unisexual flowers.
\Bcatnip\b \JLamiaceae\j
\BCatostomidae\b Suckers; family of freshwater cypriniform teleost fishes found throughout Central and North America, and also in China and Siberia; body deep, subcylindrical to compressed, mouth with thick lips; typically bottom-living, feeding on plankton, insect larvae and detritus; contains about 60 species including buffalo fishes, cultured for food in United States.
\Bcattail\b \JTyphaceae\j
\Bcattle\b \JBovidae\j
\Bcatworm\b \JPhyllodocida\j
\BCaudata\b Salamanders, newts; order of tailed Amphibia comprising about 330 species in 8 families, having a primarily holarctic distribution; adults aquatic, terrestrial, occasionally arboreal; forelimbs and hindlimbs usually present and of subequal size; many parts of skeleton cartilaginous; egg and larvae primitively aquatic; direct development and viviparity also present; some forms neotenic.
\BCaudofoveata\b Class of molluscs containing less than 70 species of marine infaunal burrowers which are vermiform and feed on microorganisms and detritus; characterized by the small, cylindrical body covered with a mantle which secretes a chitinous cuticle and embedded imbricating scales, by the bipartite radula, by a reduced gliding surface on the foot, and by the presence of a pair of ctenidia; sometimes treated as an order of the Aplacophora.
\Bcauliflory\b The production of flowers on secondarily thickened plant tissues such as branches or trunks.
\Bcaulocarpous\b Used of a plant producing fruit in each of 2 or more successive years.
\BCaulophrynidae\b Family of small (to 200 mm) pelagic, marine anglerfishes (Lophiiformes) comprising 2 species found from depths of 10 m to 1500 m; body of female rounded, naked; mouth large with pointed teeth; pectoral fins fan-like; lure lacking apical bulb; male slender and ectoparasitic on female.
\Bcave cricket\b \JRhaphidophoridae\j
\Bcavefish\b \JAmblyopsidae\j
\Bcavernicolous\b Living in subterranean caves or passages; \Bcavernicole.\b
\BCavibelonia\b Order of solenogastres (Mollusca) possessing a mantle with layers of hollow, mainly needle-like, calcareous bodies.
\BCaviidae\b Guinea-pigs; family containing 12 species of small to large terrestrial hystricomorph rodents confined to the Neotropical Region; 4 digits on forelimbs, 3 on hindlimbs; tail vestigial; habits diurnal or nocturnal, herbivorous, living in burrows.
\BCaytoniales\b An order of gymnosperms known as fossils from the Jurassic period.
\BCebidae\b New World monkeys; family of primarily arboreal, herbivorous, Neotropical primates; body and limbs elongate, tail long to short, prehensile or not; ischial callosities absent; typically forming family groups; contains about 35 species including capuchin, squirrel, howler, spider, and woolly monkeys.
\BCecidomyiidae\b Gall midges; cosmopolitan family of minute fragile flies (Diptera) containing more than 4000 species; larvae often phytophagous living in galls, others saprophagous or predacious.
\BCecropiaceae\b Family of Urticales found in tropical regions containing about 300 species of trees, shrubs or woody vines with stilt or aerial roots; sometimes included in the family \JUrticaceae\j
\BCelastraceae\b Climbing bittersweet, spindle tree; large, cosmopolitan family of usually glabrous woody plants containing about 800 species; small, regular flowers arranged in cymose inflorescences, each flower typically with 3-5 sepals, petals and stamens, and a superior ovary producing a capsular fruit.
\BCelastrales\b Order of Rosidae, containing about 2000 species of alkaloid-producing woody plants or herbs arranged in 11 families.
\Bcelery\b \JApiaceae\j
\Bcellular\b Composed of cells; pertaining to cells; See also \Jacellular\j
\Bcellular slime moulds\b A group of independently motile, phagotrophic, uninucleate amoeba-like organisms which aggregate into a mass that transforms itself into a spore-producing fruiting body; classified as a phylum of Protoctista (Acrasiomycota), as a class of fungal slime moulds (Acrasiomycetes), or as a class of rhizopod protozoans (Acrasea).
\BCelsius scale\b (░C) A scale of temperature with the melting point of ice as zero and boiling point of water as 100 degrees at normal atmospheric pressure; equivalent to Centigrade scale.
\BCenophytic\b \JCaenophytic\j
\BCenozoic\b A geological era (\Ic.\i 65-0 million years B.P.) comprising the Quaternary and Tertiary periods; the age of mammals; Caenozoic; Cainozoic; Kainozoic; see geological time scale.
\Bcenozoology\b The study of extant animals.
\Bcenti-\b Prefix meaning hundredth; used to denote unit x 10\U-2 \u; see metric prefixes.
\BCentigrade scale\b (░C) A scale of temperature that takes the melting point of ice as zero and the boiling point of water as 100 degrees; now abandoned in favour of the Celsius scale.
\Bcentipede\b \JChilopoda\j
\BCentrales\b Centric diatoms; order of primarily marine algae found in planktonic and epibenthic habitats and in damp terrestrial situations; typically with circular valves which are radially symmetrical; non-motile but with flagellate male gametes; also treated as a class of the phylum Bacillariophyta.
\BCentrarchidae\b Sunfishes; family of North American freshwater perciform teleost fishes containing about 30 species; first dorsal fin strongly spined, united with second; tail deep.
\BCentriscidae\b Shrimpfishes; family containing 4 species of tropical Indo-Pacific shallow marine gasterosteiform teleost fishes usually found living amongst the body spines of sea urchins; body strongly compressed with armour of thin bony plates; snout elongate; dorsal fin with 3 spines, located at end of body.
\BCentroceratida\b Extinct order of cephalopod molluscs (Nautiloidea) in which the sutures are trilobed and the siphuncle subcentral; known from the Lower Devonian to the Upper Jurassic.
\BCentrohelida\b Order of Heliozoa characterized by a skeleton composed of siliceous or organic plates or spines and by the presence of a centroplast on which the axopodal microtubules insert.
\BCentrolenidae\b Family containing about 60 species of small (to about 30 mm) tropical South American arboreal leaf frogs (Anura); body usually with green coloration; eggs laid on vegetation above water, tadpoles aquatic; feet with pads and extra-digital cartilaginous elements.
\BCentrolepidaceae\b Small family of Restionales comprising about 35 species of small, tufted, mostly annual grass-like or moss-like herbs with solid stems and leaves with slender blades; has a widespread but patchy distribution.
\BCentrolophidae\b Medusa fishes; family containing about 22 species of pelagic marine stromateoid teleosts (Perciformes); length to 1.4 m, head naked, mouth large; juveniles live in association with jellyfishes.
\BCentrophrynidae\b Monotypic family of tiny (to 50 mm) deep-sea anglerfishes (Lophiiformes); female body elongate, slender posteriorly, skin densely spinose; eyes subcutaneous; lure located on snout; male smaller than female, lacking teeth.
\BCentropomidae\b Snooks; family of large (to 2 m) inshore marine and brackish water perciform teleost fishes popular as sport and food-fishes; body elongate, compressed, with dorsal fin fully divided.
\Bcentury plant\b \JAgavaceae\j
\BCephalaspidea\b Bubble shell; order of marine opisthobranch molluscs most of which are bottom-living carnivores, preying on other invertebrates; typically with an external shell, a broad creeping foot and a flattened dorsal head shield used for burrowing; the stomach has grinding gizzard plates.
\BCephalaspidiformes\b Extinct order of fish-like vertebrates known from the Silurian and Devonian; body flattened, head broad; 10 pairs of ventral gill openings present; mouth ventral and lacking jaws.
\BCephalaspidomorphi\b Lampreys, hagfishes; class of agnathan vertebrates lacking true gillarch jaws; contains 2 extant orders, Petromyzoniformes, Myxiniformes, and the fossil Cephalaspidiformes.
\BCephalobaenida\b Order of pentastome arthropods comprising 18 species; head pointed, hooks arranged in trapezoidal pattern; two families recognized, one parasitic in lizards and snakes, the other in aquatic or semiaquatic birds; secondary insect host known only in the case of the lizard parasites.
\BCephalocarida\b Class of small, primitive crustaceans comprising a single order, Brachypoda, found in intertidal to bathyal fine marine sediments; body elongate, comprising head, 8-segmented thorax with triramous foliaceous limbs, and naked, 12-segmented abdomen; larval development gradual through 13 naupliar and 5 juvenile stages; contains 9 species from coasts of North and South America, southwest Africa and Japan.
\BCephalochordata\b Lancelet, amphioxus; subphylum of invertebrate chordates cosmopolitan in shallow marine sand and gravel habitats; body translucent, to 70 mm length, tapered at both ends, with series of V-shaped muscle blocks; feed by filtering suspended particles from pharyngeal water current produced by gill bar cilia; sexes separate, monomorphic, fertilization external, larvae planktonic; contains about 23 species in 3 genera; Acrania.
\BCephalopoda\b Octopus, squid, cuttlefish; a class of marine carnivorous molluscs characterized by the specialization of the head-foot into a ring of arms (tentacles) generally equipped with suckers or hooks, by the funnel of the mantle cavity used for propulsive locomotion, by a powerful parrot-like beak, and by well developed eyes; consists of 2 subclasses, Nautiloidea and Coleoidea.
\BCephalotaceae\b Family of Rosales containing a single insectivorous herb species with some leaves modified as pitchers; found in bog habitats in southwestern Australia; flowers small, hexamerous and borne on a long scape.
\BCephalotaxaceae\b Small, monogeneric family of conifers (Pinatae) native to temperate eastern Asia; foliage yew-like; male cones small, usually globose; female structure erect with a fleshy aril enclosing most of the seed.
\BCepolidae\b Bandfishes; family of bottom-dwelling marine teleosts (Perciformes) found amongst rocks or burrowing in soft sediments; body extremely elongate, compressed, ribbon-like, to 700 mm length; dorsal and anal fins continuous with caudal; 7 species found in Indo-Pacific and eastern North Atlantic.
\BCeractinomorpha\b Subclass of demosponges with a skeleton composed of siliceous spicules and spongin fibres, or spongin fibres alone; variable in body form but commonly branching, found from the intertidal zone down to 7000 m; typically viviparous with incubated parenchymella larvae.
\BCerambycidae\b Long-horned beetles, timber beetles; family of medium-sized, elongate beetles (Coleoptera) containing about 35 000 species in 4000 genera distributed worldwide; adults typically feeding on nectar and pollen; larvae bore into living or dead plant material, including timber.
\BCeramiales\b Large order of predominantly marine algae of filamentous or pseudoparenchymatous body form.
\BCeratiidae\b Sea devils; family of deep-sea anglerfishes (Lophiiformes) comprising 2 species found at depths up to 2000 m; female body robust, skin rough and spinose, length to 1.2 m, lure elongate; males about 60 mm in length, ecto-parasitic on female.
\BCeratiomyxomycetidae\b Subclass of plasmodial slime \Jmoulds\j (Myxomycetes) comprising a single order, Ceratiomyxales, characterized by a fruiting body with hair-like stalks over its surface, each of which bears a single spore at the tip; spores produce flagellate cells which fuse to initiate the plasmodial stage, found migrating through the interstices of wood.
\BCeratodontidae\b Australian lungfish; monotypic family of freshwater fishes found in rivers and reservoirs of northeastern Australia; body compressed, to 1.8 m length, pectoral and pelvic fins broad; the unpaired swim bladder functions as a lung.
\BCeratomorpha\b Suborder of mammals (Perissodactyla) comprising the tapirs and rhinoceroses.
\BCeratophyllaceae\b Small but cosmopolitan family of submersed, rootless perennial herbs (Nymphaeales); flowers small, unisexual; perianth tiny with many narrow lobes, 10-20 stamens; fruit a one-seeded nut.
\BCeratopongonidae\b Biting midges, punkies; cosmopolitan family of minute biting flies (Diptera) comprising about 1200 species that feed on the blood of warm-and cold-blooded vertebrates and are of considerable medical and veterinary importance in some areas as vectors of disease.
\BCeratoporellida\b Order of sclerosponges known from warm shallow waters in the Caribbean, in which the living sponge tissue forms a thin surface layer over the basal calcareous skeleton and extends down into it in places.
\BCeratopsia\b Horned ornithischian dinosaurs with a large head and extensive bony frill extending back over the neck; jaws beak-like; includes \ITriceratops.\i
\Bcercaria\b Tadpole-shaped larval stage of a digenean trematode parasite produced asexually from redia in the molluscan intermediate host; typically with a short free-swimming phase; may infect the definitive host or a second intermediate host.
\BCercidiphyllaceae\b Family containing 2 species of deciduous, dioecious trees with small wind-pollinated flowers, native to Japan and China; flowers unisexual, with 4 perianth parts; fruit is a follicle.
\BCercopidae\b Froghoppers, spittlebugs; large family of dark-coloured, frog-like, hopping insects (Homoptera) that feed on trees, shrubs and herbaceous plants, and lay eggs which hatch into sedentary nymphs protected from predators and desiccation by a mass of frothy spittle; comprising about 2300 species distributed worldwide.
\BCercopithecidae\b Old World monkeys; diverse family of primarily arboreal primates (infraorder Catarrhini); tail present or absent, non-prehensile; ischial callosities present; habits typically diurnal, herbivorous or omnivorous; most form small to large social groups; family includes baboons, mandrills, langurs and is distributed through the Ethiopian, Oriental and Palaearctic regions.
\BCercopithecoidea\b Superfamily comprising the Old World monkeys and their fossil relatives.
\Bceremony\b A complex pattern of display behaviour used to promote and maintain social bonds in some groups.
\BCeriantharia\b Tube anemones; order of solitary ceriantipatharians found mostly in warm temperate and tropical seas in both shallow and deep water; typically with an elongate column buried upright in soft sediment to the level of the oral disk; form tube out of mucus and interwoven cnidae into which the animal retracts; lack a pedal disk at the aboral end.
\BCeriantipatharia\b Subclass of anthozoans comprising the black corals (Antipatharia) and the tube anemones (Ceriantharia); typically with weak mesenteric musculature and coupled but not paired mesenteries; sometimes included in the subclass Zoantharia.
\BCerthiidae\b Tree creepers; family containing 8 species of small passerine birds widespread in forests and wooded habitats of northern hemisphere and Africa; bill slender, curved, pointed; legs short, feet and claws strong; habits solitary, arboreal, feeding on insects gleaned from tree bark; cup-shaped nests placed in crevice or on tree branch.
\BCervidae\b Deer; family containing about 35 species of herbivorous terrestrial ungulates (Artiodactyla: Ruminantia) widespread in most parts of the world except the Australian region, occupying diverse habitats from Arctic tundra to rainforest; forming small to large herds; some species migratory; antlers are commonly present, at least in males, and are shed and regrown annually; includes reindeer (caribou) and moose (elk).
\BCervoidea\b Superfamily of artiodactyls (Pecora) comprising the deer (Cervidae) and giraffe and okapi (Giraffidae).
\BCestida\b Small order of pelagic ctenophores with a worldwide distribution; characterized by a ribbon-like body that is extremely compressed in the tentacular plane and elongated in the stomodeal plane; tentacles are present and are involved in prey capture.
\BCestoda\b Tapeworms; class of exclusively parasitic flatworms found mostly in the intestines of vertebrates as adults and within a vertebrate or invertebrate intermediate host during development; characterized by a body usually consisting of an anterior holdfast (scolex), an unsegmented neck and a chain of segments called proglottids formed by serial budding or strobilation; body covered with a syncytial tegument; typically with one or more sets of male and female reproductive systems; shelled embryos are released, and are eaten by the intermediate host within which larval development takes place; comprising 2 subclasses, Cestodaria and Eucestoda.
\BCestodaria\b Small subclass of tapeworms found in primitive fishes and turtles distinguished by the lack of a scolex (an anterior holdfast), an unsegmented body and by the possession of a single set of male and female reproductive organs; the first larval stage, the lycophore, has 10 hooks; comprising 2 orders, Amphilinidea and Gyrocotylidea.
\BCetacea\b Whales, dolphins, porpoises; order of marine mammals comprising 2 extant suborders, Mysticeta (baleen whales) and Odontoceta (toothed whales); body fusiform, forelimbs modified as flippers, hindlimbs absent, tail bearing lateral flukes; nares dorsal; eyes small, pinnae absent; skin essentially hairless with thick layer of subcutaneous fat for insulation.
\Bcetology\b The study of cetaceans; \Bcetological.\b
\BCetomimidae\b Whalefishes; cosmopolitan family containing 10 species of small (to 150 mm) bathypelagic beryciform teleost fishes; body flabby, fragile, naked; head large, eyes and teeth minute; pelvic fins absent.
\BCetopsidae\b Family of small (to 150 mm) Amazonian catfishes (Siluriformes) comprising 12 species; body robust, cylindrical, naked; gas bladder enclosed in bony capsule; aerial respiration may occur through vascularized hindgut.
\BCetorhinidae\b Basking sharks; family of extremely large (to 13 m) inoffensive, filter-feeding, lamniform elasmobranchs having a widespread temperate distribution, second only to the whale shark as the largest fish; eyes very small, external gill openings extend onto dorsal surface, gill rakers abundant; mouth large; pelagic, feeding on planktonic crustaceans.
\BChacidae\b Monotypic family of small (to 200 mm) freshwater catfishes (Siluriformes) found in slow-moving lowland streams of India, Burma and Sumatra; body depressed anteriorly, compressed posteriorly, dorsal fin short with single spine; 3 pairs of barbels.
\BChaenichthyidae\b Crocodile icefishes; family containing 15 species of Southern Ocean bottom-dwelling perciform teleost fishes; body naked, to 600 mm length, head large and spinose; blood lacking haemoglobin, oxygen carried in plasma.
\BChaetodermatida\b Alternative name for the \JCaudofoveata\j
\BChaetodontidae\b Butterfly fishes, angelfishes; family containing 150 species of colourful shallow-water perciform teleost fishes commonly associated with coral reefs, widespread in tropical and subtropical seas especially of the Indo-Pacific; body deep, compressed, to 600 mm length; snout prolonged, mouth small and protractile, teeth minute; larval stage termed a tholichthys.
\BChaetognatha\b Arrow worms; small phylum of bilaterally symmetrical, free-living, predatory marine coelomates; body slender, head armed with 2-3 pairs of sharp spines around the mouth, translucent trunk bearing lateral and caudal fins; hermaphrodite but reciprocal cross fertilization common. Most chaetognaths are planktonic, a few benthic; may be exceptionally abundant. About 70 species in 2 orders, Phragmophora, Aphragmophora. Evolutionary relationships uncertain, presently linked with deuterostomes.
\BChaetomiales\b Order of pyrenomycete fungi comprising about 100 cellulose-decomposing species found in soil, dung and plant debris.
\BChaetonotida\b Order of aquatic and semiaquatic gastrotrichs, of variable body form but lacking pharyngeal pores.
\BChaetophoriales\b Order of predominantly freshwater green algae; typically with thallus of branched filaments composed of uninucleate cells, each containing a single parietal laminate chloroplast; also treated as a class of the protoctistan phylum Chlorophyta.
\Bchaetoplankton\b Planktonic organisms having spiny outgrowths to reduce their rate of sinking.
\BChaetopterida\b Order of filter-feeding tubicolous polychaete worms that inhabit leathery or parchment-like tubes embedded in soft sediments; body fragile, divided into 3 distinct regions; prostomium indistinct, peristomium collar-like; longitudinal groove produces abundant mucus; contains about 45 species in single family; sometimes included in the order Spionida.
\Bchaetotaxy\b The pattern or distribution of bristles, chaetae, setae, spines etc., used as taxonomic characters.
\BChaetothyriales\b Sooty moulds; order of loculoanoteromycetid fungi that are superficial parasites of green plants or saprophytic on plants and other fungi.
\Bchafer\b \JScarabaeidae\j
\BChalastogastra\b \JSymphyta\j
\Bchalazogamy\b Fertilization in flowering plants in which the pollen tube reaches the nucellus of the ovule by passing through the placenta and the basal region where nucellulus and integuments are fused (the chalaza).
\Bchalcid wasp\b \JChalcididae\j (Apocrita).
\BChalcididae\b Chalcid wasps; diverse cosmopolitan family of small to large robust parasitic wasps (Hymenoptera) comprising over 1400 species; mostly solitary parasites of other insects, including Lepidoptera, Hymenoptera, Coleoptera, Neuroptera, Diptera.
\Bchalicophilous\b Thriving on gravel slides; \Bchalicophile\b, \Bchalicophily.\b
\Bchalicophyte\b A plant inhabiting gravel slides.
\BChalicotheriidae\b Extinct suborder of perissodactyls known from the Eocene to the Pleistocene; front legs slightly longer than hindlegs.
\Bchallenge display\b A high intensity aggressive display performed by a male to a conspecific male.
\BChamaeleontidae\b Chamaeleons; family containing about 70 species of arboreal and terrestrial lizards (Sauria) widespread in Africa and Madagascar; length to about 65 mm; eyes highly mobile, can be moved independently; tongue extensible; digits opposable; tail prehensile, non-autotomic; may exhibit very rapid change of colour.
\Bchamaephyte\b A perennial plant having renewal buds at or just above ground level (up to 250 mm); usually low-growing woody or herbaceous plants common in dry or cold climates and having buds on aerial branches near the ground; sometimes divided into active chamaephyte, passive chamaephyte and suffructicose chamaephyte; see Raunkiaerian life forms.
\Bchamomile\b \JAsterales\j
\BChanidae\b Milkfish; monotypic family of herbivorous Indo-Pacific marine and brackish-water teleost fishes (Gonorhynchiformes); body terete, herring-like, compressed, to 1.7 m length; pelvic fins below dorsal fin, caudal deeply forked; exceptionally fecund; widely cultured in tidal ponds in Indonesia and Philippines.
\BChannidae\b Snakeheads; family containing 10 species of piscivorous freshwater teleost fishes (Channiformes) from tropical Africa and eastern Asia; body elongate, to 1.2 m length, cylindrical anteriorly, compressed posteriorly; head broad; dorsal and anal fins elongate; an accessory respiratory organ (suprabranchial organ) is present in the upper part of the gill chamber for aerial respiration.
\BChanniformes\b Order of small to large predatory freshwater teleost fishes comprising the Channidae (snakeheads).
\BChaoboridae\b Family of small fragile dipteran insects (flies) which have predacious aquatic larvae that use strong prehensile antennae to catch mosquito larvae and other small arthropods.
\BChaparral biome\b A mild temperate region with a Mediterranean climate of cool moist winters and long dry summers with a vegetation of varied sclerophyllous evergreen shrubs and a diverse fauna; see biomes.
\Bchar\b \JSalmonidae\j
\BCharacidae\b Large family of mostly small South American freshwater characiform teleost fishes comprising over 700 species; the taxonomy of the group is confused and it may include African taxa as well.
\BCharacidiidae\b South American darters; family containing about 55 species of small (to 100 mm) tropical South American freshwater characiform teleost fishes resembling the true darters, Percidae; mostly benthic, occasionally mid-water; parental care lacking.
\BCharaciformes\b Characins; diverse order of mostly small, colourful freshwater teleost fishes from South America and Africa; upper jaw protractile; jaws bearing teeth; pharyngeal teeth well developed; pectoral and pelvic fins soft-rayed, spines only rarely present in median fins; pelvics posterior to pectorals; gas bladder simple and connected to inner ear by bony Weberian ossicles; contains over 1300 species in about 15 families; of prime importance in aquarium trade; including tetras, darters, piranhas, pencil fishes, hatchetfishes, leporins, citharinids, and curimatos.
\BCharadriidae\b Plovers; family containing about 65 species of small to medium-sized shorebirds cosmopolitan in open countryside, marshes, and freshwater and marine coastal habitats; legs and bill usually short, wings slender or rounded; habits gregarious, often migratory, monogamous; feed on invertebrates and plant material; nest solitary, in hollow in ground.
\BCharadriiformes\b Diverse order of mostly small to medium-sized shorebirds and sea birds, comprising 16 families and including oystercatchers, snipes, plovers, sandpipers, avocets, stilts, curlews, gulls, terns, and auks.
\BCharales\b The only order of \JCharophyceae\j; also treated as a class of the protoctistan phylum Chlorophyta.
\BCharophyceae\b Stoneworts; class of fresh-and brackish-water chlorophycote green algae; characterized by a large thallus differentiated into rhizoids, stem and whorls of branchlets; sometimes forming calcareous deposits; comprising a single order, Charales; resemble bryophytes in the presence of a sterile envelope enclosing sex organs.
\Bchart datum\b The permanently established surface from which depth soundings or tide levels are referenced; formerly referred to low water but more recently to lowest astronomical tide.
\Bchasmochomophyte\b A plant growing on detritus in rock fissures and crevices.
\Bchasmocleistogamic\b Used of plants bearing some flowers that open and are pollinated after opening and other flowers that remain unopened and within which self-pollination takes place; \Bchasmocleistogamy.\b
\Bchasmodichogamic\b Used of plants bearing both cleistogamic and chasmogamic flowers in the same inflorescence; \Bchasmodichogamy.\b
\Bchasmogamy\b Pollination occurring after the opening of a flower; \Bchasmogamic\b, \Bchasmogamous\b; See also \Jcleistogamy\j
\Bchasmophilous\b Thriving in rock crevices and fissures; \Bchasmophile\b, \Bchasmophily. \b
\Bchasmophyte\b A plant growing on rocks, rooted in detritus and debris in crevices and fissures.
\Bchat\b 1: \JMaluridae\j 2: \JTurdidae\j
\BChauliodontidae\b Viperfishes; family containing 6 species of deep-sea stomiiform teleost fishes found over a daytime depth range of 500-3500 m, often migrating towards the surface at night; body slender, to 300 mm length; anterior dorsal fin ray elongate, carrying distal light organ acting as lure; teeth fang-like.
\BChaunacanthida\b Order of acantharians in which the 20 radial spines have loosely articulated, conical or pyriform bases.
\BChaunacidae\b Sea toads; family containing 4 species of anglerfishes (Lophiiformes) widespread on muddy bottoms to depths of 500 m or more; body globose, to 450 mm length; mouth broad oblique.
\Bcheetah\b \JFelidae\j
\BCheilodactylidae\b Morwongs; family of shallow marine perciform teleost fishes widespread in southern hemisphere and northern Pacific; body elongate, slender, to 1.2 m length; single dorsal fin present; pectoral fin rays elongate; contains 15 species; popular in Australia as sport and food-fishes.
\BCheilostomata\b Large order of gymnolaemantan bryozoans having diverse colony morphology; may be encrusting, creeping, nodular, fanshaped, scroll-like or diskoid; zooids typically box-shaped, calcified; polymorphism extensive - autozooids (feeding), gynozooids (female reproductive), androzooids (male reproductive), kenozooids (structural), avicularia (grasping), vibracula (cleaning); cheilostomes are almost entirely marine and comprise the most diverse and successful extant order of bryozoans.
\BCheimarrichthyidae\b Torrentfish; monotypic family of small (to 130 mm) freshwater teleost fishes (Perciformes) found in fast-flowing mountain streams of New Zealand; body depressed anteriorly, dorsal and anal fins elongate, pelvic fins broad and located well in front of pectorals; migrate downstream to breed and spawning may take place in the sea.
\BCheirogaleidae\b Family containing 4 genera of small lemurs (Strepsirhini) in which the eyes are large and the muzzle short.
\Bchelation\b The process of combining a metal ion with another substance that has the effect of keeping the metal in solution and rendering it non-toxic.
\BChelicerata\b Subphylum of arthropods comprising 3 extant classes, Merostomata (horseshoe crabs), Arachnida (spiders, scorpions, mites), Pycnogonida (sea spiders); body divided into prosoma (cephalothorax) consisting of a prostomium and 6 trunk segments variously amalgamated, and an opisthosoma (abdomen) of up to 12 segments forming an anterior mesosoma and posterior metasoma; antennae absent, first pair of appendages termed chelicerae, second pair pedipalps, and 4 pairs of legs; opisthosomal segments bearing gills, book lungs or spinnerets. Chelicerates are primarily predatory although many mites (Acari) are parasitic.
\BChelidae\b Snake-necked turtles; family containing 30 species of side-necked turtles (Pleurodira) from South America, Australia and New Guinea; head incompletely retractable.
\BChelonethida\b \JPseudoscorpiones\j
\BChelonia\b Alternative name for \JTestudines\j
\BCheloniidae\b Sea turtles; family of large (to 1.5 m) marine turtles (Testudines: Cryptodira) comprising 4 species; carapace covered with horny scutes, forelimbs specialized as flippers; distribution pantropical, oceanic.
\BChelydridae\b Snapping turtles; family containing 3 species of aquatic freshwater turtles (Testudines: Cryptodira) with large heads and beaks; carapace bearing horny scutes; found in eastern North America to northwestern South America.
\Bchemoautotrophic\b Used of those microorganisms that obtain metabolic energy by the oxidation of inorganic substrates, such as sulphur, nitrogen or iron; chemotrophic; \Bchemoautotroph\b; See also \Jphotoautotrophic\j
\Bchemocline\b The boundary zone in a lake between the deep stagnant water (monimolimnion) and the overlying region of freely circulating water (mixolimnion).
\Bchemoheterotrophic\b \JChemoorganotrophic\j
\Bchemokinesis\b A change of linear or angular velocity in response to a chemical stimulus; \Bchemokinetic.\b
\Bchemolithotrophic\b Used of organisms that obtain energy from oxidation/reduction reactions and use inorganic electron donors; \Bchemolithotroph\b; See also \Jchemoorganotrophic\j
\Bchemonasty\b A reponse to a diffuse chemical stimulus; a change in the structure or position of an organ in response to a diffuse chemical stimulus; \Bchemonastic.\b
\Bchemoorganotrophic\b Used of organisms that obtain energy from oxidation/reduction reactions and use organic electron donors; chemoheterotrophic; \Bchemoorganotroph\b; See also \Jchemolithotrophic\j
\Bchemostat\b A steady state laboratory culture apparatus.
\Bchemosynthesis\b The synthesis of organic compounds using chemical energy derived from the oxidation of simple inorganic substrates; \Bchemosynthetic\b; See also \Jphotosynthesis\j
\Bchemotaxis\b The directed reaction of a motile organism towards (positive) or away from (negative) a chemical stimulus; \Bchemotactic.\b
\Bchemotrophic\b \JChemoautotrophic\j
\Bchemotropism\b An orientation response to a chemical stimulus; \Bchemotropic.\b
\Bchemozoophobous\b Used of plants which protect themselves from herbivorous animals by the production of noxious chemical substances (allelochemics); \Bchemozoophobe.\b
\BChenopodiaceae\b Beet, spinach, goosefoot, greasewood; large family of Caryophyllales containing herbs or sometimes woody plants, with stems often succulent, jointed or both; cosmospolitan in distribution but most abundant in dry regions; flowers inconspicuous, borne in dense clusters, variable in morphology; fruits are one-seeded nuts.
\Bcheradophilous\b Thriving on wet sandbars; \Bcheradophile\b, \Bcheradophily.\b
\Bcheradophyte\b A plant living on a sandbar.
\BChernozem\b A zonal soil, typically formed in cool subhumid climates under tall prairie grasses, with a thick black A-horizon and calcium carbonate-rich surface layer, over a lighter intermediate B-horizon and a calcareous C-horizon; black earth.
\Bcherry\b \JRosaceae\j
\Bchersophilous\b Thriving in dry wasteland habitats; \Bchersophile\b, \Bchersophily. \b
\Bchersophyte\b A plant growing on dry wasteland or in poor shallow soil.
\Bchestnut\b \JFagaceae\j
\BChestnut soil\b A zonal soil with a thick dark brown, slightly alkaline A-horizon over a lighter coloured B-horizon and a calcareous lower horizon; formed in temperate to cool, subhumid to semi-arid climates beneath mixed tall and short grasses.
\Bchevrotain\b \JTragulidae\j
\Bchewing louse\b \JMallophaga\j
\BChiasmodontidae\b Swallowers; family containing 15 species of small (to 200 mm) deep-sea perciform teleost fishes; body slender, black; jaws very large and highly mobile, teeth fang-like; stomach extremely capacious; photophores sometimes present.
\Bchickadee\b \JParidae\j
\Bchicken\b \JPhasianidae\j
\Bchickweed\b \JCaryophyllaceae\j
\Bchigger\b Any of predatory mites in the family Trombiculidae, some of which bite humans and, in the Oriental region, carry scrub typhus disease.
\BChilean jasmine\b \JApocynaceae\j
\BChilopoda\b Centipedes; class of carnivorous terrestrial arthropods commonly found in soil, leaf litter and decomposing wood; body typically flattened without division into distinct thorax and abdomen, length 6-200 mm; each trunk segment bearing single pair of appendages, first pair specialized as poison fangs; head bearing single pair of antennae, mandibles, 2 pairs of maxillae; eyes present or absent; sexes separate, oviparous, monomorphic; contains about 2500 species in 2 subclasses, Anamorpha and Epimorpha.
\Bchimaera\b 1: An organism having tissues of two or more genetic types, formed by mutation, abnormal chromosome segregation, or by artificial grafting; usually used of a plant, rarely of an animal. 2: \JHolocephalii\j
\BChimaeriformes\b Chimaeras, rabbitfishes, ratfishes; small order of cartilaginous fishes (Holocephalii) comprising about 35 species in 3 families; body more or less compressed, naked or with placoid denticles; length 0.5-2 m; 4 pairs of gill openings covered by operculum; notochord unsegmented, vertebral centra not developed; reproduction oviparous, eggs encased in horny capsules; widespread bottom-dwelling, sluggish, feeding on benthic fishes and invertebrates.
\Bchimnochlorous\b Pertaining to plants with thin herbaceous leaves that persist over winter.
\Bchimnophilous\b Thriving during the winter; used of plants that exhibit maximum development during the winter; \Bchimonophile\b, \Bchimonophily.\b
\Bchimopelagic\b Pertaining to deep-water marine organisms which occur in surface waters only during the winter.
\Bchimous\b Pertaining to winter or to cold climatic conditions.
\Bchimpanzee\b \JPongidae\j
\BChinchillidae\b Chinchillas, viscachas; family containing 6 species of southern Neotropical herbivorous hystricomorph rodents; habits diurnal or nocturnal, colonial, inhabiting burrows; hindlimbs long with 3 or 4 digits, forelimbs short with 4 or 5 digits.
\BChinese gooseberry\b \JActinidiaceae\j
\BChinese lantern\b \JSolanaceae\j
\Bchionophilous\b Thriving in snow-covered habitats; \Bchionophile\b, \Bchionophily\b; See also \Jchionophobous\j
\Bchionophobous\b Intolerant of snow-covered habitats; \Bchionophobe\b, \Bchionophoby\b; See also \Jchionophilous\j
\Bchionophyte\b A plant living in or under snow.
\BChirocentridae\b Wolf herring; monotypic family of very large (to 3.7 m) predatory marine clupeiform fishes found in warm waters of the Indo-Pacific; body long, compressed, teeth large, fang-like; pelvic fins minute.
\BChironemidae\b Kelpfishes; family of marine teleost fishes (Perciformes) comprising 4 species resembling hawkfishes or morwongs, found on rocky coasts of Australia and New Zealand.
\BChironomidae\b Midges; cosmopolitan family of small delicate flies (Diptera) that swarm in vast numbers in damp habitats; larvae typically aquatic feeding on algae, diatoms or detritus, some predacious or parasitic; the blood of some larvae (bloodworms) contains haemoglobin; family comprises about 5000 species in 120 genera.
\BChiroptera\b Bats; order of mostly small nocturnal mammals in which the forelimbs are modified as wings for flight with thin skin membranes extending from sides of body and legs and enclosing elongate digits; most use echolocation for navigation; many are insectivorous, but diet of other species includes fruit, nectar, small vertebrates and blood; some forms hibernate, others are migratory; 2 suborders are recognized, Megachiroptera (16 families).
\Bchiropterophilous\b Used of plants pollinated by bats; \Bchiropterophile\b, \Bchiropterophily. \b
\Bchitinolytic\b Capable of degrading chitin.
\Bchiton\b \JPolyplacophora\j
\BChlamydoselachidae\b Frilled shark; monotypic family of primitive hexanchiform sharks; body elongate, eel-like, to about 2 m length; head broad and depressed, gill slits large; reproduction ovoviviparous; depth range about 100-75 m.
\Bchlamydospore\b A thick-walled resting spore found in some fungi.
\BChledophilous\b Thriving in wasteland habitats and rubbish heaps; \Bchledophile\b, \Bchledophily.\b
\Bchledophyte\b A plant growing on rubbish heaps.
\BChloramoebales\b Order of mostly freshwater, unicellular xanthophyceaen algae.
\BChloranthaceae\b Small family of woody or herbaceous plants (Piperales) widely distributed in subtropical and tropical regions; the tiny flowers with 1-3 stamens are borne in compound spikes; fruit is a tiny drupe.
\Bchlorinated hydrocarbon\b A synthetic contact insecticide, such as DDT, which is relatively resistant to biodegradation and persists in the food web, often accumulating in non-target organisms.
\Bchlorinity\b A measure of chloride and bromide ion concentration in sea water (in grams per kilogram, or parts per thousand); used in estimating salinity; (salinity = 1.80655 x chlorinity.)
\BChlorococcales\b Diverse order of non-motile green algae common in freshwater plankton, soil and in subaerial habitats such as snow and ice, occasionally lichenised; typically found as solitary cells, but sometimes forming colonial structures; also treated as a class of the protoctistan phylum Chlorophyta.
\BChlorodendrales\b Order of predominantly marine flagellate \JPrasinophyceae\j in which the cells are often non-motile and are enclosed within a pectin-like wall (lorica); occasionally found as symbionts on invertebrates.
\BChlorokybales\b Order of green algae containing a single species found in subaerial habitats in Europe; characterized by a thallus formed from aggregations of cells embedded in a gelatinous matrix.
\BChloromonadales\b Alternative name for the only order of \JRaphidophyceae\j
\BChloromonadida\b \JRaphidophyceae\j treated as an order of the protozoan class Phytomastigophora.
\BChlorophthalmidae\b Greeneyes; family containing 20 species of bottom-living, mainly deep-sea, myctophiform teleost fishes; body cylindrical becoming compressed posteriorly; teeth small, needle-like; adipose fin conspicuous; photophores absent; hermaphroditic.
\BChlorophyceae\b Large, diverse class of green algae containing over 8500 species characterized by the possession of the photosynthetic pigments chlorophylls \Ia\iand \Ib,\i \Fa\n, \Fb\n and \Fg\n carotenes and various xanthophylls; typically producing motile zoospores with 2 or 4 flagella arising from an apical pit.
\BChlorophycota\b Green algae; division of eukaryotic algae containing chlorophylls \Ia\i and \Ib\i; comprising 3 classes, Charophyceae, Chlorophyceae and Prasinophyceae; about equivalent in composition to the phyla Chlorophyta and Gamophyta of the kingdom Protoctista.
\Bchlorophyll\b A photosynthetic pigment reflecting green light and imparting the typical green colour to plants; chlorophyll \Ia\i is found in all autotrophic plants, chlorophyll \Ib\i in land plants, the Chlorophyta and Charophyceae, chlorophylls \Ic\i and \Id\i occur only in certain groups of algae.
\BChlorophyta\b Phylum of Proctoctista comprising those green algae that form zoospores or gametes having cup-shaped, grass-green chloroplasts and at least 2 equal anterior flagella; possessing chlorophylls \Ia\i and \Ib\i as well as various carotenoid derivatives; comprising 9 classes; Chlorococcales, Volvocales, Ulotrichales, Oedogoniales, Chaetophorales, Cladophorales, Siphonales, Charales and Prasinophycales.
\BChloropidae\b Frit flies; family containing about 1200 species of flies (Diptera) characterized by a triangular ocellular plate on the dorsal surface of the head; larvae feed on plants; includes several economically important pest species.
\BChlorosarcinales\b Small order of mostly soil-inhabiting, multicellular green algae, exhibiting an advanced type of cell division, desmochisis, in which each daughter protoplast forms a new wall over its entire surface.
\BChloroxybacteria\b \JProchlorophycota\j
\BChoanichthyes\b Choanates; group of vertebrates possessing functional lungs, internal and external nares and fleshy, lobe-like paired fins or limbs; comprises the lungfishes (Dipnoi) and the tetrapods.
\BChoanoflagellida\b Choanoflagellates; order of mostly unicellular, often stalked zooflagellates containing about 140 species found in aquatic habitats and characterized by possession of a single emergent flagellum surrounded proximally by a funnel-like collar of tentacles; feed on bacteria extracted by the tentacles from currents set up by the flagellum.
\Bchomophilous\b Thriving in wastelands and rubbish heaps; \Bchomophile\b, \Bchomophily. \b
\Bchomophyte\b A plant growing in detritus and other litter.
\BChondrichthyes\b Cartilaginous fishes; class of carnivorous jawed vertebrates having cartilaginous skeleton that may undergo calcification but not ossification; mostly marine, littoral to abyssal; nostrils and mouth ventral, teeth not fused to jaw, skin usually bearing strong dermal scales; swim bladder absent; reproduction oviparous to viviparous, fertilization internal; eggs develop inside horny cases; feed on a wide range of vertebrates and invertebrates; contains about 800 species in 14 orders in 2 subclasses, Elasmobranchii (sharks and rays) and Holocephalii (rat fishes).
\BChondrophora\b Order of marine colonial Hydrozoa found at or near the ocean surface; lacking a medusa generation they comprise numerous polymorphic zooids attached to a central, chambered, chitinous float; a large feeding gastrozooid is surrounded by reproductive gonozooids which are in turn encircled by stinging dactylozooids; includes the by-the-wind sailor.
\BChondrostei\b Group of bony fishes (Actinopterygii) comprising the sturgeons (Acipenseriformes) and a number of fossil forms; characterized by a heterocercal tail, spiracle, spiral valve and a partly cartilaginous skeleton.
\BChonotrichida\b Order of hypostomatan ciliates found as ectocommensals on the gills and limbs of aquatic crustaceans; cilia are limited to the atrial area which often forms an apical funnel with the pharynx at the base.
\BChordariales\b Order of brown algae containing small to medium-sized forms characterized by an alternation of gametophyte and sporophyte generations; sporophytes filamentous in construction, sometimes forming large erect thalli composed of compact pseudoparenchymatous filaments.
\BChordata\b Phylum of bilateral coelomate animals characterized by the presence of a notochord, gill slits, dorsal hollow nerve chord and a post-anal tail at some stage of development; 3 subphyla are recognized, Cephalochordata, Tunicata and Vertebrata.
\BChordeumatida\b Order containing about 500 species of small active helminthomorphan diplopods (millipedes); body cylindrical, legs elongate; allomone-producing pores (ozadenes) absent.
\BChordodea\b Order of gordioidan horsehair worms typically possessing cuticular organs called areoles.
\BC-horizon\b The lowest layer of a soil profile above the bedrock (R-horizon), comprising mineral substrate with little or no structure; containing gleyed layers or layers of accumulation of calcium carbonate or calcium sulphate in some soils; parent material; see soil horizons.
\Bchorology\b The description and delimitation of the distributional ranges of taxa.
\Bchresard\b That portion of the total soil water that is available to plants;see also \Jechard\j \Jholard\j
\BChromadoria\b Subclass of adenophorean nematodes found free-living in soil, marine or freshwater habitats; typically with a striated or ornamented cuticle and characterized by their looping locomotion rather than the normal sinusoidal movement.
\BChromadorida\b Order of chromadorian nematodes found in marine, freshwater and soil habitats; typically with punctate cuticular ornamentation, the cephalic sensory organs arranged in 1 or 2 whorls at the extreme anterior end of the body.
\BChromatography\b A technique for separating and identifying the components in a mixture of compounds; involves passing the dissolved mixture along a piece of filter paper (paper chromatography) or through a column of charged resin (ion-exchange chromatography).
\Bchromatotropism\b An orientation response to stimulation by light of a particular colour; \Bchromatotropic.\b
\BChromophycota\b A division of eukaryotic algae; a heterogeneous assemblage of 9 classes grouped together mainly on the basis of their possession of chlorophylls \Ia\i and \Ic\i and their lack of chlorophyll \Ib\i; containing the following classes, Chrysophyceae, Prymnesiophyceae, Xanthophyceae, Eustigmatophyceae, Bacillariophyceae, Dinophyceae, Phaeophyceae, Raphidophyceae and Cryptophyceae.
\Bchromosome\b A deeply staining nuclear body composed largely of DNA and protein, and comprising a linear sequence of genes.
\Bchromosome complement\b The actual number of chromosomes in a nucleus.
\Bchromosome deletion\b A chromosome mutation involving loss of genes.
\Bchromosome insertion\b A chromosome mutation involving the gain of duplicate genes.
\Bchromosome inversion\b A mutation involving alteration or reversal of a sequence of genes within a chromosome.
\Bchromosome map\b A plan of an individual chromosome showing the gene sequence as an arrangement of nucleotide bases.
\Bchromosome translocation\b A mutation involving the transfer of a segment of one chromosome from one member of a homologous pair to the other.
\Bchromosome pair\b The two homologous chromosomes that become intimately associated during meiosis and mitosis.
\Bchronistic\b Pertaining to, or in relation, to time or a time scale.
\Bchronocline\b A gradual change in a character or group of characters over an extended period of geological time.
\Bchronogenesis\b The time sequence of occurrence of organisms in stratified rock.
\Bchronospecies\b 1: A species which is represented in more than one geological time horizon. 2: The successive species replacing each other in a phyletic lineage which are given ancestor and descendant status according to the geological time sequence.
\Bchronotropism\b An orientation response due to age; used particularly with reference to the movement of leaves in plants; \Bchronotropic\b.
\BChroococcales\b Primitive order of unicellular, blue-green algae which reproduce by binary fission or, rarely, by the formation of nannocytes; contains important primary producers distributed widely in freshwater, soil and marine habitats, and as symbionts in lichens.
\Bchrymosymphily\b An amicable relationship between ants and lepidopterous larvae, based on the scent produced by the larvae; \Bchrymosymphile\b, \Bchrymosymphilous.\b
\Bchrysalis\b A hard shell enclosing an insect pupa.
\Bchrysanthemum\b \JAsterales\j
\BChrysididae\b Cuckoo wasps, gold wasps; family of robust, strongly sculptured, often metallic-coloured, wasps (Hymenoptera) the larvae of which live typically as parasitoids of other insects.
\BChrysobalanaceae\b Coco plum; family of Rosales containing about 450 species of trees or shrubs with a pantropical distribution; flowers irregular, variable; fruit is a drupe.
\BChrysochloridae\b Golden moles; family containing 18 species of small fossorial mammals (Insectivora) found in central and southern Africa; external ears absent; eyes covered with skin; fur has metallic sheen.
\BChrysomelidae\b Leaf beetles, Colorado potato beetle; family of often brightly coloured beetles (Coleoptera) most of which are surface feeders on leaves of flowering plants; some larvae feed on roots or as stem borers; includes numerous agricultural pests amongst the 35000 known species.
\BChrysomonadida\b \JChrysophyceae\j treated as an order of the protozoan class Phytomastigophora.
\BChrysophyceae\b Class of mainly planktonic chromophycote algae common in temperate and high latitude freshwater bodies; typically unicellular but sometimes forming complex branching colonies; characterized by the possession of 1 or 2 golden yellow plastids containing chlorophylls \Ia\i and \Ic\i, some xanthophylls and carotenoid pigments and by the presence in the life cycle of a stage with 2 unequal flagella, one smooth and one flimmer type; comprises 2 subclasses, Chrysophycidae and Dictyochophycidae; also classified as a phylum of Protoctista, under the name Chrysophyta, or as an order of the protozoan class Phytomastigophora under the name Chrysomonadida.
\BChrysophycidae\b Subclass of typically unicellular chrysophyceaen algae characterized by the presence in the life cycle of a silicified resting stage formed within the cell.
\BChrysophyta\b The \JChrysophyceae\j treated as a separate phylum of Protoctista.
\BChrysopidae\b Golden-eyes, chrysopids; the largest family of neuropteran insects many of which produce a noxious odour from glands on the thorax; many larvae feed on plant lice or aphids and some have been used in biological control; contains about 1500 species.
\Bchtonophyte\b A terrestrial plant obtaining water from the soil through roots.
\Bchylophyte\b A terrestrial plant rooted on a physically dry and hard substratum
\BChytridiales\b Chytrids; order of chytridiomycete fungi comprising about 900 species of parasites of various aquatic organisms worldwide; typically with a unicellular thallus within the host cells; sexual reproduction involving fusion of isogametes; also classified as a class of the protoctistan phylum Chytridiomycota, under the name Chytridia.
\BChytridiomycetes\b Class of parasitic and saprobic true fungi found in aquatic and soil habitats; fungal body unicellular to hyphal and generally without cross walls except at reproductive structures; asexual reproduction by production of zoospores bearing a single whiplash flagellum posteriorly; comprises 3 orders, Blastocladiales, Chytridiales and Monoblepharidales; sometimes treated as a phylum, Chytridiomycota, of the Protoctista.
\BChytridiomycota\b \JChytridiomycetes\j; treated as a phylum of Protoctista.
\BChytriodiniales\b Small order of marine parasitic dinoflagellates found infesting animal and plant hosts.
\Bcicada\b \JCicadidae\j (Homoptera).
\BCicadellidae\b Leafhoppers; family comprising about 20 000 species of insects (Homoptera) that feed by sucking plant juices; includes many pests of cultivated plants.
\BCicadidae\b Cicadas; family of large insects (Homoptera) the males of which typically have well developed sound-producing organs; eggs laid in twigs and branches of trees; hatching nymphs fall to ground and dig into soil using powerful forelegs; feed on sap of roots; often with long life cycle mostly spent as nymph; contains about 1500 species.
\BCichlidae\b Cichlids; large family of primarily freshwater perciform teleost fishes comprising more than 700 species; body typically perch-like, weakly to strongly compressed with single dorsal fin; feeding habits, reproductive strategies and behaviour extremely variable. Cichlids show immense radiation in African Great Lakes and in South America, with high levels of endemicity; very popular in the aquarium trade; locally important as food-fishes.
\BCicindelidae\b Tiger beetles; family of active brightly-coloured beetles (Coleoptera) found in open sunny situations, the larvae typically inhabiting burrows; adults and larvae feed mainly on small insects.
\BCiconiidae\b Storks; family containing 17 species of large wading birds (Ciconiiformes) with long legs, long straight bills, and long broad wings; feed mostly on fishes, amphibians and insects; solitary or colonial breeders, the nest comprising a large platform of sticks in tree or on cliff; cosmopolitan in tropical and temperate shallow freshwater lakes, marshes, or grassland.
\BCiconiiformes\b Order of medium to large neognathous wading birds comprising 6 families, cosmopolitan in marine and freshwater coastal habitats; characteristically long-necked and long-legged; includes herons, storks, spoonbills and ibises.
\BCidaroida\b Pencil urchins; order of primitive echinoids (Echinozoa) comprising about 140 extant species found mostly at continental shelf and slope depths, rarely littoral or abyssal; body globular with long spines, ambulacral plates small, interambulacral plates large; gills absent; fossil record dating from Palaeozoic.
\BCiliophora\b Ciliates, Infusoria; diverse phylum of protozoans characterized by the possession of two types of nuclei (micronuclei and macronuclei), simple cilia or compound ciliary organelles, and commonly a cell mouth (cytostome) and pharynx (cytopharynx); found free-living in all types of aquatic and terrestrial habitats and as symbionts and parasites on or in a variety of hosts; includes 3 classes, Kinetofragminophora, Oligohymenophora and Polyhymenophora; also treated as a phylum of Protoctista.
\BCimicidae\b Bedbugs; family of flightless bugs (Heteroptera) which suck blood of mammals or birds or, more typically, are predators of other arthropods.
\BCinclidae\b Dippers; small family containing 5 species of active aquatic passerine birds found along mountain streams and lake shores of Eurasia and western parts of North and South America; habits solitary, non-migratory, swim well underwater using short pointed wings; feed on aquatic invertebrates and small fish; nest in bank or cliff.
\Bcineraria\b \JAsterales\j
\BCingulata\b Infraorder of edentate mammals (Xenarthra) comprising the glyptodonts (Glyptodontidae) and the armadillos (Dasypodidae).
\Bcircadian rhythm\b A biological rhythm having a periodicity of about one daylength (24 hours).
\BCircaeasteraceae\b Small family of herbaceous Ranunculales containing 2 species from southeast Asia characterized by their dichotomously veined leaves lacking anastomoses.
\Bcircalittoral\b The lower subdivision of the marine sublittoral zone below the infralittoral zone, dominated by photophilic algae; sometimes used for the depth zone between 100 m and 200 m; see marine depth zones.
\Bcircumaustral\b Distributed around the high latitudes of the southern hemisphere; See also \Jcircumboreal\j
\Bcircumboreal\b Distributed around the high latitudes of the northern hemisphere; See also \Jcircumaustral\j
\Bcircumneutrophilous\b Thriving in conditions of about neutral pH; \Bcircumneutrophile\b, \Bcircumneutrophily.\b
\Bcircumnutation\b Growth movements of a plant about an axis.
\Bcircumpolar\b Distributed around the north or south polar regions.
\Bcircumtropical\b Occurring throughout the tropics.
\BCirratulida\b Order of burrowing, deposit-feeding, polychaete worms comprising about 245 species in 3 families; included by some authors in the order Spionida.
\BCirrhitidae\b Hawkfishes; family containing 35 species of Indo-Pacific shallow marine perciform teleost fishes; body elongate, to 500 mm length, single dorsal fin present; lower pectoral fin rays enlarged and used for perching on hard surfaces.
\BCirripedia\b Barnacles; class of exclusively sessile marine and brackish water crustaceans typically with calcareous shells enclosing modified filtering limbs; contains about 1000 free-living and parasitic species classified in 4 orders, Acrothoracica, Ascothoracica, Rhizocephala and Thoracica.
\BCistaceae\b Small family of Violales containing about 200 species of shrubs or herbs, common in the Mediterranean region; flowers often showy with 3 or 5 sepals, 5 large petals, many stamens and a one-celled ovary; fruit is a capsule.
\Bcistern epiphyte\b An epiphyte lacking roots and gathering water between the bases of its leaves.
\BCitharidae\b Family containing 5 species of small (to 250 mm) pleuronectoid flatfishes comprising 2 subfamilies, one right-eyed (dextral), the other left-eyed (sinistral).
\BCitharinidae\b Family containing 80 species of large African freshwater characiform teleost fishes; dorsal fin in mid-body position, adipose fin usually present, lateral line straight; mostly herbivorous or micropredatory; parental care lacking, eggs spread over substratum or vegetation.
\Bcitrus family\b \JRutaceae\j
\Bcivet\b \JViverridae\j
\Bclade\b A branch of a cladogram; a monophyletic group of taxa sharing a closer common ancestry with one another than with members of any other clade.
\Bcladistic method\b A method of classification employing phylogenetic hypotheses as the basis for classification and using recency of common ancestry alone as the criterion for grouping taxa; cladism; cladistics; See also \Jphenetic method\j
\BCladocera\b Water fleas; order of diplostracan crustaceans containing about 450 mostly freshwater species, but with a few marine and brackish forms; characterized by jerky swimming using large antennae; often parthenogenetic; trunk enclosed by carapace, head free.
\BCladocopina\b Suborder of marine halocypridan ostracods comprising a single family, Polycopidae, with 40 species, found mainly in shallow waters; efficient swimmers but probably benthic; small body, typically less than 1 mm long.
\BCladophorales\b Order of green algae widely distributed in marine freshwater and brackish water habitats; typically with a thallus comprising uniseriate filaments of multinucleate cells attached by rhizoids; also treated as a class of the protoctistan phylum Chlorophyta.
\Bcladoptosis\b The periodic shedding of twigs.
\BCladoselachiformes\b Extinct order of sharks (Elasmobranchii) known from the Devonian to the Carboniferous; body elongate; 2 dorsal fins, each with a spine.
\Bclam shrimp\b \JConchostraca\j
\BClariidae\b Family of Old World freshwater catfishes (Siluriformes) found throughout much of southern Asia and Africa; body eel-like, dorsal fin long, without spines; 4 pairs of barbels; accessory organ present in gill chamber for aerial respiration; contains 100 species, known as walking catfishes as some species may leave the water and move on land for short periods.
\Bclassification\b A process of establishing, defining and ranking taxa within hierarchical series of groups.
\Bclastic\b 1: Used of sediments that are formed of rock fragments or of clay minerals. 2: Producing or undergoing fragmentation.
\Bclastizoic\b Used of rock comprising fragmented animal remains.
\BClathrinida\b Order of calcinian sponges which are constructed as a complex system of anastomosing tubes lined with choanocytes, each system terminating in an osculum; widely distributed and ranging from the intertidal to about 850 m.
\BClavicipitales\b Order of pyrenomycete fungi typically parasitic on grasses, insects, spiders and other fungi; characterized by production of filiform ascospores which are forcibly discharged; includes ergot of rye.
\Bclay\b Sediment particles between 0.002 mm and 0.004 mm in diameter and having colloidal properties; sometimes used for all sediment particles less than 0.004 mm in diameter; fine clay; see sediment particle size.
\Bcleg\b \JTabanidae\j
\Bcleistogamy\b The condition of having flowers, typically small and inconspicuous, which remain unopened and within which self-pollination takes place; \Bcleistogamic\b, \Bcleistogamous\b; See also \Jchasmogamy\j
\Bclematis\b \JRanunculaceae\j
\BClethraceae\b Small family of Ericales containing 65 species of tanniferous shrubs and small trees usually with stellate hairs; chiefly tropical in distribution; flowers fragrant, bell-shaped, with 5 free imbricate petals, 10-12 stamens and a superior ovary; fruit is a capsule.
\Bclick beetle\b \JElateridae\j
\Bclimacteric\b A critical phase or period in the life cycle of an organism.
\Bclimagraph\b A chart plotting one climatic factor against another, commonly a diagram of mean monthly temperature plotted against mean monthly rainfall or humidity.
\Bclimate\b The long-term average condition of weather in a given area; See also \Jweather\j
\Bclimatic climax\b A more or less stable community in which the major factors affecting the vegetation are climatic, typical of zonal soils.
\Bclimatic rule\b Any generalization describing a trend in geographical variation of animals which can be correlated with a climatic gradient; see also \JAllen's law\j \JBergmann's rule\j, \JGloger's rule\j, \JRensch's laws\j
\BClimatiiformes\b Extinct order of fishes (Acanthodii) possessing bony jaws and skeleton, ganoid scales, heterocercal tail and a stout spine in front of each fin.
\Bclimatology\b The study of climate; See also \Jmeteorology\j
\Bclimax\b A more or less stable biotic community which is in equilibrium with existing environmental conditions and which represents the terminal stage of an ecological succession.
\Bclimbing bittersweet\b \JCelastraceae\j
\Bclimbing gourami\b \JAnabantidae\j
\Bcline\b A character gradient; continuous variation in the expression of a character through a series of contiguous populations; \Bclinal.\b
\Bclingfish\b \JGobiesocidae\j
\BClinidae\b Scaled blennies; family containing 180 species of mostly tropical, intertidal and shallow marine, perciform teleost fishes; body length to 600 mm, but usually much smaller; viviparity common.
\Bclinodeme\b A \Jdeme\j that forms part of a graded sequence of demes distributed over a given geographical area.
\Bclinotaxis\b A directed reaction or orientation response of a motile organism to a gradient of stimulation; \Bclinotactic.\b
\Bclinotropism\b An orientation response to a gradient of stimulation; \Bclinotropic.\b
\Bclisere\b An ecological succession resulting from a major change in climate.
\BClistogastra\b \JApocrita\j
\BClitellata\b Group of annelid worms possessing a clitellum, comprising the Oligochaeta and Hirudinoidea.
\Bclitochorous\b Dispersed by gravity; \BClitochore\b, \Bclitochory.\b
\Bclod\b A compacted mass of soil between about 5 mm and 250 mm in diameter.
\Bclone\b An assemblage of genetically identical organisms derived by asexual or vegetative multiplication from a single sexually derived individual; \Bclonal\b; see also \Jgenet\j \Jortet\j, \Jramet\j
\Bclonodeme\b A local interbreeding population composed of predominantly vegetatively reproducing individuals; See also \Jdeme\j
\Bclosed community\b An assemblage of plants which cover the entire ground area of the habitat in which they live, effectively preventing the establishment of other species.
\Bclothes moth\b \JTineidae\j
\Bclover\b \JFabaceae\j
\Bclubmoss\b \JLycopodiopsida\j
\BClupeidae\b Herrings, shads, sardines, menhaden; large family of mostly small planktotrophic teleost fishes (Clupeiformes), typically marine but also found in brackish and freshwater habitats; body compressed to subcylindrical, caudal fin strongly forked; eggs pelagic or benthic; contains about 180 species, many forming large schools; support extremely important commercial fisheries.
\BClupeiformes\b Large order of mostly small planktivorous teleost fishes comprising 3 families, Clupeidae (herrings, shads, sardines, menhaden), Engraulidae (anchovies) and Chirocentridae (wolf herring); swim bladder diverticula connected to inner ear; lateral line absent; no leptocephalus larval stage; contains about 70 genera distributed worldwide; includes many commercially important species.
\BClusiaceae\b Large family of Theales including 1200 species ranging from tropical and woody plants to temperate herbs; produce resinous secretions in canals or chambers and have an oily embryo.
\Bclusium\b An ecological succession on flooded soil.
\Bcluster fly\b \JCalliphoridae\j
\Bclutch\b The number of eggs laid at any one time; clutch size.
\BClypeasteroida\b Sand dollars; order of irregular echinoids (Gnathostomata) comprising about 130 species typically found burrowing in soft sediments of shallow tropical or temperate seas; test flattened and disk-like, anus close to posterior margin on adoral surface; tube-feet within petal-like array of aboral ambulacra, serving respiratory function; spines especially abundant on lower surface.
\BCneoraceae\b Family of Sapindales containing only 3 species of glabrous shrubs native to the western Mediterranean region; flowers borne in axillary cymes; flowers tri- or tetramerous; fruit comprising 1-4 small drupes.
\BCnidaria\b Coelenterates; phylum of mostly marine multicellular animals characterized by a body plan that comprises two primary layers, ectoderm and endoderm, separated by a layer of gelatinous connective tissues, the mesoglea, by a basic radial symmetry and by the possession of nematocysts, consisting of an intracellular capsule containing a thread which can be everted in response to a variety of stimuli; two body forms are found, an erect, solitary or colonial, polyp which is attached to the substratum and typically has tentacles surrounding its mouth, and a medusa which is disc-shaped, solitary and pelagic; all are carnivorous, although some may derive nutritive benefit from intracellular symbiotic algae; also known as the Radiata because of their radial symmetry; comprises 4 extant classes, Anthozoa, Cubozoa, Hydrozoa and Scyphozoa.
\BCnidosporida\b Phylum of Protoctista containing unicellular organisms that parasitize animals; characterized by the production of a polar filament or thread; equivalent to the protozoan phyla Microspora and Myxozoa.
\BCO\B\D2\d compensation concentration\b\b The minimum atmospheric carbon dioxide concentration allowing net photosynthesis.
\Bcoacervation\b The aggregation of organic molecules to form particulate matter; \Bcoacervate.\b
\Bcoaetaneous\b Of the same age; existing or appearing simultaneously; \Bcoetaneous.\b
\Bcoati\b \JProcyonidae\j
\Bcoat-of-mail shell\b \JPolyplacophora\j
\Bcobble\b A sediment particle between 64 mm and 256 mm in diameter; large gravel; see sediment particle size.
\BCobitidae\b Loaches; family containing about 145 species of northern hemisphere cypriniform teleost fishes; body terete to vermiform, flattened ventrally, with 3-6 pairs of mouth barbels; gas bladder partly enclosed in bony capsule; primarily nocturnal, feeding on bottom-living invertebrates; some species absorb oxygen from air swallowed through vascularized intestine.
\Bcobra\b \JElapidae\j
\Bcobra plant\b \JSarraceniaceae\j
\Bcobweb spider\b Any of the labidognath spider family Theridiidae, also called comb-footed spiders; comprising about 2000 species including the venomous widow spiders; typically contruct irregular webs in vegetation, amongst stones and litter, and beneath buildings.
\Bcocaine\b \JErythroxylaceae\j
\BCoccidia\b Subclass of sporozoans, mostly parasitic in vertebrates and found throughout the world; mature gamonts are small and typically intracellular; life cycle involves 3 types of multiple fission, merogony, gametogony and sporogony; also treated as a subclass, Coccidiasina, of the protoctistan class Sporozoasida.
\BCoccinellidae\b Ladybirds; family of often brightly coloured, rounded beetles (Coleoptera) which are typically predators both as adults and larvae, feeding mainly on other insects including aphids, mealybugs and scale insects; contains about 4500 species, common worldwide.
\Bcoccoid\b \JCoccoidea\j (Homoptera).
\BCoccoidea\b Scale insects, coccoids, mealybugs; a group of insect (Homoptera) families in which the wingless adult females are usually protected by a scale-like wax covering over the body; feed on plant juices, and many are destructive pests of economically important plants.
\Bcoccolith ooze\b A pelagic sediment comprising at least 30% calcareous material predominantly in the form of coccolith remains. See also \Jooze\j
\Bcoccolithophorids\b Unicellular marine algae (Prymnesiophyceae) that have the body embedded in a gelatinous sheath covered with calcareous plates (coccoliths); common as fossils.
\BCoccosphaerales\b Order of calcareous scale-covered flagellate algae (Prymnesiophyceae) found mostly in the marine plankton of warm seas; includes many fossil species.
\Bcockatoo\b \JPsittacidae\j
\Bcockchafer\b \JScarabaeidae\j
\Bcockle\b \JVeneroida\j
\Bcocklebur\b \JAsterales\j
\Bcockroach\b \JBlattaria\j
\Bcockscomb\b \JAmaranthaceae\j
\Bcoco plum\b \JChrysobalanaceae\j
\Bcocoon\b 1: The silken covering around an insect pupa. 2: A brood chamber spun by some spiders to receive their eggs.
\Bcod\b \JGadidae\j
\BCodiales\b \JBryopsidales\j
\Bcod icefish\b \JNototheniidae\j
\Bcodlet\b \JBregmacerotidae\j
\Bcodling moth\b \JTortricidae\j
\Bcodon\b The unit of genetic coding; a triplet of adjacent nucleotides in DNA or in messenger RNA, which specifies a particular amino acid; coding triplet.
\Bcoelacanth\b \JLatimeriidae\j
\BCoelacanthiformes\b Tassel-finned fishes; order of bony fishes (Crossopterygii) represented by the single recent family Latimeriidae, but with an extensive fossil record from the Devonian to the Cretaceous; fins supported by movable lobes.
\BCoelenterata\b Coelenterates; this name has been used to refer to the \JCnidaria\j, \Jand to both the Cnidaria and the \JCtenophora\j
\BCoelocheta\b Superorder of helminthomorphan diplopods (millipedes) comprising 2 orders, Callipodida and Chordeumatida; body with median pleurotergal suture, sterna free; spinnerets present posteriorly.
\BCoelomycetes\b Class of deuteromycotine fungi containing the conidial states of ascomycotine fungi and asexual fungi for which no sexual state is known; most produce closed fruiting bodies, the nature of which determines the systematic position; contains 2 orders, Melanconiales and Sphaeropsidales.
\BCoelopidae\b Kelp flies; family of small flies (Diptera) found in large swarms around accumulations of kelp; comprising about 20 species, absent from tropical regions and from South America.
\Bcoelozoic\b Living in the lumen of an organ of the host individual.
\BCoelurosauria\b Group of agile, bipedal carnivorous dinosaurs (Saurischia) known from the Triassic to the Cretaceous; up to 3 m in length.
\Bcoenocarpium\b A type of multiple fruit with a fleshy axis, which incorporates the receptacles, ovaries and floral parts of many flowers; includes the pineapple.
\Bcoenocline\b A sequence of communities distributed along an environmental gradient.
\Bcoenosis\b An assemblage of organisms having similar ecological preferences.
\Bcoenosite\b An organism that habitually shares food with another organism.
\Bcoenosium\b A plant community.
\Bcoevolution\b The interdependent evolution of two or more species having an obvious ecological relationship, usually restricted to cases in which the interactions are beneficial to both species; also used for the evolutionary interaction between species in which one is detrimental to the other, such as a parasite and its host, and far wider interactions within an evolving community, such as those between species employing a similar feeding strategy.
\Bcoexistence\b The occurrence of two or more species in the same area or habitat, usually used of potential competitors.
\Bcoffee\b \JRubiaceae\j
\Bcoffee-bean weevil\b \JAnthribidae\j
\Bcohort\b A group of individuals of the same age recruited into a population at the same time; age class.
\Bcoition\b Copulation; sexual intercourse; coitus.
\Bcold blooded\b \JPoikilothermic\j
\Bcold hardiness\b The tolerance of an organism to low temperatures.
\Bcold monomictic lake\b A lake having a summer overturn and in which the temperature of the water never rises above 4░C; See also \Jwarm monomictic lake\j
\Bcold resistance\b The ability to survive exposure to temperatures below 0░C.
\Bcold temperate zone\b A latitudinal zone extending between 45░and 58░in both northern and southern hemispheres.
\BColeochaetales\b Small order of aquatic epiphytic or endophytic green algae; thallus typically consisting of cells united or clustered into branched filaments; asexual reproduction involves scaly biflagellate zoospores.
\BColeoidea\b Dibranchiata: the larger subclass of cephalopod molluscs characterized by an internal shell, sometimes lost, by the possession of 8-10 prehensile arms or tentacles often equipped with suckers, by one pair of gills and by spermatophore transfer involving a specially modified pair of arms in the male; comprises 4 orders, Octopoda (octopus), Sepioidea (cuttlefish), Teuthoidea (squid) and Vampyromorpha (vampire squid).
\BColeoptera\b Beetles; large order of holometabolous insects having immense morphological and biological diversity; body typically depressed and heavily sclerotized, forewings modified as rigid elytra covering membranous hindwings; wings may be reduced or absent; development incorporating distinct larval and pupal stages; 4 suborders recognized, Archostemata, Myxophaga, Adephaga and Polyphaga.
\BColiidae\b Mousebirds; small family of gregarious, agile, African forest birds comprising 6 species; wings short and rounded, tail long, feet strong; feed mostly on fruits, seeds and other plant material.
\BColiiformes\b Monofamilial order of small neognathous African forest birds.
\Bcollaplankton\b Planktonic organisms gaining buoyancy from gelatinous or mucous envelopes.
\BCollembola\b Springtails; order containing about 2000 species of blind, primitively wingless insects with entognathous biting mouthparts and short antennae; mostly less than 6 mm in length; leaping movement by means of a forked springing organ on the underside of the abdomen; sometimes treated as a distinct class of hexapods.
\Bcolloid\b 1: A dispersion of one substance within another, having the properties of both a solution and a suspension; the system is composed of two phases, a continuous phase (the dispersion phase) and a discontinuous phase (the dispersed phase) which consists of discrete particles; colloidal system. 2: Very fine sediment particles less than 0.002 mm in diameter; see sediment particle size.
\BCollothecaceae\b Small order of mostly sessile rotifers which have an expanded funnel-shaped anterior end and typically live in a gelatinous case, attached to the substrate by a long foot and basal disk.
\Bcolluvial deposit\b Material transported to a site by gravity; as in rock deposits at the base of a scree slope; \Bcolluvium\b; see also \Jalluvial deposit\j \Jaeolian deposit\j
\Bcolonist\b 1: Used of a plant introduced unintentionally as a result of the activities of man, typically a weed of cultivation, and now found only in more or less artificial habitats. 2: An organism which invades and colonizes a new habitat or territory.
\Bcolonization\b 1: The successful invasion of a new habitat by a species. 2: The occupation of bare soil by seedlings or sporelings.
\Bcolony\b Used loosely to describe any group of organisms living together or in close proximity to each other; more precisely it refers to an integrated society in which members may be specialized subunits.
\Bcolony fission\b Multiplication of a colony of social insects by the departure of one or more member groups to establish new colonies whilst leaving the parent colony still viable.
\Bcolony odour\b The particular odour found on the bodies of social insects, providing a basis for colony recognition.
\BColorado potato beetle\b \JChrysomelidae\j
\BColpodida\b Order of vestibuliferan ciliates with highly organized oral ciliature in the vestibulum; mostly found free-living in freshwater or soil habitats.
\BColubridae\b Large and extremely diverse family of snakes (Serpentes); habits terrestrial, fossorial, arboreal and aquatic; feed on wide range of invertebrates and vertebrates; many are venomous; reproduction oviparous and ovoviviparous; contains over 1500 species with an almost cosmopolitan distribution, although largely absent from Australia; teeth usually solid, although grooved in a few venomous species.
\BColubroidea\b Superfamily of morphologically advanced snakes (Serpentes) comprising 4 families that contain the majority of living species; pelvic girdle absent; left lung absent or vestigial; venomous and non-venomous; oviparous and ovoviviparous; contains about 1900 species, worldwide.
\Bcolugo\b \JCynocephalidae\j (Dermoptera).
\BColumbidae\b Pigeons, doves; family containing about 300 species of small to medium-sized, terrestrial and arboreal birds found worldwide in woodland, forest and arid areas; habits solitary to gregarious, feeding mostly on seeds and fruit, and nesting in trees, cliffs or on the ground; the young are fed on crop-milk.
\BColumbiformes\b Small order of small to medium-sized arboreal and terrestrial birds comprising 2 extant families, Pteroclididae (sandgrouse) and Columbidae (pigeons, doves), and the Raphidae (dodo).
\BColumelliaceae\b Small family of Rosales containing 4 species of bitter shrubs or trees native to the northern part of the Andes.
\BComatulida\b Feather stars; order of articulate crinoids comprising about 550 extant species, found from the intertidal to upper slope depths, and abundant on coral reefs; stalk absent in adult but present in early juvenile; cirri present, and may have 40 or more brightly coloured arms.
\Bcomb jelly\b \JCtenophora\j
\Bcombfish\b \JZaniolepididae\j
\BCombretaceae\b Indian almond, Rangoon creeper, white mangrove; family of Myrtales containing nearly 400 species of trees or climbing shrubs widespread in tropical and subtropical regions; flowers usually bisexual, regular and with 4 or 5 sepals, 4, 5, or 0 petals, 4, 5, 8 or 10 stamens and an inferior ovary.
\Bcombtooth blenny\b \JBlenniidae\j
\BComephoridae\b Oilfishes; family or small (to 200 mm) viviparous freshwater scorpaeniform teleost fishes comprising 2 species confined to Lake Baikal; body slender, covered with thin transparent skin, pectoral and anal fins elongate, pelvics absent.
\BCommelinaceae\b Wandering jew, tradescantia, spiderwort; family containing about 700 species of often succulent herbs with stems swollen at nodes, simple alternate leaves, and flowers pollinated by insects although lacking nectaries; widespread in warm regions; flowers bisexual, usually regular, with 3 sepals and petals, 6 stamens and a superior ovary.
\BCommelinales\b Order of Commelinidae consisting of 4 families of herbs with alternate leaves and flowers lacking nectar but pollinated by insects, producing small abundant seeds.
\BCommelinidae\b Subclass of monocotyledons (Liliopsida) comprising 7 orders of mostly herbs with simple, alternate, parallel-veined leaves and usually with insect or wind-pollinated flowers; seed endosperm largely starchy.
\Bcommensalism\b A symbiotic relationship between two species in which one derives benefit from a common food supply whilst the other is not adversely affected; \Bcommensal.\b
\Bcommon carpetweed\b \JMolluginaceae\j
\Bcommon flax\b \JLinaceae\j
\Bcommon pokeweed\b \JPhytolaccaceae\j
\Bcommon rue\b \JRutaceae\j
\BCommunal\b Pertaining to the cooperation between members of the same generation in nest building but not in care of the brood.
\Bcommune\b A society or group of conspecific organisms which have a social structure and consist of repeated members or modular units with a high level of coordination, integration and genotypic relatedness.
\Bcommunicable\b Used of a disease which is readily transferred from one organism to another, usually used of diseases of man and domestic animals.
\Bcommunication\b Any action of one organism that modifies the behaviour pattern of another organism.
\Bcommunity\b Any group of organisms comprising a number of different species that co-occur in the same habitat or area and interact through trophic and spatial relationships.
\Bcompatible\b 1: Capable of cross fertilization. 2: Used of plants having the capacity for self-fertilization.
\Bcompensation depth\b 1: The depth at which primary production and respiration are equal so there is no net production; compensation level; compensation point. 2: The ocean depth at which the rate of solution of calcium carbonate increases to the point that dissolution of calcareous shells begins; typically a depth of about 4000 m, below which calcareous sediments are not found.
\Bcompetition\b The simultaneous demand by two or more organisms or species for an essential common resource that is actually or potentially in limited supply (exploitation competition), or the detrimental interaction between two or more organisms or species seeking a common resource that is not limiting (interference competition); \Bcompetitor.\b
\Bcompetitive exclusion principle\b The principle that complete competitors cannot coexist; two species having identical ecological requirements cannot coexist indefinitely.
\Bcomplemental male\b A male which lives permanently attached to a female, often small and degenerate except for well developed reproductive organs.
\Bcomplete flower\b A flower that has all four parts,pistil, stamen, petal and sepal; See also \Jincomplete flower\j
\BCompositae\b \JAsterales\j
\Bcomposite species\b 1: A species comprising two or more subspecies; polytypic species. 2: In palaeontology, a species represented by a group of specimens that were obtained from two or more localities and that are not all of the same geological age.
\Bcomposites\b \JAsterales\j
\Bcompound nest\b A nest formed by two or more species of social insects in which individuals from the separate colonies may intermingle but in which the broods remain separate.
\Bcompression\b A process of fossilization in which the organic remains have been flattened by overlying strata.
\BCompsopogonales\b Small order of tropical and subtropical red algae tyically with parenchymatous thalli which pass through a filamentous stage in early development.
\BConcentricycloidea\b Sea daisy; recently discovered class of minute (2-9 mm) deep-sea echinoderms found in submerged driftwood off the New Zealand coast; body circular resembling small jellyfish with spines and tube feet around the periphery; dorsal surface bearing calcareous plates; paired gonads arranged in pentamerous symmetry; mouth, anus and arms absent; unlike other echinoderms the sea daisy has 2 water vascular rings instead of one; the young are brooded in the gonads.
\Bconch\b \JMesogastropoda\j
\Bconchology\b The study of shells; \Bconchological.\b
\Bconchometry\b The study of the morphometrics of shells.
\BConchostraca\b Clam shrimps; order of diplostracan crustaceans containing about 180 species of detritus and suspension feeders found mostly in freshwater temporary pools; body up to 20 mm in length, enclosed in a bivalved carapace and bearing up to 28 pairs of foliaceous limbs; produce eggs resistant to desiccation.
\Bconcolorous\b Having uniform coloration; \Bconcolour.\b
\Bconcrescent\b Coalesced; growing together.
\Bconditioning\b Modification of the behaviour of an organism such that it responds to a given stimulus with a behaviour pattern normally associated with some other stimulus when the two stimuli have been applied concurrently a number of times.
\Bcondor\b \JCathartidae\j
\BCondylarthra\b Extinct order of mammals (Protoungulata) comprising several families of primitive ungulates; somewhat intermediate in form between insectivores and true ungulates; some may have possessed claws but others had hooves and ungulate dentition; known from the Late Cretaceous to the Miocene.
\Bcone shell\b \JNeogastropoda\j
\Bconeflower\b \JAsterales\j
\Bcongenital\b Present at time of birth; used of a condition that has resulted from an embryonic aberration.
\Bconger eel\b \JCongridae\j
\BCongiopodidae\b Pigfishes, racehorses; family of little-known marine scorpaeniform teleost fishes found in shallow waters of the southern hemisphere; body deep, compressed, naked; length to 0.8 m; snout prominant.
\Bconglobate\b To roll up, as in some woodlice and millipedes; \Bconglobation.\b
\BCongregate\b To collect together or assemble into a group.
\BCongridae\b Conger eels; diverse family containing about 100 species of marine anguilliform teleost fishes; body smooth, to 3 m length; dorsal and anal fins long, caudal present or absent, pectorals variable, large to absent; predatory, scavenging or zooplanktotrophic, commonly nocturnal; some large species exploited commercially.
\Bconifer\b \JPinatae\j
\BConiferae\b The largest group of gymnosperms, treated under the alternative name Pinatae
\Bconiophilous\b Thriving on substrates enriched by dust; used of lichens which thrive when covered with a coat of dust; \Bconiophile\b, \Bconiophily. \b
\Bconjugation\b 1: Union of gametes, nuclei, cells or individuals. 2: A type of sexual reproduction during which two cells unite but with only limited genetic exchange between the cells.
\BConnaraceae\b Family of Rosales containing about 400 species of often highly poisonous woody plants widespread in tropical regions; flowers pentamerous; fruit usually a one-seeded follicle.
\Bconnascent\b Produced at the same birth.
\BConocardioida\b Extinct order of rostroconch molluscs with an elongate posterior part to the shell; known from the Lower Ordovician to Upper Permian.
\BConopodina\b A suborder of \JAmoebida\j; also treated as a class of the protoctistan phylum Rhizopoda.
\Bconsanguinity\b Relationship by descent from a common ancestor.
\Bconsecutive hermaphrodite\b An organism having functional male and female reproductive organs which mature at different times, either the male organs mature first (protandrous hermaphrodite) or the female organs (protogynous hermaphrodite); See also \Jsynchronous hermaphrodite\j
\Bconservation\b The planned management of natural resources; the retention of natural balance, diversity and evolutionary change in the environment; See also \Jpreservation\j
\Bconsistence\b A measure of cohesion of soil particles.
\Bconsociation\b A small climax plant community dominated by one particular species (the physiognomic dominant) which has the life form characteristic of the association.
\Bconspecific\b Belonging to the same species.
\Bconstant plankton\b The perennial permanent planktonic organisms of an area.
\Bconstant species\b 1: A species invariably present in a given community. 2: A species occurring in at least 50% of samples taken from a given community.
\Bconstipated\b Crowded together.
\Bconstrictor snake\b \JBoidae\j
\Bconsumer\b An organism that feeds on another organism or on existing organic matter; includes herbivores, carnivores, parasites and all other saprotrophic and heterotrophic organisms.
\Bconsummatory act\b A behavioural act which constitutes the terminal phase of an instinctive behaviour sequence; See also \Jappetitive behaviour\j
\Bconsumption\b In ecological energetics, the total intake of food or energy by a heterotrophic individual, population or trophic unit per unit time.
\Bcontagious disease\b Any disease transmitted through physical contact.
\Bcontact herbicide\b A herbicide that kills on contact rather than after absorption, such as Paraquat.
\Bcontamination\b The introduction of an undesirable agent such as a pest or pathogen, into a previously uninfested situation.
\Bcontiguous\b Having boundaries that make contact but areas that do not overlap.
\Bcontinental climate\b Any climate in which the difference between summer and winter temperatures is greater than the average range for that latitude because of distance from an ocean or sea.
\Bcontinental drift\b The theory that the continental landmasses have drifted apart over the course of geological time; See also \Jplate tectonics\j
\Bcontinental island\b An island that is close to, and geologically related to, a continental landmass, and was formed by separation from the continent; See also \Joceanic island\j
\Bcontinental rise\b The gently sloping sea bed from the continental slope to the abyssal plain, with an average angle of slope of about 1░; see marine depth zones.
\Bcontinental shelf\b The shallow gradually sloping sea bed around a continental margin, not usually deeper than 200 m and formed by submergence of part of the continent; see marine depth zones.
\Bcontinental slope\b The steeply sloping sea bed leading from the outer edge of the continental shelf to the continental rise, with an average angle of slope of about 4░and a maximum of about 20░near the upper margin; see marine depth zones.
\Bcontinuum\b A gradual or imperceptible intergradation between two or more extreme values.
\BContortae\b \JGentianales\j
\Bcontranatant\b Swimming, moving, or migrating against the current; See also \Jdenatant\j
\Bcontrol\b A parallel experiment or test carried out to provide a standard against which an experimental result can be evaluated.
\BConulata\b Extinct subclass of scyphozoan Cnidaria known from the Middle Cambrian to the Triassic; bodies exhibited tetramerous symmetry; tentacles present around mouth.
\Bconvection\b A mode of heat transfer within a fluid, involving the movement of substantial volumes of the fluid from one place to another as a result of changes in the density of heated and non-heated areas.
\Bconvective rain\b Rainfall produced by convection, resulting from solar radiation heating the ground; see also \Jfrontal cyclonic rain\j \Jorographic rain\j
\Bconvergence\b 1: Convergent \Jevolution\j 2: An oceanic region in which surface waters of different origins come together and where the denser water sinks beneath the lighter water\j, \Jas in the Antarctic convergence; See also \Jdivergence\j
\Bconvergent evolution\b The independent evolution of structural or functional similarity in two or more unrelated or distantly related lineages or forms that is not based on genetic similarity; See also \Jparallel evolution\j
\BConvolvulaceae\b Bindweed, morning glory, sweet potato; family of Solanales containing about 1500 species of commonly twining or climbing herbs; nearly cosmopolitan in distribution; flowers regular and usually bisexual, typically with 5 sepals, petals and stamens, and a superior ovary.
\Bcony\b \JOchotonidae\j
\Bcoot\b \JRallidae\j
\BCopepoda\b Class of mostly small aquatic crustaceans exhibiting a great diversity of form and life history; includes many commensals, parasites of all major animal groups, and free-living forms, abundant in planktonic, benthic and interstitial habitats; primitively with many-segmented antennae, modified for grasping in the male; each pair of swimming legs joined by a rigid plate; contains about 9000 species in 8 orders.
\Bcopepodid\b Larval stage of copepods, possessing functional swimming thoracic legs.
\BCope's rule\b The generalization that there is a trend towards increasing body size within an evolutionary series.
\Bcopper\b \JLycaenidae\j
\Bcoppicing\b Woodland management by regularly cutting back of trees to ground level to encourage adventitious shoot production; See also \Jpollarding\j
\BCoprinaceae\b Ink caps; family of mushroom-like fungi (Agaricales) in which the spore masses appear dark brown or black; mostly found on dung or rotting wood; gills typically liquefy as spores mature.
\Bcoprobiont\b Any animal (coprozoite) or plant (coprophyte) living or feeding on dung; \Bcoprobiontic.\b
\Bcoprolites\b Fossilized faecal material.
\Bcoprology\b The study of animal faeces; \Bcoprological.\b
\Bcoprophagous\b Feeding on dung or faecal material; \Bcoprophage\b, \Bcoprophagy.\b
\Bcoprophilous\b Thriving on or in dung or faecal material; \Bcoprophile\b, \Bcoprophily.\b
\Bcoprophyte\b A plant living on dung or faecal material; \Bcoprophytic.\b
\Bcoprozoite\b An animal living on or in dung or faecal material; \Bcoprozoic.\b
\Bcopulate\b 1: To engage in sexual intercourse; the act of introducing spermatozoa into the female; coition; \Bcopulation\b, \Bcopulatory.\b 2: Conjugate; to fuse together, as in the case of gametes.
\Bcoquina\b A deposit of drifted shells.
\BCoraciidae\b Rollers; small family of colourful arboreal birds known for their acrobatic tumbling courtship flight; habits solitary, sedentary, aggressive, monogamous, often migratory: feed mainly on insects caught on the wing or by swooping from a perch; nest in hole in bank or tree; widespread in tropical and warm temperate open woodlands of the Old World.
\BCoraciiformes\b Diverse order of hole-nesting arboreal birds comprising 10 small families; includes Alcedinidae (kingfishers), Meropidae (bee eaters), Upupidae (hoopoe Bucerotidae (hornbills) and Coraciidae (rollers); most widespread in tropical regions of the Old World.
\Bcoral snake\b \JElapidae\j
\Bcoral-billed nuthatch\b \JHyposittidae\j
\BCorallimorpharia\b Order of solitary or gregarious zooantharians found mainly in tropical, shallow seas often on coral reefs; lacking a hard skeleton and characterized by an adherent pedal disk, radially arranged and non-retractile tentacles, and numerous complete mesenteries.
\BCordaitales\b Extinct order of gymnosperms known from the Carboniferous to the Permian; included trees up to 30 m tall, often with strap-like leaves; cones primitive.
\Bcordillera\b An entire mountain system, including all subordinate ranges, interior plateaux and basins.
\BCordylidae\b Family of terrestrial lizards containing about 55 species found in xeric rocky and grassland habitats of Africa and Madagascar; mainly insectivorous, sometimes predatory on small vertebrates; reproduction oviparous or ovoviviparous; transverse rows of ossified scales may be elongated into spines.
\Bcore\b A vertical column of bottom sediment.
\Bcoriander\b \JApiaceae\j
\BCoriariaceae\b Small family of strongly tanniferous shrubs producing ellagic acid and poisonous terpenoids; contains only 5 species having an interrupted cosmopolitan distribution; sepals imbricate, petals with internal keels, 5-10 free carpels.
\BCoriolis force\b The deflecting force of the Earth's rotation that causes a body of moving water to be deflected to the right in the northern hemisphere and to the left in the southern hemisphere.
\Bcorkscrew flower\b \JApocynaceae\j
\Bcorm\b A short, underground stem, specialized as a perennating organ, producing flowers and foliage from one or more buds.
\Bcormidium\b An assemblage of zooids budded off the coenosarc in some colonial hydrozoan cnidarians (Siphonophora).
\Bcormorant\b \JPhalacrocoracidae\j
\BCornaceae\b Dogwood; family of about 100 species of mostly trees and shrubs, widespread especially in northern temperate regions; flowers with 4, 5 or 0 sepals and petals, 4 and 5 stamens and an inferior ovary.
\BCornales\b Small order of Rosidae containing 4 families of mostly woody plants, Alangiaceae, Cornaceae, Garryaceae and Nyssaceae.
\Bcornetfish\b \JFistulariidae\j
\Bcorolla\b The petals, the second outermost whorl of a flower; may be fused into a corolla tube.
\BCoronata\b Extinct order of crinoids (Inadunata) in which there was a single circlet of plates beneath the radial plates bearing the arms; plates covering ambulacra; known from the Middle Ordovician to Upper Silurian.
\BCoronatae\b Primitive order of Scyphozoa comprising about 25 species of large, dark red or purple jellyfish found mostly in the bathypelagic zone of the world's oceans.
\BCoronophorales\b Small order of pyrenomycete fungi found mainly on wood with the mycelium produced within the host; characterized by carbonaceous ascocarps which are completely enclosed.
\Bcorrasion\b Erosion by the mechanical action of a moving agent such as running water, wind or glacial ice.
\Bcorridor\b A more or less continuous connection between adjacent landmasses which has existed for a considerable period of geological time.
\BCorsiaceae\b Small family of Orchidales comprising about 9 species of mycotrophic herbs lacking chlorophyll and with leaves reduced to scales and flowers solitary and terminal, restricted to New Guinea and Chile.
\Bcorticolous\b Inhabiting or growing on bark; \Bcorticole.\b
\BCorvidae\b Crows, jays, magpies; cosmopolitan family containing about 100 species of small to large passerine birds found in wide variety of wooded and open habitats; plumage uniformly dark, or with bold coloration; bill strong, slender; habits gregarious to solitary, non-migratory, often aggressive; feeding on wide range of plant and animal material; nest of sticks in trees or on cliffs.
\BCorydalidae\b Dobsonflies; family containing about 200 species of large neuropteran insects with a wingspan usually of 40-160 mm but which do not fly well; subaquatic larvae are voracious predators possessing 8 pairs of simple abdominal gills.
\BCorylaceae\b Hornbeam, hazel; family of deciduous trees and shrubs (Fagales) widely distributed in the temperate and cold-temperate northern hemisphere; flowers arranged in unisexual catkins; fruit is a nut; sometimes included within the \JBetulaceae\j
\Bcorymb\b A racemose inflorescence in which lower flower stalks are longer than the upper so the flowers lie in a flattish dome.
\BCoryneliales\b Small order of mostly tropical pyrenomycete fungi which are mostly parasitic on conifers; typically with evanescent asci at maturity.
\BCorynocarpaceae\b Family of Celastrales containing only 5 species of trees producing bitter, toxic glucosides; native to Australia and New Zealand.
\BCoryphaenidae\b Dolphinfishes; family of predatory, pelagic, teleost fishes (Perciformes) comprising only 2 species, cosmopolitan in tropical oceans; body elongate, compressed, to 1.5 m length; single long dorsal fin present, caudal deeply forked; very popular as game fishes.
\Bcoryphilous\b Thriving in alpine meadows; \Bcoryphile\b, \Bcoryphily.\b
\Bcoryphophyte\b A plant inhabiting alpine meadows.
\Bcosmopolitan\b Having a worldwide distribution, effect or influence; pandemic; ubiquitous.
\Bcosmotropical\b Circumtropical; occurring throughout the tropics.
\BCossurida\b Order of small (to 15 mm) deposit-feeding polychaete worms that burrow in soft sediments, comprising a single family and about 20 species; prostomium and peristomium naked; pharynx eversible, unarmed; parapodia biramous.
\BCostaceae\b Small family of Zingiberales comprising about 150 species of mostly leafy-stemmed herbs with silica cells along the veins, occurring in wet, shady situations in tropical rainforests; flowers with 6 stamens, 1 producing pollen in 2 sacs, the other 5 fused to form a large, petaloid labellum.
\Bcoterie\b A social group of animals which defends a common territory against members of other coteries.
\Bcotinga\b \JCotingidae\j
\BCotingidae\b Cotingas; family containing about 80 species of neotropical passerine forest birds; male often with bold patterned plumage, some with elaborate courtship display; habits mostly solitary, arboreal, non-migratory, monogamous or polygamous; feed on insects and fruit, and nest in trees or among rocks.
\BCottidae\b Sculpins, bullheads; family containing about 300 species of primarily northern hemisphere marine and freshwater scorpaeniform teleost fishes; body slender to stout, to 750 mm length, often with marked cryptic coloration; head depressed and spinose.
\BCottocomephoridae\b Longwing sculpins; family containing 25 species of small (to 200 mm) freshwater scorpaeniform teleost fishes confined to Lake Baikal and its tributary rivers, ranging from surface waters to 1000 m
\Bcotton\b \JMalvaceae\j
\Bcottonwood\b \JSalicales\j
\BCottunculidae\b Family of little-known marine sculpins (Scorpaeniformes) having a tadpole, shaped body covered by loose warty skin; head bearing bony processes, mouth large; contains 6 species, widely distributed, mostly in moderately deep water.
\Bcotyledon\b The first leaf or leaves in the embryo of flowering plants and other seed plants.
\BCotylosauria\b Group of anapsid reptiles which flourished in the late Palaeozoic, becoming extinct in the Triassic.
\Bcougar\b \JFelidae\j
\Bcountershading\b The condition of an animal having a darkly coloured dorsal surface and a lighter ventral surface, that serves to disrupt the silhouette in a gradient of downwelling light.
\Bcoural\b \JLeptosomatidae\j
\Bcourt\b 1: The group of workers that surround a queen in an insect colony; retinue. 2: That part of a communal display area defended by a particular male.
\Bcourtship\b Any behavioural interaction between males and females that facilitates mating.
\Bcover\b 1: Plant material, living (vegetative cover) and dead (litter cover), on the soil surface. 2: The area of ground covered by vegetation of a particular plant species; expressed as a scale (Braun-Blanquet scale, Domin scale), or as a percentage.
\Bcoverage\b That part of a sampled area covered by a particular plant species or individual plant canopy.
\Bcovert\b A shelter; a hiding place.
\Bcow killer\b \JMutillidae\j
\Bcow shark\b \JHexanchidae\j
\Bcowbird\b \JIcteridae\j
\Bcowrie\b \JMesogastropoda\j
\Bcowslip\b \JPrimulaceae\j
\Bcoypu\b \JMyocastoridae\j
\Bcrab\b \JBrachyura\j
\Bcrab louse\b \JPthiridae\j
\BCracidae\b Curassows; family containing about 50 species of medium sized Neotropical tree-living or terrestrial gallinaceous birds (Galliformes) found in forest habitats from Texas to Paraguay.
\BCracticidae\b Butcherbirds; family comprising about 10 species of medium-sized gregarious, arboreal birds found in Australia and Papua New Guinea; bill typically short and stout, wings pointed; feed on insects, small vertebrates and fruit.
\Bcranberry\b \JEricaceae\j
\Bcrane\b \JGruidae\j
\Bcranefly\b \JTipulidae\j
\Bcranesbill\b \JGeraniaceae\j
\BCraniata\b Those groups of animals possessing a dorsal vertebral column and a bony or cartilaginous skull.
\BCranoglanidae\b Family of Chinese freshwater catfishes (Siluriformes) containing only 3 species; body naked, to 300 mm length, dorsal fin short with single spine; snout depressed bearing 4 pairs of barbels; Cranoglanididae.
\Bcrape myrtle\b \JLythraceae\j
\BCraseonycteridae\b Bumblebee bat; monotypic family of small microchiropteran bats from Thailand; tail absent; nose simple with narial pad and open nostrils; second digit partly free; includes the smallest mammal.
\Bcrash\b A precipitous decline in the size of a population; See also \Jflush\j
\BCrassulaceae\b Sempervivum, houseleek, crassula; large family of Rosales containing about 900 species of succulent herbs or shrubs often with red root tips, commonly with crassulacean acid \Jmetabolism\j; of nearly cosmopolitan distribution and familiar as ornamentals; flowers arranged in cymes, with 3-30 sepals, petals and stamens.
\Bcrawfish\b \JPalinura\j
\Bcrayfish\b \JAstacidea\j
\Bcreationism\b The belief that all forms of life were created \Ide novo\i, and have undergone little subsequent change; \Bcreationist.\b
\Bcrêche\b A group of young animals which have left their nests.
\BCreediidae\b Family of small (to 90 mm) Indo-Pacific coastal marine, sand-burrowing, teleost fishes (Perciformes), comprising 3 monotypic genera; body slender, eel-like; mouth protractile; dorsal and anal fins elongate, lacking fin spines.
\Bcremnophilous\b Thriving on cliffs; \Bcremnophile\b, \Bcremnophily.\b
\Bcremocarp\b A dry fruit, developed from 2 fused carpels, that divides into 2 one-seeded units at maturity.
\Bcrenic\b Pertaining to a spring and the adjacent brook water flowing from the spring.
\Bcrenicolous\b Living in springs, or in brook water fed from a spring; \Bcrenicole.\b
\Bcrenogenic meromixis\b Mixing in a lake caused by a saline spring delivering dense water into the bottom of a lake displacing the \Jmixolimnion\j; see also \Jbiogenic meromixis\j \Jectogenic meromixis\j
\Bcrenon\b The spring-water biotope; see also \Jstygon\j \Jthalasson\j, \Jtroglon\j
\Bcrenophilous\b Thriving in or near a spring; \Bcrenophile\b, \Bcrenophily.\b
\BCrenuchidae\b Family containing 3 species of tiny (to 50 mm), colourful, South American freshwater characiform teleost fishes found in parts of the Amazon and Orinoco basins.
\BCreodonta\b An extinct order of carnivorous mammals (Ferae) known from the late Cretaceous through to the Pliocene that included mustelid-like and hyaena-like forms; rather small-brained and slow moving; shearing carnassial teeth formed by the molars.
\Bcreophagous\b Carnivorous; used particularly of insectivorous plants; \Bcreophage\b, \Bcreophagy.\b
\Bcreosote bush\b \JZygophyllaceae\j
\Bcrepitation\b A defence mechanism in insects in which fluid is explosively discharged.
\Bcrepuscular\b Active during twilight hours; of the dusk and dawn; see also \Jdiurnal\j \Jnocturnal\j
\Bcrestfish\b \JLophotidae\j
\BCretaceous\b A geological period of the Mesozoic era (\Ic.\i 140-65 million years B.P.); see geological time scale.
\BCricetidae\b New World rats and mice, gerbils, hamsters, lemmings, voles; large cosmopolitan family of small (adult length 100-600 mm) terrestrial to arboreal myomorph rodents comprising about 560 species; habits may be fossorial or semiaquatic, often nocturnal, feeding on a variety of plant material and insects.
\Bcricket\b \JGryllidae\j
\Bcricket wasp\b \JRhopalosomatidae\j
\BCricoconarida\b Extinct class of molluscs known from the Palaeozoic; shell narrow, with tapering cones of laminated calcium carbonate.
\BCrinoidea\b Sea lilies, feather stars; class of shallow- to deep-water echinoderms containing about 625 species in a single extant subclass, Articulata, comprising 5 orders, Millericrinida, Cyrtocrinida, Bourgueticrinida, Isocrinida and Comatulida, widespread but especially abundant in the tropical western Pacific; body globoid, aboral surface forming cup-like calyx, with or without stalk; arms multibranched, fern- or feather-like; most crinoids are non-selective suspension feeders.
\BCrinozoa\b Subphylum of echinoderms comprising about 8 classes only one of which, Crinoidea, survived beyond the Palaeozoic; exhibit radial symmetry; body cup-shaped or globular, enclosed in a plated test; arms or brachioles supporting extensions of feeding ambulacra; also known as Pelmatozoa.
\Bcroaker\b \JSciaenidae\j
\Bcrocodile\b \JCrocodylidae\j
\Bcrocodile icefish\b \JChaenichthyidae\j
\Bcrocodile shark\b \JPseudocarchariidae\j
\BCrocodylia\b Crocodiles, alligators, gavials; order of amphibious archosaurian reptiles found in freshwater or brackish marsh and river habitats; all are carnivorous, feeding on a variety of mammals, fish and other vertebrates; reproduction oviparous; contains 22 living species.
\BCrocodylidae\b Family of small to very large (up to 7 m) amphibious carnivorous reptiles containing 22 species in 3 subfamilies, Alligatorinae (alligators, caiman, from New World), Crocodylinae (crocodiles, pantropical) and Gavialinae (gavials, India and Burma); may also be regarded as families.
\Bcrocus\b \JIridaceae\j
\BCromerian interglacial\b An interglacial period of the Quaternary Ice \JAge\j in the British Isles.
\Bcron\b A unit of time equal to one million (10\U6\u) years.
\Bcross fertilization\b The union of male and female gametes from different individuals of the same species; See also \Jself-fertilization\j
\Bcross infection\b The transfer of a disease organism from one individual to another of the same species.
\Bcross pollination\b Transfer of pollen from one flower to the stigma of a flower on another plant of the same species; See also \Jself-pollination\j
\Bcrossing\b The mating of individuals of different breeds, races or strains in order to promote genetic recombination; hybridize; crossbreed.
\BCrossomataceae\b Small family of Rosales containing about 9 species of glabrous xerophytic shrubs native to arid parts of North America.
\BCrossopterygii\b Subclass of bony fishes (Osteichthyes) comprising the tassel-finned fishes belonging to the Coelacanthiformes and Rhipidistia.
\BCrotalidae\b Pit vipers, sidewinder; family containing about 130 species of snakes (Serpentes) that possess heat-sensitive organs just behind the nostrils; feed on small vertebrates; sometimes included in the Viperidae.
\Bcroton\b \JEuphorbiaceae\j
\Bcrotovina\b A former animal burrow in one soil horizon that has been filled with organic matter or sediment from another horizon.
\Bcrow\b \JCorvidae\j
\Bcrowberry\b \JEmpetraceae\j
\Bcrown\b The highest part or layer; typically used of the uppermost foliage of a tree.
\Bcrown conch\b \JNeogastropoda\j
\Bcrown-of-thorns\b \JSpinulosida\j
\BCruciferae\b Crucifers; \JBrassicaceae\j
\BCrustacea\b Subphylum of arthropod animals including many types of shrimps, lobsters, crabs, barnacles, water fleas, scuds, sand hoppers, slaters, fish lice, whale lice, pill bugs; found in marine, freshwater, and terrestrial habitats, ubiquitous at all depths from the littoral to ocean trenches; characterized by 2 pairs of antennae but exhibiting an immense diversity of form, life history and habit; contains about 40 000 described species, arranged in 10 extant classes, Cephalocarida, Branchiopoda, Remipedia, Mystacocarida, Tantulocarida, Cirripedia, Copepoda, Branchiura, Ostracoda and Malacostraca.
\Bcrymnion\b The planktonic organisms of perpetual ice and snow.
\Bcrymophilous\b Thriving in polar habitats; \Bcrymophile\b, \Bcrymophily.\b
\Bcrymophyte\b A plant of polar regions.
\Bcryochore\b Those regions of the Earth's surface perpetually covered by snow.
\Bcryoconite\b Organisms and wind-blown detritus that induce surface melt pits in glaciers.
\Bcryogenic lake\b A lake formed by local thawing in an area of permanently frozen ground.
\Bcryophilic\b Thriving at low temperatures; \Bcryophile\b; \Bcryophily\b.
\Bcryophylactic\b Resistant to low temperatures.
\Bcryophyte\b 1: A plant growing on ice or snow. 2: A plant thriving at low temperatures.
\Bcryoplankton\b Planktonic organisms of persistent snow, ice and glacial waters.
\Bcryotropism\b An orientation response to the stimulus of cold or frost; \Bcryotropic.\b
\Bcryoturbation\b The physical mixing of soil materials by the alternation of freezing and thawing.
\Bcrypsis\b Concealment.
\BCrypteroniaceae\b Small family of Myrtales including 4 species of trees native to India, Malaysia and Philippines; fruit is a capsule.
\Bcryptic\b Used of coloration and markings that resemble the substratum or surroundings and aid in concealment; See also \Jphaneric\j
\Bcryptobiosis\b The condition in which all external signs of metabolic activity are absent from a dormant organism.
\Bcryptobiotic\b Used of organisms which are typically hidden or concealed in crevices or under stones; \Bcryptobios.\b
\BCryptobranchidae\b Small family of large (to 1.5 m) stream-dwelling salamanders (Caudata) comprising 3 species, one from eastern North America the others from China and Japan; metamorphosis incomplete, eyelids absent, gills slits present or absent; fertilization external, eggs laid in paired strings; larvae with short gills and caudal fins.
\BCryptodira\b Suborder of testudine reptiles in which the head is withdrawn directly into the shell; contains majority of living taxa, 175 species in 9 families and 3 superfamilies, Trionychoidea (freshwater turtles), Chelonioidea (sea turtles) and Testudinoidea (tortoises, terrapins); distribution mainly northern temperate and tropical.
\BCryptodonta\b Subclass of bivalve molluscs with thin equivalve shells composed of aragonite; lived within the sediment.
\Bcryptofauna\b The fauna of protected or concealed microhabitats.
\Bcryptogam\b A lower plant, lacking conspicuous reproductive structures such as flowers or cones; See also \Jphanerogam\j
\BCryptomonadales\b Order of flagellate algae (Crytophyceae).
\BCryptomonadida\b \JCryptophyceae\j treated as an order of the protozoan class Phytomastigophora.
\Bcryptomonads\b \JCryptophyceae\j
\BCryptonemiales\b Large order of red algae with a thallus that may be encrusting or erect and frondose; sometimes calcareous.
\BCryptophyceae\b Cryptomonads; class of chromophycote algae occurring in freshwater, brackish and marine habitats; consisting of biflagellate unicells, with 2 anterior flagella inserted in an oral groove and typically possessing phycobilin pigments in addition to chlorophylls \Ia\i and \Ic\i; comprises 2 orders, Cryptomonadales and Tetragonidiales; also treated as a separate phylum of Protoctista, under the name Cryptophyta, and as an order of the protozoan class Phytomastigophora, under the name Cryptomonadida.
\BCryptophyta\b The \JCryptophyceae\j treated as a phylum of Protoctista.
\Bcryptophyte\b A perennial plant with renewal buds below ground or water level, including \Jgeophyte\j, \Jhelophyte\j and \Jhydrophyte\j; see Raunkiaerian life forms.
\BCryptostigmata\b \JOribatei\j
\BCryptostomata\b Extinct order of bryozoans in which the colony had a frond-like, reticulate form and a calcite skeleton; individual apertures hidded in a short shaft; known from the Ordovician to the Permian.
\BCryptozoic\b The period of geological time during which only the most primitive life forms are found; a subdivision of the Precambrian era, preceding the Proterozoic period; see geological time scale.
\Bcryptozoic\b Pertaining to small terrestrial animals (cryptozoa) inhabiting crevices, living under stones, in soil or litter.
\Bcryptozoology\b The study of cryptozoic organisms.
\Bcrystallochorous\b Dispersed by glaciers; \Bcrystallochore\b, \Bcrystallochory.\b
\Bcteinophyte\b A parasitic plant which destroys its host; cteinotrophic plant.
\BCtenocladales\b Order of branched filamentous green algae in which the filaments are composed of uninucleate cells, each containing a parietal laminate chloroplast; found in marine, brackish and freshwater habitats.
\BCtenodrilida\b Order of minute polychaete worms comprising about 12 species in 2 families; body with few segments; prostomium naked, pharynx globular, eversible, unarmed; asexual reproduction by fragmentation common, some forms protandric hermaphrodites.
\BCtenoluciidae\b Pike-characins; family containing 4 species of predatory, piscivorous, freshwater characiform teleost fishes found in rivers and streams of South America; body elongate, to 1 m length, pike-like; jaws prolonged, dorsal fin posteriorly positioned; adipose fin present.
\BCtenomyidae\b Family containing about 26 species of burrowing hystricomorph rodents found in South America; body compact; legs short, pentadactyl with strong claws; eyes and ears small; soles of feet bordered with bristles.
\BCtenophora\b Ctenophores, sea gooseberries, comb jellies; phylum of carnivorous marine animals comprising about 80 species found in pelagic and benthic habitats but mostly in the open sea; characterized by gelatinous bodies with biradial symmetry and by the possession of mesenchymal muscles, anal openings and 8 rows of fused ciliary plates (ctenes) typically used for swimming; all are bioluminescent; paired tentacles are used to catch prey and pass it into the mouth; most are simultaneous hermaphrodites; divided into 7 orders, Cydippida, Platyctenida, Ganeshida, Thalassocalycida, Lobata, Cestida and Beroida.
\BCtenostomata\b Order of gymnolaematan bryozoans in which the colonies are frequently creeping and stolonate, or dense, tufty, encrusting, or frond-like; skeleton membranous, gelatinous, non-calcified; typically marine with some brackish and freshwater forms.
\Bctetology\b The study of acquired characters; \Bctetological.\b
\BCubomedusae\b \JCubozoa\j
\BCubozoa\b Sea wasps, cubomedusae; class of marine pelagic Cnidaria found in all tropical and subtropical waters; typically a tall, colourless medusa with a bell that is square in section and has one or more tentacles at each corner of the umbrella; comprises a single order, Carybdeida; the stings of certain large Australian species are extremely virulent, fast-acting and frequently fatal.
\Bcuckoo\b \JCuculidae\j
\Bcuckoo shrike\b \JCampephagidae\j
\Bcuckoo wasp\b \JChrysididae\j
\BCuculidae\b Family containing about 130 species of birds (Cuculiformes) comprising cuckoos and roadrunners; cuckoos found in woodland habitats worldwide, commonly migratory, many Old World species are nest parasites; roadrunners are terrestrial in open arid regions; habits mostly solitary, feeding on invertebrates, small vertebrates, and fruit.
\BCuculiformes\b Order of small to large arboreal and terrestrial birds comprising 2 suborders, Musophagi (touracos) and Cuculi (cuckoos).
\Bcucumber\b \JCucurbitaceae\j
\BCucurbitaceae\b Pumpkin, squash, watermelon, cucumber, gourd, muskmelon and vegetable sponge (\ILuffa\i); large cosmopolitan family of Violales containing about 900 species of herbaceous mostly climbing or trailing plants commonly with spiral tendrils at nodes; includes mainly cultivated genera; fruits are berries, often very large.
\BCulicidae\b Mosquitoes; cosmopolitan family of small dipteran insects (flies) of primary medical and veterinary importance comprising about 3000 species; adults with piercing proboscis for feeding on nectar or blood; larvae aquatic living suspended beneath the surface film; some species transmit pathogens causing malaria, yellow fever, filariasis and dengue.
\Bcull\b To reduce the number of animals in a breeding group by removing inferior stock or by killing selected animals.
\Bculmicolous\b Growing on the stems of grasses; \Bculmicole.\b
\Bcultigen\b An organism known only in cultivation; cultivar.
\Bcultivar\b A variety of a plant produced and maintained by cultivation.
\Bcultivation\b The preparation and use of land for crop production.
\BCumacea\b Order of small, tadpole-like peracarid crustaceans containing about 1000 species found in marine bottom sediments.
\Bcumaphyte\b A surf plant.
\Bcumatophytic\b Pertaining to structural modifications of plants in response to wave action.
\Bcuniculine\b Living in burrows resembling those of rabbits.
\BCunoniaceae\b Family of Rosales containing about 350 species of strongly tanniferous shrubs or trees mostly native to the southern hemisphere; flowers small, tetra- or pentamerous; fruit usually a capsule.
\Bcup fungi\b \JDiscomycetes\j
\BCupressaceae\b Cypress, juniper; family of evergreen conifers (Pinatae) with leaves scale-like and obscuring the branchlets or occasionally needle-like; mature pistillate cones leathery to woody or berry-like.
\Bcuprophyte\b A plant adapted to, or tolerating, high copper levels in the soil; frequently used as an indicator of this particular soil type.
\Bcurassow\b \JCracidae\j
\BCurculionidae\b Weevils, bark beetles; family of small to medium-sized beetles (Coleoptera) with a characteristic rostrum on the head; most feed as larvae on rotting wood or on living plants; contains over 50 000 species including many economically important pests such as cotton-boll weevil, grain weevil and rice weevil.
\BCurimatidae\b Family of small to medium-sized South American freshwater characiform teleost fishes; body deep, compressed, dorsal fin anterior to mid-body; contains about 130 species; small species popular in aquarium trade, some large forms exploited as food-fish.
\Bcurlew\b \JScolopacidae\j
\Bcurrant\b \JGrossulariaceae\j
\Bcurrent\b 1: A non-tidal horizontal movement of the sea. 2: In limnology, a continuous flow of water.
\Bcursorial\b Adapted for running; running.
\Bcuscus\b \JPhalangeridae\j
\BCuscutaceae\b Dodder; nearly cosmopolitan family of Solanales containing about 150 species of twining parasitic herbs with little or no chorophyll, attached by haustoria to stems of the host; sometimes included in the Convolvulaceae.
\Bcusk eel\b \JOphidiidae\j
\Bcustard apple\b \JAnnonaceae\j
\BCuterebridae\b Rodent botflies; family of large robust flies (Diptera), comprising about 70 species confined to the New World, that are serious pests of livestock; the larvae are typically parasitic in the skin of mammals, especially rodents and lagomorphs but also others, including man, and occasionally in birds.
\Bcutlassfish\b \JTrichiuridae\j
\BCutleriales\b Small order of brown algae with a parenchymatous construction and anisogamous sexual reproduction.
\Bcutthroat eel\b \JSynaphobranchidae\j
\Bcuttlefish\b \JSepioidea\j
\Bcutworm\b \JNoctuidae\j
\BCyamidae\b Whale lice; family of amphipod crustaceans found exclusively as external parasites of whales, dolphins and porpoises.
\BCyanastraceae\b Small family of Liliales comprising only 7 species of perennial herbs arising from a tuberous base, native to forests of tropical Africa; leaves all basal with a broad blade and curved-convergent veins with evident crossveins.
\BCyanobacteria\b Blue-green bacteria; sometimes used as a replacement name for the \JCyanophycota\j
\Bcyanogenic\b Used of living organisms that produce hydrocyanic acid.
\BCyanophyceae\b The sole class of \JCyanophycota\j, comprising 4 orders, Chroococcales, Nostocales, Pleurocapsales and Stigonematales.
\BCyanophycota\b Blue-green algae; division of photosynthetic moneran microorganisms with an alga-like biology and bacterium-like organization; characterized by the possession of chlorophyll a located in single thylakoids not enclosed by membranes and of phycobiliproteins on the thylakoid surface; comprises a single class, Cyanophyceae; also known as the Cyanobacteria.
\Bcybernetics\b The study of control and communication in systems, including information systems and feedback control systems.
\Bcycad\b \JZamiaceae\j (Cycadicae).
\BCycadatae\b Sole extant class of \JCycadicae\j
\BCycadicae\b Cycads; subdivision of Gymnosperms (Pinophyta); evergreen, perennial shrubs or trees with stems that are usually unbranched but thickened by some secondary growth; large pinnate or bipinnate leaves borne spirally near apex of stem; dioecious; male structures arranged like scales on a large cone-like strobilus; female structures, ovules on stalked scales arranged in cone-like strobili; ovule with micropyle pore.
\Bcyclamen\b \JPrimulaceae\j
\BCyclanthales\b Fan palms; order of Arecidae consisting of a single family, Cyclanthaceae, of about 180 species of herbaceous perennials, erect shrubs or lianas with alternate leaves comprising a sheath, petiole and expanded blade; fruit juicy and berry-like; confined to tropical America.
\Bcyclic parthenogenesis\b Reproduction by a series of parthenogenetic generations alternating with a single sexually reproducing generation; See also \Jparthenogenesis\j
\Bcyclic succession\b An ecological succession in which the original community is ultimately restored.
\BCyclocystoidea\b Extinct class of free-living echinoid echinoderms known from the Ordovician to the Devonian; single marginal ring of cuboidal ossicles surrounded a central disk on both dorsal and ventral surfaces.
\Bcyclomorphosis\b Cyclical changes in form, such as seasonal changes in morphology.
\Bcyclonic\b Used of a region of low atmospheric sea-level pressure; also of the wind system around such a low pressure centre that has a clockwise rotation in the northern hemisphere and an anticlockwise motion in the southern hemisphere; \Bcyclone\b; See also \Janticyclonic\j
\BCyclophyllidea\b Large order of tapeworms parasitic in amphibians, reptiles, birds and mammals, and utilizing a large variety of intermediate hosts; characterized by a scolex of 4 suckers often with a rostellum armed with hooks, by the presence of a neck, and by a well segmented body with each proglottid containing usually one set of reproductive organs.
\BCyclopoida\b Order of copepod crustaceans containing about 450 species of marine and freshwater planktonic forms and many parasites and commensals; characterized by grasping antennae in the males and by the presence of paired, dorsal egg sacs in the female.
\BCyclopteridae\b Lumpfishes, snailfishes; family containing about 140 species of mostly bottom-living inshore scorpaeniform teleosts, few forms bathypelagic; body globular and tuberose, or elongate and naked; pelvic fins modified as ventral sucker, or absent, pectorals large; utilized as food-fish in some
\BCyclorhagida\b Diverse order of kinorhynchs found mainly in muddy sediments of intertidal estuarine habitats and sandy beaches but also known from deep water; neck typically consisting of a ring of 14-16 plates; cavity of the pharynx round in cross-section; middorsal, lateral and caudal spines present; possessing lateral and ventral adhesive tubes.
\BCyclostomata\b Sole order of bryozoan class, \JStenolaemata\j
\BCydippida\b Primitive order of pelagic ctenophores found from polar to tropical seas; characterized by well developed comb rows and with paired tentacles retractile into tentacle sheaths; usually globular or ovoid in shape.
\BCyemidae\b Monotypic family of bathypelagic snipe eels (Anguilliformes) having short stout dart-like body with short dorsal and anal fins; jaws very slender, upper longer than lower.
\Bcyesis\b That period between fertilization and birth in animals that produce a single offspring per brood.
\Bcymaphyte\b A surf plant.
\Bcyme\b An inflorescence in which the first-opening flower develops at the apex of the central flowering shoot and any further flower buds are formed from lateral growths beneath; cymose inflorescence.
\BCymodoceaceae\b Family of Najadales comprising about 19 species of glabrous, rhizomatous, submerged marine herbs with small naked, water-pollinated flowers; native to tropical and subtropical sea coasts.
\BCynipidae\b Gall wasps; family of small to very small wasps (Hymenoptera) which, as larvae, typically produce galls on various organs of flowering plants although some are parasites of other insects; containing approximately 2000 species distributed worldwide.
\BCynocephalidae\b Colugos; flying lemurs; family containing 2 species of herbivorous nocturnal arboreal mammals (Dermoptera) found in tropical forests of southeast Asia; possess broad membranes of skin (patagia) extending from sides of neck, between fore-and hindlimbs to the tail, for gliding from tree to tree.
\BCynoglossidae\b Tongue soles; family of tropical marine soleiform flatfishes in which the eyes are on the left side of the head; pectorals and right pelvic fin absent; body length to 300 mm; contains 100 species, many important locally as food-fishes.
\BCyperaceae\b Sedges; cosmopolitan family containing about 4000 species of mostly herbs tending to accumulate silica, usually with elongate parallel-veined leaf blades, small and generally wind-pollinated flowers arranged in spikes; includes species such as papyrus.
\BCyperales\b Order of Commelinidae comprising 2 large and widely distributed families, the Cyperaceae and Poaceae; mainly herbs, sometimes woody, tending to accumulate silica, with small, typically wind-pollinated flowers generally subtended by a chaffy bract; seeds with copious starchy or mealy endosperm.
\Bcyphonautes\b Ciliated larval stage of bryozoans possessing a triangular bivalve shell; functional digestive system degenerates upon attachment of the larva to the substratum.
\Bcypress\b \JCupressaceae\j
\BCyprinidae\b Carps, minnows, barbs; very large family of omnivorous or herbivorous freshwater cypriniform teleost fishes with worldwide distribution except for Australia, New Zealand and South America; body typically moderately compressed, mouth terminal, lips thin; adipose fin absent; contains about 1600 species, many important as food-fish and used widely in pisciculture.
\BCypriniformes\b Order of small to medium-sized freshwater teleost fishes widespread in North America, Eurasia and Africa; upper jaw protractile, jaw teeth absent, pharyngeal bones forming feeding mill; pectoral and pelvic fins soft-rayed, spines rarely present on medium fins; gas bladder simple, connected to inner ear by bony Weberian ossicles; contains about 2000 species in 6 families; important in pisciculture and popular in aquarium trade; includes carps, minnows, barbs, suckers, loaches.
\BCyprinodontidae\b Killifishes, toothcarps, top minnows; family containing about 300 species of small (to 150 mm) mainly freshwater cyprinodontiform teleost fishes widespread in tropical and temperate parts of the New World; body slender, often colourful, upper jaw protrusible; sexual dimorphism may be well developed; reproduction oviparous, fertilization usually external.
\BCyprinodontiformes\b Order of mostly small freshwater, occasionally brackish or coastal marine, teleost fishes widespread in the tropics and subtropics; sexual dimorphism may be well developed; reproduction oviparous to viviparous; comprises about 500 species in 8 families, including killifishes, ricefishes, live-bearers and four-eyed fishes.
\Bcypris\b Motile planktonic larval stage of barnacles; larval body with 6 pairs of swimming thoracic legs, enclosed within bivalved carapace.
\Bcypsela\b A dry indehiscent fruit developed from one-seeded inferior ovary so that it incorporates some non-carpellary tissue.
\BCyrillaceae\b Small family of Ericales containing 14 species of glabrous, tanniferous shrubs confined to the warmer parts of the New World; flowers borne in racemes, with 5 sepals and petals, and a superior ovary which develops into a capsule or drupe.
\BCyrtocrinida\b Order of articulate crinoids typically possessing a short stalk, but stalk absent in sole living representative found in shallow waters of the Caribbean.
\BCyrtophorida\b A widespread, mostly marine order of hypostomatan ciliates in which the oral area is occupied by 3 short double rows of kinetosomes derived from the ciliary rows of the left ventral surface.
\Bcyrtopia\b Late developmental stage of euphausiacean, possessing functional natatory pleopods.
\Bcysticercus\b Fluid-filled, bladder-like larval stage of cestodes.
\Bcytogamy\b 1: The fusion of two cells. 2: The fusion of both male nuclei of one of two conjugating organisms with the female nucleus of the other.
\Bcytogenetics\b The study of chromosomal mechanisms, their behaviour and their effect on inheritance and evolution.
\Bcytokinesis\b Division of the cytoplasm, usually following meiosis or mitosis; See also \Jkaryokinesis\j
\Bcytokinin\b A growth substance which stimulates cell division in plants.
\Bcytology\b The study of the structure and function of living cells.
\Bcytophagous\b Feeding on cells; \Bcytophage\b, \Bcytophagy.\b
\Bcytotaxis\b 1: The movement of cells in relation to each other; used to describe cells separating (negative cytotaxis) or aggregating (positive cytotaxis); \Bcytotactic\b. 2: The arrangement of cells within an organ.
\Bcytozoic\b Intracellular; used of an organism living within a host cell.
\BCyttariales\b Small order of discomycete fungi comprising 10 species all of which parasitize southern beeches of the genus \INothofagus\i; producing clustered fruiting bodies in galls on host branches, each consisting of a sterile stroma containing many embedded apothecia.
\B2,4-D\b 2,4-dichlorophenoxyacetic acid; a translocated hormone weed killer, used to control broad-leaved herbaceous plants, and as a defoliant.
\Bdab\b \JPleuronectidae\j
\BDacnonympha\b Suborder of lepidopterous insects comprising about 25 species; adult typically possessing reticulate or marbled wing pattern; mandibles functional or reduced and non-biting, maxillae forming small proboscis in some species; larvae mostly leaf or seed miners; pupal mandibles hypertrophied.
\BDactylochirotida\b Order of mainly deep-sea holothurians (Dendrochirotacea) comprising about 35 species that have typically unbranched tentacles and a rigid U-shaped test, and which burrow in soft sediments.
\BDactylopteridae\b Flying gurnards; family of small (to 350 mm) tropical and warm temperate marine, bottom-living, dactylopteriform teleost fishes; head large, spinose and ridged; pectoral fins large with ventral fin rays free; feed on benthic invertebrates and small fishes, resting on the free pectoral fin rays.
\BDactylopteriformes\b Order of marine teleost fishes comprising a single family, Dactylopteridae (flying gurnards).
\BDactyloscopidae\b Sand stargazers; family containing 25 species of small (to 100 mm) New World tropical marine teleost fishes (Perciformes), typically found in shallow water partly buried in sandy sediments; body slender, mouth vertical, eyes dorsal; dorsal and anal fins elongate.
\Bdactylozoid\b A specialized defensive or protective polyp in colonial cnidarians.
\Bdaddylonglegs\b \JTipulidae\j
\Bdaddy-longlegs spider\b Any of the longlegged spiders of the family Pholcidae (suborder Labidognatha); comprising about 350 species distributed worldwide but most abundant in tropical cave habitats; typically spin a loose cobweb and wrap prey in silk.
\Bdaffodil\b \JLiliaceae\j
\Bdaggertooth\b \JAnotopteridae\j
\Bdahlia\b \JAsterales\j
\Bdaisy\b \JAsterales\j
\Bdam\b In animal breeding, the female parent; See also \Jsire\j
\Bdamselfish\b \JPomacentridae\j
\Bdamselfly\b \JZygoptera\j (Odonata)
\Bdance\b A highly stylized repetitive movement often associated with courtship.
\Bdance fly\b \JEmpididae\j
\Bdandelion\b \JAsterales\j
\BDaphniphyllales\b Order of Hamamelidae comprising a single family, Daphniphyllaceae, of about 35 species of trees or shrubs native to eastern Asia and Malaysia; containing a unique type of alkaloid and often accumulating aluminium; flowers typically small, lacking petals.
\Bdark respiration\b Respiration in photosynthetic plants occurring during the night.
\Bdarter\b 1: \JCharacidiidae\j; South American darters. 2: \JPercidae\j 3: \JAnhingidae\j
\BDarwinism\b The view of evolution expressed by Charles Darwin; evolution occurring by means of natural selection (the struggle for life) acting on spontaneous variation arising within populations and species, resulting in the survival of the fittest.
\BDarwin's finch\b \JEmberizidae\j
\BDasyatidae\b Stingrays; family of medium-sized marine, brackish or freshwater myliobatiform fishes; body disk rhomboidal to circular, tail whip-like bearing one or more serrated spines, dorsal and caudal fins absent; habits mainly benthic, feeding on small fishes and bottom invertebrates; contains about 60 species in tropical or warm temperate waters to depths of 100 m.
\BDasycladales\b Mermaid's wine glass; small order of tropical and subtropical marine green algae, characterized by a siphonous, non-septate thallus attached to the substrate by rhizoids and containing a single enormous basal nucleus; includes many fossil forms.
\BDasypodidae\b Armadillos; family containing about 20 species of primarily Neotropical ground-living mammals (Edentata); body protected by armour of dermal bone and scales; teeth peg-like; limbs powerful, bearing strong claws for digging; feed on invertebrates, fruit and carrion.
\BDasyproctidae\b Agoutis, pacas; family of Neotropical terrestrial hystricomorph rodents containing about 10 species that excavate burrows and feed on a variety of plant material, including roots, seeds and fruit; hindlimbs elongate for swift locomotion; tail vestigial.
\BDasyuridae\b Marsupial mice, native cats, Tasmanian devil; family of small to medium-sized (50 mm - 1 m) carnivorous marsupials found in Australia, Tasmania and New Guinea; marsupium opens posteriorly, sometimes absent; tail non-prehensile; habits mainly nocturnal, terrestrial.
\BDatiscaceae\b Small family of Violales containing 4 species of perennial herbs to large trees; flowers unisexual, with an inferior ovary; producing capsular fruit with many seeds.
\BDaubentoniidae\b Aye aye; monotypic family of arboreal, nocturnal prosimians found only in northern Madagascar; tail long and bushy; all digits except big toe have claws rather than nails; feed on insects and a variety of plant material.
\Bdaughter\b Any of the offspring of a given generation, applicable to both sexes.
\BDavidsoniaceae\b Family of Rosales comprising a single species of small tree covered with pungent red hairs on twigs, leaves and fruit; native to northeastern Australia.
\Bday lily\b \JLiliaceae\j
\Bday-neutral\b A plant in which the flowering response is not dependent on photoperiodism.
\BDBH\b Abbreviation of diameter at breast height (1.4 m) of a tree; measured either over the bark or under the bark.
\BDDT\b Dichlorodiphenyltrichloroethane; a persistent organochlorine insecticide.
\BDe Vriesianism\b The belief that evolution in general and speciation in particular are the results of drastic and sudden mutational changes.
\Bdead man's fingers\b A soft coral of the \JAlcyonacea\j
\Bdeadly nightshade\b \JSolanaceae\j
\Bdeadnettle\b \JLamiaceae\j
\Bdeath\b The total and irreversible cessation of all life processes.
\Bdeath feint\b \JThanatosis\j
\Bdeath rate\b Mortality; the number of deaths in a population per unit time.
\Bdeath-watch beetle\b \JAnobiidae\j
\Bdebris\b Accumulated plant and animal remains.
\Bdecalcification\b Removal of calcium carbonate from the soil by leaching.
\BDecapoda\b Crabs, lobsters, shrimps; large order of eucaridan crustaceans; carapace fused with all thoracic segments to form a gill chamber above the leg bases; first 3 of the 8 pairs of thoracic legs commonly modified as maxillipeds; comprises 2 suborders, Dendrobranchiata and Pleocyemata, containing about 10 000 recent species found in aquatic and sometimes terrestrial habitats.
\Bdecay\b Organic decomposition during which almost total oxidation of organic substances occurs; see also \Jmouldering\j \Jputrefaction\j
\Bdecennial\b Pertaining to periods of tens of years; see also \Jmillennial\j \Jsecular\j
\Bdeci-\b Prefix used to denote unit x 10\I\U-1\u\i; see metric prefixes.
\Bdeciduous\b Used of structures that are shed at regular intervals, or at a given stage in development.
\Bdecomposer\b Any organism that feeds by degrading organic matter.
\Bdecomposition\b Metabolic degradation of organic matter into simple organic and inorganic compounds, with consequent liberation of energy; \Bdecomposer. \b
\Bdecoy\b A crop of low value cultivated to attract pests away from a more valuable crop.
\Bdeductive method\b A scientific method involving the formulation of theories or hypotheses from which singular statements (predictions) are deduced that can be tested; See also \Jinductive method\j
\Bdeep scattering layer\b A more or less well defined layer present in most oceanic waters which reflects sound from echosounding equipment; produced by stratified populations of organisms which scatter sound waves and are recorded on an echosounder as a horizontal layer.
\Bdeer\b \JCervidae\j
\Bdeer brush\b \JRhamnaceae\j
\Bdeerfly\b \JTabanidae\j
\Bdefaecate\b To discharge faeces.
\Bdefinitive host\b The host in which a parasite attains sexual maturity; primary host; See also \Jintermediate host\j
\Bdeflation\b Erosion of surface layers by wind action.
\Bdeflection display\b Distraction \Jdisplay\j
\Bdefoliant\b A chemical, such as 2,4-D and 2,4,5-T, that causes a plant to shed its leaves.
\Bdeforestation\b The permanent removal of forest and undergrowth.
\BDegeneriaceae\b Family of primitive flowering plants (Magnoliales) containing a single species of large tree native to Fiji; characterized by laminar stamens and 3 or 4 cotyledons.
\Bdegradation\b Breakdown into smaller or simpler parts; reduction of complexity.
\BDegraded Chernozem soil\b A zonal soil with very dark brown or black A-horizon over a grey leached horizon and a brown lower horizon; formed in cool climates under forest-prairie transitional vegetation.
\Bdegression\b Regression to a less specialized condition; \Bdegressive.\b
\Bdehiscence\b Spontaneous opening of ripe plant structures to liberate seeds or spores; \Bdehiscent.\b
\Bdeimatic behaviour\b The adoption of an intimidating posture by one animal in order to frighten another.
\BDeinotherioidea\b Suborder of extinct elephant-like mammals (Proboscidea) with a long trunk and large downward-curving tusks on the lower jaw; lived from Miocene through to Pleistocene.
\Bdeka-\b Prefix meaning ten, tenfold; used to denote unit x 10; deca-; see metric prefixes.
\Bdeleterious\b 1: Having an adverse effect. 2: Used of a trait which impairs survival, or of a mutation that reduces fitness.
\Bdeletion\b The loss of a segment from a chromosome.
\Bdeliquescent\b Becoming fluid by the uptake of water from air; becoming soft or liquid with age.
\Bdelitescence\b The incubation period of a pathogenic organism.
\BDelphinidae\b Dolphins, pilot whale, killer whale; family containing about 30 species of marine toothed whales (Odontoceta) widespread in temperate and tropical oceans and seas; head profile typically showing distinct beak; feed on fishes, squid, crustaceans and, in the case of the killer whale, also on marine birds and mammals.
\Bdelphinium\b \JRanunculaceae\j
\Bdelta\b A deposit of fine alluvial sediments at the mouth of a river.
\Bdeltaic\b Pertaining to a delta; used of the succession or cycle of processes involved in the formation of a delta.
\Bdeme\b A local interbreeding group; also used loosely to refer to any local group of individuals of a given species; used as a neutral term in combination with qualifying prefixes, including agamodeme, autodeme, clinodeme, clonodeme, ecodeme, endodeme, gamodeme, genodeme, hologamodeme, phenodeme, serodeme, topodeme and xenodeme.
\Bdemersal\b Living at or near the bottom of a sea or lake but having the capacity for active swimming.
\Bdemography\b The study of populations, especially of growth rates and age structure.
\BDemospongiae\b Large class of sponges with a skeleton of spongin fibres with or without siliceous spicules; ranging in shape from thin encrusting forms to massive lobed, cylindrical or spherical forms and found at all depths in the sea and in fresh water; sexual reproduction typically involves a dispersal stage, the parenchymella larva, with an outer layer of flagellated cells.
\Bdenatant\b Swimming, moving, or migrating with the current; See also \Jcontranatant\j
\Bdenaturation\b An alteration in the structural properties of a protein producing a change in its biochemical activity.
\BDendrobatidae\b Family containing about 70 species of small (to 50 mm) terrestrial frogs (Anura) from the New World tropics; skin secretions often highly toxic, used for poison darts and arrows; reproduction unique, amplexus absent, copulation occurring in horizontal vent-to-vent position; eggs terrestrial, carried to water on backs of adults.
\BDendrobranchiata\b Suborder of decapod crustaceans containing about 450 species found in freshwater, brackish and marine habitats from the surface to about 2000 m depth; anterior 3 pairs of legs chelate; gills with branching primary filaments; eggs typically hatching as nauplii; includes the penaeid and sergestid shrimps.
\BDendroceratida\b Order of ceractinomorph sponges found in the intertidal zone and down to 650 m from tropical to polar seas; skeleton typically arising from a basal plate, and with a branching or reticulate pattern.
\BDendrochirotacea\b Subclass of holothurians (sea cucumbers) comprising 2 orders, Dendrochirotida and Dactylochirotida, in which the tentacles are retractile, and tube feet and respiratory trees are present.
\BDendrochirotida\b Order of holothurians (Dendrochirotacea) comprising about 410 species in which the tentacles are multibranched; found on hard substrate or burrowing in soft sediments from the littoral to 1000 m depth.
\Bdendrochore\b That part of the Earth's surface covered by trees.
\Bdendrochronology\b A method of dating using annual tree-rings; tree-ring chronology.
\Bdendroclimatology\b The determination of past climatic conditions from the study of the annual growth rings of trees.
\BDendrocolaptidae\b Woodcreepers; family containing about 50 species of small Neotropical passerine birds found in forests and woodlands from Mexico through South America; bill strong and compressed, wings long; legs short with strong claws; habits solitary or gregarious, arboreal, non-migratory, monogamous; feed mostly on insects and spiders, and nest in tree holes or crevices.
\Bdendrocolous\b Living in, or growing on, trees; \Bdendrocole.\b
\BDendrogaea\b The Neotropical \Jregion\j excluding temperate South America.
\Bdendrology\b The study of trees.
\Bdendrophagous\b Feeding on wood; \Bdendrophage\b, \Bdendrophagy.\b
\Bdendrophilous\b Thriving in trees; living in orchards; \Bdendrophile\b, \Bdendrophily. \b
\Bdenitrification\b The release of gaseous nitrogen or the reduction of nitrates to nitrites and ammonia by the breakdown of nitrogenous compounds, typically by microorganisms when the oxygen concentration is low; on a global scale thought to occur primarily in oxygen deficient environments in the oceans.
\Bdenizen\b A plant species found growing in the wild but considered to have been originally introduced for cultivation; established alien.
\Bdensity\b The number of individuals or observations within a given area or volume.
\Bdensity dependence\b A change in the influence of an environmental factor (a density-dependent factor) that affects population growth as population density changes, tending to retard population growth (by increasing mortality or decreasing fecundity) as density increases or to enhance population growth (by decreasing mortality or increasing fecundity) as density decreases.
\BDentaliida\b Order of scaphopod molluscs characterized by a typically sculptured shell and by the position of the radula midway along the body.
\BDenticipitidae\b Monotypic family of small herring-like teleosts restricted to Nigerian freshwater streams; head covered with small tooth-like denticles.
\Bdenudation\b 1: Erosion of surface material to expose underlying rock. 2: The removal of surface vegetation; \Bdenude.\b
\Bdeoxygenated\b Used of an environment depleted in free oxygen; \Bdeoxygenation\b; See also \Joxygenated\j
\Bdeoxyribonucleic acid\b \JDNA\j
\Bdepauperate\b Impoverished; moribund.
\Bdeplumation\b Moulting in birds.
\Bdeposit feeder\b Any organism feeding on fragmented particulate organic matter in or on the substratum.
\Bdepuration\b The cleansing activity of shellfish effected by immersion in clean water prior to harvesting resulting in the removal of pathogenic organisms and pollutants potentially harmful to man.
\BDerichthyidae\b Longneck eels; family of small mesopelagic anguilliform teleosts comprising 2 species; body smooth, eyes large; dorsal, caudal and anal fins continuous; pectorals present.
\Bderived\b Used of a character or character state not present in the ancestral stock; apomorphic.
\BDermaptera\b Earwigs; order of orthopterodean insects comprising about 1500 species, abundant in tropical regions, preferring cryptic habitats and feeding as scavengers or predators; body length 3-55 mm, posterior cerci modified as large pincers used variously for predation, defence, courtship and grooming; forewings forming short elytra, hindwings membranous; wings frequently reduced or absent.
\BDermatemydidae\b Monotypic family of large (to 600 mm) river turtles (Testudines: Cryptodira) with long necks and webbed feet; found in eastern parts of Central America, from southern Mexico to Honduras.
\Bdermatophyte\b A fungal skin parasite.
\Bdermatotrophic\b Living and feeding on skin; \Bdermatotroph\b, \Bdermatotrophy.\b
\Bdermatozoon\b An animal parasite of skin.
\BDermestidae\b Carpet beetle, skin beetle; family of small, usually dark coloured beetles (Coleoptera) often found associated with stored products but feeding on a wide range of animal and plant materials; contains about 850 species.
\BDermochelyidae\b Leatherback turtle; monotypic family of very large (to 2.5 m) marine turtles (Testudines: Cryptodira); carapace covered with leathery skin, horny scutes absent; forelimbs modified as flippers; ribs and vertebrae free from carapace; widely distributed in tropical and warm temperate oceans.
\BDermoptera\b Flying lemurs, colugo; order of arboreal placental mammals of southeast Asia comprising a single family, Cynocephalidae.
\Bdesalinization\b The removal of salts; as in the leaching of saline soils.
\Bdescendants\b 1: All the individuals derived from the sexual union of two individuals. 2: The derivatives of a prototype, ancestor or other source.
\Bdesert\b An arid area with insufficient available water for dense plant growth; more precisely, an area of very sparse vegetation in which the plants are typically solitary and separated from each other by more than their diameter on average.
\Bdesert biome\b Desert: a region of environmental extremes having less than 250 mm annual rainfall, high evaporation and low humidity; typically with a large proportion of barren ground, sparse vegetation of solitary plants or small aggregations, and nocturnal animals.
\Bdesert forest\b Arboreous \Jdesert\j
\BDesert soil\b A very shallow light coloured zonal soil overlying calcareous material, formed under arid conditions; typically with a pale grey or brown shallow A-horizon, a slightly darker neutral or alkaline B-horizon and a calcareous and often compacted lower horizon; characteristically with sparse vegetation.
\Bdesert wind\b A dry wind blowing from a desert region, hot in summer and cold in winter.
\Bdeserticolous\b Living mostly on open ground in an arid or desert region; \Bdeserticole.\b
\Bdesertification\b The development of desert conditions as a result of human activity or climatic changes.
\Bdesiccation\b Removal of water; the process of drying; \Bdesiccate.\b
\Bdesman\b \JTalpidae\j
\BDesmarestiales\b Order of brown algae occurring in cold waters, especially in the suthern hemisphere; typically with a large thallus and differentiated holdfast.
\BDesmidoideae\b Desmids; class of the protoctistan phylum Gamophyta; typically comprising a pair of cells joined by a cytoplasmic isthmus which houses the shared nucleus; cell walls of cellulose and pectic substances are often ornate and covered with a mucilaginous sheath secreted through pores in cell wall; reproduce asexually by separation of partners in pair, and sometimes sexually by leaving shells and conjugating with another to form a zygote.
\Bdesmids\b Freshwater, unicellular green algae treated either as a suborder of the \JZygnematales\j or as a class, the Desmidoideae, of the protoctistan phylum, Gamophyta.
\BDesmocapsales\b Small order of rare photosynthetic, unicellular dinoflagellates occurring in marine and freshwater habitats.
\BDesmodontidae\b Vampire bats; usually included within the family \JPhyllostomatidae\j
\BDesmodorida\b Order of chromodorian nematodes found principally in marine habitats; body cuticle annulate; possessing a cephalic helmet formed from additional cuticular layers in the head capsule.
\BDesmoscolecida\b Small order of chromodorian nematodes found mostly in marine habitats; markedly annulate bodies typically ornamented with concretion rings, scales or bristles.
\BDesmothoracida\b Order of Heliozoa containing mostly sedentary organisms in which the adult stage is usually stalked and enclosed in an organic lattice; development involves a flagellated, amoeboid spore.
\Bdeterminate growth\b Growth that is limited during the life span of an individual, so that the organism reaches a maximum size after which growth ceases; See also \Jindeterminate growth\j
\Bdetoxification\b The biological removal of toxic substances by conversion into a less toxic substances by conversion into a less toxic or more readily disposable form.
\Bdetriophagous\b Feeding on detritus; \Bdetriophage\b, \Bdetriophagy.\b
\Bdetritivorous\b Feeding on fragmented particulate organic matter; \Bdetritivore\b, \Bdetritivory.\b
\Bdetritus\b Fragmented particulate organic matter derived from the decomposition of plant and animal remains; organic debris; \Bdetrital.\b
\BDeuteromycota\b \JDeuteromycotina\j
\BDeuteromycotina\b Fungi Imperfecti; an artifical subdivision of true fungi (Eumycota) characterized by the absence of a sexual state but including forms with an ascomycotine-like or basidiomycotine-like mycelium; a cosmopolitan group including both saprobic and pathogenic forms.
\BDeuterostomia\b A large group of animals characterized by a radial pattern of cleavage in early embryology; comprising the phyla Chaetognatha, Chordata, Echinodermata, Hemichordata and Pogonophora.
\Bdeuterotoky\b Parthenogenesis in which both male and female offspring are produced; \Bdeuterotokous.\b
\Bdeutonymph\b Immature stages of mites (Acari) possessing more complex chaetotaxy and genitalia than preceding protonymph; deuteronymph.
\Bdevelopment\b The regulated growth and differentiation of an individual, including cellular, tissue and organ differentiation; ontogeny.
\BDevensian glaciation\b The most recent glaciation of the Quaternary Ice \JAge\j in the British Isles with an estimated duration of about 70000 years.
\Bdevil ray\b \JMobulidae\j
\Bdevil's herb\b \JPlumbaginales\j
\BDevonian\b A geological period within the Palaeozoic (\Ic.\i 413-365 million years B.P.); see geological time scale.
\Bdew point\b The temperature at which liquefaction of a vapour begins.
\BD-horizon\b Any layer underlying a soil profile that differs from the parent material of the soil; see soil horizons.
\Bdiachronous\b Belonging to different geological periods.
\Bdiacmic\b Exhibiting two abundance peaks per year; see also \Jmonacmic\j \Jpolyacmic\j
\BDiadematacea\b Superorder of euechinoidean echinoids comprising 3 orders, Echinothuroida, Diadematoida and Peninoida; anus at aboral pole, dental apparatus and gills usually present.
\BDiadematoida\b Order of littoral to abyssal echinoids (Diadematacea), comprising about 50 species, having a flat or spherical fragile test with large hollow spines; may represent conspicuous part of coral reef fauna.
\Bdiadromous\b Migrating between fresh water and sea water.
\Bdiagenesis\b The chemical and physical processes, in particular compaction and cementation, involved in rock formation after the initial deposition of a sediment.
\Bdiageotropism\b Orientation at right angles to the direction of gravity; typically resulting in growth parallel to the soil surface; \Bdiageotropic.\b
\Bdiaheliotropism\b Orientation response of part or all of a plant aligning itself at right angles to the direction of incident sunlight; \Bdiaheliotropic.\b
\Bdialect\b A local geographical variant of behaviour involved in communication.
\BDialypetalanthaceae\b Family of Rosales containing a single tree species from Brazil.
\Bdiapause\b A resting phase; a period of suspended growth or development, characterized by greatly reduced metabolic activity, usually during hibernation or aestivation.
\BDiapensiales\b Small order of Dilleniidae containing only 18 species of evergreen perennial herbs and shrubs native to Arctic and northern temperate regions; flowers typically with 5-lobed calyx and corolla, and 5 stamens; fruit capsular.
\Bdiaphototaxis\b An orientation response of an organism or structure at right angle to the direction of incident light; \Bdiaphototactic.\b
\Bdiaphototropism\b Orientation at a right angle to the direction of incident light; \Bdiaphototropic.\b
\BDiaporthales\b Order of pyrenomycete fungi containing many parasites or inhabitants of woody substrates including pathogens causing leaf-spot disease of various plants and chestnut blight; typically with persistent asci.
\BDiapsida\b Class of reptiles with two temporal openings in the skull behind the eyes.
\Bdiaspore\b Any part of an organism produced either sexually or asexually that is capable of giving rise to a new individual; propagule.
\Bdiastem\b A gap in the fossil record, denoted by a bedding plane, representing a period of time during which no deposition took place.
\Bdiatom\b \JBacillariophyceae\j
\Bdiatomaceous ooze\b A pelagic sediment comprising at least 30% siliceous material mainly in the form of diatom tests, generally restricted to high latitudes or areas of upwelling; See also \Jooze\j
\Bdiatropism\b Orientation at a right angle to the direction of stimulus; \Bdiatropic.\b
\BDibamidae\b Small family of limbless fossorial lizards (Sauria) comprising 4 species found in the Indo-Pacific region and in Mexico.
\BDibranchiata\b \JColeoidea\j
\BDicaeidae\b Flowerpeckers; family containing about 60 species of small active passerine birds found in variety of forest and open habitats of southeast Asia and Australia; bill slender to stout, occasionally serrated for cutting into flowers, tongue cleft and somewhat tubular distally; habits solitary to gregarious, arboreal, non-migratory; feed on insects, nectar and berries, and nest in bush or in hole in tree or bank.
\Bdicentra\b \JFumariaceae\j
\BDiceratiidae\b Family of small (to 150 mm) anglerfishes (Lophiiformes) found in surface waters of Altantic and Indian Oceans to 100 m depth; contains 4 species known mostly from larval stages.
\BDichapetalaceae\b Family of Celastrales containing about 200 species of often poisonous woody plants with a pantropical distribution; flowers variable, commonly with 5 sepals, 4 or 5 petals, 5 stamens and a superior ovary; fruit usually a drupe.
\Bdichlorvos\b 2,2-Dichlorovinyl dimethylphosphate (DDVP); an organophosphorus insecticide and acaricide of relatively short persistence.
\Bdichogamy\b The maturation of male and female reproductive organs at different times in a flower or hermaphroditic organism, thereby preventing self-fertilization; \Bdichogamic\b, \Bdichogamous\b; See also \Jadichogamy\j
\Bdichopatric\b Pertaining to populations or species having geographical ranges separated to the extent that individuals from the two populations never meet and gene flow is not possible; \Bdichopatry\b; see also \Jallopatric\j \Jparapatric\j, \Jsympatric\j
\Bdichotomy\b Division into two parts or categories; \Bdichotomous.\b
\Bdichotypic\b \JDimorphic\j; used particularly of plants having two types of leaves or flowers.
\Bdiclinous\b Having male and female organs in separate flowers on the same or different plants; \Bdiclinism\b, \Bdicliny\b; See also \Jmonoclinous\j
\Bdicotyledon\b \JMagnoliopsida\j; major group of flowering plants characterized by 2, rarely more, cotyledons in the embryo.
\BDicranales\b Diverse order of mosses (Bryidae) frequently found at high latitudes or altitudes; plants with erect, little-branched gametophytes; apical cell of stem with 3 cutting faces; sporophyte usually borne terminally.
\BDicruridae\b Drongos; family containing 20 species of insectivorous Old World passerine birds found in forest and grassland habitats from Africa to Australia; plumage uniformly dark with some bright feathers; bill strong and hooked; habits solitary or weakly gregarious, arboreal, aggressive; feed on the wing; nest in trees.
\BDictyoceratida\b Order of ceractinomorph sponges with a skeleton lacking spicules, composed of anastomosing spongin fibres which typically vary in size; abundant in shallow tropical and subtropical waters; includes the commercial bath sponges of the family Spongiidae.
\BDictyochophycidae\b Silicoflagellates; subclass of typically unicellular and uniflagellate chrysophyceaen algae, characterized by the possession of a siliceous skeleton; sometimes classified as an order of the protozoan class Phytomastigophora, under the name Silicoflagellida.
\BDictyoptera\b An order of insects formerly used to group the cockroaches and mantids, each now treated as distinct orders.
\BDictyosiphonales\b Large order of brown algae which exhibit alternation between a large parenchymatous sporophyte and a microscopic filamentous gametophyte generation, and in which isogamous sexual reproduction occurs.
\BDictyostelia\b Subclass of cellular slime moulds typically with amoeboid trophic stages with filose pseudopodia and a fruiting body with cellulose walls of the cells and tubes that comprise the stalk; found mostly on humus and in forest soils.
\BDictyotales\b Order of brown algae with a flattened ribbon-like or fan-like body form, occurring in tropical and subtropical waters, possessing uniflagellate male gametes.
\BDicyemida\b Order of rhombozoan mesozoans found as parasites in the kidneys (renal system) of cephalopod molluscs.
\BDidelphidae\b Opossums; family containing about 70 species of mostly small (to about 1 m) arboreal or terrestrial marsupials widespread in South and Central America with single species extending to Canada; tail prehensile; marsupium present or absent; habits crepuscular to nocturnal.
\BDidereaceae\b Small family of spiny, cactus-like shrubs and trees confined to Madagascar.
\BDidymelales\b Order containing two species of glabrous, dioecious, evergreen trees occurring only in Madagascar.
\Bdiecdysis\b Continuous moulting, with one ecdysis grading rapidly into the next.
\Bdiecodichogamic\b Used of a population of dichogamic plants in some individuals of which the male flowers mature first while in others the female flowers mature first; \Bdiecodichogamy.\b
\Bdiel\b Daily; pertaining to a 24 hour period.
\Bdientomophilous\b Used of a plant polhnated by two different insect species and having two kinds of flowers each adapted for one of the insect pollinators; \Bdientomophily.\b
\Bdifferentiation\b The process of specialization and the progressive diversification of structure or function; integrated cellular specialization during embryonic development.
\Bdiffuse competition\b Simultaneous interspects competition between numerous species each having a small degree of niche overlap with other species.
\Bdiffusion\b 1: Passive movement of molecules of solution from a region of high concentration to a region of low concentration. 2: The intermixing of particles as a result of movement caused by thermal agitation.
\Bdigametic\b Having two kinds of gametes, one producing male offspring and the other female; \Bdiagamety.\b
\BDigenea\b Flukes; subclass of trematodes containing nearly 7000 species most of which are endoparasites in vertebrates, especially fishes; possessing 1 or 2 muscular suckers for attachment to the host, and a digestive system composed of a mouth, pharynx, oesophagus and intestinal caeca; most are hermaphrodites; life cycles are indirect involving one or more intermediate hosts in which a series of larval stages, such as cercariae, metacercariae, rediae and sporocysts develop; the cercarial stage usually has a brief free-living phase.
\Bdigenesis\b The regular alternation of sexual and asexual generations.
\Bdigenetic\b Pertaining to a symbiont requiring two different hosts during its life cycle; see also \Jmonogenetic\j \Jtrigenetic\j
\Bdigitigrade\b Walking with only the digits in contact with the ground.
\Bdigoneutic\b Producing two broods per season or year; \Bdigoneutism\b; see also \Jmonogoneutic\j \Jpolygoneutic\j, \Jtrigoneutic\j
\Bdigonic\b Producing male and female gametes in different gonads of the same individual; \Bdigony\b; See also \Jsyngonic\j
\BDigonota\b \JBdelloidea\j
\Bdilatent\b Used of a sediment that becomes more solid as a result of agitation or pressure; \Bdilattency\b; See also \Jthixotropic\j
\Bdill\b \JApiaceae\j
\BDilleniaceae\b Snake vine; family of mostly woody and tanniferous evergreen plants, usually containing a flavonol (myricetin); mostly tropical or subtropical, particularly in the Australian region; flowers typically showy with many stamens and a superior ovary.
\BDilleniales\b Order of woody or herbaceous plants mostly without alkaloids; comprising 2 families, Dilleniaceae and Paeoniaceae.
\BDilleniidae\b Large subclass of dicotyledons that produce various kinds of repellents, often tanniferous and with mustard oils in some groups, but poor in alkaloids; flowers usually regular and with separate petals, pistil usually compound with 2 or more carpels; contains over 25 000 species arranged in 13 orders.
\Bdiluvial\b 1: In the geological time scale, the present time. 2: Pertaining to a flood.
\BDimargaritales\b Order of zygomycete fungi, all but one of which are obligate parasites on other fungi, of the order Mucorales.
\Bdimictic\b Used of a lake having two seasonal overturn periods of free circulation, with accompanying disruption of the thermocline; See also \Jmictic\j
\Bdimonoecious\b Used of an individual plant having hermaphrodite, male, female and neuter flowers.
\Bdimorphic\b 1: Pertaining to a population or taxon having two genetically determined, discontinuous morphological types; \Bdimorphism, dimorphy;\b see also \Jmonomorphic\j \Jpolymorphic. 2
\BDinamoebales\b Order comprising a single species of marine non-photosynthetic dinoflagellate.
\Bdingo\b \JCanidae\j
\BDinocerata\b Extinct suborder of mainly North American ungulates known from the late Palaeocene to Eocene; some with horn-like bony swellings on the head.
\BDinocloniales\b Small order of marine filamentous dinoflagellates.
\BDinoflagellata\b Dinoflagellates; a group of common, typically marine, planktonic organisms which are usually heterotrophic but occasionally phototrophic; characterized by 2 flagella, one typically lying in an equatorial groove round the cell, the other directed posteriorly; most with rigid test comprising cellulose plates encrusted with rigid test comprising cellulose plates encrusted with silica; treated as a protozoan group (a subphylum of Mastigophora), as a phylum of Protoctista, or a class of Chromophycote algae, the Dinophyceae.
\BDinophilida\b Order of interstitial marine and brackish-water polychaete worms comprising a single family and about 20 species; body transparent, segmentation indistinct; prostomium and peristomium fused, pharynx eversible, parapodia absent; copulate by hypodermic injection.
\BDinophyceae\b Dinoflagellates; \JDinoflagellata\j treated as a class of Chromophycote algae, comprising 4 subclasses, Dinophycidae, Ebriophycidae, Ellobiophycidae and Syndiniophycidae.
\BDinophycidae\b The largest subclass of dinoflagellates (Dinophyceae) in the algal classification, comprising 15 orders of predominantly unicellular free-living, ectoparasitic or symbiotic forms; characterized by the longitudinal flagellum lying in a posteriorly directed groove and by the possession of the pigments chlorophyll a, \Ic\i\D2\d and peridinin.
\BDinophysiales\b Order of thecate dinoflagellates widely distributed in marine plankton.
\BDinornithidae\b Moas; extinct family of large emu-like ratites, up to 3 m tall; confined to New Zealand but died out during the last few centuries; habits herbivorous and groundnesting.
\BDinornithiformes\b Moas; order of large ratite birds from New Zealand; comprising the Dinornithidae, now extinct.
\Bdinosaur\b Heterogeneous assemblage of diapsid reptiles belonging mainly to two groups of archosaurs, Ornithischia and Saurischia; related to the crocodiles and birds; flourished during the Mesozoic era but became extinct at the end of the Cretaceous period.
\BDiodontidae\b Porcupine fishes, burrfishes; family containing 15 species of shallow-water tropical marine pufferfishes (Tetraodontiformes); length to 0.9 m, body covered with sharp spines, jaw teeth fused to form parrot-like beak; typically inflate body with water when threatened.
\Bdioeciopolygamy\b The presence of both unisexual and hermaphrodite individuals in the same species.
\Bdioecious\b Used of plants or plant species having male and female reproductive organs on different individuals; unisexual; \Bdiecious\b, \Bdioecy\b; see also \Jmonoecious\j \Jtrioecious\j, \Jtrimonoecious\j
\Bdioestrus\b The quiescent period between breeding periods in polyoestrous animals; \Bdioestrous\b; see also \Janoestrus\j \Jmonoestrous\j, \Jpolyoestrous\j
\BDiomedeidae\b Albatrosses; family containing 13 species of large oceanic sea birds (Procellariformes) found in Southern and Pacific Oceans, specialized for dynamic soaring flight close to water surface; wings long and narrow (up to 3.5 m span); feed on fishes and squid; breed in colonies on islands.
\BDioncophyllaceae\b Small family of Violales containing only 3 species of lianas or shrubs, climbing by hooked or cirrhose leaf tips; all native to rainforests of tropical Africa.
\BDioscoreaceae\b Yams; family of Liliales comprising about 600 species of twining-climbing, herbaceous vines or erect herbs arising from a tuber or rhizome; largely tropical in distribution; flowers usually small and inconspicuous with an inferior ovary.
\Bdioxin\b Tetrachlorodibenzoparadioxin (TCDD); a highly toxic and environmentally persistent product of the manufacture of 2,4,5-T.
\BDipentodontaceae\b Family of Santalales containing a single small tree species native to southern China and Burma.
\BDiphyllidea\b Small order of tapeworms parasitic in rays, characterized by a scolex of 2 spoonshaped bothridia lined with minute spines, and an apical organ or rostellum.
\Bdiplanetic\b Having two motile stages during a single life cycle; \Bdiplanetism\b; see also \Jmonoplanetic\j \Jpolyplanetic\j
\Bdipleurula\b Bilaterally symmetrical ciliated larval stage of echinoderms.
\Bdiplobiont\b 1: A plant flowering twice in a single season. 2: An organism exhibiting a regular alternation of haploid and diploid generations during the life cycle; See also \Jhaplobiont\j
\BDiplocheta\b Large and diverse superorder of helminthomorphan diplopods (millipedes) comprising 3 orders, Spirostreptida, Julida and Siphoniulida; body cylindrical, 5-300 mm in length, body segments possessing 2 tergal and 2 sternal sclerites, no pleural element apparent.
\BDiplogasteria\b Subclass of secernentean nematodes containing free-living microbe feeders and parasites of plants and insects; external cuticle ornamented with annulations which may also be traversed by longitudinal striae; oesophagus with a muscular corpus divided into 3 regions, the middle one usually bearing valves; comprises 3 orders, Aphelenchida, Diplogasterida and Tylenchida.
\BDiplogasterida\b Order of mostly free-living diplogasterian nematodes which includes predators, omnivores, bacterial feeders and fungal feeders, as well as a few parasites of insects; characterized by the absence of an axial spear in the stoma.
\Bdiplohaplontic\b Used of an organism exhibiting a regular alternation of haploid and diploid generations during its life cycle.
\Bdiploid\b Having a double set of homologous chromosomes, typical of most organisms derived from fertilized egg cells; See also \Jploidy\j
\BDiplomonadida\b Order of small, mostly parasitic, zooflagellates with 1 or 2 nuclei, no mitochondria and 1-4 flagella, one of which is recurrent; reproducing by binary fission.
\BDiplomystidae\b Family containing 2 species of small (to 250 mm) primitive South American freshwater catfishes (Siluriformes); body smooth with short dorsal and anal fins; adipose fin large; maxillary teeth present.
\Bdiplont\b 1: The diploid stage of a life cycle. 2: An organism having a life cycle in which the direct products of meiosis are haploid and act as gametes; See also \Jhaplont\j
\Bdiplontic life cycle\b A life cycle characterized by a diploid adult stage producing haploid gametes by meiosis, the zygote forming by fusion of a pair of gametes.
\Bdiplophyte\b A diploid plant; See also \Jhaplophyte\j
\BDiplopoda\b Millipedes; class of mostly small terrestrial arthropods having coalesced double trunk segments typically bearing 2 pairs of legs; body often mineralized and specialized for enrollment into a ball, coil or spiral; many produce toxic secretions (allomones) from glands in trunk; sexes separate, reproduction oviparous, fertilization internal; young typically hatch with 3 pairs of legs and pass through a series of anamorphic growth stages; contains about 10 000 species in 3 subclasses, Penicillata, Pentazonia and Helminthomorpha.
\BDiplostraca\b Subclass of branchiopodan crustaceans comprising the clam shrimps (Conchostraca) and the water fleas (Cladocera); body contained within a valvate carapace.
\BDiplura\b Cosmopolitan order containing about 660 species of small, slender, blind, whitish insects found in damp soil, under logs and stones; mouthparts enclosed by head capsule.
\BDipneusti\b \JDipnoi\j
\BDipnoi\b Lungfishes; subclass of lobe-finned bony fishes (Osteichthyes, Sarcopterygii); Dipneusti.
\BDipodidae\b Jerboas; family containing about 25 species of small herbivorous myomorph rodents found in arid habitats of central Palaearctic and northern Ethiopian regions; hindlimbs elongate, adapted for bipedal hopping locomotion; inhabit burrows by day; typically hibernate during winter.
\Bdipper\b \JCinclidae\j
\BDiprotodontia\b Order of small to large herbivorous, terrestrial, arboreal and fossorial marsupials confined to the Australasian region; comprises 7 families, Phalangeridae (phalangers, cuscuses), Burramyidae (pigmy phalangers), Petauridae (gliding phalangers), Macropodidae (kangaroos, wallabies), Phascolarctidae (koala), Vombatidae (wombats) and Tarsipedidae (honey possum).
\BDipsacaceae\b Teasel, scabious; family of mostly herbs with flowers typically grouped into dense cymose heads; comprises about 270 species native to Africa and Eurasia.
\BDipsacales\b Order of Asteridae containing 4 families of herbs or woody plants producing iridoid compounds and various alkaloids, with opposite or whorled leaves; most of its 1000 species are contained in the Caprifoliaceae, Dipsacaceae and Valerianaceae.
\BDiptera\b True flies; order of holometabolous insects comprising about 150000 species in 2 suborders, Nematocera and Brachycera; forewings membranous, hindwings modified as minute club-like balancing organs (halteres); head typically large and mobile with well developed compound eyes; mouthparts adapted for sucking or lapping, occasionally for piercing; feed on nectar, plant and animal secretions, blood or decomposing organic matter; larvae typically cylindrical, lacking true thoracic limbs, exhibiting enormous diversity of feeding strategies; flies are of great medical and veterinary importance as disease vectors, although many are also beneficial as parasitoids and pollinators.
\BDipterocarpaceae\b Family of Theales; comprising usually evergreen trees especially abundant in Malaysian tropical rainforest.
\Bdirective coloration\b Surface markings which divert the attention or attack of a predator to the non-vital parts of the prey body.
\Bdirective species\b A species that attracts a predator, of which it is not a normal prey item, to an area rich in prey species.
\BDiretmidae\b Spinyfins; family containing 10 species of little-known deep-sea beryciform teleost fishes; body deep and compressed, almost circular in outline, to 400 mm length, scales ctenoid; eyes extremely large, teeth minute; dorsal and anal fins elongate, lacking spines.
\Bdisclimax\b A disturbed climax; an ecological succession maintained below climax by rapid expansion of introduced species, climatic instability, fire, grazing or by the activities of man.
\BDiscoglossidae\b Family containing about 10 species of primitive frogs (Anura) found in Europe, North Africa, and temperate regions of Asia to Japan, also Borneo and Philippines, tongues disk-like.
\Bdiscolorous\b Having a non-uniform coloration.
\BDiscomycetes\b Cup fungi; class of ascomycotine fungi typically producing cup-shaped fruiting bodies (apothecia) which open at maturity to expose a fertile layer or tuft consisting of asci interspersed with sterile filaments (paraphyses); comprises mostly saprobic forms with some parasitic, mycorrhizal and lichenized forms as well; contains 7 orders, Cyttariales, Helotiales, Medeolariales, Ostropales, Pezizales, Phacidiales and Tuberales.
\Bdiscontinuity\b A marked interruption in an otherwise continuous sequence of variation, populations or events.
\BDiscosorida\b Order of fossil nautiloid cephalopod molluscs found from Middle Ordovician to Upper Devonian.
\Bdiserotization\b Interference with, or inhibition of, copulation by low temperatures.
\Bdisjunct\b Distinctly separate; used of a discontinuous range in which one or more populations are separated from other potentially interbreeding populations by sufficient distance to preclude gene flow between them.
\Bdisoperation\b A symbiosis in which one or both participants is adversely affected.
\Bdispermy\b The penetration of a single ovum by two spermatozoa at the time of fertilization; \Bdispermic\b; see also \Jmonospermy\j \Jpolyspermy\j
\Bdispersal\b 1: Outward spreading of organisms or propagules from their point of origin or release. 2: The outward extension of a species' range, typically by a chance event.
\Bdispersion\b 1: The pattern of distribution of organisms or populations in space. 2: The non-accidental movement of individuals into or out of an area or population, typically a movement over a relatively short distance and of a more or less regular nature; See also \Jmigration\j
\Bdisplacement activity\b The performance of a behavioural act outside the particular functional context of behaviour to which it is normally related.
\Bdisplay\b A behaviour pattern or signal which conveys information.
\Bdisruptive coloration\b A distinct coloration which delays recognition of the whole animal by attracting the attention of the observer to certain elements of the colour pattern.
\Bdissemination\b Scattering or spreading, as of infectious agents, seeds, spores or other propagules; \Bdisseminate.\b
\Bdisseminule\b A disseminated propagule; a seed, fruit, spore or other structure modified for dispersal.
\Bdissogony\b Sexual maturation at two separate stages of a life cycle, with an intervening period during which no gametes are produced.
\Bdissophyte\b A plant with xerophytic leaves and stems, and a mesophytic root system.
\Bdistillation\b A mode of fossilization involving removal of volatile organic matter, leaving a carbon residue.
\Bdistraction display\b An elaborate pattern intended to attract the attention of an aggressor away from other more vunerable members of a group.
\Bdistrophyte\b A plant living in firm moist soil.
\Bditch grass\b \JRuppiaceae\j
\Bditokous\b Producing two offspring per brood; see also \Jmonotokous\j \Joligotokous\j, \Jpolytokous\j
\BDitrysia\b Largest suborder of lepidopteran insects comprising about 136000 species including many months and all butterflies; adult mouthparts variable; wings occasionally reduced, especially in females; genitalia of female with separate copulatory opening on abdominal sternite 8, and egg-laying aperture on 9-10; larvae extremely diverse ecologically and morphologically.
\Bditypic\b Having two distinct morphs; exhibiting marked sexual dimorphism; used of characters possessing two alternative states: \Bditypism.\b
\Bdiurnae\b Pertaining to day-flying insects; See also \Jnocturnae\j
\Bdiurnal\b 1: Active during daylight hours; see also \Jcrepuscular\j \Jnocturnal. 2: Lasting for one day only\j
\Bdiurnal rhythm\b A biological rhythm having a periodicity of about one day length (24 hours); circadian rhythm.
\Bdiver\b \JGaviidae\j
\Bdivergence\b A zone of oceanic upwelling where deep water rises and spreads out over the surface, as in the Antarctic divergence; See also \Jconvergence\j
\Bdiversionary display\b Behaviour intended to attract the attention of a predator away from the more vulnerable members of a group.
\Bdiversity\b 1: The absolute number of species in a community; species richness. 2: A measure of the number of species and their relative abundance in a community; low diversity refers to few species or unequal abundances, high diversity to many species or equal abundances.
\Bdivision\b 1: Separation into parts; fission. 2: A rank in the hierarchy of plant classification; the principle category between Kingdom and class.
\Bdixenic\b Used of a mixed culture of one organism together with two other species; see also \Jaxenic\j \Jmonaxenic\j
\Bdixenous\b Used of a parasite utilizing two host species during its life cycle; \Bdixeny\b; see also \Jheteroxenous\j \Jmonoxenous\j, \Joligoxenous\j, \Jtrixenous\j
\BDixidae\b Family of small frail dipteran insects (flies) possessing long legs and reduced mouthparts; contains about 150 species with cosmopolitan distribution but most frequent in temperate regions.
\Bdizygotic\b Used of twins derived from two separate fertilized eggs; fraternal (twins); See also \Jmonozygotic\j
\BDL\B\D50\d\b\b A measure of drought lethality, the degree of dryness that causes injury to 50% of a population.
\BDNA\b Deoxyribonucleic acid; the primary genetic material of a cell; a polymer of the nucleotides adenine, guanine, cytosine and thymine, typically containing two polynucleotide chains in the form of a double helix; the sequence of nucleotide pairings in the chains is the basis of the genetic code; DNA molecules are the largest biologically active molecules known.
\Bdobsonfly\b \JCorydalidae\j (Neuroptera).
\BDOC\b Dissolved organic matter (carbon), expressed as grams of carbon per litre.
\Bdock\b \JPolygonales\j
\Bdodder\b \JCuscutaceae\j
\Bdodo\b \JRaphidae\j
\Bdog\b \JCanidae\j
\Bdog-bear\b \JAmphycyonidae\j
\Bdogfish\b Any of the small sharks belonging to the families \JSqualidae\j, \JScyliorhinidae\j and \JCarcharhinidae\j
\BDogger\b A geological epoch of the middle Jurassic period (\Ic\i.. 175-160 million years B.P.).
\Bdogwhelk\b \JNeogastropoda\j
\Bdogwood\b \JCornaceae\j
\Bdoliolaria\b Barrel-shaped larva of some crinoids and holothurians possessing 3-5 ciliated girdles.
\BDoliolida\b Order of pelagic tunicates (Thaliacea) that exhibit an alternation of solitary, sexually reproducing, and compound, asexually produced, forms; zooids small, up to only 5 mm length, inhalent opening anterior, exhalent aperture posterior, body transparent with circular muscles producing locomotory water currents; free-living tailed larva develops into primary asexual oozooid from which colony is produced by budding; colony zooids polymorphic, including gastrozooids (feeding), phorozooids (structural) and gonozooids (sexual, hermaphrodite).
\BDollo's law\b The general principle that evolution is irreversible and that structures and functions once lost are not regained.
\Bdomestication\b The adaptation of plants and animals for life in intimate association with man.
\Bdomicile\b A home, nest, burrow, tube, den or other refuge; See also \Jhibernaculum\j
\Bdomicolous\b Living in a tube, nest or other domicile; \Bdomicole.\b
\BDomin scale\b A scale for estimating cover and abundance of a plant species, comprising 11 categories: + (single individual), 1 (very few individuals), 2 (sparsely distributed, less than 1% cover), 3 (frequent but less than 4% cover), 4 (4-10% cover), 5 (11-25% cover), 6 (26-33% cover), 7 (34-50% cover), 8 (51-75% cover), 9 (76-90% cover) and 10 (91-100% cover).
\Bdominance\b 1: The extent to which a given species predominates in a community because of its size, abundance or coverage, and affects the fitness of associated species. 2: The tendency of the phenotypic traits controlled by one allele (dominant) to be expressed over traits controlled by other alleles (recessives) at the same locus; See also \Jrecessiveness. 3: Physical domination initiated and sustained by aggression or other behavioural patterns of an individual\j
\Bdominance hierarchy\b A social order of dominance sustained by aggressive or other behaviour patterns.
\Bdominant\b 1: The highest ranking individual in a dominance hierarchy; alpha. 2: An organism exerting considerable influence upon a community by its size, abundance or coverage. 3: An allele which determines the phenotype of a heterozygote; See also \Jrecessive\j
\Bdominule\b A dominant organism in a microhabitat.
\BDonatiaceae\b Family of Campanulales containing only 2 species of dwarf herbs with spirally arranged leaves; native to South America, New Zealand and Tasmania: sometimes included in the \JStylidiaceae\j
\BDonau glaciation\b An early glaciation of the Quaternary Ice \JAge\j in the Alpine area, with an approximate duration of 260000 years, tentatively subdivided into 4 separate glacial periods.
\Bdonkey\b \JEquidae\j
\Bdoor snail\b \JStylommatophora\j
\BDoradidae\b Large family of mainly crepuscular tropical South American freshwater catfishes (Siluriformes); body partly covered with spinose bony plates, dorsal and anal fins short, dorsal bearing single spine; 3 pairs of barbels: some species capable of aerial respiration through vascularized intestine; utilized locally as food-fish and also popular in aquarium trade.
\Bdormancy\b 1: A state of relative metabolic quiescence, such as aestivation, cryptobiosis, diapause, hibernation and hypobiosis. 2: A state in which viable seeds, spores or buds fail to germinate under favourable conditions; See also \Jquiescence\j
\Bdormouse\b \JGliridae\j
\Bdory\b \JZeidae\j
\BDorylaimida\b Large order of enoplian nematodes found free-living in soil and freshwater habitats and as ectoparasites of plants; most free-living forms are predators or algal-feeders; characterized by the formation of the anterior tooth or a hollow axial spear by a special cell in the anterior part of the oesophagus.
\BDothideales\b Order of loculoparenchemycetid fungi that are parasitic or saprobic in plant tissues; some are occasionally lichenized.
\BDrepanididae\b Hawaiian honeycreepers; family containing 23 species of small arboreal passerine birds confined to forest habitats of the Hawaiian Islands; plumage often colourful; bill variable indicating the wide spectrum of feeding strategies; tongue occasionally tubular and frilled; feed on invertebrates, seeds, fruit, nectar and other plant material.
\Bdriftfish\b \JNomeidae\j
\Bdrimophilous\b Thriving in salt basins or alkaline plains; \Bdrimophile\b, \Bdrimophily.\b
\Bdrive\b A motivating, impelling internal physiological condition.
\Bdromaeosaurid\b A group of theropod dinosaurs with relatively large brains; known from the Cretaceous.
\BDromaiidae\b Emus; family containing 2 species of large (to 1.8 m tall) Australian ratite birds (Palaeognathae) found in grassland and open forest; legs long, powerful, bearing 3 digits; neck partly naked; habits cursorial, gregarious, monogamous; feeding on fruit, plant material and insects.
\BDromornithidae\b Group of large subfossil ratite birds from Australia.
\Bdromotropism\b An orientation response in climbing plants that results in spiral growth; \Bdromotropic.\b
\Bdrone\b The functional male of social Hymenoptera that plays no part in brood maintenance.
\Bdrongo\b \JDicruridae\j
\BDroseraceae\b Sundews, Venus' fly-trap; cosmopolitan family of insectivorous perennial herbs catching insects either by an active trap or by irritable, mucilage-tipped hairs.
\BDrosophilidae\b Vinegar flies, fruit flies; cosmopolitan family containing about 1500 species of small brownish yellow flies (Diptera) with red eyes that feed on decaying and fermenting plant material; species of \IDrosophila\i have been the subject of extensive genetic and evolutionary studies both in the laboratory and in the field.
\Bdrosphilous\b Pollinated by dew; \Bdrosophilous\b, \Bdrosphile\b, \Bdrosphily.\b
\Bdrought\b 1: A prolonged chronic shortage, usually of water. 2: A period without precipitation during which the soil water content is reduced to such an extent that plants suffer from lack of water.
\Bdrought-evading\b Used of plants sensitive to drought which can survive dry periods by the production of desiccation-resistant seeds or structures.
\Bdrought resistance\b The capacity to withstand periods of dryness, including both desiccation avoidance and desiccation tolerance.
\Bdrum\b \JSciaenidae\j
\Bdrupe\b A fleshy indehiscent fruit containing one or more seeds, each enclosed within a hard endocarp; includes plum, peach, avocado.
\Bdubiofossil\b A structure or object having a marked resemblance to a known fossil but of which the organic or inorganic nature cannot be ascertained or confirmed; problematic fossil.
\Bduck\b \JAnatidae\j
\Bduckbill eel\b \JNettastomatidae\j
\Bduck-billed platypus\b \JOrnithorhynchidae\j
\BDuckeodendraceae\b Family of Solanales containing a single species of tall tree native to the Amazon basin.
\Bduckweed\b \JLemnaceae\j
\Bduff\b A product of litter decomposition; incompletely decomposed organic matter in which the original structure is no longer discernible.
\BDugongidae\b Dugong; monotypic family of large nocturnal, herbivorous, aquatic mammals (Sirenia) found along tropical coasts of the Indian Ocean and western Pacific; incisor and cheek teeth present in adults but absent in older specimens, being replaced by horny plates; tail fluke with median cleft. The recently extinct Steller's sea cow from the Bering Sea is sometimes included in this family.
\Bdulosis\b Symbiosis in which workers of an ant species capture the brood of another species and rear them as slaves; \Bdulotic.\b
\BDuplicidentata\b Older name for the \JLagomorpha\j
\BDurvillaeales\b Small order of kelp-like brown algae found only in the southern hemisphere.
\Bdusty wing\b \JNeuroptera\j
\BDutch elm disease\b \JEurotiales\j
\Bdwarfism\b The condition of being stunted, much smaller than normal; having restricted growth: \Bdwarf.\b
\Bdysanthous\b Pertaining to the condition of being fertilized by pollen from another plant; \Bdysanthic.\b
\Bdyschronous\b Pertaining to plant species that do not overlap in their flowering periods.
\Bdysgenesis\b The condition of infertility between hybrids which are themselves cross-fertile with the parental stocks; \Bdysgenetic.\b
\Bdysgenic\b Pertaining to, or having, the capacity for decreasing the fitness of a race or breed; See also \Jeugenics\j
\Bdysphotic zone\b The zone of intermediate light intensity in a water body, with insufficient light for photosynthesis but sufficient light for behavioural responses; \Bdisphotic zone\b; see also \Jeuphotic zone\j \Jphotic zone\j
\BDyssomidae\b Arrowtooth eels; family containing 8 species of small (to 250 mm), littoral to bathyal bottom-living anguilliform teleost fishes; body smooth, eyes and gill openings small, dorsal, caudal and anal fins continuous, pectorals present or absent; snout ridged and grooved ventrally.
\Bdystric\b Pertaining to unhealthy soils; See also \Jeutric\j
\Bdystrophic\b 1: Used of freshwater bodies rich in organic matter mainly in the form of suspended plant colloids and larger plant fragments, but having low nutrient content; dystrophic lake; see also \Jeutrophic\j \Jmesotrophic\j, \Joligotrophic. 2: Used of species characteristic of dystrophic habitats\j
\Bdyticon\b An ooze-inhabiting community.
\BDytiscidae\b Family of powerful, predatory beetles (Coleoptera) found in various aquatic habitats both as adults and larvae; feeding on insect larvae, molluscs and small aquatic vertebrates; contains about 3000 species in 120 genera.
\Beagle\b \JAccipitridae\j
\Beagle ray\b \JMyliobatidae\j
\Bearless monitor\b \JLanthanotidae\j
\Bearth star\b \JLycoperdales\j
\Bearthworm\b \JLumbricina\j (Oligochaeta).
\Bearwig\b \JDermaptera\j
\BEast Australia Current\b A warm surface ocean current that flows southwards off the east coast of Australia, forming the western limb of the South Pacific Gyre; see ocean currents.
\BEast Indian pitcher plant\b \JNepenthaceae\j
\Bebb current\b The tidal current associated with a receding tide; See also \Jflood current\j
\Bebb tide\b A receding tide; See also \Jflood tide\j
\BEbenaceae\b Ebony, persimmon; family containing about 450 species of trees or shrubs with hard dark wood; mostly tropical in distribution; flowers typically unisexual, with fused sepals and petals and a superior ovary; fruit usually a berry.
\BEbenales\b Order of Dilleniidae containing 5 families of trees or shrubs, Ebenaceae, Lissocarpaceae, Sapotaceae, Styracaceae and Symplocaceae.
\Bebony\b \JEbenaceae\j
\BEbriida\b Order of colourless, marine zooflagellates with 2 flagella and an internal siliceous skeleton; also regarded as a subclass of algae, \JEbriophycidae\j
\BEbriophycidae\b Small subclass of marine phagotrophic dinoflagellates possessing an internal siliceous skeleton; mostly fossil forms but two extant species in order Ebriales.
\Becad\b A plant or animal form produced in response to particular habitat factors, the characteristic adaptations not being heritable; a habitat form.
\BEccrinales\b Order of trichomycete fungi comprising obligate gut symbionts of various crustaceans and uniramians.
\Becdemic\b Foreign; non-native; See also \Jendemic\j
\Becdysis\b The act of shedding or moulting the outer exoskeleton or cuticle.
\Becesis\b The pioneer stage of dispersal to a new habitat; successful invasion and establishment by colonizing plants.
\Bechard\b That part of soil water not available for plant use; see also \Jchresard\j \Jholard\j
\BEcheneidae\b Remoras; family containing 8 species of marine teleost fishes (Perciformes) that attach to other aquatic vertebrates, such as sharks, swordfishes, rays, turtles and whales, by means of a large sucking disk on the flattened dorsal surface of the head, derived from a modified anterior dorsal fin.
\Bechidna\b \JTachyglossidae\j
\BEchimyidae\b Rock rats, spiny rats; family containing about 40 species of small northern Neotropical terrestrial and arboreal hystricomorph rodents; mostly herbivorous, inhabiting burrows or crevices in rocks.
\BEchinacea\b Superorder of intertidal to abyssal regular echinoids (Euechinoidea) comprising 5 orders, Salenoida, Phymosomatoida, Arbacioida, Temnopleuroida and Echinoida, and including most of the familiar sea urchins; oral membrane encircled with 5 pairs of ambulacral plates, body spines solid.
\BEchinodera\b \JKinorhyncha\j
\BEchinodermata\b Phylum of exclusively marine, radially symmetrical (pentamerous), unsegmented, solitary marine coelomates that possess a diverse array of skeletal spicules, plates, spines and larger ossicles composed of calcium carbonate (calcite), and a unique water vascular system the outgrowths of which form tube feet and tentacles used variously for attachment, locomotion and gas exchange; sexes are separate, fertilization normally external, development direct or with planktonic larvae; asexual reproduction by fission common; 3 extant subphyla recognized, Crinozoa (feather stars, sea lilies), Asterozoa (sea stars), Echinozoa (sea urchins, sea cucumbers); echinoderms have an extensive fossil record.
\BEchinoida\b Order of intertidal to lower continental slope echinoids comprising about 65 extant species; test lacking sculpturing, to 300 mm diameter, dentition camarodont; gonads of some species considered a gastronomic delicacy.
\BEchinoidea\b Sea urchins, heart urchins, sand dollars; class of echinozoan echinoderms characterized by a hollow globular body formed by fused skeletal plates (test) bearing stiff articulating spines; oral pole facing downwards, anus on upper surface at aboral pole but moved into interambulacral position in bilaterally symmetrical, irregular, burrowing echinoids; a complex buccal apparatus, Aristotle's lantern, is usually present; echinoids are exclusively benthic, feeding by grazing, scavenging or ingestion of sediment; development includes planktonic echinopluteus larva; about 950 extant species in 2 subclasses, Perischoechinoidea and Euechinoidea; rich fossil record comprising about 5000 recognized species.
\Bechinopluteus\b The \Jpluteus\j larval stage of a sea urchin.
\BEchinorhinidae\b Bramble shark; family containing 2 species of heavy-bodied squaliform sharks; length to 3.5 m, skin rough bearing thorn-like spines; dorsal fins small, posteriorly positioned, anal fin absent; habits benthic, sluggish; depth range to about 900 m.
\BEchinorhynchida\b Large order of palaeacanthocephalan thorny-headed worms found commonly as parasites of fishes and, occasionally, of amphibians and reptiles.
\BEchinosteliales\b Small order of slime moulds (Myxogastromycetidae) with stalked sporangia usually less than 0.5 mm in height, and bearing light-coloured spores; most of the 18 species are restricted to bark of living trees and vines.
\BEchinosteliida\b The slime mould order \JEchinosteliales\j, treated as an order of the protozoan group Myxogastria.
\BEchinostomida\b Order of digenetic trematodes possessing one pair of flame cells (excretory organs) in the miracidia larva; cercariae with abundant cystogenous glands, forming cysts on vegetation or in secondary intermediate host.
\BEchinothuroida\b Order of deep-sea echinoids (Diadematacea) comprising about 50 living species having a light flexible test, up to 300 mm diameter, that often collapses when removed from water; some spines armed with poison glands; development direct.
\BEchinozoa\b Subphylum of echinoderms characterized by a globular compact body with 5 meridional ambulacra that radiate from the oral pole and converge at the aboral pole; body may be elongate (sea cucumbers) or compressed (sand dollars) along oral/aboral axis, some species showing secondary bilateral symmetry; two extant classes, Echinoidea (sea urchins, heart urchins, sand dollars) and Holothuroidea (sea cucumbers).
\BEchiura\b Spoonworms; small phylum of soft bodied, unsegmented, coelomate, marine worms; body divided into 2 regions, a sac-like or cylindrical trunk with an extensible ciliated proboscis used in respiration and food collection, and a smooth, annulate or papillose trunk bearing a pair of setae that assist in burrowing and anchorage; inhabit burrows in soft sediments, rock crevices, empty shells or tests, feeding on detritus; contains about 140 species in 3 orders, Echiuroinea, Xenopneusta and Heteromyota; also known as Echiurida.
\BEchiuroinea\b Order of echiuran marine worms in which the longitudinal muscles of the trunk body wall are between the outer circular and inner oblique layers; blood system closed; up to 7 pairs of nephridia; contains about 130 species found from the intertidal to abyssal depths.
\Bechiurus\b Trochophore larva of sipunculan worm.
\BEchmatocrinea\b Extinct order of pelmatozoan echinoderms known from the Middle Cambrian; possessing 8-10 short arms and an irregular attachment holdfast.
\Becholocation\b The perception of objects using high-frequency sound waves, used by some animals for navigation and orientation within the environment.
\Bechosounding\b The use of sound waves (acoustic signals) to measure depth of water, plot the bottom profile, or locate submerged objects and dense aggregations of relatively small organisms.
\Beclipse plumage\b Dull inconspicuous plumage of birds which alternates with a much brighter breeding plumage.
\Beclosion\b The emergence of an adult insect from the pupal case; sometimes also used for the hatching of an egg.
\Becochronology\b The dating of biological events using palaeoecological evidence.
\Becocide\b Any toxic substance that penetrates and kills an entire biological system.
\Becoclimate\b The immediate climate of an individual organism; microclimate.
\Becoclimatology\b The study of plants and animals in relation to climate; bioclimatology.
\Becocline\b 1: A more or less continuous character variation in a sequence of populations distributed along an ecological gradient, with each population exhibiting local adaptation to its particular segment of the gradient. 2: The differences in community structure resulting from changes in slope aspect around a mountain or ridge.
\Becodeme\b A local interbreeding group occurring in a particular habitat; See also \Jdeme\j
\Becogeographical rule\b Any generalization describing a trend of geographical variation correlated with environmental conditions; climatic rule.
\Becography\b Descriptive ecology.
\Becological amplitude\b The range of a given enviromental factor over which an organism or process can function; range of tolerance.
\Becological efficiency\b The efficiency of transfer of energy from one trophic level to the next.
\Becological isolation\b The absence of interbreeding between populations occurring in the same area because of ecological barriers.
\Becological longevity\b The average life span of an individual in a given population and under stated conditions.
\Becological niche\b The concept of the space occupied by a species, which includes both the physical space as well as the functional role of the species; conceptualized as a multidimensional hypervolume which defines the biological space occupied by a species, and which is unique to the species; niche; see also \Jfundamental niche\j \Jrealized niche\j
\Becological pyramid\b A model of the trophic structure of a community which takes the form of a pyramid of numbers, biomass or energy, in which producers form the base of the pyramid and successive levels represent consumers of higher trophic levels; food pyramid.
\Becological race\b A local race of a species having conspicuous adaptive characters correlated with a given habitat type.
\Becological succession\b The gradual process of progressive community change and replacement, leading towards a stable climax.
\Becology\b The study of the interrelationships between living organisms and their environment; \Becological.\b
\Becon\b A local vegetational unit; \Beca.\b
\Becoparasite\b A parasite restricted to a specific host or to a small group of related host species.
\Becophene\b All the naturally occurring phenotypes produced within a given habitat by a single genotype.
\Becophenotype\b A phenotype exhibiting non-genetic adaptations associated with a given habitat, or to a given environmental factor.
\Becoproterandry\b The maturation of staminate flowers before pistillate flowers.
\Becoproterogyny\b The maturation of pistillate flowers before staminate flowers.
\Becospecies\b A group of populations having the capacity for free exchange of genetic material without loss of fertility or vigour, but having a lesser capacity for such exchange with members of other ecospecies groups.
\Becosphere\b \JBiosphere\j
\Becostratigraphy\b The study and classification of stratified rocks according to their mode of origin or to the environment at the time of deposition; \Becostratigraphic.\b
\Becosystem\b A community of organisms and their physical environment interacting as an ecological unit.
\Becotone\b The boundary or transitional zone between adjacent communities or biomes.
\Becotope\b A particular habitat type within a larger geographical area.
\Becotype\b A locally adapted population; a race or infraspecific group having distinctive characters which result from the selective pressures of the local environment; ecological race.
\BEctocarpales\b Order of brown algae, typically of small size with a tufted filamentous growth form; commonly found in the intertidal zone, growing on rocks or on other algae.
\Bectocommensal\b A commensal symbiont that lives on the external surface of its host; See also \Jendocommensal\j
\Bectogenic meromixis\b The mixing of a lake as a result of an external event or agency; as in the influx of saline water into a freshwater lake producing a density stratification; \Icf\i biogenic meromixis, crenogenic meromixis.
\Bectogenous\b Arising or originating outside the organism or system; \Bectogenesis\b;\B See also\\Jbendogenous\j
\BEctognatha\b A superorder of insects possessing well developed, protruding mouthparts; comprises the Thysanura and the Pterygota.
\Bectoophagous\b Used of an insect larva that hatches from an egg deposited on or near a supply of host eggs and feeds upon them; \Bectoophage\b, \Bectoophagy\b; See also \Jendoophagous\j
\Bectoparasite\b A parasite that lives on the outer surface of its host; See also \Jendoparasite\j
\Bectophagous\b Feeding on the outside of a food source; \Bectophage\b, \Bectophagy\b; See also \Jendophagous\j
\Bectophloedic\b Growing on the outside of bark; See also \Jendophloedic\j
\Bectophyte\b A plant parasite living on the outer surface of another organism; \Bectophytic\b; See also \Jendophyte\j
\Bectopic\b Occurring in an abnormal place or manner.
\BEctoprocta\b \JBryozoa\j
\Bectosymbiosis\b A symbiosis in which both symbionts are external, neither lives within the body of the other; \Bectosymbiont\b; See also \Jendosymbiosis\j
\Bectothermic\b 1: Poikilothermic; having a body temperature determined primarily by the temperature of the environment; cold-blooded; \Bectotherm\b, \Bectothermal\b. 2: Pertaining to a chemical reaction releasing heat energy; See also \Jendothermic\j
\Bectotrophic\b Obtaining nourishment externally without marked penetration into the food source; \Bectotroph;\b See also \Jendotrophic\j
\Bectotropism\b Orientation movement away from the central axis; \Bectotropic\b; See also \Jendotropism\j
\Bedaphic\b Pertaining to, or influenced by, the nature of the soil.
\Bedaphology\b The study of soils, particularly with reference to the biota and man's use of land for plant cultivation.
\Bedaphon\b The soil flora and fauna; those organisms living in the interstitial water and pore spaces of soil.
\Bedaphotropism\b An orientation response to a soil water stimulus; \Bedaphotropic.\b
\BEdentata\b Order of New World placental mammals in which incisor and canine teeth are absent; premolars and molars absent or peg-like and lacking enamel; contains 3 families, Myrmecophagidae (anteaters), Bradypodidae (tree sloths) and Dasypodidae (armadillos).
\BEdiacarian period\b The period of geological time immediately preceding the Cambrian (\Ic.\i 700-570 million years B.P.); the last of the Precambrian periods.
\Bedible frog\b \JRanidae\j
\Bedible mushroom\b \JAgaricales\j
\Bedible snail\b \JStylommatophora\j
\Bedobolous\b Having seeds dispersed by propulsion by means of turgor pressure; \Bedobole.\b
\BEdrioasteroidea\b Group of fossil echinoderms known from mid-Cambrian to Lower Carboniferous; upper (oral) surface with 5 ambulacral grooves radiating from a central mouth; test flexible; anus interambulacral; lower (aboral) surface concave in some forms perhaps forming a sucker for temporary fixation.
\Beel\b \JAnguillidae\j, freshwater eels.
\Beelgrass\b \JZosteraceae\j
\Beelpout\b \JZoarcidae\j
\Beelworm\b \JNematoda\j
\BEemian interglacial\b The interglacial period preceding the Weichselian glaciation in northern Germany and Poland; see Quaternary Ice Age.
\BEEZ\b Exclusive economic \Jzone\j
\Beffete\b Functionless; no longer fertile or no longer functioning as a result of age.
\Beffluent\b The discharge of industrial or urban waste material into the environment; the outflow from a lake or river.
\Begesta\b In ecological energetics, that part of consumption expelled as faecal material or regurgitated, and thus not absorbed.
\Begestion\b Defaecation; the voiding of faecal or regurgitated matter.
\Begg plant\b \JSolanaceae\j
\Begret\b \JArdeidae\j
\BE-horizon\b A pale coloured layer below the A-horizon of a soil profile, having a lower organic content than the layers above and below; a zone of high eluviation; see soil horizons.
\BElaeagnaceae\b Russian olive, oleaster, silver berry, sea buckthorn; small family of Proteales containing about 50 species of often thorny trees or shrubs commonly with root nodules containing nitrogen-fixing bacteria; flowers unisexual or bisexual, often arranged in inflorescences (racemes).
\BElaeocarpaceae\b Lantern tree, bead tree; family of Malvales containing about 400 species of trees and shrubs, widespread in tropics and subtropics except Africa; typically possessing racemes or panicles of small flowers with 4-5 sepals and petals, many stamens and a superior ovary.
\Belaioplankton\b Planktonic organisms utilizing of droplets for buoyancy.
\Belaphocaris\b Early zoeal larval stage of sergestoid shrimps (Decapoda).
\BElaphomycetales\b Small order of plectomycete fungi which are mycorrhizal associates of trees forming underground fleshy ascocarps which produce odours attractive to small mammals.
\BElapidae\b Cobras, mambas, kraits, coral snakes family of small to medium-sized, highly venomous snakes (Serpentes) that feed mainly on cold-blooded vertebrates; contains about 170 species grouped in 2 subfamilies, one primarily terrestrial and oviparous, the other aquatic marine and ovoviviparous; widespread in Australia and Indo-Pacific region.
\BElasipodida\b Order of deep-sea holothurians (Aspidochirotacea) comprising about 110 species which have a fragile, often gelatinous, test that may bear dorsal processes; respiratory trees absent; some species swim, others walk on sea bed using enlarged ventral tube feet; may be locally abundant comprising up to 95% of the biomass.
\BElasmobranchii\b Sharks and rays; subclass of cartilaginous fishes (Chondrichthyes); body elongate and subcylindrical to markedly flattened; 5-7 pairs of gill openings, no gill operculum; upper jaw not fused to cranium; teeth numerous; comprises 4 extant superorders, Squalomorphii, Squatinimorphii, Batoidea and Galeomorphii.
\BElateridae\b Click beetles, wireworms; widely distributed family of common elongate beetles (Coleoptera) which can jump while making a clicking noise; includes predators, plant feeders and saprophages all of which digest food externally and take in liquids; plant-feeding larvae found in soil known as wireworms.
\BElatinaceae\b Small, cosmopolitan family of Theales, containing about 40 species of herbs growing in shallow-water or wet habitats; flowers tiny, solitary or clustered in leaf axils, and with 3-5 sepals and petals.
\BElbe glaciation\b A glaciation of the Quaternary Ice \JAge\j in northern Germany and Poland, with an estimated duration of 100 000 years.
\Belderberry\b \JCaprifoliaceae\j
\Belectric catfish\b \JMalapteruridae\j
\Belectric eel\b \JElectrophoridae\j
\Belectric ray\b \JTorpedinidae\j
\Belectrophoresis\b A technique for separating mixtures of organic molecules, based on their different rates of travel in an electric field.
\BElectrophoridae\b Electric eel; monotypic family of large (to 2.4 m) predatory South American catfishes (Siluriformes); body elongate, cylindrical; dorsal, caudal and pelvic fins absent, anal fin extends most of body length; produce powerful electric shocks to stun prey, or for defence, sufficient to immobilize a large mammal.
\Belectrotaxis\b A directed reaction of a motile organism in response to an electric field; \Belectrotactic.\b
\Belectrotropism\b An orientation in response to an electric field; \Belectrotropic.\b
\BEleotridae\b Gudgen; family containing about 150 species of small teleost fishes (Perciformes) distributed worldwide; body round, head blunt with eyes located almost above jaws; 2 dorsal fins present.
\Belephant\b \JElephantidae\j
\Belephant bird\b \JAepyornithidae\j
\Belephant fish\b \JMormyridae\j
\Belephant shrew\b \JMacroscelididae\j
\BElephantidae\b Elephants; family of massive herbivorous terrestrial mammals (Proboscidea) comprising 2 surviving monotypic genera, one Oriental (Indian elephant), the other Ethiopian (African elephant); upper incisors forming large tusks of solid dentine (ivory); only 2 functional cheek teeth present in each quadrant of the jaw, nasal region greatly prolonged into prehensile trunk; includes the extinct mammoth.
\Belfin forest\b A forest of higher elevation in warm moist regions, characterized by stunted trees with abundant epiphytes; See also \Jkrummholz\j
\Belimination\b In ecological energetics, any loss of biomass or energy by a population or trophic unit, including losses due to mortality, predation, emigration and moulting.
\Belittoral\b The zone of the sea bed below the sublittoral, extending to the limit of light penetration; sometimes used for the sea bed below 40 m.
\Belk\b \JCervidae\j
\BEllesmeroceratida\b Extinct order of primitive cephalopods found from Upper Cambrian to Lower Silurian.
\BEllobiophycidae\b Subclass of marine dinoflagellates comprising a single order, Thalassomycetales, of ectoparasitic forms infecting arthropods and polychaetes.
\Belm\b \JUlmaceae\j
\Belodea\b \JHydrocharitales\j
\BElopidae\b Tenpounders; family containing 4 species of tropical marine teleost fishes (Elopiformes) found mainly in shallow coastal waters; body subcylindrical, superficially herring-like, to 1.2 m length, mouth terminal; highly prized as game fish by anglers.
\BElopiformes\b Small order of mainly marine teleost fishes; body rounded to slender and compressed, pelvic fins abdominal, caudal deeply forked; leptocephalus larval stage present; comprises about 7 species in 2 families, Elopidae (tenpounders) and Megalopidae (tarpons).
\BElsterian glaciation\b A glaciation of the Quaternary Ice \JAge\j in northern Germany and Poland, with an estimated duration of 90 000 years.
\Belutriation\b A method of removing interstitial organisms from a sediment sample by continuous flushing with water.
\Beluvial layer\b The leached upper layer of a soil profile.
\Beluviation\b The translocation of suspended or dissolved soil material by the action of water; usually the removal of substances in solution is termed \Jleaching\j
\Belver\b Juvenile stage of the common eel (Anguillidae).
\Bemasculation\b The removal of the male reproductive organs or the inhibition of male reproductive capacity; geld; See also \Jspay\j
\BEmballonuridae\b Sac-winged bats; family of small insectivorous microchiropteran bats comprising 40 species widespread in tropical and subtropical regions of both Old and New World.
\BEmberizidae\b Buntings, cardinals, Darwin's finches, sparrows; diverse family containing about 320 species of passerine birds found in a variety of forest, grassland and open habitats of the New and Old World; coloration cryptic or bold; bill short, conical, robust; habits solitary to gregarious, arboreal to terrestrial, monogamous to polygamous, migratory or not; feed on seeds, other plant material, and insects; nest on or off the ground.
\BEmbiidina\b Embioptera; webspinners; order of orthopterodean insects comprising about 200 species, most common in tropical forest habitats; inhabit extensive galleries or labyrinths of silk on bark, litter, moss, lichens or within the soil; body slender, legs short; females and some males wingless.
\BEmbioptera\b \JEmbiidina\j
\BEmbiotocidae\b Surfperches, sea perches; family of North Pacific coastal marine teleost fishes (Perciformes); body deep, compressed, to 450 mm length; single dorsal fin present, anal fin of male modified as intromittant organ; reproduction viviparous.
\BEmbrithopoda\b Extinct order of subungulates known only from the lower Oligocene; contains \IArsinoitherium\i, a large form with massive limbs and 2 pairs of horns.
\Bembryo\b The developing organism between fertilization and hatching or birth, contained within egg membranes or the maternal body.
\BEmbryobionta\b Embryophytes; a subkingdom of plants; predominantly terrestrial plants which exhibit well developed alternation of generations in which the sporophyte is initially parasitic on the gametophyte; produce spores by meiosis as part of the sexual life cycle but asexual reproduction does not involve spore formation; photosynthetic pigments include chlorophylls \Ia\i and \Ib\i, \Fb\n -carotene is the main carotene and lutein the main xanthophyll; most have specialized conducting tissues (xylem and phloem) and epidermal openings (stomata) through which gaseous exchange takes place; See also \JThallobionta\j
\Bembryotrophy\b The process of nutrition of a mammalian egg before implantation at which point it becomes dependent upon the maternal blood supply.
\Bemergent\b 1: An aquatic plant having most of the vegetative parts above water. 2: A tree which reaches above the level of the surrounding canopy; See also \Jsubmergent\j
\Bemersed\b Pertaining to a plant structure that projects above the water surface; See also \Jsubmersed\j
\Bemersion zone\b 1: The uppermost part of the eulittoral zone of a lake which is above water level for most of the year. 2: That part of the seashore covered only by extreme high tides.
\Bemigration\b The movement of an individual or group out of an area or population; \Bemigrant\b; See also \Jimmigration\j
\Bemmenophyte\b An aquatic plant devoid of any floating parts; \Bemmophyte.\b
\Bemperor\b \JLethrinidae\j
\Bemperor butterfly\b \JNymphalidae\j
\Bemperor moth\b \JSaturniidae\j
\BEmpetraceae\b Crowberry; small family of Ericales containing 5 species of evergreen shrubs with small inconspicuous flowers, often borne in clusters; fruit a drupe.
\BEmpididae\b Dance flies; cosmopolitan family containing over 3000 species of small predatory flies (Diptera) commonly found in swarms in damp wooded habitats.
\Bempirical\b Based upon direct observation and experience rather than theory or preconception.
\Bempress tree\b \JBignoniaceae\j
\Bemu\b \JDromaiidae\j
\Bemu bush\b \JMyoporaceae\j
\BEmydidae\b Terrapins; large family of aquatic, semiaquatic and terrestrial turtles (Testudines: Cryptodira) having a depressed carapace and webbed feet; contains about 80 species, widespread in tropical and temperate regions especially of North America and the Oriental region.
\Benantiobiosis\b Inhibition of, or interference with, one species or population by the action of another.
\Benation\b A small outgrowth from plant stem or leaf.
\Benaulophilous\b Thriving in sand dunes; \Benaulophile\b, \Benaulophily.\b
\Benaulophyte\b A sand dune plant.
\BEncalyptales\b Small order of mosses (Bryidae) found mostly in montane and tundra habitats in the northern hemisphere; small dull plants forming tufts on soil generally in calcareous areas.
\Bencasement theory\b The theory that the embryo is contained within the sperm or egg cell and that it unfolds during development; preformation theory.
\BEnchytraeidae\b Pot worms; family of small, primarily freshwater, oligochaete worms; sometimes included in the order Haplotaxida, or placed in a separate order, Prosotheca.
\Bendangered species\b A species threatened with extinction.
\Bendemic\b Native to, and restricted to, a particular geographical region; \Bendemicity\b, \Bendemism\b; See also \Jecdemic\j
\Bendobenthic\b Living within the sediment; boring into a solid substratum; see also \Jepibenthic\j \Jhyperbenthic\j
\Bendobenthos\b Organisms living within the sediment on the sea bed or lake floor; infauna; endobenthic; See also \Jbenthos\j
\Bendobiontic\b Used of organisms that live within the substratum; \Bendobiotic.\b
\BEndoceratida\b Extinct order of nautiloid cephalopods known only from the Ordovician.
\Bendocommensal\b A commensal symbiont that lives inside its host; See also \Jectocommensal\j
\Bendodeme\b A local interbreeding group composed of predominantly inbreeding but dioecious individuals; See also \Jdeme\j
\Bendoectothrix\b Growing in or on hair.
\Bendogamy\b 1: Inbreeding; sexual reproduction between closely related individuals. 2: Pollination of a flower by pollen from another flower on the same plant; self-pollination; See also \Jexogamy\j
\Bendogenous\b Arising or originating from within the organism or system; growing on the inside; \Bendogenetic\b; see also \Jectogenous\j \Jexogenous\j
\Bendogenous clock\b Any physiological system which shows an inherent sustained periodicity.
\BEndogonales\b Order of zygomycete fungi containing a single family; many enter endomycorrhizal associations with higher plants.
\Bendolithic\b Growing within a rock or other hard inorganic substratum; See also \Jepilithic\j
\Bendolithophytic\b Pertaining to plants that penetrate rock or other hard inorganic substratum; \Bendolithophyte\b; see also \Jepilithophytic\j \Jexolithophytic\j
\Bendomitosis\b The doubling of chromosomes within a nucleus which does not subsequently divide.
\Bendomixis\b Self-fertilization in which male and female nuclei from one individual fuse; \Bendomictic.\b
\BEndomycetales\b Yeast; order of hemiascomycete fungi containing mostly saprophytic forms but also some parasites, includes many of the yeasts used in fermentation processes; often unicellular forms reproducing asexually by fission and budding.
\Bendomycorrhiza\b A mycorrhiza in which the fungal hyphae penetrate the root cells of the host plant.
\Bendoophagous\b Used of an insect larva that hatches from an egg deposited within a host egg and feeds upon the contents of that single egg; \Bendoophage\b, \Bendoophagy\b; See also \Jectoophagous\j
\Bendoparasite\b An internal parasite which lives within the organs or tissues of its host; endosite; entoparasite; See also \Jectoparasite\j
\Bendopelic\b Used of aquatic organisms that live within the sediment; See also \Jepipelic\j
\Bendophagous\b Feeding from within the food source; \Bendophage\b, \Bendophagy\b; See also \Jectophagous\j
\Bendophloedic\b Living or occurring within the bark; See also \Jectophloedic\j
\Bendophyllous\b Living or growing in leaves; See also \Jepiphyllous\j
\Bendophyte\b A plant living within another plant; \Bendophytic\b; See also \Jectophyte\j
\BEndoprocta\b \JEntoprocta\j
\Bendopsammon\b The microscopic biota inhabiting sand and mud.
\BEndopterygota\b \JHolometabola\j
\Bendorheic region\b An area in which rivers arise but do not reach the sea as they are lost in closed basins or dry courses; see also \Jarheic region\j \Jexorheic region\j
\Bendosymbiosis\b Symbiosis in which one symbiont lives within the body of the other; See also \Jectosymbiosis\j
\Bendosymbiosis theory\b That the three classes of intracellular organelles (mitochondria, basal bodies/flagella/cilia, photosynthetic plastids) of eukaryotes evolved from free-living prokaryotic ancestors through a series of endosymbiotic relationships.
\Bendothermic\b Warm-blooded; maintaining a body temperature largely independent of the temperature of the environment; homoiothermic; \Bendotherm\b, \Bendothermal\b; See also \Jectothermic\j
\Bendotrophic\b Obtaining nourishment internally, as of a \Jmycorrhiza\j in which the fungus penetrates the host root system; \Bendotrophism\b; See also \Jectotrophic\j
\Bendotropism\b Orientation movement towards the central axis; \Bendotropic\b; See also \Jectotropism\j
\Bendoxylic\b Living or growing within wood; See also \Jepixylic\j
\Bendozoic\b 1: Living within or passing through the body of an animal; See also \Jepizoic. 2: Used of a method of seed dispersal in which seeds are ingested by an animal and later voided in the faeces\j
\Bendozoochorous\b Dispersed by the agency of animals, typically after passage through the gut; \Bendozoochore\b, \Bendozoochory\b; See also \Jepizoochorous\j
\Benergetics\b The study of energy transformation within a community or system; ecological energetics.
\Benergy flow\b The passage of energy into and out of an organism, population or system; the passage of energy through the different trophic levels of a food chain.
\BEngraulidae\b Anchovies: family of small (to 200 mm) plankotrophic teleost fishes (Clupeiformes) cosmopolitan in tropical to temperate seas; typically marine but also found in brackish and freshwater habitats; body fusiform, silvery, tip of snout projecting over large mouth; caudal fin strongly forked; eggs pelagic; many species support important commercial fisheries, primarily for fish meal and bait.
\Benhalid\b Used of plants that grow in saltings or in loose soil under salt water.
\BEnopla\b Class of nemerteans in which the mouth and proboscis typically share a common pore and in which the mouth is anterior to the brain; comprising 2 orders, Bdellonemertea and Hoplonemertea.
\BEnoplia\b Large subclass of adenophorean nematodes containing over 3000 species including the majority of nematodes found in the marine environment as well as many freshwater and soil-inhabiting, free-living forms, and parasites; most are predatory or omnivorous but herbivorous forms are known; cuticle typically smooth; chemosensory organs on head (amphids) non-spiral; exhibit a great diversity of form and structure which makes this assemblage difficult to characterize.
\BEnoplida\b Order of free-living enoplian nematodes found in marine, fresh-and brackish-water habitats, feeding as predators, omnivores or on algae; possessing pouch-like chemoreceptors (amphids) with an external slit-like or ellipsoid opening which are positioned behind the lips on the head; other head sensory organs arranged in 3 whorls.
\BEnsifera\b Suborder of typically nocturnal orthopteran insects containing about 8500 species including crickets, katydids and long-horned grasshoppers; although widespread ensiferans tend to prefer tropical and arboreal habitats.
\BEnterogona\b Order of ascidiacean tunicates comprising 2 suborders sometimes treated as distinct orders, Aplousobranchia and Phlebobranchia.
\BEnteropneusta\b Class of mainly littoral, vermiform, hemichordates comprising about 70 species found in soft sediments amongst algal holdfasts and stones; body soft and cylindrical, 250 mm - 2.5 m in length, devoid of appendages, divided into 3 regions, proboscis, collar and trunk; mouth anteroventral in collar; pharynx bearing U-shaped gill slits supported by skeletal elements; coelom greatly reduced; development direct or via tornaria larva.
\Benterozoon\b A parasitic animal living within the gut of its host.
\BEntodiniomorphida\b Order of vestibuliferan ciliates in which the vestibular and body ciliature is reduced to tufts or bands, found commonly as endocommensals in herbivorous mammals.
\BEntognatha\b A rarely used superorder of insects comprising the Collembola, Diplura and Protura; characterized by mouthparts contained within an invagination of the head.
\Bentomochoric\b Dispersed by the agency of insects; \Bentomochore\b, \Bentomochory\b.
\Bentomogamous\b Used of flowers pollinated by insects; entomophilous; \Bentomogamy.\b
\Bentomogenous\b Living in or on insects.
\Bentomography\b Description of an insect or of its life history.
\Bentomology\b The study of insects; \Bentomological.\b
\Bentomopathogenic\b Causing disease in insects.
\Bentomophagous\b Feeding on insects; insectivorous; \Bentomophage\b, \Bentomophagy\b.
\Bentomophilous\b Pollinated by, or dispersed by the agency of, insects; \Bentomophile\b, \Bentomophily\b.
\BEntomophthorales\b Order of zygomycete fungi comprising 2 families, one saprobic, the other containing many obligate pathogens of plants and animals; characteristically releasing spores by forcible dehiscence; mycelium coenocytic in young stages becoming septate with age; also treated as a class of the phylum Zygomycota.
\Bentomophyte\b Any fungus growing on or in an insect.
\Bentomosis\b A disease caused by an insect parasite.
\BEntomostraca\b Obsolete name formerly used to group all the lower crustaceans together as distinct from the Malacostraca.
\Bentomotaxy\b The preservation and preparation of insects for study.
\Bentophagous\b Feeding from within a food source; \Bentophage\b, \Bentophagy\b.
\Bentophytic\b Used of a plant (an entophyte) growing within another plant.
\BEntoprocta\b Small phylum of sessile, solitary or colonial, marine (rarely freshwater) invertebrates typically possessing a cylindrical stalk and rounded calyx bearing a horseshoeshaped ring of ciliated tentacles; gut U-shaped; hermaphroditic, larvae planktotrophic or lecithotrophic; intertidal to 500 m, attached to algae, stones, shells or other surfaces. Relationships remain obscure; sometimes classified as a separate phylum of acoelomates sometimes as a subphylum of the Bryozoa; Endoprocta; Kamptozoa.
\Bentozoic\b Living or passing through the body of an animal.
\Bentrainment\b Coupling or synchronization of a biological rhythm to an external time source.
\Bentropy\b A measure of randomness or disorder in a system.
\Benvironment\b The complex of biotic, climatic, edaphic and other conditions which comprise the immediate habitat of an organism.
\Benzootic\b A disease occurring in a given animal species within a limited geographical area.
\Benzyme\b A protein molecule specialized to catalyse a biological reaction.
\BEoacanthocephala\b Class of thorny-headed worms found as adults mainly in fish hosts, but also in amphibians and reptiles, usually utilizing crustaceans as intermediate hosts; characterised by a retractable proboscis with radially arranged hooks and by the absence of a protonephridial system; comprising 2 orders Gyracanthocephala and Neoechinorhynchida.
\Beobiogenesis\b The transformation of prebiotic macromolecular systems into the first living organisms (eobionts).
\Beobionts\b The earliest living organisms developed from prebiotic macromolecular precursors.
\BEocene\b A geological epoch within the Tertiary period (\Ica.\i 54-38 million years B.P.); see geological time scale.
\BEocrinoidea\b Extinct class of cystoid-like echinoderms (Pelmatozoa) found from the Lower Cambrian to Middle Silurian.
\BEogaea\b A zoogeographical region incorporating Africa, South America and Australasia; See also \JCaenogaea\j
\BEognathostomata\b An assemblage of irregular echinoids containing forms drawn from the orders Holectypoida and Pygasteroida.
\Beolation\b \JAeolation\j
\Beolian\b \JAeolian\j
\Beon\b 1: An indefinitely long period of geological time; aeon. 2: A unit of time equal to 10\U9\u years.
\BEophytic\b The period of geological time during which the Algae were abundant; see also \JAphytic\j \JArchaeophytic\j, \JCaenophytic\j, \JMesophytic, Palaeophytic\j
\Beosere\b A major ecological succession within the climatic climax of a geological period; the ecological succession of vegetation of an era or eon.
\BEozoic\b The Precambrian \Jera\j; sometimes used to refer to the earliest part of the Precambrian only.
\Bepacme\b The period in phylogenetic or ontogenetic development of a group or organism just prior to the point of maximum vigour or adulthood; See also \Jacme\j
\BEpacridaceae\b Family of Ericales containing about 400 species of glabrous shrubs or small trees found mostly in Australia, New Zealand and the East Indies; flowers often fragrant, with usually 5 free sepals, 5 petals joined to form a tube, 5 stamens and a 5-celled ovary.
\Bepedaphic\b Pertaining to climatic factors or conditions.
\Bepeiric sea\b A shallow sea covering part of a continental landmass, typically less than 200 m in depth; sometimes also used to include pericontinental \Jseas\j; epicontinental sea.
\Bephaptomenon\b Organisms which are adnate or attached to a surface; see also \Jplanomenon\j \Jrhizomenon\j
\Bephebic\b Pertaining to the adult stage, between the juvenile and old age; See also \Jneanic\j
\BEphedridae\b Subclass of Gneticae; low evergreen shrubs with slender branches and scale-like leaves; male and female cones in clusters of 2 or 4 at the stem nodes; comprises single family, Ephedraceae, native to arid and desert regions of the Americas and Eurasia.
\Bephemeral\b Lasting for only a day; short-lived or transient, as in an organism that grows, reproduces and dies within a few hours or days, or a flower that lasts for a day or less.
\BEphemerida\b \JEphemeroptera\j
\BEphemeroptera\b Mayflies; order of paleopterous insects comprising about 2000 species in 20 families; adults non-feeding, living from 2 to 72 hours, commonly less than 1 day; mouthparts vestigial, compound eyes often sexually dimorphic (large in males, small in females); forewings triangular, distally fluted; hindwings present or absent, up to half length of forewings; male forelegs modified for grasping female in flight; larvae (nymphs, naiads) aquatic in fresh water, feeding on detritus, diatoms, and microscopic epiphytes, some carnivorous; mayflies unique in having a winged subimago lasting up to 2 days; Ephemerida.
\BEphippidae\b Spadefishes; family containing 15 species of tropical and subtropical reefdwelling perciform teleosts; body deep, compressed, to 1 m length; mouth protrusible; 2 dorsal fins present.
\BEphthianuridae\b Australian chats; family of small, brightly coloured passeriform birds with decurved bills; feed on insects caught on ground; nest in low bushes; sometimes treated as part of family Maluridae.
\BEphydridae\b Brine flies, shore flies; family containing over 1000 species of tiny flies (Diptera) that feed on decaying plant material and faecal matter in aquatic or semiaquatic habitats; larvae inhabit diverse fresh, saline and polluted waters feeding on vegetable matter, microorganisms and insect larvae.
\Bephydrogamous\b Having water-borne pollen grains transported at the water surface; or being pollinated by such pollen; See also \Jhyphydrogamous\j
\Bepibenthic\b Living on the sea bed or on the lake floor; see also \Jendobenthic\j \Jhyperbenthic\j
\Bepibenthos\b The community of organisms living at the surface of the sea bed or lake floor; See also \Jbenthos\j
\Bepibiontic\b Living attached to another organism; \Bepibiotic\b, \Bepibiont.\b
\BEpicaridea\b Suborder of mainly marine isopod crustaceans found exclusively as parasites of other crustaceans; adult female often extremely modified, dwarf male retaining isopod-like form; larvae commonly parasitic on planktonic crustaceans.
\Bepiclysile\b Pertaining to the tide pools of the upper shore.
\Bepicolous\b Living attached to the surface of another organism but without benefit or detriment to the host; \Bepicole.\b
\Bepicontinental sea\b Epeiric \Jsea\j
\Bepidemic\b Used of a disease affecting a high proportion of the population over a wide area; see also \Jepiphytotic\j \Jepizootic\j
\Bepidemiology\b The study of factors affecting the spread of diseases in populations.
\Bepidendric\b Pertaining to epiphytes growing on trees and shrubs.
\Bepifauna\b The total animal life inhabiting a sediment surface or water surface; See also \Jinfauna\j
\Bepigamic\b Used of any character that serves to attract or stimulate individuals of the opposite sex during courtship, other than essential structures and behaviour of copulation; \Bepigamous.\b
\Bepigean\b Living or growing at or above the soil surface.
\Bepigenetic\b Pertaining to the interaction of genetic factors and developmental processes, through which the genotype is expressed in the phenotype.
\Bepigenetics\b The study of the causal mechanisms of development.
\Bepigeotropism\b An orientation response of a plant producing growth across the surface of the soil; \Bepigeotropic.\b
\Bepigyny\b The arrangement of the parts of a flower so that the sepals, petals and stamens are inserted above the ovary (an inferior ovary); see also \Jhypogyny\j \Jperigyny\j
\Bepilimnion\b The warm upper layer of circulating water above the thermocline in a lake; \Bepilimnetic\b; See also \Jhypolimnion\j
\Bepilithic\b Growing on rocks or other hard inorganic substrata; See also \Jendolithic\j
\Bepilithophytic\b Pertaining to a plant growing on the surface of stones, rocks and other hard inorganic substrata: \Bepilithophyte\b; See also \Jendolithophytic\j
\Bepilittoral\b 1: The zone on the seashore above the intertidal zone, which is influenced by the effects of salt spray; spray zone. 2: The zone surrounding a lake, lying above water level and uninfluenced by spray.
\Bepimeletic\b Used of social behaviour patterns in animals relating to the care of other individuals; See also \Jetepimeletic\j
\BEpimorpha\b Subclass of chilopods in which young hatch with full complement of trunk segments and legs, at least 25 segments and 23 pairs of legs; egg clusters brooded by female; comprises 2 orders, Geophilida and Scolopendrida.
\Bepimorphosis\b A form of development in arthropods in which all larval forms are suppressed or passed within the egg prior to hatching and the juvenile hatches with the adult morphology.
\Bepinasty\b Downward curvature of a plant structure due to differential growth of upper and lower surfaces; \Bepinastic.\b
\Bepinekton\b Organisms attached to actively swimming (nektonic) forms but which are incapable of independent movement against water currents; \Bepinektonic.\b
\Bepineuston\b Organisms living in the air on the surface film of a water body; \Bepineustonic\b; See also \Jhyponeuston\j
\Bepipelagic zone\b The upper oceanic zone extending from the surface to about 200 m; see marine depth zones.
\Bepipelic\b Used of those aquatic organisms moving over the sediment surface or living at the sediment/water interface; See also \Jendopelic\j
\Bepiphenomenon\b An event which occurs together with another but which is not causally linked and has no effect upon it.
\Bepiphloedic\b Growing on the surface of bark.
\Bepiphloeophyte\b A plant living on the surface of bark.
\Bepiphyllous\b Used of an epiphyte (an epiphyll) growing on a leaf; See also \Jendophyllous\j
\Bepiphyte\b 1: A plant growing on another plant (the phorophyte) for support or anchorage rather than for water supply or nutrients. 2: Any organism living on the surface of a plant.
\Bepiphytology\b The study of the nature and ecology of plant diseases.
\Bepiphytotic\b Pertaining to an epidemic disease amongst plants; see also \Jepidemic\j \Jepizootic\j
\Bepiplankton\b 1: Planktonic organisms living within the surface 200 m (the epipelagic zone); \Bepiplanktonic\b; See also \Jbathyplankton. 2: Organisms living attached to larger planktonic organisms or to floating objects\j
\Bepipleuston\b Organisms which move over the surface film of a water body with most or all of their bodies above the water; \Bepipleustonic.\b
\BEpipolasida\b Order of demosponges exhibiting a radial structure; appeared first in the Cambrian.
\Bepipsammon\b Organisms living on the surface of a sandy sediment or on the surface of the sand particles; episammic.
\Bepirhizous\b Growing on the surface of roots.
\Bepisematic\b Pertaining to a character that aids in recognition, as in some colour markings; \Bepisematism\b; see also \Jantepisematic\j \Jproepisematic\j, \Jpseudepisematic\j
\Bepitokous\b Reproductive; having or producing offspring; See also \Jatokous\j
\Bepixylic\b Living or growing on wood; \Bepixylous\b; See also \Jendoxylic\j
\Bepizoic\b 1: Living or growing to the body of an animal; used of a non-parasitic animal that lives attached to the outer surface of another animal; \Bepizoite\b, \Bepizoon\b; See also \Jendozoic. 2: Dispersed by attachment to the surface of an animal\j
\Bepizoochorous\b Dispersed by attachment to the surface of animals; \Bepizoochore\b, \Bepizoochory\b; See also \Jendozoochorous\j
\Bepizoon\b An organism living attached to the body of an animal; epizoite.
\Bepizootic\b Pertaining to an epidemic disease in animals; see also \Jepidemic\j \Jepiphytotic\j
\Bepoch\b 1: A major interval of geological time; a subdivision of a period. 2: An event or time which marks the beginning of a new phase of development.
\BEquatorial Current\b A warm surface ocean current that flows westwards in the tropical Pacific Ocean; see ocean currents.
\Bequatorial tide\b The tides that occur at intervals of about 2 weeks when the moon is over the equator.
\BEquidae\b Horses, zebras, asses, donkey; family of large terrestrial mammals (Perissodactyla) comprising 7 species, now cosmopolitan as result of domestication; all are herbivorous, grazing primarily on grasses, living in small to large herds; Przewalski's horse from central Asia is the only extant wild horse; the group also contains the quagga, an extinct wild zebra from southern Africa.
\Bequinoctial\b 1: Used of a plant which has flowers which open and close at particular times during the day; horological.
\Bequinoctial tide\b A tide of high amplitude occurring when the sun is at or near the equinox.
\Bequinox\b Either of the two occasions each year when the sun crosses the equator, producing day and night of equal duration; \Bequinoctial.\b
\BEquisetophyta\b Horsetails, scouring rushes; division of terrestrial plants primarily found in moist muddy habitats; stems creeping underground and producing erect annual or perennial branches; stems hollow and grooved; leaves minute, whorled into sheaths around stem and non-photosynthetic; sporangia borne in terminal cones on stem; homosporous; comprises single order (Equisetales) and genus of about 20 species; also known as Sphenopsida.
\Bera\b Any of the major intervals of geological time; the sequence of eras being Precambrian, Palaeozoic, Mesozoic and Cenozoic; see geological time scale.
\Beremacausis\b The process of humus formation by the oxidation of plant matter.
\Beremic\b Pertaining to deserts or sandy regions.
\Beremobiontic\b Living in desert regions.
\BEremolepidaceae\b Family of Santalales containing 12 species of hemiparasitic shrublets producing thickened haustoria on branches of trees; found in tropical America.
\Beremology\b The study of deserts.
\Beremophilous\b Thriving in desert regions; \Beremophile\b, \Beremophily.\b
\Beremophyte\b A desert plant.
\BErethizontidae\b New World porcupines; family containing 8 species of arboreal hystricomorph rodents found primarily in the northern Neotropical region but also ranging into the Nearctic; body covered with strong barbed spines; habits nocturnal, feeding on leaves, fruit, and a variety of plant material.
\BEretmophoridae\b Cosmopolitan family of little-known deep-water gadiform teleost fishes; 1-3 dorsal and 1-2 anal fins; to 600 mm body length with photophores present in some species; gas bladder with connection to inner ear.
\Berg\b A sandy desert.
\Bergasiaphyte\b A plant introduced by man for cultivation.
\Bergasiapophytic\b Used of plants that colonize cultivated fields.
\Bergatandromorphic\b Used of social insects in which worker and male characters are blended; \Bergatandromorph\b; See also \Jergatogynomorphic\j
\Bergatandrous\b Having worker-like males, as in some social insects; See also \Jergatogynous\j
\Bergatogynomorphic\b Used of social insects in which worker and female characters are blended; \Bergatogynomorph\b; See also \Jergatandromorphic\j
\Bergatogynous\b Having worker-like females, as in some social insects; \Bergatogyne\b; See also \Jergatandrous\j
\Bergatomorphic\b Resembling a worker.
\Bergonomics\b The quantitative study of work, performance and efficiency.
\Bergot\b \JClavicipitales\j
\BEricaceae\b Heath, heather, madrone, mountain laurel, sourwood, rhododendron, azalea, blueberry, cranberry; large family of mostly mycorrhizal shrubs often growing in acid soils; widespread in cool temperate to subtropical regions, containing about 3500 species many of which are cultivated; flower morphology variable but often with a 4- or 5-lobed corolla, 4-5 sepals, 5-10 stamens and an ovary with 2-5 cells.
\BEricales\b Order of Dilleniidae containing about 4000 species of typically mycotrophic, tanniferous plants; leaves often ericoid (small, firm and evergreen); includes 8 families, the largest of which is Ericaceae.
\Bericetal\b Growing on heathland or moorland.
\Berichthus\b Larval stage of stomatopods derived from the earlier antizoea or pseudozoeal larva.
\Bericophyte\b A plant growing on heathland.
\BErinaceidae\b Hedgehogs, moon rats; family containing 14 species of small terrestrial mammals (Insectivora) in which dorsal part of body is covered with long hairs or spines; habits nocturnal or crepuscular, some species hibernate; feed on variety of invertebrates, carrion and fruit; widely distributed in Ethiopian, Palaearctic and Oriental regions.
\BEriocaulales\b Order of Commelinidae comprising a single family of herbs, Eriocaulaceae, growing in wet places mainly in warm regions; having narrow grass-like leaves crowded at base and very small flowers pollinated insects or wind.
\Bermine\b \JMustelidae\j
\Berosion\b Wearing away; weathering; the removal of the land surface by water, ice, wind or other agencies; \Berode.\b
\Berpoglyph\b A fossil worm cast.
\BErrantia\b Errant polychaetes; a group name formerly used for all motile polychaete worms; See also \JSedentaria\j
\Berratic\b 1: Pertaining to unattached organisms that are moved around by physical agencies. 2: A rock fragment transported into an area from outside, found either incorporated into the sediment or lying free; glacial erratic.
\Berucivorous\b Feeding on caterpillars; \Berucivore\b, \Berucivory\b.
\Berumpent\b Protruding or bulging out; breaking or bursting through.
\BErysiphales\b Powdery mildews; order of pyrenomycete fungi found widely through temperate and tropical regions as an external hyaline mycelium growing over the surface of the stems, buds, leaves and fruit of flowering plants; producing small spherical fruiting bodies on the mycelium.
\BErythrinidae\b Trahiras; family containing 5 species of predatory South American freshwater characiform teleost fishes found in stagnant weedy pools; body cylindrical, to 1 m length; teeth large; adipose fin absent; gas bladder functioning as accessory respiratory organ.
\BErythroxylaceae\b Family of Linales containing about 200 species of glabrous trees and shrubs often producing tropane alkaloids (including cocaine); mostly tropical New World distribution; includes Andean species, \IErythroxylum coca\i, from which cocaine is extracted.
\Bescape\b A cultivated plant which has become established in the wild.
\Bescatophyte\b A plant of a climax community.
\BEscherichia\b A genus of rod-shaped enterobacteria comprising one species, \IE. coli\i, found naturally in the gut of mammals and widely studied by biochemists and bacteriologists.
\BEschrichtiidae\b Grey whale; monotypic family of large (up to 15 m) marine mammals (Mysticeta) found in the northern Pacific Ocean; dorsal fin absent; baleen plates short.
\Besculent\b Edible.
\BEsocidae\b Pikes; family containing 5 species of predatory piscivorous freshwater salmoniform teleost fishes found mostly in weedy lakes and ponds; confined to Arctic and temperate parts of the northern hemisphere; body elongate, to 1.6 m length, snout prolonged; prized as sport fishes.
\BEsocoidei\b Suborder of freshwater salmoniform teleost fishes comprising 2 families, Esocidae (pikes) and Umbridae (mudminnows); dorsal and anal fins positioned posteriorly, adipose fin absent.
\Bessential element\b A chemical element which is essential to the life of an organism.
\Bestivation\b \JAestivation\j; \Bestivate\b.
\BEstrildidae\b Waxbills, mannikins; family containing about 125 species of small usually colourful passerine birds found in variety of forest, grassland and open arid habitats of Africa, southern Asia and Australia; bill short, conical; habits gregarious, terrestrial to arboreal, non-migratory; feed on seeds and insects; nest domed, constructed from loose mass of grass in a tree.
\Bestrus\b \JOestrus\j
\Bestuary\b Any semi-enclosed coastal water, open to the sea, having a high freshwater drainage and with marked cyclical fluctuations in salinity; usually the mouth of a river.
\Betaerio\b A cluster of fruits formed from the unfused carpels of a single flower, as in the drupe cluster of a blackberry.
\Betepimeletic\b Used of social behaviour patterns in young animals serving to elicit care from adults; See also \Jepimeletic\j
\BEthiopian region\b A zoogeographical region comprising that part of the African continent south of the Sahara, tropical Arabia, Madagascar and neighbouring islands; subdivided into East African, Malagasy, South African and West African subregions; Madagascar and its neighbouring islands are sometimes excluded and regarded as a separate region; Palaeotropical region.
\Bethnobotany\b Study of the use of plants by the races of man.
\Bethnology\b Study of the character, history and culture of the races of man; ethnography.
\Bethnozoology\b Study of the use of animals and animal products by the races of man.
\Bethological isolation\b The absence of interbreeding between members of different populations because of behavioural differences that preclude effective mating.
\Bethology\b The study of animal behaviour; \Bethological\b.
\Betiolation\b Abnormal growth of a green plant when grown in darkness; such plants are pale yellow due to the absence of chlorophyll and the stems are typically elongate bearing small leaves.
\Betiology\b \JAetiology\j
\BEubacteria\b One of the three primary kingdoms (\Jurkingdoms\j) of living organisms; comprising all typical bacteria; see also \JArchaebacteria\j \JUrkaryota\j
\Beubiosphere\b That part of the biosphere in which the physiological processes of living organisms can occur; comprising the allobiosphere and autobiosphere.
\Beucalyptus\b \JMyrtaceae\j
\BEucarida\b Diverse superorder of eumalacostracan crustaceans comprising about 10 000 species in 3 orders, Amphionidacea, Euphausiacea (krill) and Decapoda (crabs, lobsters and shrimps).
\Beucaryotic\b \JEukaryotic\j; \Beucaryote.\b
\BEucestoda\b Tapeworms; subclass of cestodes containing all the tapeworms of medical and veterinary importance; all are parasites of vertebrates except for a single genus which matures in freshwater oligochaetes; body typically segmented with one or more sets of reproductive organs in each proglottid; 6 hooks present on the first larval stage, the oncosphere.
\BEucoccidiida\b Order of coccidians exhibiting 3 types of multiplication in the life cycle, merogony, gametogony and sporogony; host cells, from both vertebrates and invertebrates, are invaded by sporozoites which are ingested by the host or injected by vectors; includes \IPlasmodium\i, which causes malaria in man.
\BEucommiales\b Order containing a single species of tree native to montane forests of western China; dioecious; producing a milky juice; fruit is a samara.
\BEuconjugatae\b Class of the protoctistan phylum Gamophyta; comprising generally filamentous forms exhibiting true conjugation during which filaments lie side by side and grow conjugation tubes through which the amoeboid male gamete can pass into the female filament.
\BEucryphiaceae\b Small family of Rosales containing 6 species of gum-producing evergreen trees or shrubs native to Australia, Tasmania and Chile; flowers large and white, with 4 sepals and petals, many stamens and winged, fleshy seeds.
\BEucyphidea\b \JCaridea\j
\BEuechinoidea\b Subclass of echinoids (Echinozoa) containing the vast majority of living species and exhibiting great diversity of form; 14 orders recognized in 4 superorders, Diadematacea, Echinacea, Gnathostomata and Atelostomata.
\Beuephemerous\b Used of flowers that have a single opening period; \Beuphemeral.\b
\Beugenics\b The science of breeding; the application of genetic principles to the improvement of the hereditary qualities of a race or breed.
\BEuglenales\b Order of euglenoid flagellates with one emergent and one internal flagellum; including \IEuglena\i.
\BEuglenamorphales\b Order of parasitic euglenoid flagellates infesting the rectum of amphibian tadpoles.
\BEuglenida\b \JEuglenophycota\j treated as an order of the protozoan class Phytomastigophora.
\Beuglenoids\b \JEuglenophycota\j
\BEuglenophycota\b Euglenoids; a division of mostly freshwater flagellates comprising about 1000 species, most of which are unicellular, distributed worldwide; characterized by an anterior locomotory flagellum and a preemergent flagellum associated with the eyespot; most are photosynthetic green algae containing chlorophylls \Ia\i and \Ib\i in their chloroplasts, but many lack chlorophyll and are osmotrophic or phagotrophic; also classified as a phylum of Protoctista under the name Euglenophyta, and as an order of the protozoan class Phytomastigophora, under the name Euglenida.
\BEuglenophyta\b Euglenoids; the \JEuglenophycota\j treated as a phylum of Protoctista.
\BEugregarinida\b Order of parasitic gregarines found mainly in the intestinal tract of annelid and arthropod hosts and which do not reproduce asexually in their hosts by multiple fission but produce gametes or sporozoites.
\Beuhaline\b Living only in saline inland water bodies.
\Beuhydatophyte\b Any fully submerged plant that never produces aerial structures.
\Beuhydrophilous\b Thriving submerged in fresh water; \Beuhydrophile\b, \Beuhydrophily. \b
\BEukaryotae\b Superkingdom of organisms possessing cells with an organized nucleus surrounded by a nuclear envelope, and paired chromosomes containing DNA which are recognizable during mitosis and meiosis; also characterized by elaborate cytoplasmic organelles such as cilia or flagella, the latter exhibiting a universal 9+2 microtubular structure; comprising either 2 kingdoms, Plantae and Animalia, or 4 kingdoms, Protoctista, Fungi, Plantae and Animalia, according to which classification is followed.
\Beukaryotic\b Used of organisms the cells of which have a discrete nucleus separated from the cytoplasm by a membrane, with DNA as the genetic material and with defined cytoplasmic organelles; eucaryotic; \Beukaryote\b; See also \Jprokaryotic\j
\Beulittoral\b 1: The shore zone between the highest and lowest seasonal water levels in a lake; often a zone of disturbance by wave action. 2: The intertidal zone of the seashore; see marine depth zones.
\BEumalacostraca\b The largest subclass of higher crustaceans (Malacostraca) comprising 13 orders grouped into 4 superorders, Peracarida, Eucarida, Syncarida and Pancarida.
\BEumenidae\b Solitary wasps, mason wasps, potter wasps; diverse family containing about 3000 species of wasps (Hymenoptera) which usually construct nests consisting of a few cells in burrows in soil, twigs or wood; each cell is provisioned, predominantly with lepidopteran or beetle larvae, before the egg is laid; adults feed on nectar.
\BEumetazoa\b Metazoans; the subkingdom of animals characterized as being multicellular and at the tissue and organ levels of organization as compared to sponges which are multicellular but at the cellular level of organization; comprising 30 phyla.
\BEumycetozoa\b An archaic term formerly used for both the cellular slime \Jmoulds\j and the plasmodial slime \Jmoulds\j
\BEumycota\b True fungi; a division of the kingdom Plantae; a group of ubiquitous heterotrophic organisms with a thallus either in the form of a mycelium of branched thread-like hyphae, or sometimes unicellular; cell walls usually chitinous, occasionally with cellulose; obtain nourishment as parasites or by secretory enzymes that dissolve insoluble food externally before absorption; store food as glycogen or lipid; comprising five subdivisions based on type of reproduction, Mastigomycotina, Zygomycotina, Ascomycotina, Basidomycotina and Deuteromycotina.
\BEunicida\b Order of errant, pelagic, tubicolous and parasitic polychaete worms comprising about 800 species in 10 families; body length up to 2 m; pharynx eversible with well developed jaws; parapodia distinct; one aberrant group occurs in gill chamber of decapod and isopod crustaceans.
\Beupelagic\b Used of planktonic organisms found only in open oceanic water away from the influence of the sea bed.
\BEuphausiacea\b Krill; order containing 85 species of pelagic shrimp-like eucaridan crustaceans: typically marine oceanic forms often undertaking extensive diurnal vertical migrations and aggregating into vast swarms; filter feeders with exposed gills not covered by carapace; often with photophores.
\Beuphemeral\b Used of flowers that open and close within a single day.
\Beuphilous\b Used of a plant or flower that has morphological adaptations for attracting and guiding a specialized pollinator; \Beuphile\b, \Beuphily\b; See also \Jallophilous\j
\BEuphorbiaceae\b Euphorbia, castor bean, poinsettia, croton; family containing about 7500 species of generally woody, sometimes succulent or herbaceous plants, often with a milky or coloured latex and characterized by features of the female organs; seeds usually oily and often poisonous; includes many economically important species such as the sources of Para rubber, castor oil and cassava.
\BEuphorbiales\b Order of Rosidae containing 4 families of woody or sometimes herbaceous plants often producing alkaloids and milky or coloured juice; dominated by the very large family Euphorbiaceae.
\Beuphotic zone\b The surface zone in the sea or large lake with sufficient light penetration for net photosynthesis to occur; see also \Jdysphotic zone\j \Jphotic zone\j
\Beuphototropism\b Orientation response of plant structures to maximize incident illumination; \Beuphototropic.\b
\Beuploid\b A polyploid with an exact multiple of the basic chromosome number; \Beuploidy\b; See also \Janeuploid\j
\BEupomatiaceae\b A distinctive family of primitive flowering plants (Magnoliales) comprising a single genus of small trees or herbs confined to New Guinea and eastern Australia; flowers typically large, lacking both sepals and petals, and possessing laminar stamens.
\Beupotamic\b Pertaining to an aquatic organism thriving in both flowing and standing fresh water; see also \Jautopotamic\j \Jtychopotamic\j
\BEupteleaceae\b Family containing two species of deciduous shrubs or small trees possessing small wind-pollinated flowers lacking sepals and petals; native to Japan, China and Assam.
\BEupteriomorphia\b A superorder of Pteriomorphian bivalves comprising the Pterioida (pearl oysters), Limoida (file shells) and Ostreoida (oysters and scallops).
\BEuramerica\b A continental landmass comprising Europe and North America formed from \JEurasia\j after the break up of Pangaea; see also \JAngara\j \JCathaysia\j
\BEurasia\b The northern supercontinent formed by the break up of Pangaea in the Mesozoic (\Ic.\i 150 million years B.P.), comprising North America, Greenland, Europe and Asia, excluding India; Laurasia; See also \JGondwana\j
\Beuroky\b The ability to tolerate a wide range of environmental conditions.
\BEurotiales\b Heterogeneous order of plectomycete fungi occurring in a wide variety of habitats including soil, dung and organic debris; includes numerous forms of economic importance, in causing food spoilage (\IAspergillus\i), in antibiotic production (\IPenicillium\i), for contaminating jet aircraft fuel tanks (\IHormoconis resinae\i) and in causing diseases of trees (Dutch elm disease).
\Beurotophilous\b Thriving in or on leaf mould; \Beurotophile\b, \Beurotophily.\b
\BEuryapsida\b Extinct group of reptiles characterized by a single upper temporal opening behind the eye; includes the plesiosaurs, nothosaurs and placodonts; known from the Permian through to the end of the Mesozoic.
\Beurybaric\b Tolerant of a wide range of atmospheric or hydrostatic pressure; See also \Jstenobathic\j
\Beurybathic\b Tolerant of a wide range of depth; See also \Jstenobathic\j
\Beurybenthic\b Living on the sea or lake bed over a wide range of depth; See also \Jstenobenthic\j
\Beurybiontic\b Used of an organism tolerating a wide range of a particular environmental factor; See also \Jstenobiontic\j
\Beurychoric\b Widely distributed; \Beurychorous\b; See also \Jstenochoric\j
\Beuryhaline\b Used of organisms that are tolerant of a wide range of salinity; see also \Jholeuryhaline\j \Joligohaline\j, \Jpolystenohaline\j, \Jstenohaline\j
\Beuryhydric\b Tolerant of a wide range of moisture levels or humidity; See also \Jstenohydric\j
\Beuryhygric\b Tolerant of a wide range of atmospheric humidity; See also \Jstenohygric\j
\Beuryionic\b Having or tolerating a wide range of pH; See also \Jstenoionic\j
\BEurylaimidae\b Broadbills; small family containing about 15 species of passerine birds found in the Old World tropical forests of Africa and Asia; head large, bill broad, flattened and hooked; feed on variety of insects, small vertebrates or fruit; nest typically long and pendulous, positioned over water.
\Beurylumic\b Tolerant of a wide range of light intensity; See also \Jstenolumic\j
\Beuryoecious\b Tolerant of a wide range of habitats and environmental conditions; see also \Jamphioecious\j \Jstenoecious\j
\Beuryphagous\b Utilizing or tolerant of a wide variety of foods or food species; \Beuryphage\b, \Beuryphagy\b; See also \Jstenophagous\j
\BEurypharyngidae\b Monotypic family of bizarre deep-water anguilliform teleost fishes (gulpereels), widespread in temperate seas and locally quite numerous; body elongate, mouth enormous, teeth small; tail tapering.
\Beuryphotic\b Tolerant of a wide range of light intensity; See also \Jstenophotic\j
\BEurypterida\b Water scorpions; extinct group of merostomes, often of large size; body length up to 3 m; known from the Ordovician to the end of the Palaeozoic.
\BEurypygidae\b Sunbittern; monotypic family of heron-like gruiform birds found in wooded stream and pond habitats of the Neotropical region; bill, neck and legs long; wings broad; habits solitary, monogamous; feed on aquatic arthropods and nest in trees.
\Beurythermic\b Tolerant of a wide range of temperatures; \Beurytherm\b, \Beurythermous\b; See also \Jstenothermic\j
\Beurythermophilic\b Tolerant of a wide range of relatively high temperatures; \Beurythermophile\b; See also \Jstenothermophilic\j
\Beurytopic\b 1: Tolerant of a wide range of habitats; physiologically tolerant; \Beurytopy\b. 2: Having a wide geographical distribution; see also \Jamphitopic\j \Jstenotopic\j
\Beurytropic\b Used of organisms exhibiting a marked response or adaptation to changing environmental conditions; \Beurytropism\b; See also \Jstenotropic\j
\Beuryxenous\b Used of a parasite that tolerates a wide range of host species; See also \Jstenoxenous\j
\Beusexual\b Used of organisms that display a regular alternation of karyogamy and meiosis; See also \Jparasexual\j
\Beusocial\b Used of a social group in which members are fully integrated and cooperate in caring for young, with non-reproductive individuals assisting those involved in producing offspring, and in which different generations contributing to colony labour overlap; See also \Jpresocial\j
\Beuspory\b The formation of spores by normal meiotic divisions; \Beusporic.\b
\Beustatic\b Pertaining to worldwide changes in sea level, such as would be produced by melting of continental glaciers, but excluding relative changes in level resulting from local coastal subsidence or elevation.
\BEustigmatida\b \JEustigmatophyceae\j treated as an order of the protozoan class Phytomastigophora.
\BEustigmatophyceae\b Small class of aquatic, unicellular chromophycote algae characterized by their flagellate zoospores which have a large extraplastidial eyespot and a single yellowish green chloroplast containing chlorophylls \Ia\i, \Ic\i\I\D1\d\i, \Ic\i\I\D2\d\i and \Ie\i; also classified as a separate phylum of Protoctista under the name Eustigmatophyta, and as an order of the protozoan class Phytomastigophora.
\BEustigmatophyta\b The \JEustigmatophyceae\j treated as a phylum of Protoctista.
\BEusuchia\b Sole extant suborder of Crocodylia.
\BEutaeniophoridae\b Tapetail; family containing 3 species of pelagic lampridiform teleost fishes widespread in tropical seas; body elongate, to 70 mm length, naked; dorsal and anal fins close to caudal, pelvics fan-like; caudal fin prolonged as ribbon-like filament.
\BEutardigrada\b Order of freshwater and terrestrial (rarely marine) tardigrades comprising about 200 species; head without appendages or cirri; legs bearing compound claws.
\Beutelegenesis\b The improvement of breeding stock by artificial insemination.
\BEutheria\b Placentals; infraclass of live-bearing (viviparous) mammals (Theria) in which embryos are nourished by a placenta; uteri separate or fused, vagina single.
\Beutraphent\b Used of an aquatic plant typical of water bodies with high nutrient concentrations; see also \Jmesotraphent\j \Joligotraphent\j
\BEutremellales\b Jelly fungi; order of phragmobasidiomycete fungi in which the fruiting body has a gelatinous texture when wet; some species are edible; some are saprobic on wood, others are parasitic.
\BEutreptiales\b Order of euglenoid flagellates with both flagella emergent.
\Beutric\b Pertaining to healthy or fertile soils; See also \Jdystric\j
\Beutrophic\b 1: Having high primary productivity; pertaining to waters rich in the mineral nutrients required by green plants. 2: Used of a lake in which the hypolimnion becomes depleted of oxygen during the summer by the decay of organic matter sinking from the epilimnion; see also \Jdystrophic\j \Jmesotrophic\j, \Joligotrophic\j
\Beutrophication\b Over-enrichment of a water body with nutrients, resulting in excessive growth of organisms and depletion of oxygen concentration.
\Beutrophy\b The pollination of particular kinds of flowers only by certain specialized insects.
\Beutropism\b The orientation of growth in a plant so that it twines in a direction that follows the passage of the sun across the sky; \Beutropic\b; See also \Jantitropism\j
\Beutropous\b Used of specialized insect species adapted to feed on particular kinds of flowers; See also \Jallotropous\j
\Bevanescent\b Transient; quickly fading.
\Bevaporation\b Loss of moisture in the form of water vapour.
\Bevapotranspiration\b The actual total loss of water by evaporation from soil and from water bodies, and transpiration from vegetation, over a given area with time.
\Bevening primrose\b \JOnagraceae\j
\Bevergreen\b A plant, typically a tree or shrub, that has leaves all year round, and sheds them more or less regularly through all seasons.
\BEvermannellidae\b Sabretooths; family containing 6 species of small (to 150 mm) pelagic myctophiform teleost fishes; body compressed, naked, skeleton fragile; head and jaws large, teeth fang-like; eyes telescopic in some forms; photophores absent.
\Bevolution\b 1: Any gradual directional change; unfolding. 2: Any cumulative change in the characteristics of organisms or populations from generation to generation.
\Bevolutionary biology\b The integrated science of evolution, ecology, behaviour and systematics.
\Bevolutionary tree\b A branching diagram in the form of a tree representing inferred lines of descent; phylogenetic tree.
\Bevolve\b To change, produce or emit; to undergo gradual directional change; \Bevolution.\b
\Bexa (E)\b Prefix, used to denote unit x 10\U18\u; see metric prefixes.
\Bexaration\b Erosion by the action of ice.
\Bexcitability\b Sensitivity; the capacity of a living organism to respond to a stimulus.
\Bexclusive economic zone (EEZ)\b The 200 mile wide marine zone under the jurisdiction of the coastal state.
\Bexcreta\b That part of the energy assimilated by an organism that is removed from the body as secretion, excretion or exudation.
\Bexcretion\b The process of eliminating waste material from the body; \Bexcretory\b; See also \Jsecretion\j
\Bexendotrophic\b Used of a flower pollinated by pollen from another flower of the same or different plant.
\BExobasidiales\b Small order of parasitic hymenomycete fungi containing 20 species found on stems, leaves and buds of host plants; producing an intracellular or intercellular mycelium which can induce gall formation.
\Bexobiotic\b Living on the outer surface of another organism or on the surface of the substrate; \Bexobiont.\b
\BExocoetidae\b Flying fishes; family of surfaceliving marine beloniform teleost fishes widespread in open oceanic waters; body elongate, to 450 mm length, subcylindrical; mouth small, teeth reduced or absent; pectoral and pelvic fins markedly enlarged, caudal deeply forked; contains 50 species, well known for ability to jump out of water and glide considerable distances on the expansive paired fins.
\Bexogamy\b 1: Outbreeding; sexual reproduction between individuals that are not closely related. 2: Pollination of a flower by pollen from a flower on a different plant; cross pollination; See also \Jendogamy\j
\Bexogenous\b Originating from outside the organism or system; due to, or triggered by, external environmental factors; See also \Jendogenous\j
\Bexolithophytic\b Pertaining to plants that grow on the surface of rock or other hard inorganic substrata; \Bexolithophyte\b; See also \Jendolithophytic\j
\BExoporia\b Suborder of lepidopteran insects comprising about 520 species, the vast majority of which are in one family, Hepialidae (ghost or swift moths); adult with small or much reduced proboscis; larvae typically burrowing into plant stems and roots.
\Bexorheic region\b An area in which rivers arise and from which they flow to the sea; see also \Jarheic region\j \Jendorheic region\j
\Bexotic\b Not native; alien; foreign; an organism or species that has been introduced into an area.
\Bexotropism\b An orientation movement of lateral organs away from the main axis; \Bexotropic.\b
\Bexovation\b The act or process of hatching.
\Bexpanding Earth hypothesis\b That the Earth has increased its volume and hence crustal surface area as a result of global expansion from about 80% of the present dimensions during the last 180-200 million years.
\Bexpatriate\b An individual carried out of its normal range to another area in which it can survive but is unable to reproduce.
\Bexpression\b The manifestation of a character or trait; \Bexpressivity.\b
\Bexsiccate\b To dry up; to remove moisture; \Bexsiccation.\b
\Bexsiccation\b Desertification; the development of desert conditions as a result of human activity or of climatic changes.
\Bextant\b Existing or living at the present time; See also \Jextinct\j
\Bextinct\b No longer in existence; no longer living; See also \Jextant\j
\Bextinction\b The disappearance of a species or taxon from a given habitat or biota.
\Bextirpate\b To remove surgically; to destroy totally; to pull up by the roots; \Bextirpation.\b
\Bextraneous\b Existing or originating outside the habitat, community or system.
\Bextrinsic\b Existing or having its origins outside an individual, group or system.
\Bextrorse dehiscence\b Spontaneous opening of ripe fruit from the inside outwards; See also \Jintrorse dehiscence\j
\Bexudativorous\b Feeding on gum and other exudates from trees; \Bexudativore\b, \Bexudativory.\b
\Bexude\b To ooze out, or diffuse out; \Bexudate\b, \Bexudation.\b
\Bexuvium\b The cast exoskeleton left by an arthropod after moulting.
\BFabaceae\b Pea, bean, soybean, peanut, lupin, lentil, wisteria, luburnum, gorse broom, sweet pea, alfalfa, clover, vetch; large family of over 10 000 species widespread in cold temperate and tropical regions containing many species of agricultural importance; typically leguminous forms with root nodules containing nitrogen-fixing bacteria and legume seed pods; characterized by butterfly-like (papilionaceous) flowers in which 1 petal is large and erect at the back of the bloom, 2 lateral petals form the wings and the other 2 petals are joined along their lower margins forming a keel; formerly known as the subfamily Papilionoideae of the family Leguminosae.
\BFabales\b Legumes, Leguminosae; large order of Rosidae containing about 14 000 species in 3 widely distributed families; herbs, shrubs, trees or vines often with root nodules containing nitrogen-fixing bacteria, the fruit a typical dry legume, usually dehiscent along both sutures; includes the families Caesalpiniaceae, Fabaceae and Mimosaceae which were formerly treated as subfamilies of the family Leguminosae.
\BFacetotecta\b A group of barnacle-like crustaceans known only from their larval stages; also known as y-nauplius, y-cyprid.
\Bfacies\b The general appearance or aspect of an individual, population or community; also the general aspect or appearance of sedimentary rocks or fossils.
\Bfacilitation\b Enhancement of the behaviour or performance of an organism by the presence or actions of others.
\Bfacultative\b Contingent; assuming a particular role or mode of life but not restricted to that condition; used of organisms having the facility to live, or living, under atypical conditions; See also \Jobligate\j
\Bfacultative anaerobe\b An organism that normally grows anaerobically but which is able to grow under aerobic conditions.
\Bfacultative parthenogenesis\b The process by which some eggs develop parthenogenetically if not fertilized.
\Bfaeces\b Excrement; waste material voided through the anus; \Bfeces\b, \Bfaecal.\b
\BFagaceae\b Beech, chestnut, oak; large family of trees or shrubs with small flowers usually arranged in catkins and wind-pollinated; fruit usually a nut.
\BFagales\b Order of Hamamelidae containing 3 families of strongly tanniferous trees and shrubs with inconspicuous flowers often arranged in catkins.
\BFahrenheit scale (\b░\BF)\b A scale of temperature that has the freezing point of water at 32░and the boiling point of water at 212░.
\Bfairy fly\b \JMymaridae\j
\Bfairy shrimp\b \JAnostraca\j
\BFalconidae\b Falcons; cosmopolitan family containing about 60 species of small to medium-sized raptors (Falconiformes); wings usually long and slender, flight rapid; capture prey using powerful feet; one group (caracaras) long-legged, cursorial, feeding on carrion; habits solitary, monogamous, nesting in trees, cliffs or on the ground.
\BFalconiformes\b Birds of prey; diverse order of small to large diurnal raptors, typically with powerful clawed feet and strong hooked bill; contains about 285 species in 5 families, including vultures, hawks, eagles, falcons, osprey, secretary bird.
\BFalkland Current\b A cold surface ocean current that flows northwards off the east coast of Argentina, originating in part as a northerly deflection from the Antarctic Circumpolar Current; see ocean currents.
\Bfall wind\b A strong cold wind descending from an elevated plateau or glacier.
\Bfalse cat shark\b \JPseudotriakidae\j
\Bfalse conch\b \JNeogastropoda\j
\Bfalse fruit\b \JPseudocarp\j
\Bfalse moray eel\b \JXenocongridae\j
\Bfalse scorpion\b \JPseudoscorpiones\j
\Bfalse toadflax\b \JSantalaceae\j
\Bfalse vampire\b \JMegadermatidae\j
\Bfamily\b 1: A group comprising parents, offspring and others closely related or associated with them. 2: A category comprising one or more genera or tribes of common evolutionary origin, more or less separated from other such groups by a marked gap; a rank within the hierarchy of taxonomic classification.
\Bfamily tree\b A diagrammatic representation of the lineage of a family or group.
\Bfan palm\b \JCyclanthales\j
\Bfangtooth\b \JAnoplogastridae\j
\Bfanworm\b \JSabellida\j
\Bfar red light\b Solar \Jradiation\j in the spectral range 700-800 nm.
\Bfarinaceous\b Containing or comprising flour; starchy.
\Bfat\b A triacylglycerol that is solid at room temperature.
\Bfauna\b 1: The entire animal life of a given region, habitat or geological stratum; \Bfaunal\b, \Bfaunistic.\b 2: A faunal work; See also \Jflora\j
\Bfaunal province\b A zoogeographical subregion containing a distinct fauna which is more or less isolated from other regions by barriers to migration.
\Bfaunation\b The assemblage of animal species in a particular area; See also \Jvegetation\j
\Bfaunistics\b The study of all or part of the animal species of a particular locality or region.
\Bfaunula\b The animal population of a small geographical area or microhabitat.
\Bfecundity\b The potential reproductive capacity of an organism or population, measured by the number of gametes or asexual propagules; See also \Jfertility\j
\Bfeedback\b Those elements of a control system or homeostatic mechanism linked by reciprocal influences, such that the source or input is continuously modified by the product of the process in order to maintain the necessary degree of constancy; a feedback loop may be negative and have a stablizing or inhibitory effect or positive and have a disruptive or facilitative effect.
\BFelidae\b Cats; cosmopolitan family containing about 35 species of small to large carnivorous mammals including the cheetah, cougar (puma), ocelot, lynx, bobcat, lion, tiger, leopard, and jaguar; most are terrestrial and arboreal.
\Bfell\b A bare rocky hillside or mountain slope.
\Bfell-field\b A type of tundra ecosystem having sparse dwarfed vegetation and flat, very stony soil.
\BFeloidea\b Superfamily of carnivorous mammals comprising the cats (Felidae), mongooses (Viverridae) and hyenas (Hyaenidae).
\Bfemale\b The egg-producing form of a bisexual or dioecious organism; symbolized by $$$ See also \Jmale\j
\Bfemto- (f)\b Prefix used to denote unit x 10\U-15\u; see metric prefixes.
\Bfen\b A eutrophic mire, with a winter water table at ground level or above, usually dominated by herbaceous grasses.
\Bfennel\b \JApiaceae\j
\BFerae\b Superorder of placental mammals (Ferungulata) represented by the order Carnivora but also containing the extinct order Creodonta.
\Bferal\b Used of a plant or animal that has reverted to the wild from a state of cultivation or domestication.
\Bfermentation\b The enzymatically controlled anaerobic breakdown of organic substrates.
\Bfern\b \JFilicophyta\j
\Bferret\b \JMustelidae\j
\Bfertile\b Producing or having the capacity to produce offspring, fruit, pollen or abundant growth.
\Bfertility\b The actual reproductive performance of an organism or population, measured as the actual number of viable offspring produced per unit time; birth rate; See also \Jfecundity\j
\Bfertilization\b The union of a male and a female gamete to form a zygote, but sometimes used more generally for the act of insemination, impregnation or pollination.
\BFerungulata\b Diverse group of placental mammals comprising the Artiodactyla, Perissodactyla, Carnivora and the primitive ungulates; sometimes classified as a cohort of the Eutheria, sometimes regarded as an artificial assemblage of unrelated forms.
\BFeyliniidae\b Family containing 4 species of limbless lizards (Sauria); body cylindrical; head flattened with tiny eyes under transparent scales; feed mainly on termites.
\Bfidelity\b The degree of restriction of a plant species to a particular situation, community or association; assessed according to a five point scale: 5, exclusive; 4, selective; 3, preferential; 2, indifferent; 1, strange.
\Bfield capacity\b The amount of water retained by a previously saturated soil when free drainage has ceased; see also \Jchresard\j \Jechard\j, \Jholard\j
\Bfield layer\b The horizontal vegetation stratum in woodland comprising all herbaceous plants, mosses and lichens, as well as woody plants not more than 500 mm in height.
\Bfig\b \JMoraceae\j
\Bfig marigold\b \JAizoaceae\j
\Bfig shell\b \JMesogastropoda\j
\Bfig wasp\b \JAgaonidae\j (Apocrita).
\Bfile shell\b \JLimoida\j
\Bfilefish\b \JBalistidae\j
\BFilicales\b Largest order of ferns (Filicopsida), containing an estimated 9000 species; producing only one kind of spore (homosporous); gametophytes green, free-living and usually heart-shaped.
\BFilicophyta\b Ferns; division of vascular plants which reproduce by spores produced in sporangia borne on the leaves, usually in clusters (sori); stems mostly creeping, sometimes erect or trunk-like, leaves with branching veins, roots wiry to fleshy; gametophytes free-living, green prothalli bearing sex organs on lower surface; contains between 12 000 and 15 000 species classified in 3 subdivisions, Filicopsida, Ophioglossopsida and Marattiopsida; formerly known as Pteridophyta.
\BFilicopsida\b Subdivision of ferns (Filicophyta); characterized by specialized sporangia having thin walls and opening by means of a patch or annulus of thickened cells; fronds unroll circinately; comprises 3 orders, Filicales, Marsileales and Salviniales.
\BFilosa\b Class of rhizopod protozoans; amoeboid organisms with filose pseudopodia which are often branching but not reticulate; comprises 2 orders, Aconchulinida and Testaceafilosida.
\BFilospermoidea\b One of 2 orders of gnathostomulids found especially in marine sands of the North Sea; characterized by a filiform sperm and by the absence of a female bursa-vagina system and of paired sensory organs from the rostrum.
\Bfilter feeder\b Any animal that feeds by filtering suspended particulate organic matter from water.
\Bfimbricolous\b Growing in or on dung; \Bfimbricole.\b
\Bfimetarious\b Pertaining to dung; \Bfimetarius.\b
\Bfimicolous\b Growing in or on dung; \Bfimicole.\b
\Bfire climax\b A more or less stable plant community, the structure and composition of which is dependent on regular burning.
\Bfire coral\b \JMilleporina\j
\Bfirebrat\b \JThysanura\j
\Bfirefly\b \JLampyridae\j
\Bfirewheel tree\b \JProteaceae\j
\Bfireworm\b \JAmphinomida\j
\Bfirnification\b The process by which newly fallen snow becomes granular and compacted; \Bfirn.\b
\Bfishes\b A loose assemblage of cold-blooded limbless vertebrates possessing fins and a series of gills either side of the pharynx; typically with scales and paired pectoral and pelvic fins; once accorded the status of a class (Pisces).
\Bfish louse\b \JBranchiura\j
\BFissiculata\b Extinct order of blastoid echinoderms known from the Silurian to the Permian.
\BFissidentales\b Cosmopolitan order of small mosses (Bryidae) commonly found in moist tropical and subtropical forests; leaves distinctive, divided into dorsal and ventral lamina.
\Bfission\b Asexual reproduction or division by splitting into two (binary fission) or more (multiple fission) parts.
\Bfissiparous\b Used of organisms that reproduce by division of the body into two or more equal parts.
\BFissipedia\b Suborder of placental carnivores comprising the Canoidea, Feloidea and Miacidae.
\BFistulariidae\b Cornetfishes, flutemouths; family of tropical shallow marine gasterosteiform teleost fishes containing 4 species, found on reefs and sea grass beds; body very slender, depressed, naked, to 2 m length; snout tubular; dorsal fin without spines, caudal bearing 1 or 2 elongate fin rays.
\Bfitness\b A measure of the contribution of a given genotype to the next generation relative to that of other genotypes.
\Bfjord\b A deep narrow inlet of the sea between steep slopes or mountains; fiord.
\BFlabellifera\b Suborder of free-living and parasitic isopod crustaceans widespread in marine, brackish and freshwater habitats; body typically flattened, the limbs simple or prehensile, and the uropods forming a tail fan with the pleotelson; includes the wood-boring gribble that may cause extensive damage to boat hulls and submerged timbers.
\BFlabelligerida\b Order of sluggish deposit feeding polychaete worms, comprising about 160 species in 3 families; found burrowing in soft sediments from littoral to abyssal depths; body long and papillose, prostomium reduced and fused to peristomium; pharynx non-eversible, unarmed; parapodia biramous.
\BFlabellina\b A suborder of \JAmoebida\j; also treated as a class of the protoctistan phylum Rhizopoda.
\BFlacourtiaceae\b Azaras, fried egg tree; large family of Violales containing about 800 species of often cyanogenic trees and shrubs found mostly in tropical regions; characterized by generally alternate, leathery leaves and by flowers with 2-15 sepals, 0-15 petals, many stamens and a superior ovary.
\BFlagellariaceae\b Family of glabrous, solid-stemmed, cyanogenic herbs tending to accumulate silica, with alternate leaves well distributed along the stem and small trimerous flowers; producing seeds with mealy endosperm containing starch grains; native to the tropical regions of the Old World.
\Bflark\b A local wet area of sparse, weakly peat-forming fen vegetation interspersed with drier areas or features.
\Bflash colour\b The bright contrasting colour located on concealed surfaces of some animals; thought to attract attention when presented to a predator, thus promoting concealment of the animal when the colour is suddenly withdrawn.
\Bflatfish\b \JPleuronectiformes\j
\Bflathead\b \JPlatycephalidae\j
\Bflatworm\b \JPlatyhelminthes\j
\BF-layer\b Fermentation layer; the upper or humus layer of a soil profile, exhibiting initial stages of plant decomposition; see soil horizons.
\Bflea\b \JSiphonaptera\j
\Bflesh fly\b \JSarcophagidae\j
\Bflocculation\b The aggregation of fine particles in the dispersed phase of a colloid.
\Bfloccule\b An aggregation of microorganisms or particles in a liquid; \Bflocculate.\b
\Bflood current\b The tidal current associated with an incoming or flood tide; See also \Jebb current\j
\Bflood plain\b The area of lowland along a water course that is subject to periodic flooding and sediment deposition.
\Bflood tide\b Incoming tide; See also \Jebb tide\j
\Bflora\b 1: A floral work; a published work describing the plant life of an area. 2: The plant life of a given region, habitat or geological stratum; \Bfloral\b, \Bfloristic\b; See also \Jfauna\j
\BFlorida Current\b A warm surface ocean current derived from the Caribbean current system, that sweeps past Florida from the Gulf of Mexico and flows northeastwards into the Atlantic; see ocean currents.
\BFlorideae\b The \JFlorideophycideae\j treated as a class of the phylum Rhodophyta.
\BFlorideophycideae\b Subclass of red algae with thalli that are obviously filamentous or pseudoparenchymatous and in which cell division is mostly restricted to apical cells of constituent filaments; gametangia well differentiated; contains 6 orders, Nemaliales, Cryptonemiales, Gigartinales, Rhodymeniales, Palmariales and Ceramiales; also treated as a class of the phylum Rhodophyta, under the name Florideae.
\Bfloristics\b The study of species composition of vegetation, or of the plant species of a particular locality or region.
\Bflorology\b The study of the production and development of plant communities.
\Bflorula\b 1: The plant species of a small area; a local flora. 2: An assemblage of plant fossils from a single stratum or group of adjacent strata; the floral assemblage of a small zone.
\BFlosculariaceae\b Small, diverse order of rotifers containing free-swimming planktonic and sessile forms; characterized by a circumapical girdle on the corona, divided into trochal and cingular parts, and by the lack of toes on the foot.
\Bflounder\b \JPleuronectidae\j
\Bflower\b The specialized structure in flowering plants (Magnoliophyta) concerned with sexual reproduction; typically with the female organs (gynoecium) in the centre, surrounded by the male organs (androecium), petals (corolla) and sepals (calyx).
\Bflowering\b The maturation of the floral organs and the expansion of their envelopes; florification.
\Bflowering plant\b \JMagnoliophyta\j
\Bflowering rush\b \JButomaceae\j
\Bflowerpecker\b \JDicaeidae\j
\Bfluke\b \JDigenea\j
\Bflumineous\b Pertaining to running water.
\Bflush\b An explosive increase in the size of a population; See also \Jcrash\j
\Bflushing\b The deposition of dissolved substances in the upper layers of a soil profile by the action of water; See also \Jleaching\j
\Bflutemouth\b \JFistulariidae\j
\Bfluvial\b Pertaining to rivers and river action.
\Bfluviatile\b Inhabiting rivers and streams; fluvial.
\Bfluvioglacial\b Pertaining to streams flowing from a glacier, or to deposits laid down from glacial streams; glaciofluvial.
\Bfluviology\b The study of rivers.
\Bfluviomarine\b Inhabiting rivers and the sea.
\Bfluvioterrestrial\b Inhabiting streams and the surrounding land.
\Bfluviraption\b Erosion by running water or wave action.
\Bfollicle\b A dry dehiscent fruit developed from a single carpel and containing many seeds; splits along one suture only to release seeds on ripening.
\Bfontaneous\b Pertaining to a freshwater spring.
\Bfood chain\b A sequence of organisms on successive levels within a community, through which energy is transferred by feeding; energy enters the food chain during fixation by primary producers (mainly green plants) and passes to the herbivores (primary consumers) and then to the carnivores (secondary and tertiary consumers).
\Bfood chain efficiency\b The efficiency of transfer of energy from one level to the next in a food chain.
\Bfood pyramid\b A graphical representation of the food relationships of a community, expressed quantitatively as numbers, mass or total energy at each trophic level, with the producers forming the base of the pyramid and successive levels representing consumers of higher trophic levels.
\Bfood web\b The network of interconnected food chains of a community.
\Bfootballfish\b \JHimantolophidae\j
\Bforage\b 1: To search for food; \Bforaging.\b 2: The plant material actually consumed by a grazing animal; See also \Jherbage\j
\Bforaminiferal ooze\b Pelagic calcareous sediment comprising more than 30% calcium carbonate predominantly in the form of foraminiferal tests; See also \Jooze\j
\BForaminiferida\b Foraminiferans; order of rhizopod protozoans which are predominantly marine in distribution; possessing a mineralized, agglutinated or organic shell or test which encloses the amoeboid body; tests varied in form, often with chambers; a pseudopodial net is usually formed through one or more openings in the test and is used in locomotion and in feeding; includes a large number of fossil taxa; also treated as a distinct phylum of Protoctista.
\Bforb\b A broad-leaved herbaceous plant.
\Bforbicolous\b Living on broad-leaved plants; herbicolous; \Bforbicole.\b
\Bforbivorous\b Feeding on broad-leaved plants; \Bforbivore\b, \Bforbivory.\b
\BForcipulata\b Large order of intertidal to deepsea asteroidean echinoderms comprising 4 extant families and including many of the most familiar species of sea stars; typically with 5 arms but may be up to 50, arms rounded in cross-section, pedicellariae pincer-like, tube feet with suckers; largest species may exceed 1 m in diameter and a weight of over 10 kg.
\Bforedune\b A dune ridge, more or less stabilized by plant colonization.
\Bforeshore\b 1: The zone between mean high water and mean low water on a beach; also used of the upper intertidal zone that is covered only by exceptional spring tides. 2: The strip of land forming the margin of a lake.
\Bforest\b A relatively large area of closely canopied trees; a small stand of trees may be termed a grove.
\BForficulidae\b Large family of earwigs (Dermaptera) including the common European earwig.
\Bforget-me-not\b \JBoraginaceae\j
\Bform\b 1: The essential shape and structure of an organism or group. 2: Any minor variant or recognizable subset of a population or species; morph.
\BFormicariidae\b Antbirds; family containing about 240 species of small Neotropical passerine forest birds; habits solitary, nonmigratory; feed on insects, some species following armies of ants to catch flushed insects; nest in tree or on ground; bill usually strong and hooked, wings short and rounded, flight weak.
\BFormicidae\b Ants; family of small aculeate Hymenoptera all of which form perennial societies founded in nests made in rotten wood, crevices, plant cavities or in soil; nest contains one or more fertile, egg-laying queens, hundreds to millions of neuter workers, and seasonally produced fertile males (drones) which fertilize queens during mass nuptial flights; feed as predators of arthropods, as scavengers, or on nectar and honeydew; contains about 14 000 species.
\Bforsythia\b \JOleaceae\j
\Bfossil\b An organism, fragment, impression or trace of an organism preserved in a rock; may be either a body fossil (such as a bone or shell) or a trace fossil (such as a burrow, track or imprint); See also \Jrecent\j
\Bfossil fuel\b A fuel, such as coal, petroleum and natural gas, derived from the fossilized remains of organisms.
\Bfossiliferous\b Used of a rock, sediment or horizon containing fossils.
\Bfossorial\b Adapted for digging or burrowing.
\Bfouling\b An assemblage of organisms growing on the surface of floating or submerged man-made objects, that increases resistance to water flow or otherwise interferes with the desired operation of the structure.
\BFouquieriaceae\b Ocotillo; small family of Violales containing 11 species of woody or fleshy succulent shrubs found in desert regions from Mexico to southwestern United States.
\Bfour-eyed fish\b \JAnablepidae\j
\Bfox\b \JCanidae\j
\Bfoxglove\b \JScrophulariaceae\j
\Bfractured zone\b In geology, a zone along which displacement has occured; major fractures are found at right angles to the mid-oceanic ridges.
\BFrankeniaceae\b Small family of Violales containing about 50 species of halophytic herbs or shrubs commonly with salt-excreting glands on the leaves; best developed in the Mediterranean region and Middle East.
\BFrankfurt glaciation\b A subdivision of the Weichselian \Jglaciation\j
\Bfrass\b Faecal matter and other fine animal debris found on the soil surface.
\Bfraternal twins\b \JDizygotic\j twins.
\Bfree-living\b Living independently of any host organism.
\Bfreemartin\b A sterile female twin, partially converted towards a hermaphrodite condition by some influence of its male twin.
\Bfressia\b \JIridaceae\j
\Bfree-tailed bat\b \JMolossidae\j
\Bfreeze drying\b A method of preserving biological material by dehydration from the frozen state under high vacuum.
\BFregatidae\b Frigate birds; small family containing 5 species of tropical sea birds (Pelecaniformes) with long slender wings and long pointed tail; feed on fishes and squid caught in strong hooked bill during flight; frigate birds do not land on water; breed in colonies along coast, nesting in bushes with single egg per clutch.
\BFrenulata\b Class of pogonophoran marine worms possessing a bridle on the mesosoma; contains nearly 100 species in 2 orders, Athecanephria and Thecanephria.
\Bfresh water\b Water having 2 parts per thousand, or less, of dissolved salts.
\Bfried egg tree\b \JFlacourtiaceae\j
\Bfrigate bird\b \JFregatidae\j
\Bfright cry\b The sudden loud call made by a startled animal; distress call.
\Bfrigid climate\b A climate in which a permanently frozen soil surface is covered more or less continuously with ice and snow; polar climate.
\Bfrigid zone\b That part of the Earth's surface within the polar circles.
\Bfrigideserta\b Tundra; the open communities of cold arctic or alpine regions.
\Bfrigofugous\b Intolerant of cold conditions; \Bfrigofuge\b.
\Bfrigophilic\b Thriving in cold environments; \Bfrigophile\b, \Bfrigophily.\b
\Bfrilled shark\b \JChlamydoselachidae\j
\Bfringe tree\b \JOleaceae\j
\BFringillidae\b Finches; cosmopolitan family containing about 120 species of small to medium-sized passerine birds found in variety of forest, woodland and open habitats; bill short, conical, robust; habits solitary to gregarious, arboreal to terrestrial, many species migratory; feed mainly on seeds, flowers and buds; cup-shaped nest placed on or off the ground.
\Bfrit fly\b \JChloropidae\j
\Bfritillary\b \JNymphalidae\j
\Bfrog\b \JAnura\j
\Bfrog shell\b \JMesogastropoda\j
\Bfrogfish\b \JAntennariidae\j
\Bfroghopper\b \JCercopidae\j (Homoptera).
\Bfrogmouth\b \JPodargidae\j
\Bfront\b The boundary zone between two air or water masses differing in properties, such as density, pressure, temperature or salinity.
\Bfrontal-cyclonic rain\b Rainfall produced by major cyclonic eddies and discontinuities; of particular significance in the equatorial rain belt and in temperate maritime regions; see also \Jconvective rain\j \Jorographic rain\j
\Bfructicolous\b Living on or in fruits; \Bfructicole.\b
\Bfructification\b Any spore-bearing or seed-bearing structure, such as the aerial fruiting body of a fungus.
\Bfrugivorous\b Feeding on fruit; \Bfrugivore\b, \Bfrugivory\b.
\Bfruit\b The structure that is formed from the ovary wall in flowering plants as the enclosed seed or seeds mature.
\Bfruticolous\b Living or growing on shrubs; \Bfruticole.\b
\BFucales\b Wracks; order of brown algae having a parenchymatous body form in which apical growth occurs; often with vesicles in the thallus for buoyancy; gametophyte generation reduced, or represented only by gametes; includes \ISargassum\i weed.
\Bfuchsia\b \JOnagraceae\j
\Bfucivorous\b Feeding on seaweed; \Bfucivore\b, \Bfucivory.\b
\Bfugacious\b Evanescent; lasting for a short time; falling early from the parent plant.
\Bfugitive species\b A species which is always excluded locally under interspecific competition, but which persists in newly disturbed habitats by virtue of its high dispersal ability.
\Bfulmar\b \JProcellariidae\j
\BFumariaceae\b Dicentras; family of Papaverales containing about 400 species of herbs, generally with secretory cells but lacking latex; flowers irregular, typically with 2 sepals, 2-4 petals, 6 stamens and a superior ovary; widely distributed in northern temperate regions but also in South Africa.
\BFunariales\b Cosmopolitan order of mosses (Bryidae); small annual or ephemeral plants growing on disturbed soils, usually with erect stems bearing terminal sporophytes; leaves with single costa (longitudinal rib).
\Bfunctional morphology\b Interpretation of the function of an organism or organ system by reference to its shape, form and structure.
\Bfundamental niche\b The entire multidimensional space that represents the total range of conditions within which an organism can function and which it could occupy in the absence of competitors or other interacting species; See also \Jrealized niche\j
\Bfungi\b An assemblage of ubiquitous heterotrophic, non-vascular organisms either with a thallus in the form of a mycelium of branched thread-like hyphae, or unicellular, and which obtain nourishment either saprophytically by secreting enzymes to dissolve insoluble organic food externally before absorption, or as parasites; cell walls are usually chitinous, occasionally with cellulose; classified either as a division, the \JEumycota\j, \Jof the kingdom Plantae or as a kingdom, the \JFungi\j
\BFungi\b The fungi treated as a separate kingdom of eukaryotic organisms and characterized by their lack of flagella at all stages of the life cycle; the \JMastigomycotina\j are classified in the phylum Protoctista under this scheme: comprises 4 phyla, Zygomycota, Ascomycota, Basidiomycota and Deuteromycota.
\BFungi Imperfecti\b \JDeuteromycotina\j
\Bfungicide\b A chemical used to kill or control fungi.
\Bfungicolous\b Living in or on fungi; \Bfungicole.\b
\Bfungistasis\b Inhibition of fungal growth.
\Bfungivorous\b Feeding on fungi; \Bfungivore\b, \Bfungivory.\b
\Bfungus gnat\b \JMycetophilidae\j
\Bfur seal\b \JOtariidae\j
\Bfurcilia\b Late zoeal larval stage of euphausiacean crustaceans.
\Bfuriotile lake\b Any partially disjunct body of water, that connects with the main stream only during high water.
\BFuripteridae\b Thumbless bats; small family of bats (Chiroptera), found in tropical America, in which the first digit is reduced.
\BFurnariidae\b Ovenbirds; diverse family containing about 220 species of small to medium-sized Neotropical passerine birds that construct a large domed nest of mud and sticks variously placed on the ground, in a tree, or in a hole or burrow; habits solitary or gregarious, arboreal or terrestrial; feeding mostly on insects and other invertebrates.
\Bfurniture beetle\b \JAnobiidae\j
\BGadidae\b Cods; family of primarily northern hemisphere predatory gadiform teleost fishes of outstanding commercial importance; body length to 1.8 m, 1-3 dorsal and 1-2 anal fins present, pelvics jugular; gas bladder lacking connection to inner ear; contains about 55 species, all but one marine, most abundant in Atlantic Ocean.
\BGadiformes\b Order of primarily marine teleost fishes comprising about 500 species in 11 families, including cods, hakes, rattails, eelpouts, pearlfishes and cusk eels; body usually cod-like, lacking fin spines; barbels present; swim bladder typically without connection to inner ear.
\BGadilida\b Order of scaphopod molluscs characterized by a typically smooth shell and by the position of the radula in the anterior third of the animal.
\BGaian hypothesis\b That the development of living organisms on a planet brings about major modifications in the chemical and physical conditions on the planet and that subsequently the organisms themselves mediate the climate and major biogeochemical cycles.
\BGalagidae\b Galagos, bushbaby; family containing 7 species of small agile African arboreal prosimians; hindlimbs longer than forelimbs, used for leaping among the branches; ears large, tail elongate; feed on variety of small animals and plant material; sometimes included in the Lorisidae.
\BGalaxiidae\b Jollytails; family containing 45 species of southern hemisphere freshwater or anadromous salmoniform teleost fishes from Australia, southern Africa and South America; body slender to stout, to 700 mm in length; scales and adipose fin absent.
\BGalbulidae\b Jacamars; family of small insectivorous Neotropical forest birds (Piciformes) with long straight bill used to catch insects on the wing; habits solitary, monogamous, non-migratory; nesting in holes in bank; contains about 15 species distributed from Mexico to Brazil.
\BGaleomorphii\b Large superorder of small (250 mm) to large (12 m) neoselachian elasmobranch fishes; body mostly subcylindrical; usually 2 dorsal, anal and caudal fins present, and 5 pairs of gill openings; the dominant group of living sharks containing about 250 species in 4 orders, Heterodontiformes (bullhead sharks), Orectolobiformes (carpet sharks), Lamniformes (mackerel and thresher sharks), and Carcharhiniformes (requiem sharks).
\BGaleropygoida\b Extinct order of irregular echinoids with a small central peristome lacking gill slits; known only from the Jurassic.
\Bgall\b Swelling or abnormal growth in plants typically produced in response to microbial or fungal infection, or to attack by insects, mites and other invertebrates.
\Bgall midge\b \JCecidomyiidae\j; gall gnat.
\Bgall wasp\b \JCynipidae\j (Apocrita).
\Bgallery forest\b A narrow strip of forest along the margins of a river in an otherwise unwooded landscape.
\Bgallicolous\b Living in galls; \Bgallicole.\b
\BGalliformes\b Order of primarily terrestrial gallinaceous (fowl-like) birds comprising 6 families and including turkeys, chickens, grouse, pheasants, peafowl and guinea fowl; wings short for brief explosive flight, bill short for pecking seeds, insects and plant material; some species important as game and domesticated birds.
\Bgallinule\b \JRallidae\j
\Bgalliphagous\b Feeding on galls; \Bgalliphage\b, \Bgalliphagy.\b
\Bgallivorous\b Feeding on galls; \Bgallivore\b, \Bgallivory.\b
\Bgalvanotaxis\b A directed reaction of a motile organism to an electric current; \Bgalvanotactic.\b
\Bgalvanotropism\b An orientation response to an electric current; \Bgalvanotropic.\b
\Bgamete\b A mature reproductive cell (usually haploid) which fuses with another gamete of the opposite sex, to form a zygote (usually diploid); the male gametes are known as sperms (spermatozoa) and the female gametes as eggs (ova); See also \Jagamete\j
\Bgametic number\b The number of chromosomes in the nucleus of a gamete, usually half the somatic chromosome number.
\Bgametogamy\b The fusion of a male and female gamete to form a zygote; \Bgametogamic. \b
\Bgametogenesis\b The process of gamete production; \Bgametogenetic.\b
\Bgametophyte\b The haploid sexual phase of a plant which produces gametes usually by mitotic division; the haploid gametophyte is typically formed by meiotic division of a diploid sporophyte; haplophyte.
\Bgametropism\b Orientation movements of plant structures immediately before or after fertilization; \Bgametropic.\b
\Bgamic\b Fertilized.
\BGammaridea\b Largest of the 4 suborders of amphipods (Crustacea), comprising about 4500 species, widespread in marine, brackish, freshwater and occasionally terrestrial habitats, and having diverse morphology and habits, but excluding parasitism.
\Bgamodeme\b An assemblage of individuals forming a relatively isolated naturally interbreeding population; See also \Jdeme\j
\Bgamogenetic\b Pertaining to the formation of gametes; produced by the union of gametes; used of reproduction by the union of gametes; sexual; \Bgamogenesis.\b
\Bgamogony\b Formation of gametes by sporogony.
\Bgamone\b A substance released by one gamete and serving to attract another.
\Bgamophase\b The haploid phase of a life cycle; See also \Jzygophase\j
\BGamophyta\b Phylum of Protoctista comprising the conjugating green algae; possess chlorophylls \Ia\i and \Ib\i in complex chloroplasts, usually aligned down the long axis of the cell; flagellated stages absent; reproducing asexually by fission of vegetative cells, and sexually by the production of amoeboid gametes that fuse to form a zygote; comprises 2 classes, Desmidoideae and Euconjugatae; See also \JZygnematales\j
\Bgamosematic\b Pertaining to coloration, markings or behaviour patterns that assist members of a pair to locate each other.
\Bgamotropic\b Used of flowers that alternate between open and fully closed; see also \Jagamotropic\j \Jhemigamotropic\j
\Bgamotropism\b An orientation response of gametes to one another; the mutual attraction of gametes; \Bgamotropic.\b
\BGaneshida\b Small order of pelagic ctenophores occurring in the waters of southeastern Asia in which the body is compressed in the tentacular plane but not expanded into oral lobes.
\Bgannet\b \JSulidae\j
\Bgar\b \JLepisosteidae\j
\Bgarden four-o'clock\b \JNyctaginaceae\j
\Bgarden snail\b \JStylommatophora\j
\Bgardenia\b \JRubiaceae\j
\Bgarfish\b \JBelonidae\j
\BGarryaceae\b Small family of Cornales containing 14 species of dioecious evergreen trees and shrubs with small wind-pollinated flowers arranged in unisexual catkins; native to North America and the Greater Antilles.
\Bgasoplankton\b Planktonic organisms which make use of gas-filled vesicles or sacs for buoyancy.
\BGasteromycetes\b Cosmopolitan class of basidiomycotine fungi in which the basidia and basidiospores mature within the fruiting body; contains over 700 mostly terrestrial and saprobic species in 11 orders, Protogastrales, Hymenogastrales, Podaxales, Gauteriales, Agaricogastrales, Melanogastrales, Phallales, Lycoperdales, Tulostomatales, Sclerodermatales and Nidulariales.
\BGasteropelecidae\b Hatchetfishes; family of tiny (to 70 mm) surface-living, insectivorous, South and Central American freshwater characiform teleost fishes; body deep and strongly compressed, pectoral fins long and broad; containing 7 species, popular amongst aquarists; these fishes are capable of true flight by flapping expanded pectoral fins.
\BGasterophilidae\b Horse botflies; family containing about 45 species of flies (Diptera) in which the larvae are parasitic in the gut of ungulates, in particular horses, elephants and rhinos.
\BGasterosteidae\b Sticklebacks; family containing 8 species of gasterosteiform teleost fishes; body naked or with armour of bony plates, length to 200 mm; dorsal fin with 3-16 strong isolated spines; upper jaw protractile; mostly freshwater but including some marine or anadromous species; males exhibit nest building and territorial behaviour.
\BGasterosteiformes\b Order of mostly small to medium-sized, marine, brackish and freshwater teleost fishes comprising about 220 species in 11 families; characterized by small mouth on prolonged tubular snout; body usually armoured with dermal plates, caudal fin rounded, pelvics abdominal; including sand eels, tubesnouts, sticklebacks, sea moths, snipefishes, pipefishes, seahorses, shrimpfishes, trumpetfishes and cornetfishes.
\BGastraxonacea\b Small order of colonial octocorals known only from shallow coastal waters off southeastern Australia; possessing a single axial polyp giving rise indirectly to lateral polyps towards the apex.
\BGastromyzontidae\b \JHomalopteridae\j
\BGastropoda\b Snails; a large class of aquatic, terrestrial or parasitic molluscs comprising nearly 35 000 species; characterized by a body which has primitively undergone torsion so that the anus opens above the head; body consisting of head, foot and visceral mass covered, at least in part, by a single-valved calcareous shell which is typically spirally coiled; mouth cavity containing a radula comprising backwardly directed teeth arranged in rows; may have separate sexes or be hermaphroditic; contains 3 subclasses, Prosobranchia, Opisthobranchia and Pulmonata.
\BGastrotricha\b Phylum of small, aquatic metazoans found interstitially in loose sediments, on the surface of compacted sediments and as episymbionts on floating vegetation and benthic organisms; characterized by the presence of a true cuticle secreted by the epidermis and lining the foregut and hindgut as well as covering the body, and by oblique, longitudinal and circular muscles, a terminal mouth, a triradiate pharynx, subterminal anus and solenocytic protonephridia (excretory organs); typically hermaphroditic but usually with cross fertilization involving internal fertilization; comprises 2 orders, Chaetonotida and Macrodasyida.
\Bgastrozooid\b A feeding polyp in colonial cnidarians.
\BGauteriales\b Order of gasteromycete fungi comprising about 20 species occurring as saprophytes on forest soil; produce subglobular or kidney-shaped underground fruiting bodies.
\BGavialidae\b Gavial, gharial; family of crocodilians containing the Indian gharial, found in the Ganges, Indus and Brahmaputra river systems; snout long and narrow, teeth all similar; feed on fish; commonly included in the family Crocodylidae.
\BGaviidae\b Divers, loons; family containing 4 species of specialized aquatic birds; legs located posteriorly for efficient swimming and diving, but locomotion on land clumsy; sexes similar; feed mostly on fishes; breed on freshwater lakes and ponds of northern Holarctic, overwintering along the coast.
\BGaviiformes\b Order of neognathous birds comprising a single family Gaviidae (divers)
\Bgazelle\b \JBovidae\j
\Bgecko\b \JGekkonidae\j
\Bgeese\b \JAnatidae\j
\BGeissolomataceae\b Family of Celastrales containing a single species of xeromorphic evergreen shrub native to Cape Province of South Africa.
\Bgeitonogamy\b Fertilization between different flowers on the same plant; \Bgeitonogamic\b; See also \Jxenogamy\j
\BGekkonidae\b Geckos; diverse family containing about 730 species of arboreal and terrestrial lizards (Sauria); body often depressed with delicate granular skin, but may be rounded or compressed bearing tubercles or plate-like scales: tail usually autotomic, prehensile in some species; habits mostly nocturnal, insectivorous; reproduction oviparous.
\Bgeld\b The removal of, or interference with the activity of, the testes of a male; emasculation; See also \Jspay\j
\Bgelicolous\b Living in geloid soils having a crystalloid content of between 0.2 and 0.5 parts per thousand; \Bgelicole\b; see also \Jhalicolous\j \Jpergelicolous\j, \Jperhalicolous\j
\Bgeloid soil\b Soil type characterized by low salt content, weak solutions, strong colloidal properties and a crystalloid content of less than 0.5 parts per thousand; See also \Jhaloid soil\j
\Bgemma\b A bud or outgrowth capable of developing into an independent organism.
\Bgemmation\b A type of vegetative reproduction found in some mosses and liverworts in which a specialized group of cells (a gemma) capable of independent development is produced; usually referred to in animals as budding.
\Bgemmule\b Internal bud formed during asexual reproduction in sponges.
\BGempylidae\b Snake mackerels; family containing 20 species of scombroid teleost fishes (Perciformes) found mostly in moderately deep waters (to 1200 m); body tuna-like, length to 1.8m, jaw teeth very large; dorsal and anal fins with finlets, pelvics small or absent; feed on squid, crustaceans and other fishes.
\Bgene\b The basic unit of inheritance, comprising a specific sequence of nucleotides on a DNA molecule that has a specific function and occupies a specific locus on a chromosome; alternative forms of a gene are known as alleles.
\Bgene flow\b The exchange of genetic factors within and between populations by interbreeding or migration.
\Bgene frequency\b The proportion of one allele to the total of all alleles at the same locus in the gene pool.
\Bgene locus\b The position of a gene on a chromosome.
\Bgene mutation\b A point mutation; any heritable change in a single gene.
\Bgene pool\b 1: The total genetic material of a freely interbreeding population at a given time. 2: All the genes at a given locus in a population in a given generation.
\Bgenealogy\b 1: The study of ancestral relationships and lineages. 2: An ancestor-descendant lineage.
\Bgenecology\b The study of intraspecific variation and genetic composition in relation to environment.
\Bgeneration\b 1: Formation; production. 2: All the individuals produced within a single life cycle.
\Bgeneration time\b 1: The average duration of a life cycle between birth and reproduction. 2: The mean period of time between reproduction of the parent generation and reproduction of the following generation.
\Bgenerative parthenogenesis\b The development of a haploid organism from a female gamete that has undergone a meiotic reduction division but has not been fertilized.
\Bgenesiology\b The study of reproduction; \Bgenesiological.\b
\Bgenet\b 1: A unit or group derived by asexual reproduction from a single original zygote, such as a seeding or a clone; see also \Jortet\j \Jramet. 2: \JViverridae\\j
\Bgenetic\b Pertaining to the genes.
\Bgenetic code\b The biochemical basis of heredity; the sequence of nucleotide base pairs on the DNA polynucleotide chain which encodes the genetic information; within the code 3 successive nucleotide base pairs (a codon) code for a single amino acid.
\Bgenetic drift\b The occurrence of random changes in the gene frequencies of small isolated populations, not due to selection, mutation or immigration.
\Bgenetic engineering\b Experimental alteration of the genetic constitution of an individual.
\Bgenetic system\b The organization of the genetic material and the reproductive strategy of a species.
\Bgenetics\b The science of heredity and variation.
\Bgenodeme\b A local interbreeding population characterized by genotypic features; See also \Jdeme\j
\Bgenome\b The minimum set of non-homologous chromosomes required for the proper functioning of a cell; the basic (monoploid) set of chromosomes of a particular species; the gametic chromosome number.
\Bgenopathic disease\b A disease resulting from a genetic condition; congenital disease.
\Bgenotype\b The hereditary or genetic constitution of an individual; the genetic material of a cell, usually referring only to the nuclear material; See also \Jphenotype\j
\Bgentian\b \JGentianaceae\j
\BGentianaceae\b Cosmopolitan family containing about 1000 species of often mycorrhizal herbs, commonly accumulating iridoid compounds; flowers regular and perfect with 4-5 sepals, 4-5 petals in the form of a bell or funnel, 4 or 5 stamens, a superior ovary and, commonly, a capsule fruit with many small seeds.
\BGentianales\b Order of Asteridae containing about 5500 species of plants commonly producing iridoid compounds or alkaloids; of the 6 families, the Apocynaceae and Asclepiadaceae are the largest; Contortae.
\Bgenus\b A category in biological classification comprising one or more phylogenetically related and morphologically similar species, forming the principal category between family and species; \Bgenera.\b
\Bgeoaesthesia\b The capacity of a plant to perceive and respond to gravity.
\Bgeobenthos\b 1: The sum total of all terrestrial life. 2: That part of the bottom of a stream or lake not covered by vegetation; See also \Jphytobenthos\j
\Bgeobiology\b The study of the biosphere.
\Bgeobiont\b An organism spending its whole life in the soil; \Bgeobiontic.\b
\Bgeobios\b The total life of the land; that part of the Earth's surface occupied by terrestrial organisms; \Bgeobiontic\b; see also \Jhalobios\j \Jhydrobios\j, \Jlimnobios\j
\Bgeobotany\b Plant biogeography; the study of plants in relation to geography and ecology.
\Bgeocarpy\b Ripening of fruits underground.
\Bgeochronology\b The science of dating and the study of time in relation to the Earth history as revealed by geological data.
\Bgeocolous\b Living in the soil for part of the life cycle; \Bgeocole.\b
\Bgeocryptophyte\b A plant having perennating organs or renewal buds below the soil surface.
\Bgeodiatropism\b Orientation at right angles to gravity; \Bgeodiatropic.\b
\Bgeodyte\b A ground-living organism.
\Bgeographical race\b A race which is geographically separated from other populations of the same species.
\Bgeographical variation\b Any differences between spatially separated populations of a species.
\Bgeology\b Study of the structure, processes and chronology of the Earth.
\BGeometridae\b Carpet moths, loopers, inch worms; large cosmopolitan family of small to large moths (Lepidoptera) comprising over 20 000 species including many serious pests of trees and shrubs such as the cankerworm and winter moth; caterpillar larvae often resemble twigs and move with a characteristic looping locomotion.
\BGeomyidae\b Pocket gophers; family containing about 40 species of small New World fossorial mammals (Rodentia) that derive their name from the cheek pouches that open to the outside near the mouth; legs short and strong with large claws for digging; feed primarily on tubers and roots.
\Bgeonastic\b Growth curvature towards the ground; \Bgeonasty.\b
\Bgeonyctitropism\b Orientation movements in plants during darkness in response to gravity; \Bgeonyctitropic.\b
\Bgeoparallotropism\b An orientation movement of an organ or structure to bring it parallel to the soil surface; \Bgeoparallotropic.\b
\Bgeoperception\b The capacity of an organism to perceive and respond to gravity.
\Bgeophagous\b Feeding on soil; deriving nutrients from soil or the sediment; \Bgeophage\b, \Bgeophagy.\b
\BGeophilida\b Diverse order containing about 650 species of small to large (to 200 mm) epimorphan chilopods found mainly in soil and forest litter; some species inhabit intertidal zone; ocelli absent; trunk elongate, slender,composed of at least 33 segments, legs short and small; genital apparatus exposed.
\BGeophilomorpha\b \JGeophilida\j
\Bgeophilous\b 1: Thriving or growing in soil; \Bgeophile\b, \Bgeophily\b. 2: Used of plants that fruit below the soil surface.
\Bgeophyte\b A perennial plant having perennating organs or renewal buds, such as corms or rhizomes, buried well below the soil surface; See also \JRaunkiaerian life forms\j
\Bgeoplagiotropism\b Orientation at an oblique angle to the soil surface; \Bgeoplagiotropic.\b
\Bgeosere\b The series of climax formations in an area throughout geological time.
\BGeosiridaceae\b Family of Orchidales comprising a single species of small, mycotrophic herbs lacking chlorophyll and with alternate, reduced scale-like leaves; native to Madagascar and other Indian Ocean islands.
\Bgeotaxis\b A directed response of a motile organism towards (positive) or away from (negative) the direction of gravity; \Bgeotactic.\b
\Bgeothermal\b Pertaining to heat derived from the Earth's interior.
\Bgeotropism\b An orientation response to gravity; \Bgeotropic.\b
\BGeotrupidae\b Dung beetles; family containing about 300 species of robust, dark coloured, shiny beetles (Coleoptera); eggs laid in tunnels beneath dung which is carried down into tunnel to feed larvae.
\Bgeoxene\b An organism that becomes a temporary member of the soil fauna.
\BGeraniaceae\b Geranium, pelargonium, cranesbill; family containing about 700 species of herbs and shrubs often producing aromatic oils in glandular hairs; widespread in temperate and warm temperate regions; flowers variable but commonly with 5 sepals and petals, 5, 10 or 15 stamens and a superior ovary bearing a simple style with 5 stigmas.
\BGeraniales\b Order of Rosidae containing 5 families of mostly herbs or sometimes shrubs, some producing mustard oils; including the large families Geraniaceae and Oxalidaceae.
\Bgeranium\b \JGeraniaceae\j
\Bgeratology\b The study of decline and senescence of populations.
\Bgerbil\b \JCricetidae\j
\Bgerm cell\b A \Jgamete\j or an \Jagamete\j
\Bgerm line\b The lineage of generative cells that give rise to the gametes.
\Bgerminal\b Pertaining to, or influencing, the germ cells.
\Bgermination\b The commencement of growth of a propagule or bud.
\Bgermule\b A unit of colonization or migration.
\Bgerontic\b Pertaining to the later stage of phylogeny or ontogeny.
\BGerreidae\b Mojarras; family containing 40 species of bottom-living coastal marine teleost fishes (Perciformes) widespread in warm seas, and often found in mangrove habitats; body compressed, to 400 mm length, snout pointed, jaws highly protrusible; single dorsal fin present.
\BGerridae\b Pond skaters; family of aquatic hemipteran insects, comprising about 450 species, typically found swimming actively on the surface of flowing as well as static water; legs and body are water-repellent and the insects are supported by surface tension.
\BGesneriaceae\b African violet, gloxinia, hot water plant; family of Scrophulariales containing about 2500 species of mostly herbs, often with unequal cotyledons; widespread in tropical regions; flowers usually bisexual and irregular, with 5 sepals and a tubular corolla with 5 lobes, 2, 4 or 5 stamens and normally a superior ovary.
\Bgestation\b The period of development of an embryo within the uterus of a viviparous animal, from conception to birth; \Bgestate.\b
\Bgharial\b \JGavialidae\j
\BG-horizon\b A gley horizon.
\Bghost flathead\b \JHoplichthyidae\j
\Bghost moth\b \JHepialidae\j
\Bgiant clam\b \JVeneroida\j
\Bgiant panda\b \JAiluropodidae\j
\Bgibberellin\b A type of growth substance produced in plants which is capable of affecting growth or development.
\BGibberichthyidae\b Family of small (to 120 mm) mesopelagic beryciform teleost fishes comprising a single genus and 2 species; head cavernous, teeth setiform; dorsal and anal fins preceded by series of strong spines, caudal bearing 5-7 procurrent spines; juvenile (kasidoron stage) with characteristic elongate pelvic appendage.
\Bgibbon\b \JHylobatidae\j
\Bgiga- (G)\b Prefix used to denote unit x 10\U9\u; see metric prefixes.
\BGigantactinidae\b Family containing 18 species of piscivorous deep-sea anglerfishes (Lophiiformes); body elongate, slender, to 400 mm length, lure whip-like; males free-living, lacking teeth.
\Bgigantism\b The condition of being much larger than normal, or of exhibiting excessive growth; often associated with polyploidy; See also \Jnanism\j
\BGigantorhynchida\b Order of archiacanthocephalan thorny-headed worms found as parasites of birds and mammals and utilizing insects as intermediate hosts; characterized by a proboscis shaped like a truncated cone, which bears rooted hooks anteriorly and rootless spines basally, and by the absence of protonephridial glands (excretory organs).
\BGiganturidae\b Family containing 5 species of deep-sea salmoniform teleost fishes; body naked, silvery, to 150 mm in length; eyes large and tubular, pectoral fins fan-like; pelvic fins and girdle, and several other bony structures absent.
\BGiganturoidei\b Monofamilial suborder of deep-sea salmoniform teleost fishes with silvery bodies and large tubular eyes.
\BGigartinales\b Large order of red algae of variable body form, including crustose, discoid, erect and frondose forms.
\Bgila monster\b \JHelodermatidae\j
\Bginger\b \JZingiberaceae\j
\BGinglymostomatidae\b Nurse sharks; circumtropical family containing 4 species of small to large (to 4 m) orectolobiform elasmobranch fishes (carpet sharks) found in shallow continental coastal waters; feed on crustaceans, cephalopods and small fishes; occasionally offensive to man.
\BGinkgoatae\b Ginkgo, maidenhair tree; large fossil class containing a single extant species native to China but now widely cultivated; tall resiniferous trees with deciduous fan-shaped leaves borne in clusters on spur shoots; male strobili clustered on axillary spur shoots, female structure stalked with 2 apical ovules.
\Bginseng\b \JAraliaceae\j
\BGipping glaciation\b Wolstonian \Jglaciation\j
\BGiraffidae\b Giraffe, okapi; family of herbivorous ungulates (Artiodactyla: Ruminantia) comprising 2 genera and species confined to the Ethiopian region; limbs and neck elongate; stump-like horns present; the giraffe inhabits open savannah, forming small herds; the okapi is solitary in tropical forests of Congo.
\BGirellidae\b Family containing 15 species of coastal marine perciform teleost fishes found in the Pacific and eastern Atlantic Oceans; body deep, compressed, to 500 mm in length; feed mainly on algae and eel grass.
\Bglacial\b Pertaining to those geological intervals characterized by cold climate conditions and advancing ice sheets and caps; \Bglaciation.\b
\Bglacial marine deposit\b A marine sediment having a significant terrigenous component derived from transportation by icebergs.
\Bglacial relict\b A species that has survived from Pleistocene faunas and floras, typically in a restricted location or habitat (a Pleistocene \Jrefuge\j).
\Bglaciofluvial\b Used of sediments transported by ice and deposited from the meltwaters of a glacier.
\Bgladiolus\b \JIridaceae\j
\Bglareal\b Growing on dry exposed and typically gravelly ground; \Bglareous.\b
\BGlareolidae\b Pratincoles; family containing 16 species of tern-like charadriiform shore birds found in dry sandy and stony habitats, from the Mediterranean through southern Asia to Australia.
\Bglass sponge\b \JHexactinellida\j
\BGlaucosomatidae\b \JGlaucosomidae\j
\BGlaucosomidae\b Pearl perches; family of western Pacific marine teleost fishes (Perciformes) comprising a single genus and 5 species typically found on deep offshore reefs; body stout, deep, with large head and mouth; length to 600 mm; some members important as game and food-fishes.
\Bgley\b A soil type which is subject to periodic waterlogging because of a poorly permeable C-horizon.
\Bgley horizon\b A soil horizon characterized by the deposition of iron and manganese compounds; G-horizon.
\Bgleying\b In waterlogged soils, the removal of iron and manganese compounds from anaerobic surface layers of a soil to deeper layers where they are precipitated under oxidizing conditions; upper layers tend to be dull grey, deeper layers intensely mottled.
\BGlires\b Cohort of placental mammals comprising the rodents and the lagomorphs; possess incisors that continue to grow throughout life and are worn away by gnawing.
\BGliridae\b Dormice; family containing about 20 species of small arboreal nocturnal myomorph rodents found in the western Palaearctic and Ethiopian regions; feed mostly on fruit, seeds and insects; many hibernate during winter.
\Bglobigerina ooze\b A pelagic sediment found over extensive regions of the ocean floor, comprising more than 30% calcium carbonate in the form of foraminiferan tests of which \IGlobigerina\i is the dominant genus; See also \Jooze\j
\BGlobulariaceae\b Family of Scrophulariales containing about 300 species of heath-like herbs and shrubs producing iridoid compounds, native to Africa and western Eurasia; flowers often with a 5-lobed corolla tube, 4 stamens and a superior ovary.
\Bglochidium\b Bivalved veliger larva of fresh water mussels (Unionoida) specialized for parasitic attachment to the body surface or gills of fishes.
\BGloeodiniales\b Order of freshwater dinoflagellates containing a single species which occurs epiphytically in peat bog habitats.
\BGloger's rule\b The generalization that among warm-blooded animals those races living in warm and humid areas are more heavily pigmented than those in cool dry areas; pigments are typically black in warm humid environments, red and yellow in dry areas, and generally reduced in cool areas.
\BGlomerida\b Order of stout-bodied oniscomorphan diplopods (millipedes) containing about 200 species, widespread in the northern hemisphere.
\BGlomeridesmida\b Order of small blind tropical diplopods (millipedes) comprising about 30 species in a single family; body 22-segmented, non-conglobating; both sexes with 36 pairs of legs, the last pair in the male modified as telopods for clasping; gut simple and straight.
\BGlossinidae\b Tsetse flies; small family containing about 20 species of biting flies found in tropical Africa; adults feed on the blood of vertebrates and are of primary medical and veterinary importance as vectors of sleeping sickness and nagana.
\Bglow worm\b \JLampyridae\j
\Bgloxinia\b \JGesneriaceae\j
\Bglycogen\b A polysaccharide used for food storage, found in animals, some fungi, bacteria and blue-green algae.
\Bglycophyte\b A plant thriving in a soil of low salt concentration, typically less than 0.5% sodium chloride; See also \Jhalophyte\j
\BGlyptodontidae\b Extinct family of large armadillo-like mammals found in the New World from the Eocene to the Pleistocene.
\Bgnat\b \JNematocera\j
\Bgnatcatcher\b \JPolioptilidae\j
\BGnathiidea\b Suborder of isopod crustaceans in which the adults are non-feeding benthic forms and the juveniles (praniza larvae) are parasitic.
\BGnathobdellida\b Order of mainly parasitic or carnivorous leech-like worms (Hirudinea) possessing 3 pairs of jaws and a pharynx.
\BGnathostomata\b 1: The jawed vertebrates; a superclass of vertebrates comprising fishes (other than lampreys and hagfishes), amphibians, reptiles, birds and mammals. 2: Superorder of euechinoidean echinoids in which the anus is displaced from the aboral pole to an interambulacral position and the test has a secondary bilateral symmetry; 2 orders recognized, Holectypoida and Clypeasteroida.
\BGnathostomulida\b Jaw worms; a phylum of free-living, bilaterally symmetrical microscopic worms found worldwide in marine sands which are rich in organic detritus, at depths ranging from the intertidal to several hundred metres; characterized by the monociliated skin epithelium and by the specialized muscular pharynx possessing paired jaws and an unpaired cuticular basal plate; anus absent; typically hermaphrodite; comprises 2 orders, Bursovaginoidea and Filospermoidea.
\Bgnesiogamy\b Cross fertilization between two individuals of the same species.
\BGneticae\b Subdivision of gymnosperms (Pinophyta) comprising evergreen shrubs, lianas or small trees; leaves scale-like to broad; staminate and pistillate structures in compound strobili and cones; includes 3 widely divergent subclasses, Ephedridae, Gnetidae and Welwitschiidae, each containing a single family.
\BGnetidae\b Liana; subclass of gymnosperms comprising a single family, Gnetaceae, of evergreen climbing stems or small trees found in tropical and humid regions; large paired leaves, with reticulate venation; male cones elongate, female cone scales fused into a cuplike structure around the axis.
\Bgoat\b \JBovidae\j
\Bgoatfish\b \JMullidae\j
\Bgoatsucker\b \JCaprimulgidae\j
\BGobiesociformes\b Order of mostly bottomliving, shallow marine teleost fishes comprising about 100 species in a single family, Gobiesocidae (clingfishes).
\BGobiesocidae\b Clingfishes; family containing about 100 species of intertidal and shallow marine teleost fishes (Gobiesociformes); body flattened ventrally, to 300 mm in length but usually much smaller, head broad with large mouth; pelvic fins forming ventral sucker; body scales and swim bladder absent.
\BGobiidae\b Gobies; large family containing about 1000 species of small (to 100 mm) bottomdwelling perciform teleost fishes; 2 dorsal fins present, pelvic usually combined to form ventral sucker; often found in association with other fishes or invertebrates; internal fertilization and aerial respiration exhibited by some species.
\BGobioidei\b Gobies, wormfishes; diverse suborder of marine, brackish and freshwater perciform teleost fishes comprising about 1000 species in 2 families; pelvic fins may form ventral sucker; 2 dorsal fins typically present; lateral line and gas bladder usually absent.
\Bgoblin shark\b \JMitsukurinidae\j
\Bgoby\b \JGobiidae\j
\Bgold wasp\b Chrysididae \Iq.v\i
\Bgolden mole\b \JChrysochloridae\j
\Bgolden trumpet\b \JApocynaceae\j
\Bgolden-eye\b \JChrysopidae\j
\Bgoldenrain tree\b \JSapindaceae\j
\Bgoldenrod\b \JAsterales\j
\BGomphotheriidae\b Extinct family of long-jawed mastodons (Proboscidea) known from the Miocene through to the Pleistocene.
\BGomortegaceae\b Family of aromatic evergreen trees (Laurales) containing a single species native to central Chile; characterized by epigynous flowers arranged in racemes.
\BGondwana\b The southern supercontinent formed by the break up of \JPangaea\j in the Mesozoic (\Ic.\i 150 million years B.P.); comprising the present South America\j, \JAfrica, Arabia, Australia, Antarctica, India and New Zealand; See also \JEurasia\j
\BGoniactinida\b Sole extant order of somasteroidean echinoderms represented by a single living species found on shallow sandy beaches of western Central America.
\Bgonochorism\b The fusion of male and female gametes produced from separate unisexual individuals; sexual reproduction.
\Bgonochoristic\b 1: Used of individuals of a single sex; unisexual. 2: Used of populations having male and female individuals in the same population; \Bgonochoric\b, \Bgonochorism\b.
\Bgonogenesis\b The formation of germ cells by meiotic division.
\BGonorhynchidae\b Sand eel, mousefish; monotypic family of Indo-Pacific marine teleost fishes (Gonorhynchiformes); body very slender, cylindrical, to 600 mm length; snout pointed and prolonged, with single barbel, mouth ventral; pelvic and dorsal fins posteriorly positioned.
\BGonorhynchiformes\b Small order of mainly Old World freshwater, brackish water and marine teleost fishes comprising about 15 species in 4 families, including milkfish and sand eels.
\BGonostomatidae\b Lightfishes, bristlemouths; family containing about 60 species of luminescent meso-or bathypelagic stomiiform teleosts; body elongate, fragile, naked or with large cycloid scales, mouth and gill openings large; teeth thin and sharp; adipose fin usually present.
\Bgonozoid\b A reproductive polyp in colonial cnidarians.
\BGoodeidae\b Family containing 40 species of small (to 200 mm) viviparous freshwater cyprinodontiform teleost fishes confined to the highlands of Mexico; resemble killifishes (Cyprinodontidae) except male anal fin modified as gonopodium for sperm transfer.
\BGoodeniaceae\b Family of Campanulales containing about 300 species of often poisonous perennial herbs storing carbohydrate as inulin; widely distributed in tropical and subtropical regions especially in Australia; flowers typically zygomorphic, with a split corolla tube and an inferior ovary.
\Bgoose\b \JAnatidae\j
\Bgoose barnacle\b \JThoracica\j
\Bgooseberry\b \JGrossulariaceae\j
\Bgoosefish\b \JLophiidae\j
\Bgoosefoot\b \JChenopodiaceae\j
\BGordea\b Order of gordioidan horsehair worms characterized by the absence of cuticular organs called areoles.
\Bgordian worm\b \JNematomorpha\j
\BGordioida\b Class of freshwater or semiterrestrial horsehair worms the juveniles of which are found as internal parasites of a variety of insects; characterized by the lack of lateral rows of swimming hairs and by the presence of paired reproductive organs; comprises 2 orders, Chordodea and Gordea.
\BGorgonacea\b Sea fans, sea whips; order of arborescent colonial octocorals found most commonly in warm shallow waters, especially in association with coral reefs in the Indo-Pacific; characterized by their firm axial skeleton formed from horny proteinaceous material.
\Bgraft\b To induce the union of a tissue (a graft) from one organism with that of another by artificial means or to transplant tissue from one site to another on the same organism; in zoology the two elements are referred to as donor and recipient or host, and in botany the part being introduced is the scion and the recipient is the stock.
\Bgraft hybrid\b A hybrid produced by grafting two dissimilar plants.
\Bgrallatorial\b Adapted for wading.
\BGramineae\b The grass family; now known as the \JPoaceae\j
\Bgraminicolous\b 1: Growing on grasses. 2: Used of an animal spending most of its life in a grassy habitat; \Bgraminicole.\b
\Bgraminivorous\b Feeding on grass; \Bgraminivore\b, \Bgraminivory\b.
\Bgraminology\b The study of grasses.
\BGrammatidae\b \JGrammidae\j
\BGrammicolepidae\b Small family of little-known zeiform teleost fishes widespread in tropical and temperate regions of Pacific and Atlantic Oceans; body compressed, to 250 mm in length, bearing extremely long thin scales forming vertical ridges.
\BGrammidae\b Basslets; family containing 9 species of small (to 80 mm) colourful tropical marine perciform teleost fishes commonly found in caves and crevices to 60 m depth; differ from sea basses in having an incomplete or absent lateral line; dorsal fin elongate with 11 fin spines.
\BGrammistidae\b Soapfishes; family containing 20 species of coastal marine perciform teleosts; body stout, compressed, to 300 mm length, skin covered with a toxic mucus secretion as protection from predators; mouth large and thick-lipped; single dorsal fin present.
\Bgranite moss\b \JAndreaeopsida\j
\Bgranivorous\b Feeding on seeds; \Bgranivore\b, \Bgranivory\b.
\Bgranule\b A sediment particle between 2 mm and 4 mm in diameter; small gravel; see sediment particle size.
\BGranuloreticulosa\b Class of rhizopod protozoans possessing delicate, anastomosing pseudopodia of continuously streaming, minutely granular cytoplasm; comprising 2 orders, Athalmida and Foraminiferida.
\Bgrape vine\b \JVitaceae\j
\Bgrapefruit\b \JRutaceae\j
\BGraptolithina\b Graptolites; a class of extinct colonial marine hemichordates in which individual polyps lived in chitinous tubes arranged in single or double rows along characteristic branches (stipes); mainly epiplanktonic, sometimes sessile; known from the Cambrian to the Carboniferous.
\Bgrass\b 1: \JPoaceae\j 2: \JRestionaceae\j
\Bgrass tree\b \JXanthorrhoeaceae\j
\Bgrasshopper\b \JTettigoniidae\j (Orthoptera)
\Bgrassland\b An area of vegetation dominated by herbaceous grasses, sometimes used for any herb-dominated vegetation.
\Bgravel\b Sediment particles between 2 mm and 256 mm in diameter; sometimes used for a class of smaller particles between 2 mm and 4 mm in diameter; see sediment particle size.
\Bgraveolent\b Possessing a strong or offensive odour.
\Bgravid\b Carrying eggs or young; ovigerous; pregnant.
\Bgraviperception\b The perception of gravity.
\Bgravitational water\b Water which drains by gravity through the soil and which is readily available to soil organisms and plants.
\Bgrayling\b \JSalmonidae\j
\Bgrazing\b Feeding on herbage, algae or phytoplankton, by consuming the whole food plant or by cropping the entire surface growth in the case of herbage.
\Bgreasewood\b \JChenopodiaceae\j
\Bgreat ape\b \JPongidae\j
\BGreat Interglacial period\b The major interglacial period in the middle of the Quaternary Ice \JAge\j
\Bgreat white shark\b \JLamnidae\j
\Bgrebe\b \JPodicipedidae\j
\Bgreen alga\b \JChlorophycota\j
\Bgreen mud\b A terrigenous marine sediment, green in colour, formed under mildly reducing conditions and containing iron in the ferrous state, and some organic matter.
\Bgreenbottle\b \JCalliphoridae\j
\Bgreeneye\b \JChlorophthalmidae\j
\Bgreenfly\b \JAphididae\j
\Bgreenhouse effect\b The tendency towards increasing temperature of the lower layers of the atmosphere caused by an increase in atmosphere carbon dioxide which, together with water vapour, absorbs radiated heat more efficiently than it absorbs the incident solar radiation of short wavelengths.
\Bgreenling\b \JHexagrammidae\j
\BGregarinia\b Gregarines; sporozoans which usually live in the intestine or body cavity of invertebrates and lower chordates; the mature stages often appear segmented and commonly attach to each other, a process known as syzygy; also classified as the subclass Gregarinasina of the protoctistan class Sporozoasida.
\Bgregarious\b Tending to aggregate actively into groups or clusters.
\Bgrenadier\b \JMacrouridae\j
\Bgressorial\b Adapted for walking.
\BGrey Brown podzolic soil\b A zonal soil with a thin dark litter layer over a grey-brown, moderately acidic A-horizon and an illuviated lower horizon; formed in humid temperate climates on young land surfaces, typically glacial deposits under deciduous forest.
\BGrey Desert soil\b A soil type similar to a \JSierozem\j, but having a calcareous surface layer; formed in warm temperate arid climates.
\Bgrey mullet\b \JMugilidae\j
\Bgrey shark\b \JCarcharhinidae\j
\Bgrey whale\b \JEschrichtiidae\j
\BGrey Wooded soil\b A woodland soil having a deep litter and duff layer, a deep weakly acidic brown to grey A-horizon, and a deep neutral to moderately acidic B-horizon.
\BGreyiaceae\b Wild bottlebrush; small family of Rosales containing 3 species of soft-wooded shrubs or trees confined to South Africa; flowers brilliant scarlet, with 5 small sepals and 5 showy petals.
\Bgribble\b Wood-boring isopod crustacean (\JFlabellifera\j) that burrows into boat hulls, wharf piles and other submerged timbers, and may cause extensive damage.
\BGrimmiales\b Order of mainly xerophytic mosses (Bryidae), which are widely distributed but more common in the northern hemisphere; small dark plants usually growing as mats or tufts on rock surfaces.
\Bgrooming\b The act of cleaning the body surface to remove foreign matter and parasitic organisms, by licking, nibbling or other directed behaviour.
\Bgross primary production\b The total assimilation of organic matter by an autotrophic individual, population or trophic unit; \Bgross primary productivity\b; See also \Jnet primary production\j
\Bgross production\b 1: Total assimilation of organic matter by an individual population or trophic unit; See also \Jnet production\j
\Bgross secondary production\b The total assimilation of organic matter or energy by a primary consumer individual, population or trophic unit; \Bgross secondary productivity\b; See also \Jnet secondary production\j
\BGrossulariaceae\b Currant, gooseberry; cosmopolitan family of Rosales containing about 300 species of sometimes spiny shrubs and trees; flowers usually with 5 sepals, petals and stamens, and with an inferior ovary which develops to a juicy berry.
\Bground beetle, darkling\b \JTenebrionidae\j
\Bground beetle, predacious\b \JCarabidae\j
\Bground hopper\b \JCaelifera\j
\Bground sloth\b \JMegalonychoidea\j
\Bground water\b All the water that has percolated through the surface soil into the bedrock.
\Bground-storey\b The lowest layer of vegetation in a stratified woodland or forest community, comprising small trees and shrubs, herbs and plant debris.
\BGround-Water Laterite soil\b An intrazonal soil with hardpans rich in iron and aluminium, formed immediately above the water table.
\BGround-Water Podzol soil\b An intrazonal soil with a mat of organic surface material over a thin acid humus layer, underlain by a pale grey leached horizon and a dark brown hardpan lower horizon, formed in humid cool to tropical climates under conditions of poor drainage with forest vegetation.
\Bgrouper\b \JSerranidae\j
\Bgrouse\b \JTetraonidae\j
\Bgrowth\b Increase in size, number or complexity.
\Bgrowth form\b The characteristic appearance of a plant under a particular set of environmental conditions.
\Bgrub\b Soft-bodied, legless (apodous) larval stage characteristic of some dipterous, coleopterous and hymenopterous insects.
\BGrubbiaceae\b Small family of Ericales, containing 3 species of shrubs confined to the Cape Province of South Africa.
\BGruidae\b Cranes; family containing 15 species of large long-legged wading birds found in wet and marshy habitats throughout the world, excluding South America; bill typically long and straight, wings broad, legs strong; habits gregarious, monogamous, migratory, feeding on small animals; nest made of vegetation, solitary, on ground or in shallow water.
\BGruiformes\b Diverse order of small to large terrestrial or aquatic birds comprising 12 families and including cranes, rails, coots, bustards and several other small groups.
\Bgrumusol\b A soil rich in clay that expands and contracts under conditions of high or low water content.
\Bgrunt\b \JHaemulidae\j
\BGryllidae\b Crickets; large family of orthopterodean insects (Ensifera), mostly with box-like forewings bent down at the sides of the body; ovipositor cylindrical; many species have well developed sound producing mechanisms for auditory communication.
\BGrylloblattaria\b Rock crawlers; order of wingless orthopterodean insects comprising 13 species in a single family, found in cold habitats such as glacier margins, ice caves and upland forest; body depressed, poorly pigmented and weakly sclerotized; eyes small or absent; habits primarily nocturnal and omnivorous.
\BGryllotalpidae\b Mole crickets; small family of large, burrowing orthopterodean insects (Ensifera) with fossorial front legs, reduced forewings and no ovipositor; all produce sound by stridulation.
\Bguano\b An accumulation of sea bird droppings rich in phosphates and nitrates.
\Bgudgen\b \JEleotridae\j
\Bguest\b An animal living and/or breeding within the nest, domicile or colony of another species.
\BGuiana Current\b A warm surface ocean current that flows northwestwards to link the South Equatorial Current with the Caribbean Current; see ocean currents.
\Bguild\b A group of species having similar ecological resource requirements and foraging strategies, and therefore having similar roles in the community.
\BGuinea Current\b A warm surface ocean current that flows southwards off the west coast of North Africa, derived in part from the Canary Current; see ocean currents.
\Bguinea fowl\b \JNumididae\j
\Bguinea-pig\b \JCaviidae\j
\Bguitarfish\b \JRhinobatiformes\j
\BGulf Stream\b The warm surface ocean current derived from the Antilles Current and the Florida Current that flows northeastwards into the Atlantic and forms the northern limb of the North Atlantic Gyre; see ocean currents.
\Bgumivorous\b Feeding on gum and other exudates from trees; \Bgumivore\b, \Bgumivory.\b
\Bgunnel\b \JPholididae\j
\BGunneraceae\b Family of Haloragales containing about 50 species of terrestrial perennial herbs often with very large leaves, occurring mainly in southern hemisphere; flowers typically small and borne in large panicles.
\BGünz glaciation\b A glaciation of the Quaternary Ice \JAge\j in the Alpine area, with an estimated duration of 100 thousand years.
\BGünz-Mindel interglacial\b An interglacial period of the Quaternary Ice \JAge\j in the Alpine area.
\Bguppy\b \JPoeciliidae\j
\Bgurnard\b \JTriglidae\j
\Bguttation\b The natural exudation of water from an uninjured plant surface.
\Bguyot\b A submarine seamount rising from the abyssal plain.
\BGymnamoeba\b Amoebae; group of ubiquitous, naked, lobose amoebae lacking any obvious test and moving by protoplasmic flow; feed by engulfing with pseudopodia or by invagination of the leading edge; reproducing mainly by binary fission; including many cosmopolitan species occurring in all aquatic habitats and in soil; classified in 3 orders, Amoebida, Schizopyrenida and Pelobiontida.
\BGymnarchidae\b Monotypic family of primitive African piscivorous freshwater teleost fishes; body eel-like, to 0.9 m in length, without pelvic, anal and caudal fins; dorsal fin long; capable of producing strong electric fields; eggs laid in large floating nest.
\BGymnascales\b Order of common and widely distributed plectomycete fungi typically found in soil, dung and animal debris, such as skin, hair and horn; mostly saprophytic but occasionally pathogenic; fruiting bodies (ascocarps) mostly sessile, spherical and lacking ostiole; asci evanescent; comprises over 60 species in 2 families and includes the causative agent of ringworm in man.
\BGymnodiniales\b Order of freshwater and marine dinoflagellates including both photosynthetic and heterotrophic forms.
\BGymnolaemata\b Diverse class of bryozoans comprising 2 orders, Ctenostomata and Cheilostomata; zooids polymorphic, cylindrical or flattened, lophophore circular, epistome absent; colonies variable, encrusting or erect, calcified or soft.
\BGymnophiona\b Caecilians; order of limbless worm-like subterranean amphibians comprising about 150 species in 5 families; adults mostly terrestrial, sometimes aquatic; body elongate, length to 1200 mm, limbs and girdles absent; eyes small, often covered with bone; left lung rudimentary; fertilization internal; some species oviparous, others viviparous; pantropical in distribution; Apoda.
\BGymnosomata\b Pteropods; cosmopolitan order of oceanic opisthobranch molluscs which are active swimmers and spend their lives in the plankton feeding mainly on other invertebrates; shell lacking; possessing lateral swimming fins which are separate from the foot.
\Bgymnosperm\b \JPinophyta\j
\BGymnostomata\b Subclass of ciliates (Kinetofragminophora) typically with a uniform covering of simple cilia and a limited amount of ciliature on the body surface associated with the cell mouth (cytostome); reproducing generally by simple binary fission; widely distributed in a variety of habitats.
\BGymnotidae\b Knifefishes; family of nocturnal predatory Central and South American freshwater catfishes (Siluriformes); body elongate, compressed, to 1.4 m in length; dorsal, adipose and pelvic fins absent, anal well-developed; produce weak electric fields for detecting prey; contains 40 species sometimes classified in 3 separate families, Apteronotidae, Rhamphichthyidae and Gymnotidae.
\BGymnuridae\b Butterfly rays; family containing 12 species of medium to large, tropical to warm temperate, benthic marine myliobatiform elasmobranch fishes; body disk much broader than long, tail short and slender with or without serrated spine and dorsal fin; dorsal body surface lacking denticles.
\Bgynandromorph\b An individual of mixed sex; a sexual mosaic having some parts genotypically and phenotypically male and others female; gynander.
\Bgynic\b Female; See also \Jandric\j
\Bgynodioecious\b Used of plants or plant species having female (pistillate) and hermaphrodite (perfect) flowers on separate plants in a population or species; \Bgynodioecy\b; See also \Jandrodioecious\j
\Bgynoecious\b Used of plant having female flowers only; See also \Jandroecious\j
\Bgynoecium\b The central, female component of a flower, typically consisting of one or more carpels, which may be separate or fused.
\Bgynogamete\b A female gamete; egg; ovum.
\Bgynogenesis\b The process in which an egg develops parthenogenetically after the egg has been activated by sperm or pollen; pseudogamy; See also \Jandrogenesis\j
\Bgynogenous\b Producing female offspring only; See also \Jandrogenous\j
\Bgynomonoecious\b Having female (pistillate) and hermaphrodite (perfect) flowers on the same plant; \Bgynomonoecy\b; See also \Jandromonoecious\j
\Bgynomorphic\b Having a morphological resemblance to females; \Bgynomorphy\b; See also \Jandromorphic\j
\Bgynopleogamy\b The condition of a plant species having three sexual forms, with either perfect flowers, pistillate flowers or staminate flowers.
\Bgypsophilous\b Thriving on chalk or gypsum-rich soils; \Bgypsophile\b, \Bgypsophily\b.
\Bgypsophyte\b A plant inhabiting chalk or gypsumrich soils.
\BGyracanthocephala\b Order of eoacanthocephalan thorny-headed worms found as parasites of marine and freshwater fishes and utilizing crustaceans as intermediate hosts; characterized by the possession of trunk spines.
\Bgyre\b A circular or spiral system of movement, characteristic of oceanic currents, and other systems of water movement.
\BGyrinidae\b Whirligig beetles; family containing about 700 species of beetles (Coleoptera) found commonly on the surface of still freshwater; capable of detecting prey organisms falling onto water surface; larvae are bottom-living predators with abdominal gills.
\BGyrinocheilidae\b Family containing 3 species of small (to 250 mm) herbivorous freshwater cypriniform teleost fishes found in Borneo and southeast Asia; body elongate, mouth suctorial, lips fleshy, pharyngeal teeth absent; the 2 pairs of gill openings serve as inhalent and exhalent apertures for respiratory water current.
\BGyrocotylidea\b Small order of cestodarian tapeworms found as parasites of marine fishes; characterized by a flattened, elongate body often with crenulated margins, a simple anterior holdfast, and a ventral, preequatorial uterine pore.
\BGyrostemonaceae\b Small family of Batales containing about 17 species of trees or shrubs producing mustard oil; native to Australia; sometimes included in the Phytolaccaceae.
\Bgyttja\b Sedimentary peat comprising predominantly plant and animal residues precipitated from standing water.
\Bhabilines\b Group of hominids known from fossil remains found in East Africa, that lived about 2-1.5 million years B.P.; from the larger brain size, facial and dental features they are thought to be closer to man than to the australopithecine apes, and have been placed in the same genus, as \IHomo habilis\i, at the base of the lineage leading directly to man.
\Bhabit\b The external appearance, aspect or growth form of an organism; \Bhabitus.\b
\Bhabitat\b The local environment occupied by an organism.
\Bhabituation\b The simplest form of learning in which the reduction or loss of a reponse to a stimulus occurs as a result of repeated stimulation.
\Bhabitus\b The characteristic form and appearance of an organism.
\Bhackberry\b \JUlmaceae\j
\Bhadal zone\b Ocean depths below 6000 m; the trenches and canyons of the abyssal region; ultra-abyssal zone; see marine depth zones.
\BHadean\b Early Precambrian; the geological period prior to the Archaeozoic (\Ic.\i 3400 million years B.P.); see geological time scale.
\BHadromerida\b Large order of tetractinomorph sponges characterized by a uniform spiculation of monaxonid megascleres, found in all seas from the intertidal zone down to 4000 m; includes the burrowing sponges of the family Clionidae.
\Bhadrosaur\b An ornithischian dinosaur which was probably amphibious; up to 9 m in length, duck-billed and with webbed feet; known from the Upper Cretaceous.
\Bhaematobium\b An organism living in blood; \Bhaematobic.\b
\Bhaematocytozoon\b A parasite living within a blood cell; See also \Jhaematozoon\j
\Bhaematophagous\b Feeding on blood; \Bhaematophage\b, \Bhaematophagy.\b
\Bhaematophyte\b Any member of the blood flora.
\BHaematopodidae\b Oystercatchers; family containing 7 species of large charadriiform shore birds, cosmopolitan on tropical to temperate sandy and rocky shores and coastal marshes; bill characteristically long, robust, bright red; habits gregarious, monogamous; feed on bivalve molluscs; nest solitary, in hollow on ground.
\Bhaematozoon\b An animal parasite living free in the blood; See also \Jhaematocytozoon\j
\BHaemodoraceae\b Kangaroo-paw; family of Liliales comprising less than 100 species of perennial geophytic herbs often with a characteristic red pigment in the roots and rhizomes; leaves all basal, consisting of a sheathing base and parallel-veined, swordshaped blade; mostly southern hemisphere in distribution; flowers perfect, with 6 perianths and 3 or 6 stamens, borne as panicled inflorescences.
\Bhaemoparasite\b Any parasite inhabiting the blood of its host.
\Bhaemophagous\b Feeding on blood; \Bhaemophage\b, \Bhaemophagy.\b
\Bhaemotrophic\b Obtaining nutrients from blood.
\BHaemulidae\b Grunts; family containing 175 species of tropical and subtropical coastal marine, perciform teleost fishes usually found over shallow reefs or soft bottoms; the vernacular name refers to their ability to produce sounds by grinding their pharyngeal teeth to resonate the gas bladder; body oblong compressed, to 800 mm in length; mouth small with thick lips; single dorsal fin present; Pomadasyidae.
\Bhagfish\b \JMyxiniformes\j
\Bhair seal\b \JPhocidae\j
\Bhair-streak\b \JLycaenidae\j
\Bhairyfish\b \JMirapinnidae\j
\Bhake\b \JMerlucciidae\j
\Bhalf-beak\b \JHemiramphidae\j
\BHalf-Bog soil\b An intrazonal soil with a dark brown-black peaty surface layer over a grey mottled mineral layer, formed in humid, cool to tropical climates under conditions of poor drainage, with grasses, sedges or forest vegetation.
\Bhalf-life\b 1: A measure of radioactive decay; the time taken for the level of radioactivity to reduce by one-half. 2: The time taken for an individual or biological system to eliminate one half of a given substance introduced into it.
\Bhalibut\b \JPleuronectidae\j
\Bhalic\b Pertaining to saline conditions.
\BHalichondrida\b Order of ceractinomorph sponges, widely distributed and occurring from the intertidal zone down to 2500 m; typically with an encrusting to massive body form and a skeleton of diactinal or monactinal megascleres, or both.
\Bhalicolous\b 1: Living in haloid \Jsoils\j having a crystalloid content between 0.5 and 2 parts per thousand; see also \Jgelicolous\j \Jpe
\BHalictidae\b Sweat bees; large family of small to medium-sized bees (Hymenoptera) that feed on pollen and nectar both as adults and larvae and often lick perspiration from human skin; mostly solitary but also exhibiting primitive social nesting behaviour.
\Bhaliplankton\b Marine or inland saltwater planktonic organisms.
\Bhalobiont\b A marine organism or an organism living in a saline habitat; \Bhalobiontic.\b
\Bhalobios\b The total life of the sea; that part of the Earth's surface occupied by marine organisms; halibios; \Bhalobiontic\b; see also \Jgeobios\j \Jhydrobios\j, \Jlimnobios\j
\Bhalocline\b A salinity discontinuity; a zone of marked salinity gradient.
\BHalocyprida\b Order of marine ostracod Crustacea comprising 200 species in 2 suborders, Cladocopina and Halocypridina; found from littoral to abyssal zones in planktonic and benthic habitats.
\BHalocypridina\b Suborder containing about 160 species of marine halocypridan ostracods which are typically planktonic, from surface waters down to depths of 4000 m.
\Bhaloid soil\b A soil type characterized by high salt content, concentrated solutions and with a crystalloid content of more than 0.5 parts per thousand; See also \Jgeloid soil\j
\Bhalolimnetic\b 1: Pertaining to salt lakes. 2: \JHalolimnic\j
\Bhalolimnic\b Used of marine organisms adapted to live in fresh water; \Bhaloimnetic.\b
\Bhalomorphic\b Used of an intrazonal soil having an accumulation of salts.
\Bhalophilous\b Thriving in saline habitats;\Bhalophile\b, \Bhalophily\b; See also \Jhalophobic\j
\Bhalophobic\b Intolerant of saline habitats; \Bhalophobe\b; See also \Jhalophilous\j
\Bhalophreatophyte\b A plant utilizing saline ground water.
\Bhalophyte\b A plant living in saline conditions; a plant tolerating or thriving in an alkaline soil rich in sodium and calcium salts; See also \Jglycophyte\j
\Bhaloplankton\b Marine or inland salt-water plankton.
\BHaloragaceae\b Parrot's feather; family of aquatic, amphibious or marsh-inhabiting herbs, common in southern hemisphere; flowers typically solitary, inconspicuous and wind-pollinated, with inferior ovary.
\BHaloragales\b Order of Rosidae containing 2 families of often aquatic herbs, Haloragaceae and Gunneraceae.
\BHalosauridae\b Halosaurs; family containing about 14 species of small (to 250 mm) bottom-living notacanthiform teleost fishes widespread and locally common on continental slopes; body scales large, snout spatulate and prolonged; sensory canals cavernous.
\Bhalosere\b An ecological succession commencing in a saline habitat.
\BHamamelidaceae\b Witch hazel, sweet gum; family of tanniferous shrubs or trees often possessing stellate hairs and producing woody capsular fruit; flowers usually in a spike, with 4 or 5 sepals and petals, and up to 14 stamens.
\BHamamelidae\b Subclass of dicotyledons (Magnoliopsida) typically with small inconspicuous flowers, often lacking petals, which are usually wind-pollinated.
\BHamamelidales\b Order of woody plants comprising 5 relict families, Cercidiphyllaceae, Eupteleaceae, Hamamelidaceae, Myrothamnaceae and Platanaceae.
\Bhammada\b A rocky desert.
\Bhammer oyster\b \JPterioida\j
\Bhammerhead shark\b \JSphyrnidae\j
\Bhammerjaw\b \JOmosudidae\j
\Bhamster\b \JCricetidae\j
\BHanguanaceae\b Family of Liliales containing a single species of robust perennial herbs found in moist or wet habitats; native to Malaysia and Sri Lanka.
\Bhapaxanthous\b Having a single flowering phase during the life cycle.
\Bhaplobiont\b 1: A plant flowering once per season. 2: An organism not exhibiting a regular alternation of haploid and diploid generations during the life cycle; See also \Jdiplobiont\j
\Bhaplodiploidy\b The genetic system found in some animals in which males develop from unfertilized eggs and are haploid, and females develop from fertilized eggs and are diploid; \Bhaplodiploid\b, \Bhaplodiplont.\b
\Bhaploid\b Having only a single set of chromosomes; having the gametic chromosome number; \Bhaploidy\b; See also \Jploidy\j
\Bhaploid parthenogenesis\b The development of a haploid individual from a female gamete that has undergone meiotic reduction division but has not been fertilized.
\Bhaplometrosis\b The founding of a colony of social insects by a single fertile female; \Bhaplometrotic.\b
\Bhaplont\b 1: The haploid phase of a life cycle. 2: An organism having a life cycle in which meiosis occurs in the zygote to produce the haploid phase; See also \Jdiplont\j
\BHaplopharyngida\b Small order of free-living turbellarians found interstitially in marine sands, characterized by a simple proboscis opening just beneath the anterior end of the body and by the presence of a permanent but weakly differentiated dorsal anal pore.
\Bhaplophase\b The haploid stage of a life cycle.
\Bhaplophyte\b A haploid plant; gametophyte; See also \Jdiplophyte\j
\BHaplorhini\b Suborder of primates comprising 3 infraorders, Tarsii (tarsiers), Platyrrhini (New World monkeys) and Catarrhini (Old World monkeys, apes); nostril without lateral slit, rhinarium non-glandular, lower jaw medially fused or unfused.
\BHaplosclerida\b Order of ceractinomorph sponges including both marine and freshwater forms; characterized by a reticulate skeleton comprising triangular, rectangular or polygonal meshes formed of spicules joined with spongin.
\BHaplosporea\b Class of parasitic protozoans (Sporozoa) found in invertebrate hosts; produce resistant spores.
\BHaplotaxida\b Order of oligochaete worms comprising 3 suborders, Tubificina (freshwater), Haplotaxina (groundwater) and Lumbricina (terrestrial).
\BHaplotaxina\b Suborder of primitive groundwater oligochaete worms; clitellum comprising a single layer of cells; chaetae single or paired, simple or bifid; copulatory organs absent; comprises single family with about 20 species distributed throughout the Holarctic.
\Bhaptobenthos\b Those aquatic organisms that live closely applied to, or growing on, submerged surfaces; See also \Jbenthos\j
\BHaptomonadida\b \JPrymnesiophyceae\j treated as an order of the protozoan class Phytomastigophora.
\Bhaptonastic\b Used of growth movement of a plant in response to a touch or contact stimulus; \Bhaptonasty.\b
\BHaptophyta\b The \JPrymnesiophyceae\j treated as a phylum of Protoctista.
\BHaptorida\b Order of gymnostome ciliates containing large, active and voracious carnivores feeding mostly on other freshwater ciliates.
\Bhaptotropism\b An orientation response to a touch or contact stimulus; \Bhaptotropic.\b
\Bhard pan\b A compacted layer in the B-horizon of a soil, typically rich in deposited salts, restricting drainage and root penetration.
\Bhard tick\b Any of the tick family Ixodidae that have a rigid head plate and a forwardly directed head.
\Bhardening\b The process of increasing cold resistance in plants.
\Bhardiness\b The ability to survive exposure to sub-zero temperatures; cold resistance.
\Bhare\b \JLeporidae\j
\Bharem\b A group of females associated with a single male.
\BHarpacticoida\b Diverse order of typically free-living copepod crustaceans which are mainly epibenthic, burrowing or interstitial forms, occasionally planktonic or parasitic; characterized by the fusion of the inner branch (endopod) of the fifth leg to its base; feeding primarily on algae and a variety of microorganisms; contains about 3000 species from both marine and freshwater habitats.
\Bharpactophagous\b Feeding by preying on other animals; \Bharpactophage\b, \Bharpactophagy. \b
\BHarpadontidae\b Bombay ducks; family of marine and brackish-water myctophiform teleost fishes comprising 5 species, widespread in the Indian Ocean; body elongate, cylindrical, head compressed with eyes forwardly directed; scales confined to posterior part of body; jaws very long bearing slender curved teeth; paired fins elongate.
\BHarpellales\b Order of trichomycete fungi occurring as obligate gut symbionts in freshwater insect larvae.
\Bhaustorium\b An organ formed by a parasite and used to absorb nutriments from the host.
\BHawaiian region\b A zoogeographical region comprising the Hawaiian Archipelago; regarded either as a subdivision of the Polynesian subregion or as a separate region.
\Bhawk\b \JAccipitridae\j
\Bhawk moth\b \JSphingidae\j
\Bhawkfish\b \JCirrhitidae\j
\Bhawking\b Feeding in flight.
\Bhawkweed\b \JAsterales\j
\Bhawthorn\b \JRosaceae\j
\Bhazelnut\b \JCorylaceae\j
\Bheadstander\b \JAnostomidae\j
\Bheart shell\b \JVeneroida\j
\Bheart urchin\b \JSpatangoida\j
\Bheat\b A period of sexual activity or receptiveness.
\Bheath\b 1: Vegetation characteristic of low fertility, acidic, poorly drained soils, dominated by small leaved shrubs of Ericaceae (heathers and heaths) and Myrtaceae (myrtles). 2: \JEricaceae\j
\Bheather\b \JEricaceae\j
\Bheavy metal\b A metallic element of high specific gravity; including antimony, bismuth, cadmium, copper, gold, lead, mercury, nickel, silver, tin and zinc.
\Bhebetic\b Pertaining to adolescence; juvenile.
\Bhecto- (h)\b Prefix used to denote unit x 10\U2\u; see metric prefixes.
\Bhedgehog\b \JErinaceidae\j
\Bhedge sparrow\b \JPrunellidae\j
\Bhekistotherm\b A plant with a requirement for a temperature of less than 10░C in the warmest month, typically occurring in regions with a mean annual temperature below 0░C; sometimes used to refer to those organisms living above the tree line in areas of heavy snow; \Bhekistothermic\b; see also \Jmegatherm\j \Jmesotherm\j, \Jmicrotherm\j
\BHeleophrynidae\b Small family containing 3 species of aquatic frogs (Anura) found in mountain streams of South Africa from the Cape to eastern Transvaal.
\Bheleoplankton\b The planktonic organisms of small ponds and marshy habitats; \Bheleoplanktonic. \b
\Bhelic\b Pertaining to marshes or marsh communities.
\BHeliconiaceae\b Lobster claw; family of Zingiberales containing over 100 species of large perennial herbs with leaves having a long petiole and expanded blade and prominent midrib; native mainly to tropical and subtropical America; flowers perfect, with 6 perianth segments, 5 stamens and an inferior ovary, arranged in alternate, compound inflorescences subtended by a large colourful bract shielding several small flowers; adapted for insect pollination.
\Bheliophilous\b Thriving under conditions of high light intensity; \Bheliophile\b, \Bheliophily\b; See also \Jheliophobous\j
\Bheliophobous\b Intolerant of high light intensity; shade-loving; \Bheliophobe\b; See also \Jheliophilous\j
\Bheliophyllous\b Used of plants having leaves that can tolerate full sunlight; See also \Jsciophyllous\j
\Bheliophyte\b A plant that shows optimum growth under conditions of full sunlight; See also \Jsciophyte\j
\BHelioporacea\b Order of octocorals in which the colony produces a rigid calcareous skeleton composed of aragonite crystals anchored basally or attached by stolons.
\BHeliornithidae\b Sungrebes; family containing 3 species of medium-sized aquatic gruiform birds, widespread in tropical streams, lakes and marshland; swim and dive well, feeding on a variety of fish and invertebrates; habits solitary, secretive, monogamous; nest in bushes.
\Bheliosciophyte\b A plant which thrives in both sunlight and shade, but which grows best in sunny conditions.
\Bheliotaxis\b A directed response of a motile organism towards (positive) or away from (negative) sunlight; \Bheliotactic.\b
\Bheliothermic\b Used of organisms that maintain a comparatively high body temperature by basking in sunlight; \Bheliotherm.\b
\Bheliotropism\b An orientation response to sunlight; \Bheliotropic.\b
\Bhelioxerophilous\b Used of desert organisms thriving in both strong sunlight and drought conditions; \Bhelioxerophile\b, \Bhelioxerophily.\b
\BHeliozoa\b Class of actinopod protozoans in which the skeleton, when present, may be siliceous or chitinous and consists of independent scales, and which lack a capsular membrane; most species are freshwater, some marine; generally feed on small organisms caught with the axopods.
\Bhellebore\b \JRanunculaceae\j
\Bhelminthology\b The study of parasitic flatworms and roundworms.
\BHelminthomorpha\b Largest subclass of oniscomorphan diplopods (millipedes) comprising 11 orders in 7 superorders, Ommatomorpha, Monocheta, Anocheta, Diplocheta, Typhogena, Coelocheta and Merocheta; body typically elongate, cylindrical, each segment except first with 2 pairs of legs.
\Bhelobious\b Living in marshes.
\BHelodermatidae\b Gila monster; family containing 2 species of venomous lizards from Central America and southern United States; body length to 900 mm, limbs well developed; habits nocturnal, feeding on birds' eggs and small mammals; reproduction oviparous; producing a neurotoxin from a modified group of salivary glands.
\Bhelodric\b Pertaining to a swamp thicket.
\BHelogeneidae\b Family of small (to 100 mm) nocturnal Amazonian catfishes (Siluriformes) containing 3 species; dorsal fin lacking spine, anal fin elongate; 3 pairs of barbels present.
\Bhelohylophilous\b Thriving in wet or swampy forests; \Bhelohylophile\b, \Bhelohylophily. \b
\Bhelolochmophilous\b Thriving in meadow thicket habitats; \Bhelolochmophile\b, \Bhelolochmophily. \b
\Bhelolochmophyte\b A meadow thicket plant.
\Bhelophilous\b Thriving in marshes; \Bhelophile\b, \Bhelophily.\b
\Bhelophyte\b 1: A perennial plant with renewal buds, commonly on rhizomes, buried in soil or mud below water level; See also \JRaunkiaerian life forms. 2: Any marsh or bog plant\j
\Bheloplankton\b The floating vegetation of a marsh.
\Bhelorgadophilous\b Thriving in swampy woodlands; \Bhelorgadophile\b, \Bhelorgadophily. \b
\BHelotiales\b Large order of discomycete fungi with a worldwide distribution, possessing club-shaped inoperculate asci; comprising many parasites of higher plants, some saprophytes, and soil- and dung-dwelling forms.
\Bhelotism\b Symbiosis in which one symbiont enslaves the other.
\Bhelper\b In an avian communal breeding system, a bird that assists in nest building, care of young or gives other aid, but is not related to either parent or offspring.
\Bhemeranthous\b Flowering only during the day; \Bhemeranthy\b; See also \Jnyctanthous\j
\Bhemerocology\b The study of the ecology of cultivated areas and culture communities.
\Bhemerophilous\b Thriving in habitats influenced by the activities of man or under cultivation; \Bhemerophile\b, \Bhemerophily.\b
\Bhemerophyte\b A cultivated plant.
\BHemiascomycetes\b Class of ascomycotine fungi; characterized by the production of naked asci, not enclosed in ascocarp; includes saprophytic forms and plant and animal pathogens from terrestrial, freshwater and marine habitats; comprises 3 orders, Endomycetales, Protomycetales and Taphrinales.
\Bhemiautophytic\b Used of a parasitic plant which is also capable of photosynthesis; \Bhemiautophyte.\b
\Bhemichimonophilous\b Used of plants that thrive under cold conditions and begin their growth even during frost; \Bhemichimonophile\b, \Bhemichimonophily. \b
\BHemichordata\b Phylum of benthic marine invertebrates possessing pharyngeal gill slits for respiration, a body divided into proto-, meso- and metasome, paired coelomic cavities (except protosome), a mid-dorsal neurochord in the mesosome formed by invagination, an anterior evagination of the digestive tract termed a hemichord (not a homologue of chordate notochord), and a circulatory system comprising major dorsal and ventral vessels and a heart vesicle; development includes planktonic ciliated larva; 3 extant classes recognized, Enteropneusta, Pterobranchia and Planctosphaeroidea; includes acorn worms and the fossil graptolites; Stomochordata.
\Bhemicleistogamic\b Used of a plant having flowers that only open partially before pollination.
\Bhemicryptophyte\b A perennial plant with renewal buds at ground level or within the surface layer of soil; typically exhibiting degeneration of vegetative shoots to ground level at the onset of the unfavourable season; See also \JRaunkiaerian life forms\j
\Bhemiepiphyte\b A plant that spends only part of its life cycle as an epiphyte, producing both aerial and subterranean roots at different times.
\BHemigaleidae\b Weasel sharks; family containing 6 species of small to medium-sized (to 2.5 m), tropical, shallow water, carcharhiniform elasmobranch fishes; feed mainly on fishes; reproduction viviparous with yolk sac placenta.
\Bhemigamotropic\b Used of flowers that alternate between open and partially closed; see also \Jagamotropic\j \Jgamotropic\j
\Bhemimetabolous\b Used of the pattern of development characterized by gradual changes, without metamorphosis or distinct separation into larval, pupal and adult stages; hemimetamorphic; \Bhemimetaboly\b; see also \Jametabolous\j \Jholometabolous\j
\BHemiodidae\b \JHemiodontidae\j
\BHemiodontidae\b Family containing 50 species of small to medium-sized tropical Central and South American freshwater characiform teleost fishes; body elongate, fusiform, dorsal fin positioned anterior to mid-body.
\Bhemiparasite\b 1: A partial or facultative parasite that can survive in the absence of a host; meroparasite. 2: A parasitic plant that develops in the soil from free seeds.
\Bhemipode\b \JTurnicidae\j
\BHemiprocnidae\b Tree swifts; family containing 4 species of brown or grey swifts (Apodiformes) which perch in trees, spending less time in the air than other swifts; nest in trees on forest margins; feed on insects; known from India, southeast Asia and New Guinea.
\BHemiptera\b Bugs; large and diverse order of hemipterodean insects comprising about 35 000 species, including many of economic importance as crop pests, carriers of disease, and as predators; body often depressed, forewings typically leathery at base and membranous distally, but reduction or loss of wings common; mouthparts modified for piercing and sucking; feeding on plants, fungi and as predators; a few species are ectoparasites of vertebrates; most are terrestrial, many littoral on water surface, some aquatic; mimicry, aposematic coloration, procrypsis and sound production common within group.
\BHemipterodea\b Superorder of mostly small neopteran insects comprising 6 orders, Psocoptera (book lice, bark lice), Anoplura (sucking lice), Mallophaga (chewing lice), Thysanoptera (thrips), Hemiptera (bugs) and Homoptera (aphids); wings and/or wing venation often reduced or absent; mouthparts frequently specialized for feeding on fluids; habits commonly gregarious but not fully social; Oligonephridia.
\BHemiramphidae\b Half-beaks; family of surface-living marine and freshwater beloniform teleost fishes; body elongate, to 450 mm length, lower jaw prolonged well beyond upper; pectoral fins short; contains 60 species, many exploited as food-fishes and as baitfish.
\Bhemisaprophyte\b A plant that may be autotrophic or saprotrophic at different times.
\BHemiscyllidae\b Long-tailed carpet sharks; family containing 10 species of small (to 1 m) orectolobiform elasmobranch fishes found in shallow coastal waters of the tropical Indian Ocean and western Pacific.
\Bhemitropic\b Used of flowers adapted for pollination by particular insect species; also used of the insects that pollinate specifically adapted flowers.
\Bhemlock\b \JApiaceae\j
\Bhenbane\b \JSolanaceae\j
\BHepaticae\b \JHepaticopsida\j
\BHepaticopsida\b Liverworts; group of lower plants in which the dominant generation is the gametophyte; usually perennial, thallose or leafy in form with apical growth, and attached by rhizoids; sex organs develop from superficial cells; sperms biflagellate; sporophyte generation short-lived, determinate in growth and typically consisting of a dark brown spore-bearing capsule, a stalk (the seta) and an absorptive foot; includes 6 orders, Calobryales, Jungermanniales, Metzgeriales, Sphaerocarpales, Monocleales and Marchantiales; formerly known as the Hepaticae.
\BHepialidae\b Ghost moths; widely distributed family of medium to large moths (Lepidoptera); wings generally rounded at apex; hindwings and forewings with similar venation.
\BHepsetidae\b Monotypic family of small (to 350 mm), predatory, piscivorous African freshwater characiform teleost fishes widespread in tropical rivers; body elongate, pike-like; snout prolonged, median fins positioned posteriorly; eggs laid in floating bubble nests.
\Bherb\b A plant having stems that are not secondarily thickened and lignified (non-woody) and which die down annually; herbaceous.
\Bherbage\b Total vegetation available to a grazing animal; See also \Jforage\j
\Bherbarium\b 1: A collection of preserved (usually dried) plant specimens; \Ihortus siccus\i. 2: The building in which such a collection is kept.
\Bherbicide\b A chemical used to kill weeds or herbage.
\Bherbicolous\b Living predominantly in herbaceous habitats; \Bherbicole.\b
\Bherbivorous\b Feeding on plants; \Bherbivore\b, \Bherbivory.\b
\Bhercogamous\b Used of a flower having the stamens and stigma positioned in such a way as to prevent self-pollination; \Bhercogamy.\b
\Bhereditary\b Having a genetic basis; transmitted from one generation to the next.
\Bheredity\b The mechanism of transmission of specific characters or traits from parent to offspring.
\Bheritability\b 1: The capacity of being inherited. 2: That part of the phenotypic variability that is genetically based.
\Bhermaphrodite\b Having both male and female reproductive organs in the same individual (animal) or the same flower (plant); bisexual; the maturation of the male organs before the female is protandrous hermaphroditism, the female before the male is protogynous hermaphroditism, and simultaneously is synchronous hermaphroditism.
\Bhermatypic\b Used of reef-forming corals that contain symbiotic algae within the polyps; \Bhermatype.\b
\Bhermit crab\b \JAnomura\j
\BHernandiaceae\b Small family of woody shrubs, trees and climbers (Laurales) widely distributed in tropical regions; leaves palmately veined; flowers typically with 6-10 perianth segments and 3-5 stamens, ovary inferior.
\Bheron\b \JArdeidae\j
\Bherpesian\b Pertaining to amphibians and reptiles.
\Bherpetogeny\b The history of colonization and evolution in the establishment of the modern amphibian and reptile faunas.
\Bherpetology\b The study of amphibians and reptiles; \Bherpetological.\b
\Bherpism\b Creeping locomotion; used of protistans employing pseudopodia.
\Bherpobenthos\b Those organisms growing or moving through muddy sediments; See also \Jbenthos\j
\Bherpon\b Crawling organisms.
\Bherring\b \JClupeidae\j
\Bherring smelt\b \JArgentinidae\j
\Bhesmosis\b Colony fission in ants.
\Bhesperidium\b A type of \Jberry\j, such as an orange, which has a leathery outer skin (epicarp) and in which the locules contain fluid filled trichomes.
\BHesperiidae\b Skippers; large, widely distributed family of butterflies (Lepidoptera) typically with short wings and large bodies; antennae often club-shaped and widely separated; larvae feed on grass.
\Bheterauxesis\b The differential growth of body parts resulting in a change of shape or proportion with increase in size.
\BHeterenchelidae\b Family containing 7 species of shallow marine anguilliform teleost fishes that burrow into soft bottom sediments; body cylindrical, naked, to 0.8 m in length; dorsal, caudal and anal fins continuous, pectorals absent; eyes vestigial; Atlantic distribution, except for single Pacific species.
\BHeterobasidiomycetidae\b Subclass of saprobic phragmobasidomycete fungi producing fruiting bodies typically with a waxy or gelatinous texture and basidiospores which are usually discharged forcibly, then wind-disseminated; comprises 2 orders, Eutremellales and Septobasidiales.
\BHeterochlorida\b \JHeterochloridales\j treated as an order of the protozoan class Phytomastigophora.
\BHeterochloridales\b A class of simple Xanthophyta; including both unicellular and colonial forms; also classified as an order of the protozoan class Phytomastigophora.
\BHeterococcales\b A class of Xanthophyta, comprising coccoid cells organized into various colonial forms.
\BHeterocorallia\b Small order of extinct corals (Zoantharia) known only from the Carboniferous.
\BHeterocyemida\b Order of rhombozoan mesozoans endoparasitic in the renal glands of squid and cuttlefish.
\BHeterodonta\b A subclass of mainly bivalve molluscs characterized by a more-or-less fused mantle forming inhalent and exhalent current apertures frequently drawn out into siphons; shell never with mother-of-pearl; contains 3 orders, Hippuritoida, Myoida and Veneroida.
\BHeterodontidae\b \JHeterodontiformes\j
\BHeterodontiformes\b Bullhead sharks; order of inoffensive bottom-dwelling galeomorph elasmobranch fishes; body length to 1.5 m; mouth terminal, teeth differentiated, cusped and non-cusped; dorsal fins with strong anterior fin spine; feed on benthic invertebrates and small fishes; reproduction oviparous, egg cases of spiral shape; comprises 8 species in a single family found from the littoral to 300 m.
\BHeterodontosaur\b An ornithopod dinosaur with tusk-like canine teeth; known only from the Upper Triassic.
\Bheteroecious\b 1: Used of a parasite occupying two or more different hosts at different stages of the life cycle; See also \Jhomoecious. 2: Used of a non host-specific parasite. 3: Used of a unisexual organism in which male and female gametes are produced by different individuals\j
\Bheterogamete\b 1: A gamete produced by the heterogametic \Jsex\j 2: A gamete belonging to one of two distinguishable types.
\Bheterogametic\b Having two kinds of gametes, one producing males and the other females; \Bheterogamy\b; See also \Jhomogametic\j
\Bheterogametic sex\b The sex which is determined by a pair of dissimilar sex chromosomes (X and Y, or Z and W) or by a single unpaired sex chromosome (X or Z); the sex which produces two types of sex-determining gametes; See also \Jhomogametic sex\j
\Bheterogamy\b 1: The union of gametes (heterogametes) of different shape or size. 2: Alternation of two sexual generations, one syngamic and the other parthenogenetic. 3: The condition of a plant producing both male and female gametes from one kind of flower; \Bheterogamic\b, \Bheterogamous\b; See also \Jhomogamy\j
\Bheterogeneous\b Having a non-uniform structure or composition; \Bheterogeneity\b; See also \Jhomogeneous\j
\Bheterogenesis\b 1: Spontaneous generation. 2: Alternation of generations; See also \Jhomogenesis. 3: The appearance of a mutant in a population; \Bheterogenetic. \\j
\BHeterogloeales\b Order of non-motile algae (Xanthophyceae) lacking both flagella and pseudopodia; includes solitary and colonial forms which may be free-living or attached in freshwater or marine habitats.
\Bheterogonic life cycle\b 1: A cycle of alternating parthenogenetic and sexually reproducing phases. 2: A cycle involving an alternation of a parasitic and a free-living generation; See also \Jhomogonic life cycle\j
\Bheterogony\b 1: Allometric \Jgrowth\j; \Bheterogonic\b. 2: Cyclic parthenogensis with an alternation of one or more parthenogenetic generations with a bisexual (amphigonic) generation.
\Bheterograft\b Tissue transplanted from one organism to another of a different species.
\Bheterometabolic\b Having a pattern of development exhibiting an incomplete metamorphosis.
\Bheteromixis\b Sexual reproduction in fungi involving the union of nuclei with different genetic constitutions, each from a different fungal thallus; See also \Jhomomixis\j
\Bheteromorphic\b Having different forms at different times or at different stages of the life cycle; used of a plant having an alternation of vegetatively dissimilar generations; \Bheteromorphous\b, \Bheteromorphy\b; See also \Jhomomorphic\j
\Bheteromorphosis\b Regeneration of a part following injury, with a structurally different replacement part.
\BHeteromyidae\b Kangaroo rats, pocket mice; family containing about 75 species of small nocturnal terrestrial rodents found in arid habitats of Nearctic and Neotropical regions; cheek pouches present; tail elongate; hindlimbs longer than forelimbs, adapted for ricochetal locomotion; feed mainly on seeds.
\BHeteromyota\b Monotypic order of echiuran marine worms in which the longitudinal muscles of the trunk body wall are outside the circular and oblique layers; up to 400 unpaired nephridia present.
\BHeteronematales\b Order of colourless, phagotrophic euglenoid flagellates, possessing a complex ingestion apparatus.
\BHeteronemertea\b Order of anoplan nemerteans with 3 or more layers of body wall muscles and with the main components of the nervous system located between the outer longitudinal and middle circular muscle layers; typically found in marine sediments, beneath boulders or amongst algal holdfasts; Heteronemertini.
\Bheterophagous\b Feeding on a wide variety of food items; used of a parasite utilizing a wide variety of hosts; \Bheterophage\b, \Bheterophagy.\b
\Bheterophyte\b 1: A plant occurring in a wide range of habitats. 2: A \Jdioecious\j plant. 3: A parasitic plant devoid of chlorophyll.
\BHeteropneustidae\b Family of freshwater catfishes (Siluriformes) comprising 2 species, found in stagnant pools and swamps from India to China; body elongate, compressed, to 700 mm in length, head depressed and armoured; dorsal and adipose fin reduced; 4 pairs of barbels present; accessory organ connected to gill chamber for aerial respiration.
\BHeteropoda\b Heteropods; a group of mainly planktonic marine snails (Mesogastropoda) which are free-swimming predators in near surface oceanic waters; characterized by a reduced or absent shell, a foot modified into a fin for swimming and a powerful proboscis for seizing prey.
\BHeteroptera\b The bugs (Insecta) classified as a suborder of the order Hemiptera; now treated as an order under the name \JHemiptera\j
\BHeterosiphonales\b Class of Xanthophyta, including forms with a large multicellular thallus attached to the substrate by branched rhizoids; some producing resistant cysts.
\Bheterosis\b Hybrid vigour; the increased vigour resulting from hybridization when measured against either parental stock.
\Bheterosporous\b Having two kinds of spores, such as microspores and megaspores, that give rise to distinct male and female gametophyte generations, respectively; \Bheterosporic\b, \Bheterospory\b; See also \Jhomosporous\j
\BHeterostraci\b Alternative name for the \JPteraspidimorphi\j
\Bheterostyly\b A polymorphism of flowers in which the length of the style and stamens varies between individuals of a species, helping to prevent self-pollination; See also \Jhomostyly\j
\BHeterotardigrada\b Order of freshwater, marine and terrestrial tardigrades comprising about 175 species; head bearing appendages and lateral cirri; legs often digitate with simple claws or adhesive disks; feed mostly on algae or detritus.
\Bheterothallism\b A mode of reproduction in fungi and algae which involves the interaction of two thalli, each haploid thallus being self-incompatible; the thalli may exhibit distinct sexual differentiation into male and female (morphological heterothallism) or may be structurally similar (physiological heterothallism); \Bheterothallic\b, \Bheterothallous\b; See also \Jhomothallism\j
\Bheterotopic\b Occurring in a wide variety of habitats.
\BHeterotrichales\b A class of Xanthophyta, including many complex multicellular types, most of which are filamentous.
\BHeterotrichida\b Order of spirotrich ciliates containing large, often contractile forms, commonly with a dense, uniform covering of body cilia; found in free-living aquatic or soil habitats and occasionally in symbiotic associations.
\Bheterotrophic\b 1: Obtaining nourishment from exogenous organic material; used of organisms unable to synthesize organic compounds from inorganic substrates; \Bheterotroph\b; see also \Jautotrophic. 2: Used of plants occurring in a wide range of habitats on a wide variety of soil types\j \Jan
\Bheteroxenous\b Used of a parasite occupying more than one host during its life cycle; \Bheteroxeny\b; see also \Jdixenous\j \Jmonoxenous\j, \Joligoxenous\j, \Jtrixenous\j
\Bheterozygote\b A diploid individual formed by the fusion of gametes carrying different alleles at a given locus and which produces two kinds of gametes differeing with respect to the allele at that locus; See also \Jhomozygote\j
\Bheterozygous\b Having two different alleles at a given locus of a chromosome pair; \Bheterozygosis\b, \Bheterozygosity\b; See also \Jhomozygous\j
\BHexacorallia\b \JZoantharia\j
\BHexactinellida\b Glass sponges; class of sponges with a skeleton composed of 6-rayed siliceous spicules which are sometimes fused into a reticulum; found chiefly in deeper oceans at depths of 200-2000 m but known to penetrate below 6000 m.
\BHexactinosida\b Order of hexasterophoran sponges characterized by a rigid skeleton made up of 6-rayed spicules fused together by secondary deposits of silica enveloping adjacent rays; found in deep oceans down to a depth in excess of 4000 m.
\BHexagrammidae\b Greenlings, lingcod; family of bottom-living North Pacific marine scorpaeniform teleost fishes; body elongate, to 1.5 m in length; contains 10 species, some locally common and including important commercial and sporting species.
\BHexamerocerata\b Monofamilial suborder of tropical pauropods comprising 7 species; body with 11 pedigerous segments, antennae strongly telescopic, mandibles modified for grinding, tracheae present; feed on fungi and/or as predators on other solid food.
\BHexanchidae\b Cow sharks; family containing 6 species of hexanchiform sharks showing many primitive features; mostly benthic in tropical and subtropical waters to 2000 m depth, feeding on fish and crustaceans but also taking larger prey such as dolphins; body length 2-8 m, dorsal fin tall, mouth large, subterminal.
\BHexanchiformes\b Small order of medium-sized (2-8 m) benthic marine squalomorph sharks; body stout to slender, moderately compressed, with anal fin and single spineless dorsal fin; rostrum trough-shaped; notochord poorly constricted with only weakly calcified vertebral centra.
\BHexapoda\b An alternative name for the Insecta.
\BHexasterophora\b Subclass of hexactinellid sponges which are commonly firmly fixed to a hard substratum, but occasionally rooted by anchoring spicules; comprises 3 orders, Hexactinosida, Lychniscosida and Lyssacinosida; includes Venus' flower basket.
\Bhibernaculum\b The \Jdomicile\j in which an animal hibernates or overwinters.
\Bhibernal\b Pertaining to the winter; see also \Jaestival\j \Jhiemal\j, \Jserotinal\j, \Jvernal\j
\Bhibernation\b The act or condition of passing the winter in a torpid or resting state; See also \Jaestivation\j
\Bhibiscus\b \JMalvaceae\j
\Bhickory\b \JJuglandaceae\j
\Bhidroplankton\b Planktonic organisms that achieve buoyancy by means of surface secretions.
\Bhiemal\b Pertaining to the winter; see also \Jaestival\j \Jhibernal\j, \Jserotinal\j, \Jvernal\j
\Bhigh tide\b High water; the maximum height of the incoming tide.
\Bhigh water (HW)\b High tide; the highest surface water level reached by the rising tide.
\Bhigher high water (HHW)\b The higher of two high waters during any tidal day in areas where there are marked inequalities of tidal height.
\Bhigher low water (HLW)\b The higher of two low \Jwaters\j during any tidal day in areas where there are marked inequalities of tidal height.
\BHimantandraceae\b A primitive family of flowering plants (Magnoliales) consisting of a single genus of large, aromatic trees native to New Guinea, the Moluccas and northeast Australia; flowers with 2 sepals, 4 petals and numerous stamens and carpels.
\BHimantolophidae\b Footballfishes; family containing 4 species of piscivorous anglerfishes (Lophiiformes); body globose, to 600 mm length, spinose in male, armoured with bony plates in female; males free-living but much smaller than females, teeth absent; lure very large and branched in female.
\BHiodontidae\b Mooneyes; family of primitive North American freshwater teleost fishes; body compressed, herring-like, to about 0.5 m length; comprises 2 species, popular locally as game and food-fishes.
\Bhip\b A type of false fruit (pseudocarp) typical of roses, in which the receptacle of the flower is cup-shaped and contains numerous \Jachenes\j
\BHippocastanaceae\b Horse chestnut, buckeye; family of Sapindales containing only 13 species of shrubs and trees with palmately compound leaves and large seeds with a hard coat; flowers with 5 sepals, 4 or 5 petals, 5-8 stamens and a superior ovary, arranged in showy inflorescences.
\BHippocrateaceae\b Family of Celastrales containing about 300 species of woody plants typically with latex canals; widespread in tropical regions.
\BHippopotamidae\b Hippopotamuses; family containing 2 species of large herbivorous, amphibious ungulates (Artiodactyla) found in the Ethiopian region; incisors and canines tusk-like; feet bearing 4 digits, hooves vestigial; stomach 3-chambered; feed on land by night, spending daytime in water.
\BHipposideridae\b Old World leaf-nosed bats; family of tropical, insectivorous bats in which the nose has a prominent leaf and the nostrils open at the centre of a disk.
\BHippuridaceae\b Mare's tail; family of Callitrichales containing a single, widely distributed, species of aquatic, perennial, rhizomatous herb producing small wind-pollinated flowers on erect stems.
\BHippuritoida\b Rock oysters; order of marine heterodont bivalve molluscs found widely in tropical waters; typically filter-feeders characterized by unequal shell valves one of which is cemented to the substratum.
\BHirudinea\b Leeches; subclass of clitellate worms (Hirudinoidea) comprising 2 orders, Rhynchobdellae and Arhynchobdellae; typically blood feeders on vertebrate hosts; body highly contractile, composed of 34 segments; several species of veterinary and medical importance.
\BHirudinidae\b Swallows; cosmopolitan family containing about 80 species of small swift-flying passerine birds that feed on insects caught on the wing; wings long and pointed, tail commonly forked; legs short; bill small and flattened with broad gape; habits gregarious, often migratory; nest in crevices, burrows, or in cup-shaped mud nest on rockface.
\BHirudinoidea\b Class of clitellate worms (Annelida) comprising about 500 species in 3 subclasses, Branchiobdellida, Acanthobdellida and Hirudinea (leeches); body length 3-250 mm, with fixed number of segments each divided into rings (annuli); one or both ends bearing suckers; typically hermaphroditic employing cross fertilization; habits terrestrial, freshwater or marine, predacious or parasitic, mostly on vertebrates.
\Bhistology\b The branch of anatomy dealing with the structure of tissues; \Bhistological. \b
\Bhistophilous\b Inhabiting living host tissue; parasitic.
\Bhistophyte\b A parasitic plant.
\BH-layer\b The heavily transformed humus layer of a soil with no macroscopic plant remnants and having a strong mineral particle intermix; humified layer; see soil horizons.
\Bhoatzin\b \JOpisthocomidae\j
\BHolacanthida\b Order of simple acantharians in which 10 diametral spines are simply crossed in the centre of the organism.
\Bholandric\b Occurring only in males; used of a character carried on the Y chromosome in the heterogametic male sex; \Bholandry\b; See also \Jhologynic\j
\BHolarctic\b A zoogeographical region comprising the Palaearctic and Nearctic regions.
\Bholard\b The total water content of the soil; see also \Jchresard\j \Jechard\j
\Bholaspis\b Late larval stage of trilobites in which trunk segmentation was distinct and the body had the basic adult configuration.
\BHolasteroida\b Order of irregular echinoids with an elongate apical system; first appearing as fossils in the Lower Cretaceous.
\BHolectypoida\b Order of shallow tropical echinoids (Gnathostomata) comprising only 3 extant species, but having rich fossil record; test circular but anus displaced from aboral pole to a position adjacent to the mouth; spines simple, erect and numerous.
\Bholendophyte\b A parasitic plant which passes its entire life within its host.
\Bholeuryhaline\b Used of organisms that freely inhabit fresh water, sea water and brackish water; see also \Jeuryhaline\j \Joligohaline\j, \Jpolystenohaline\j, \Jstenohaline\j
\Bholly\b \JAquifoliaceae\j
\Bhollyhock\b \JMalvaceae\j
\BHolocene\b A geological epoch within the Quaternary period (\Ic.\i 10 000 years B.P. to the present time); Recent; see geological time scale.
\BHolocentridae\b Squirrelfishes, soldierfishes; family containing 70 species of tropical marine beryciform teleosts, nocturally active on rocky bottoms and reefs; body elongate, compressed, scales ctenoid; eyes large, teeth minute.
\BHolocephalii\b Subclass of cartilaginous fishes (Chondrichthyes) comprising the single order \JChimaeriformes\j
\Bholocyclic parthenogenesis\b Reproduction by a series of parthenogenetic generations alternating with a single sexually reproducing generation; See also \Jparthenogenesis\j
\Bhologamodeme\b A local interbreeding population comprising all those individuals which are able to interbreed with a high level of freedom; See also \Jdeme\j
\Bhologamy\b A mode of reproduction in protistans involving gametes similar in size to the vegetative cell; See also \Jmerogamy\j
\Bhologynic\b Occurring only in females; used of sex-linked characters in species with a heterogametic female sex; \Bhologyny\b; See also \Jholandric\j
\BHolometabola\b The largest superorder of neopteran insects comprising 9 orders, Neuroptera (alderflies, lacewings), Coleoptera (beetles), Strepsiptera, Hymenoptera (wasps, bees), Mecoptera (scorpion flies), Siphonaptera (fleas), Diptera (true flies), Trichoptera (caddis flies) and Lepidoptera (butterflies, moths); morphology exceptionally diverse; wings paired, or one pair specialized as balance organs, or wings absent; mouthparts mandibulate; metamorphosis complete, life cycle comprising distinct, larval and pupal stages; Neuropterodea; Endopterygota.
\Bholometabolous\b Used of the pattern of development which is characterized by a distinct metamorphosis with well defined larval and adult stages; \Bholometaboly\b; see also \Jametabolous\j \Jhemimetabolous\j
\Bholomictic\b Used of a lake having complete free circulation throughout the water column at the time of winter cooling; See also \Jmictic\j
\Bholoparasite\b A parasite that cannot survive away from its host; an obligate parasite; See also \Jmeroparasite\j
\Bholopelagic\b Used of aquatic organisms that remain pelagic throughout the life cycle; See also \Jmeropelagic\j
\Bholophytic\b Synthesizing organic compounds from inorganic substrates in the manner of a green plant; photosynthetic; \Bholophyte\b; See also \Jholozoic\j
\Bholoplankton\b Those organisms that are permanent members of the plankton; \Bholoplanktonic\b; See also \Jmeroplankton\j
\Bholosaprophyte\b A plant deriving nourishment entirely from decomposing organic matter; obligate saprophyte.
\BHolostei\b Loose assemblage of primitive bony fishes (Osteichthyes) comprising the Amiiformes (bowfin) and the Semionotiformes (gars).
\Bholostylic\b The condition in which the hyomandibular plays no part in the suspension of the lower jaw in fishes, since the palatoquadrate arch is fused with the cranium; see also \Jamphistylic\j \Jautostylic\j, \Jhyostylic\j
\BHolothuroidea\b Sea cucumbers; class of echinozoan echinoderms in which the axis of radial pentamerous symmetry is horizontal; the test is typically soft with microscopic skeletal ossicles, usually sausage-shaped but occasionally spherical or flattened; mouth at oral pole surrounded by up to 30 tentacles, anus at opposite, aboral, end; sexes separate, fertilization external, hermaphroditism and viviparity rare; development may incorporate planktonic auricularia or vitellaria larvae; sea cucumbers are widespread, epifaunal to infaunal, littoral to hadal, and in the deep sea may comprise large part of benthic biomass; 3 subclasses recognized, Dendrochirotacea, Aspidochirotacea and Apodacea.
\BHolotrichia\b Diverse assemblage of ciliates, formerly classified as a subclass but not now used; most are included in the \JKinetofragminophora\j
\Bholotrophic\b 1: Used of a plant which synthesizes all organic compounds from inorganic substrates, typically by photosynthesis. 2: Used of a predator that utilizes only one species of prey organism.
\Bholozoic\b Feeding entirely in the manner of an animal by ingesting complex organic matter; See also \Jholophytic\j
\BHolsteinian interglacial\b An interglacial period in the middle of the Quaternary Ice \JAge\j in northern Germany and Poland.
\BHomalopteridae\b Hillstream loaches; family containing 85 species of mostly small (to 130 mm) cypriniform teleost fishes found in fast flowing hill streams of India and southeast Asia; body anteriorly depressed, 3 or 4 pairs of barbels present; paired fins may form sucker; gas bladder partly enclosed in bony capsule; includes Gastromyzontidae sometimes treated as a distinct family.
\BHomalorhagida\b Order of kinorhynchs found mostly in marine muddy sediments from the subtidal down to several thousand metres; characterized by a neck consisting of 6-8 plates, by the cavity of the pharynx which is triangular in cross-section and by the lack of articulated spines on the trunk.
\BHomalozoa\b Extinct subphylum of echinoderms that exhibit no trace of radial symmetry; known from the Cambrian to the Devonian; Homoalozoa.
\Bhome\b That part of the habitat of an organism that is utilized for resting and breeding; See also \Jhotel\j
\Bhome range\b The area, usually around the domicile, over which an animal normally travels in search of food; See also \Jterritory\j
\Bhome site\b The location of the domicile or resting place regularly used by a particular animal.
\Bhomeostasis\b The maintenance of a relatively steady state or equilibrium in a biological system by intrinsic regulatory mechanisms; \Bhomeostatic.\b
\Bhoming\b The behavioural act of returning to an original location.
\BHominidae\b Humans; family of omnivorous terrestrial primates comprising a single Recent species, \IHome sapiens\i, and the extinct australopithecines.
\Bhomiogamy\b The union of two gametes of the same sex; \Bhomiogamic.\b
\Bhomobium\b The symbiosis between a fungus and an alga in a lichen.
\Bhomochronous\b Occurring at the same time, or age in successive generations; simultaneous.
\Bhomoecious\b 1: Used of a parasite occupying the same host throughout its life cycle; See also \Jheteroecious. 2: Host-specific\j
\Bhomoeosis\b The modification of one segmental appendage or structure to resemble a different appendage or structure of the same homologous series.
\Bhomogamete\b The gamete produced by the homogametic \Jsex\j
\Bhomogametic\b Having only one kind of gamete; \Bhomogamy\b; See also \Jheterogametic\j
\Bhomogametic sex\b The sex which is determined by a pair of similar sex chromosomes (X); that sex which produces only one type of gamete; See also \Jheterogametic sex\j
\Bhomogamy\b 1: The simultaneous maturation of male and female reproductive organs in a flower or hermaphrodite organism. 2: The condition of a plant producing only one kind of flower; See also \Jheterogamy\j
\Bhomogeneous\b Similar throughout; of uniform structure or composition; \Bhomogeneity\b; See also \Jheterogeneous\j
\Bhomogenesis\b Non-alternation of generations; the succession of morphologically similar generations; \Bhomogenetic\\Jb;\j heterogenesis.
\Bhomogonic life cycle\b A life cycle in which all generations are either parasitic or free-living; See also \Jheterogonic life cycle\j
\Bhomoiosmotic\b Used of organisms that maintain a relatively constant internal osmotic pressure; See also \Jpoikilosmotic\j
\Bhomoiothermic\b Used of animals that regulate their body temperature independent of ambient temperature fluctuations; warm-blooded; \Bhomoiothermy\b; See also \Jpoikilothermic\j
\Bhomologous\b Used of structures or traits having common ancestry but not necessarily retaining similarity of structure, function or behaviour; \Bhomology\b; See also \Janalogous\j
\Bhomologous chromosomes\b Structurally similar chromosomes having identical genetic loci in the same sequence and which pair during nuclear division.
\Bhomolotropism\b Growth orientation in a horizontal direction; \Bhomolotropic.\b
\Bhomomixis\b Sexual reproduction in fungi involving the union of genetically similar nuclei from one thallus; See also \Jheteromixis\j
\Bhomomorphic\b Used of a plant with a dimorphous life cycle in which two different types of individuals in the life cycle are morphologically similar; isomorphic; \Bhomomorphous\b, \Bhomomorphy\b; See also \Jheteromorphic\j
\Bhomoplasy\b Structural resemblance due to parallelism or convergent evolution rather than to common ancestry; \Bhomoplasia.\b
\BHomoptera\b Order of phytophagous hemipterodean insects comprising about 45 000 species including cicadas, plant/frog/leaf/tree hoppers, psyllids, whiteflies, aphids, coccoids, scale insects and mealybugs; often classified as a subgroup of Hemiptera; hindlegs commonly saltatory; mouthparts modified for piercing and sucking; many species are plant pests or disease vectors.
\BHomoscleromorpha\b Primitive subclass of demosponges found in shallow marine waters from the intertidal zone down to 500 m; characterized by a skeleton of equal-rayed, 4-axonid siliceous spicules, and by viviparity as they produce an amphiblastula larva; comprises a single order, Homosclerophorida.
\Bhomosporous\b Having only one kind of spore; isosporous; \Bhomospory\b; See also \Jheterosporous\j
\Bhomostyly\b The condition in which all the flowers of a species have styles of similar length; See also \Jheterostyly\j
\Bhomothallism\b A mode of reproduction in fungi and algae in which each thallus produces both male and female sex cells, and is self-fertile; \Bhomothallous\b; See also \Jheterothallism\j
\Bhomotropic\b Used of a flower fertilized by its own pollen.
\Bhomozygote\b An individual with identical alleles at the two homologous loci of a chromosome pair; See also \Jheterozygote\j
\Bhomozygous\b Having identical alleles at a given locus of a chromosome pair; See also \Jheterozygous\j
\Bhonesty\b \JBrassicaceae\j
\Bhoney bee\b \JApidae\j
\Bhoney locust\b \JCaesalpiniaceae\j
\Bhoney possum\b \JTarsipedidae\j
\Bhoneycreeper\b \JDrepanididae\j
\Bhoneyeater\b \JMeliphagidae\j
\Bhoneyguide\b \JIndicatoridae\j
\Bhoneysuckle\b \JCaprifoliaceae\j
\Bhoning\b The process of tooth sharpening.
\Bhook order\b A social dominance hierarchy found in horned mammals established by the aggressive use of horns.
\BHookeriales\b Order of mosses (Bryidae) occurring mostly in southern hemisphere and tropics; typically yellowish-green, often shiny, mat-forming perennial plants found in moist shady forests.
\Bhoopoe\b \JUpupidae\j
\Bhop\b \JCannabaceae\j
\BHoplestigmataceae\b Small family of Violales containing only 2 species of trees, native to tropical Africa.
\BHoplichthyidae\b Ghost flathead; family of little-known Indo-Pacific deep-water scorpaeniform teleost fishes; body elongate, head broad and depressed, naked.
\BHoplocarida\b Mantis shrimps; subclass of large, predatory marine malacostracan crustaceans comprising a single extant order, Stomatopoda.
\BHoplonemertea\b Order of enoplan nemerteans in which the proboscis is regionally differentiated and armed with one or more stylets; typically found free-living in marine habitats but some freshwater and terrestrial representatives are known.
\BHoraichthyidae\b Monotypic family of tiny (to 30 mm) freshwater cyprinodontiform teleost fishes from India; body translucent, anal fin in male modified as gonopodium for sperm transfer; right pelvic fin absent in female; reproduction oviparous, fertilization internal.
\Bhorehound\b \JLamiaceae\j
\Bhorizon\b Any horizontal stratum within a sediment, soil profile, water column or geological series.
\Bhormone\b A chemical substance secreted by an endocrine gland, that produces a specific physiological response on some remote target tissue.
\Bhormone weedkillers\b Synthetic organic herbicides that are similar in effect to natural plant hormones (auxins), promoting, retarding or modifying the growth and development of plants.
\Bhornbeam\b \JCorylaceae\j
\Bhornbill\b \JBucerotidae\j
\Bhorned pondweed\b \JZannichelliaceae\j
\Bhorntail\b \JSiricidae\j (Symphyta).
\Bhornwort\b \JAnthocerotopsida\j
\Bhorse\b \JEquidae\j
\Bhorse botfly\b \JGasterophilidae\j
\Bhorse chestnut\b \JHippocastanaceae\j
\Bhorse radish\b \JBrassicaceae\j
\Bhorsefly\b \JTabanidae\j
\Bhorsehair worm\b \JNematomorpha\j
\Bhorseshoe bat\b \JRhinolophidae\j
\Bhorseshoe crab\b \JXiphosura\j
\Bhorseshoe worm\b \JPhoronida\j
\Bhorsetail\b \JEquisetophyta\j
\Bhortal\b Used of an ornamental plant that has escaped from cultivation and can be found growing wild.
\Bhospitating\b Offering refuge or acting as a host (hospitator) to another organism (the hospite).
\Bhost\b 1: Any organism that provides food or shelter for another organism; may be a definitive host (infected by the mature adult stage) or an intermediate host (infected by developmental stages). 2: An animal that is the recipient of a tissue graft.
\Bhost specificity\b The extent to which an adult parasite is restricted in the variety of host species utilized.
\Bhot water plant\b \JGesneriaceae\j
\Bhotel\b That part of the habitat of an organism that is used for resting, breeding and feeding; See also \Jhome\j
\Bhottentot fig\b \JAizoaceae\j
\Bhound shark\b \JTriakidae\j
\Bhouse spider\b \JAgelenidae\j
\Bhousefly\b \JMuscidae\j
\Bhouseleek\b \JCrassulaceae\j
\Bhover fly\b \JSyrphidae\j
\Bhowler monkey\b \JCebidae\j
\BHoxnian interglacial\b An interglacial period in the middle of the Quaternary Ice \JAge\j in the British Isles.
\BHuaceae\b Small family of Violales native to tropical Africa; comprises only 3 species of woody plants, each with a characteristic garlic-like odour.
\BHugoniaceae\b Family of Linales containing about 60 species of woody plants widespread in tropical regions.
\BHumboldt Current\b A cold surface ocean current that flows northwards off the Pacific coast of South America, arising from the Antarctic Circumpolar Current and forming part of the South Pacific Gyre; see ocean currents.
\BHumic Gley soil\b An intrazonal soil with a thick peaty surface layer over an underlying gley horizon, formed in forest swamps and wet meadows.
\Bhumic lake\b A lake rich in organic matter mainly in the form of suspended plant colloids and larger plant fragments but having low nutrient content.
\Bhumicolous\b Living on or in the soil; \Bhumicole.\b
\Bhumidity\b The amount of water vapour in the atmosphere.
\Bhumification\b The transformation of dead plant material into humus.
\BHumiriaceae\b Small family of Linales containing about 50 species of evergreen trees and shrubs often with an aromatic juice; found mainly in tropical America.
\Bhummingbird\b \JTrochilidae\j
\Bhumpback whale\b \JBalaenopteridae\j
\Bhumphead\b \JKurtidae\j
\Bhumus\b A dark brown amorphous material formed by the partial decomposition of plant and animal remains; representing the organic constituent of soil although also found in colloidal suspension in water.
\Bhunting spider\b \JLycosidae\j
\Bhusbandry\b The cultivation, production and management of plants and animals; used especially with reference to domesticated species.
\Bhutia\b \JCapromyidae\j
\Bhyacinth\b \JLiliaceae\j
\BHyaenidae\b Hyenas; small family of dog-like terrestrial mammals (Carnivora) comprising 4 species found in Ethiopian, Oriental and southern Palaearctic regions; forelimbs longer than hindlimbs; feed mainly on carrion using powerful jaws.
\BHyaenodontidae\b Extinct family of carnivorous mammals known from most of the Tertiary period; slimly built, with elongated jaws.
\Bhybrid\b Offspring of a cross between genetically dissimilar individuals; in taxonomy, often restricted to the offspring of interspecific crosses.
\Bhybridization\b Any crossing of individuals of different genetic composition, typically belonging to separate species, resulting in hybrid offspring.
\BHydatellales\b Order of Commelinidae comprising a single family of only 5 species of small submerged or emergent aquatic annuals; with naked, unisexual flowers pollinated by water or self-pollinated; native to Australia and New Zealand.
\BHydnoraceae\b Family of Rafflesiales containing only 10 species of leafless herbs lacking chlorophyll which parasitize the roots of other plants and produce large, fleshy and malodorous flowers at the soil surface.
\BHydrangeaceae\b Hydrangea; family of Rosales containing about 170 species of mostly woody plants with large flowers, widespread in temperate and subtropical parts of the northern hemisphere; flowers have 4-10 sepals and petals, 4 or more stamens, a superior ovary and are arranged in cymose inflorescences.
\Bhydrarch succession\b An ecological succession commencing in a habitat with abundant water; hydrosere; see also \Jmesarch succession\j \Jxerarch succession\j
\Bhydroanemophilous\b Having airborne spores that are discharged after wetting of the spore-producing structure; \Bhydroanemophily.\b
\BHydrobatidae\b Storm petrels; cosmopolitan family containing 21 species of oceanic sea birds (Procellariformes); feed mainly on fishes and crustaceans; breed in colonies on islands, nesting in burrows or crevices; single egg per clutch.
\Bhydrobiology\b The study of life in aquatic habitats.
\Bhydrobios\b The sum total of all aquatic life; that part of the Earth's surface occupied by aquatic organisms; see also \Jgeobios\j \Jhalobios\j, \Jlimnobios\j
\Bhydrocarpic\b Used of aquatic plants that are pollinated above water but develop below the surface.
\Bhydrochamaephyte\b An aquatic plant producing renewal buds up to 250 mm from the lake floor; an aquatic chamaephyte.
\BHydrocharitales\b Elodea, turtle grass; order of Alismatidae comprising a single cosmopolitan family of about 100 species of submersed, partly emergent or free-floating perennial herbs found in freshwater or coastal marine habitats; lacking vessels; flowers with 3 sepals and petals.
\Bhydrochimous\b Pertaining to wet winters.
\BHydrochoeridae\b Capybaras; family containing 2 species of large semiaquatic Neotropical hystricomorph rodents; body robust, head large, tail vestigial; feet webbed with strong claws; habits diurnal, herbivorous; capybaras are the largest living rodents, weighing up to 50 kg.
\Bhydrochoric\b Dispersed by the agency of water; \Bhydrochory.\b
\Bhydrochthophyte\b A plant growing normally in water and producing emergent leaves or shoots.
\Bhydrocleistogamy\b Self-pollination in a flower that remains closed because it is submerged; \Bhydrocleistogamic.\b
\Bhydrocolous\b Living in an aquatic habitat; \Bhydrocole.\b
\BHydrocorallina\b Diverse group comprising the milleporine and stylasterine corals; hydrocorals.
\Bhydrogenic soil\b A soil formed under waterlogged conditions.
\Bhydrogeophyte\b An aquatic plant producing renewal buds on a buried rhizome; an aquatic geophyte.
\Bhydrohemicryptophyte\b An aquatic plant producing renewal buds at the water/sediment interface; an aquatic hemicryptophyte.
\BHydroida\b Order of Hydrozoa in which the polyp generation is dominant; most polyps are colonial, connected by a branching stolon system which extends over the substrate; polyps usually have a non-living chitinous exoskeleton, mouth generally surrounded by tentacles; polyps may be polymorphic with feeding gastrozoids and reproductive gonozoids which bud off free medusae; includes some freshwater forms, such as \IHydra\i, but most are marine.
\Bhydrologic cycle\b Water \Jcycle\j
\Bhydromegathermic\b Used of organisms inhabiting warm wet environments, such as tropical rainforests; \Bhydromegatherm.\b
\BHydrometridae\b Water measurer; cosmopolitan family containing about 100 species of slender, stick-like, hemipteran insects found crawling among aquatic vegetation or walking on the surface film of water.
\BHydromyxomycetes\b Alternative name for the Labyrinthulata (slime nets).
\Bhydronasty\b Orientation movement in plants in response to changes in atmospheric humidity; \Bhydronastic.\b
\BHydrophiidae\b Sea snakes; family of venomous marine snakes (Serpentes) with laterally compressed tails, valvular nostrils and salt-secreting glands in the head.
\Bhydrophilous\b 1: Thriving in wet or aquatic habitats; see also \Jhydrophobic. 2: Pollinated by waterborne pollen; \Bhydrophile\b\j \J\B
\Bhydrophobic\b Intolerant of water or wet conditions; water-repellent; \Bhydrophobe\b, \Bhydrophoby\b; See also \Jhydrophilous\j
\BHydrophyllaceae\b Virginian waterleaf, Californian bluebell; family of Solanales containing about 250 species of mostly rough-hairy, herbs, common in dry habitats in western United States; flowers regular with 5 sepals, 5 blue or purple petals, normally 5 stamens and a superior ovary.
\Bhydrophyllium\b In colonial hydrozoan coelenterates (Siphonophora), the shield-like zooid that covers the cormidium.
\Bhydrophyte\b 1: A perennial plant with renewal buds below water and with submerged or floating leaves; see also \JRaunkiaerian life forms. 2: Generally\j \Jany plant adapted to live in water
\Bhydroponics\b A system of plant culture in which the growing plants have their roots immersed in a nutrient rich solution or in an inert substrate which is irrigated with nutrients.
\Bhydrosere\b An ecological succession commencing in a habitat with abundant water, typically on the submerged sediments of a standing water body.
\Bhydrosphere\b The global water mass, including atmospheric, surface and subsurface waters.
\BHydrostachyaceae\b Family of about 20 species of submerged aquatic perennial herbs native to Africa and Madagascar.
\Bhydrostatic pressure\b The pressure exerted by a column of water; pressure increases by about 1 atmosphere per 10 m of depth down a water column.
\Bhydrotaxis\b The directed response of a motile organism towards (positive) or away from (negative) a water or moisture stimulus; \Bhydrotactic.\b
\Bhydrothermal\b Pertaining to hot water; used especially of hot water springs or ocean floor vents.
\Bhydrotribophilous\b Thriving in badlands; \Bhydrotribophile\b, \Bhydrotribophily.\b
\Bhydrotribophyte\b A badlands plant.
\Bhydrotropic\b Exhibiting a trend towards greater water content in an ecological succession.
\Bhydrotropism\b Orientation in response to water; \Bhydrotropic.\b
\BHydrozoa\b Class of marine and occasionally freshwater cnidarians in which the life cycle typically involves alternation between an asexually reproducing, attached polyp and a sexually reproducing, planktonic medusa; medusae usually small and transparent; polyps mostly colonial and arising from stolons, typically with a chitinous, or sometimes calcified, exoskeleton, often polymorphic with individual polyps specialized for different roles; comprises 7 orders.
\Bhygric\b Pertaining to moisture, or to moist or humid conditions.
\BHygrobiidae\b Screech beetles; family of primitive water beetles (Coleoptera) found in muddy pools; bodies highly convex, eyes prominent; swimming by alternate leg movements.
\Bhygrochastic\b Used of a fruit in which dehiscence is induced by moisture; \Bhygrochasy\b; See also \Jxerochastic\j
\Bhygrocolous\b Living in moist or damp habitats; \Bhygrocole.\b
\Bhygrokinesis\b A change in the rate of movement of an organism in response to a change in humidity; \Bhygrokinetic.\b
\Bhygroklinokinesis\b A change in the rate of random movement of an organism expressed as a change in the frequency of turning movements (rate of change of direction) in response to a humidity stimulus; \Bhygroklinokinetic.\b
\Bhygroorthokinesis\b A change in the rate of random movement of an organism expressed as a change in the linear velocity in response to a humidity stimulus; \Bhygroorthokinetic.\b
\Bhygropetric\b Used of an organism living in the surface film of water on rocks.
\Bhygrophilous\b Thriving in moist habitats; \Bhygrophile\b, \Bhygrophily\b; See also \Jhygrophobic\j
\Bhygrophobic\b Intolerant of moist conditions; \Bhygrophobe\b, \Bhygrophoby\b; See also \Jhygrophilous\j
\Bhygrophyte\b A plant living in a wet or moist habitat, typically lacking xeromorphic features; \Bhygrophytic\b; see also \Jhydrophyte\j \Jmesophyte\j, \Jxerophyte\j
\Bhygroscopic\b Readily absorbing and retaining moisture from the atmosphere; \Bhygroscopicity.\b
\Bhygrotaxis\b The directed response of a motile organism to moisture; \Bhygrotactic.\b
\Bhygrotropism\b Orientation in response to humidity or moisture; \Bhygrotropic.\b
\Bhylacolous\b Living among trees, or in woodland or forest; \Bhylacole.\b
\BHylidae\b Diverse family containing about 400 species of New World tree frogs (Anura); typically arboreal, few species terrestrial and fossorial, eggs and larvae usually aquatic; some species lay eggs on vegetation over water, others carry eggs in pits on back of female and have direct or attenuated development; widespread in tropical and temperate Americas and West Indies, with small group of species in tropical Eurasia.
\BHylobatidae\b Gibbons; family containing 6 species of arboreal primates (Catarrhini) found in southeast Asia and Indonesia; limbs elongate, forelimbs longer than hindlimbs, adapted for brachiation; tail absent; ischial callosities present; feed on variety of plant and animal material.
\Bhylodophilous\b Thriving in dry open woodland; \Bhylodophile\b, \Bhylodophily.\b
\Bhylodophyte\b A dry open woodland plant.
\Bhylophagous\b Feeding on wood; \Bhylophage\b, \Bhylophagy.\b
\Bhylophilous\b Living or thriving in forests; \Bhylophile\b, \Bhylophily.\b
\Bhylotomous\b Used of wood-cutting insects.
\BHymenogastrales\b Small order of gasteromycete fungi; often in mycorrhizal association with roots of green plants but sometimes found growing with algae on damp soil; produce underground fruiting bodies.
\BHymenomycetes\b Class of basidiomycotine fungi in which the basidia are organized into a fertile layer (hymenium) that is exposed at maturity; comprises 2 orders, Exobasidiales and Agaricales.
\BHymenoptera\b Diverse order of holometabolous insects comprising 130 000 species in 2 suborders, Symphyta and Apocrita, including sawflies, horntails, wasps, bees, ants, and many other groups; adults mandibulate, typically with 2 pairs of membranous wings; hindwings small, but may be vestigial or absent; larval morphology and habits very diverse; sociality widely exhibited.
\BHymenostomata\b Subclass of Oligohymenophora, most of which occur as free-living freshwater forms, but some are marine and a few endosymbiontic; possessing compound ciliary organelles in the buccal area.
\BHymenostomatida\b Order of hymenostome ciliates occurring mainly in freshwater and soil habitats, typically free-living but some symbiotic mainly with invertebrate hosts; includes \IParamecium\i and \ITetrahymena\i.
\BHynobiidae\b Family containing about 30 species of small primitive Asiatic salamanders; fore and hindlimbs present; metamorphosis complete; adults typically terrestrial, larvae aquatic with external gills and caudal fins; fertilization external, spermatophores absent.
\BHyolithida\b Extinct order of molluscs (Calyptoptomatida) with pyramidal shells; known from the Cambrian to the Permian.
\Bhyostylic\b The condition in which the hyomandibular is the principal suspensional element for the lower jaw in fishes; see also \Jamphistylic\j \Jautostylic\j, \Jholostylic\j
\Bhyperbenthic\b Living above but close to the substratum; \Bhyperbenthos\b; see also \Jendobenthic\j \Jepibenthic\j
\BHyperiidea\b Suborder of exclusively marine pelagic amphipod crustaceans commonly found in association with gelatinous zooplankton such as salps, medusae and siphonophores; body elongate or globular; head large, typically with massive compound eyes.
\BHypermastigida\b Order of large zooflagellates with numerous flagella, often arranged in a characteristic pattern, and a single nucleus; all are anaerobic and inhabit the hindguts of cockroaches and termites where they play an important role in the digestion of wood.
\Bhypermetamorphic\b Used of an organism having two or more distinct metamorphoses in the life cycle or having an extensive metamorphosis; \Bhypermetamorphosis. \b
\BHyperoliidae\b Family of mostly small (to 50 mm) frogs (Anura) from Africa, Madagascar and Seychelles Islands; eggs typically laid on vegetation over still water; tadpoles aquatic.
\BHyperotreti\b \JMyxiniformes\j
\Bhyperparasite\b An organism parasitic upon another parasite; superparasite; \Bhyperparasite\b, \Bhyperparasitism.\b
\Bhyperplasia\b Excessive growth due to increase in cell number; \Bhyperplastic\b; See also \Jhypertrophy\j
\Bhypersaline\b Having a high salinity, well in excess of normal sea water, typical of enclosed bodies of water with high evaporation rates.
\Bhypertrophication\b Over-enrichment with nutrients; \Bhypertrophicated.\b
\Bhypertrophy\b Excessive growth due to increase in cell size; See also \Jhyperplasia\j
\BHyphochytridiomycetes\b Class of microscopic true fungi which parasitize algae and aquatic fungi or live as saprobes on plant debris; characterized by asexual reproduction involving the production of motile zoospores possessing an anterior tinsel-type flagellum; thallus unicellular or filamentous; hyphae sometimes with cross walls; also classified as the phylum Hyphochytridiomycota of the Protoctista.
\BHyphochytridiomycota\b \JHyphochytridiomycetes\j; treated as a phylum of Protoctista.
\BHyphomycetales\b Large order of hyphomycete fungi containing over 6000 species of mostly saprophytic forms, sometimes parasitic on plants and animals; vegetative and fertile hyphae are septate and loosely arranged at the surface of the colony, not forming an organized fruiting body.
\BHyphomycetes\b An artificial class of deuteromycotine fungi containing the asexual states of ascomycotine and basidiomycotine fungi in which the reproductive hyphae and the propagative spores (conidia) are not formed inside an enclosed structure; comprises 4 orders, Hyphomycetales, Stilbellales, Tuberculariales and Agonomycetales.
\Bhyphydrogamous\b Having waterborne pollen transported below the water surface; See also \Jephydrogamous\j
\BHypnidae\b Monotypic family of shallow-water torpediniform fishes from Australia; body disk broader than long containing very powerful electric organs, tail short bearing 2 small dorsal fins; pelvics enlarged and united ventrally; mouth large, teeth tricusped.
\BHypnobryales\b Large order of mosses (Bryidae); typically large perennial, mat-forming plants growing on soil, logs, humus and rocks, commonly found in forested habitats in the northern hemisphere; stems prostrate to erect, variously branched, spore capsule typically asymmetrical and inclined on long stalk.
\Bhypnody\b A prolonged resting period (diapause) during development; \Bhypnodic.\b
\Bhypnoplasy\b Arrested development resulting in failure to reach normal size.
\Bhypnosis\b A state of dormancy in seeds that retain the capacity for normal development; \Bhypnotic.\b
\Bhypobiosis\b The condition in which only minimal outward signs of metabolic activity are present in a dormant organism.
\Bhypobiotic\b Living in sheltered microhabitats.
\Bhypocarpogean\b Producing subterranean fruit; \Bhypocarpogenous\b; See also \Jamphicarpogean\j
\BHypocreales\b Large order of pyrenomycete fungi containing many pathogens, including apple canker and pea and bean wilt, some saprobic forms and some parasites of other fungi; typically with persistent asci and forcibly discharged ascospores; ascocarps usually brightly coloured, often fleshy.
\Bhypogean\b Living or germinating underground; \Bhypogeous.\b
\Bhypogenous\b Living or growing underneath an object or on its lower surface.
\Bhypogyny\b The typical arrangement of the parts of a flower in which the sepals, petals and stamens are inserted below the ovary (a superior ovary); \Bhypogynous\b; see also \Jepigyny\j \Jperigyny\j
\Bhypolimnion\b The cold bottom water zone below the thermocline in a lake; \Bhypolimnetic\b; See also \Jepilimnion\j
\Bhypolithic\b Living beneath rocks or stones.
\Bhyponasty\b Upward growth; \Bhyponastic.\b
\Bhyponeuston\b Organisms living immediately below the surface film of a water body; a component of the neuston; \Bhyponeustonic\b; See also \Jepineuston\j
\Bhypophloeodal\b Living or occurring immediately below the surface of bark; \Bhypophloeodic. \b
\BHypophthalmidae\b Monotypic family of large planktotrophic tropical South American freshwater catfishes (Siluriformes); body naked, dorsal fin with stout spine, anal fin elongate; 3 pairs of barbels present; gill rakers long and complex.
\Bhypophyllous\b Growing on the lower surface of leaves.
\BHypoptychidae\b Sand eel; monotypic family of small (to 80 mm) shallow marine gasterosteiform teleost fishes found in the western North Pacific; body elongate, upper jaw protractile, scales and pelvic fins absent.
\Bhyporheic\b Pertaining to saturated sediments beneath or beside streams and rivers.
\BHyposittidae\b Coral-billed nuthatch; family of passeriform birds comprising a single species from Madagascar; bill stout, hook-tipped; feeds on insects gleaned from trees.
\BHypostomata\b Subclass of kinetofragminophoran ciliates characterized by the basically ventral position of the cytostome and its associated cytopharyngeal basket; contains free-living, microphagous or algivorous forms as well as many commensals and parasites.
\Bhypothermia\b The condition of a homoiothermic animal which has a lower than normal temperature; \Bhypothermic.\b
\BHypotremata\b Rays; an older name used either for the order Rajiformes or for the superorder Batoidea.
\BHypotrichida\b Order of dorsoventrally flattened spirotrich ciliates which exhibit a unique type of creeping-darting locomotion; mostly free-living in various habitats but a few are commensals.
\Bhypsilophodont\b A bipedal ornithischian dinosaur known from the Upper Triassic to the Upper Cretaceous.
\BHypsithermal period\b A postglacial interval (\Ic.\i 9000-2500 years B.P.) during which mean temperatures were above those existing at the present time; equivalent to Boreal, Atlantic and Subboreal periods combined; See also \JXerothermal period\j
\BHyracodontidae\b Extinct family of long-legged, browsing rhinoceroses known from the Eocene to the Miocene; teeth similar to modern rhinoceroses; 3 toes on each foot.
\BHyracoidea\b Order of herbivorous mammals (Ferungulata) comprising a single extant family, Procaviidae (hyraxes).
\Bhyrax\b \JProcaviidae\j
\BHysteriales\b Order of loculoedaphomycetid fungi containing saprobic, epiphytic, parasitic or lichenized forms; typically apothecioid with bitunicate asci.
\Bhysterophyte\b A plant obtaining nourishment from dead or decaying organic matter; saprophyte; \Bhysterophytic.\b
\BHystricidae\b Old World porcupines; family containing 15 species of small to large herbivorous terrestrial hystricomorph rodents in which the body is covered by stiff unbarbed spines; found primarily in the Oriental and Ethiopian regions; habits nocturnal, feeding on roots, bulbs and fruit.
\BHystricomorpha\b Diverse suborder of rodents comprising 17 families and including porcupines, guinea-pigs, viscachas and chinchillas; widespread in Neotropical region but also found throughout the Old World.
\Bibis\b \JThreskiornithidae\j
\BIcacinaceae\b Family of Celastrales containing about 400 species of woody plants with a mainly tropical distribution; flowers typically unisexual, fruit commonly a drupe.
\Bicefish\b \JSalangidae\j
\BIcelidae\b Family containing 5 species of small (to 100 mm) Arctic-boreal shallow marine sculpins (Scorpaeniformes); body slender; gill cover membrane united below the throat.
\Bichneumon fly\b \JIchneumonidae\j
\BIchneumonidae\b Ichneumon flies; diverse family containing about 15 000 species of usually slender parasitic wasps (Hymenoptera) in which the female often has a conspicuous elongate ovipositor; eggs typically deposited on the larvae or pupae of holometabolous insects, but also on spiders or their eggs, on which the ichneumon larvae feed as internal or external parasitoids.
\Bichnite\b A fossil track or footprint; ichnolite.
\Bichnocoenosis\b An assemblage of trace fossils; \Bichnocoenose.\b
\Bichnofauna\b The animal traces of an area.
\Bichnoflora\b The plant traces of an area.
\Bichnofossil\b A trace fossil.
\Bichnology\b The study of traces made by organisms, both fossil and recent.
\Bichthyofauna\b The fish fauna of a given region.
\Bichthyology\b The study of fishes; \Bichthyological.\b
\Bichthyoneuston\b The ichthyological component of the neuston, typically fish eggs or fry; \Bichthyoneustont.\b
\Bichthyophagous\b Feeding on fishes; piscivorous; \Bichthyophage\b, \Bichthyophagy. \b
\BIchthyophiidae\b Family of terrestrial Asiatic caecilians (Gymnophiona); body length to 500 mm, scales reduced, may be absent anteriorly small tail present; larvae aquatic with branched gills; feed at night on worms and arthropods; contains about 30 species found in southeast Asia, from India to Borneo.
\BIchthyosauria\b Order of typically shark-like aquatic reptiles known from the Triassic to the Cretaceous.
\BIcosteidae\b Ragfish; monotypic family of bathypelagic perciform teleost fishes from the North Pacific; body slender, to 2 m in length, strongly compressed, naked; pelvic fins absent in adults; skeleton mostly cartilaginous.
\BIctaluridae\b Family containing about 40 species of small to medium-sized (to 1.6 m) freshwater catfishes (Siluriformes) native to eastern North America; body smooth, dorsal fin short with stout spine; some have venom gland at base of pectoral fin; 4 barbels present around mouth; adipose fin large; some species important in pond aquaculture.
\BIcteridae\b Blackbirds, orioles, cowbirds; diverse New World family containing about 95 species of small to large passerines found in a variety of forest, grassland and open arid habitats; plumage black or colourful, patterns bold or cryptic; bill short to long, slender to robust, with broad gape; habits solitary to gregarious, arboreal to terrestrial, monogamous to polygamous; feed on invertebrates, seeds, fruit, nectar; nest colonial to solitary, on or off ground.
\Bidentical twins\b \JMonozygotic\j twins.
\BIdiacanthidae\b Black dragonfishes; family containing 3 species of luminescent deep-sea stomiiform teleost fishes; body eel-like, naked, dorsal and anal fins long, pectorals absent, pelvics absent in male only; sexual dimorphism marked, female body length 400 mm, male 70 mm; larvae transparent with eyes on long stalks.
\Bidiobiology\b That aspect of biology concerned with study of individual organisms.
\Bidiochromosome\b A sex chromosome.
\Bidiogamy\b Self-fertilization; \Bidiogamous.\b
\BIdiospermaceae\b Family of evergreen trees (Laurales) comprising a single species native to rainforests of northeast Australia; possesses a massive embryo with 3 or 4 cotyledons.
\Bidiotype\b The total hereditary determinants of an individual, comprising both chromosomal and extrachromosomal factors.
\Bidiotypic\b Sexual; pertaining to sex or sexual reproduction.
\Bigneous rock\b Rock formed by solidification of molten magma; see also \Jmetamorphic rock\j \Jsedimentary rock\j
\BIguanidae\b Iguanas; large and extremely diverse family of mainly New World arboreal and terrestrial lizards (Sauria); length to 2 m, body usually compressed; tail autotomic, non-prehensile; coloration commonly different between males and females; habits usually diurnal, insectivorous, occasionally herbivorous; reproduction oviparous; contains about 600 species found in Central and South America, Caribbean, Galapagos Islands, with a few representatives in other Pacific Islands and Madagascar.
\BIguanodont\b A bipedal ornithischian dinosaur known from the Jurassic to the Cretaceous.
\BIlliciaceae\b Star anise; small family of glabrous, aromatic evergreen shrubs or trees which accumulate a toxic lactone; contains about 40 species native to southeast Asia and the Caribbean; usually with solitary, axillary flowers which are bisexual, with 7 or more perianth segments, 4 or more stamens and superior ovaries.
\BIlliciales\b Small order of woody plants (Magnoliidae) with mostly solitary flowers and poorly differentiated sepals and petals; pollen grains unusual in possessing either 3 or 6 germinal furrows.
\BIllinoian glaciation\b A glaciation of the Quaternary Ice \JAge\j in North America with an estimated duration of 100 000 years.
\Billuvial layer\b A zone of illuviation; the B-horizon of a soil profile.
\Billuviation\b The process of deposition and precipitation of material in the B-horizon, that was leached or eluviated from the A-horizon of a soil.
\Bimagination\b The final stage of development that produces the imago (adult).
\Bimago\b The adult stage of an insect; \Bimagine\b; See also \Jinstar\j
\Bimbibition\b The non-active absorption or uptake of water; \Bimbibe.\b
\Bimbibitional water\b That part of the soil water held within the lattice structure of colloidal matter.
\BImbricata\b Extinct order of eocrinoids known from the Lower Cambrian in which the stalk is composed of overlapping plates.
\Bimmature\b Used of the developmental stages of an organism preceding the attainment of sexual maturity.
\Bimmature soil\b A recently formed soil in which profile development is incomplete for the prevailing climatic and biological conditions.
\Bimmersed\b Used of an aquatic plant growing entirely beneath the water surface.
\Bimmigration\b The movement of an individual or group into a new population or geographical region; \Bimmigrant\b; See also \Jemigration\j
\Bimmobilization\b The conversion of an element from an inorganic to an organic state by an organism; See also \Jbiological mineralization\j
\Bimmunity\b The state in which a host is more or less resistant to an infective agent; includes inherited natural immunity and acquired resistance arising from exposure to the agent and consequent stimulation of an immune response.
\Bimmunology\b The study of immunity and immunological reactions.
\Bimpatiens\b \JBalsaminaceae\j
\BImpennes\b Superorder of birds comprising a single order, Sphenisciformes and family, Spheniscidae (penguins).
\Bimperfect flower\b A unisexual flower; a flower lacking either pistils or stamens.
\Bimpervious\b Not permeable; usually with reference to the passage of water or air; \Bimpermeable.\b
\Bimplantation\b 1: In mammals, the attachment of an embryo to the uterus wall. 2: The insertion of a graft into the host or stock.
\Bimpoundment\b An artificially enclosed body of water; typically with fluctuating water levels and high turbidity.
\Bimprinting\b The imposition of a stable behaviour pattern in social species by exposure, during a particular period in early development, to one of a restricted set of stimuli.
\BInadunata\b Extinct subclass of sea lilies (Crinoidea) in which the arms were completely free; known from the Ordovician to the Permian.
\BInarticulata\b Class of lamp shells (brachiopods) characterized by the absence of hinge teeth and sockets, the valves held together by muscles alone; pedicle absent to elongate; lophophore without skeletal support; gut terminates in a functional anus; habits epifaunal to infaunal, intertidal to 7500 m; contains about 45 species in 2 extant orders, Lingulida, and Acrotretida.
\Binbreeding\b Mating or crossing of individuals more closely related than average pairs in the population; endogamy; See also \Joutbreeding\j
\Binch worm\b \JGeometridae\j
\Bincidence of infection\b The number of infected hosts as a proportion of the host population; See also \Jintensity of infection\j
\Bincipient\b About to become or occur; used of the initial stage in the development of a structure or event.
\Binclination\b Aspect; the direction of a slope face.
\Bincompatibility\b 1: The inability to unite, fuse or form any homogeneous or viable association; \Bincompatible\b. 2: Failure of either cross fertilization or self-fertilization as a result of structural, physiological or genetic factors. 3: Failure of a graft to unite with the host or stock tissue.
\Bincomplete dominance\b The partial expression of both alleles at a given locus so that the phenotype of the heterozygote is intermediate between both homozygotes.
\Bincomplete flower\b A flower that lacks one or more of the four basic parts (pistil, stamen, petal and sepal); See also \Jcomplete flower\j
\Bincross\b Breeding or mating between homozygotes; See also \Jintercross\j
\Bincubation\b 1: The maintenance of eggs under conditions favourable for hatching; \Bincubate\b. 2: The period between infection by a pathogen and the appearance of symptoms.
\Bindehiscent\b Used of fruits that do not open spontaneously when ripe; \Bindehiscence\b.
\Bindependent assortment, law of\b Mendel's second law; that the random distribution of alleles to the gametes results from the random orientation of the chromosomes during meiosis.
\Bindeterminate growth\b Growth that continues throughout the life span of an individual such that body size and age are correlated; See also \Jdeterminate growth\j
\Bindex fossil\b A fossil apparently restricted to a narrow stratigraphic unit or time unit.
\Bindex species\b Indicator \Jspecies\j
\BIndian almond\b \JCombretaceae\j
\BIndian Equatorial Countercurrent\b A warm surface ocean current that flows eastwards in the equatorial Indian Ocean and forms the southern winter countercurrent to the North Equatorial Current; see ocean currents.
\BIndian North Equatorial Current\b A warm surface ocean current that flows westwards in the equatorial Indian Ocean, generated largely by the northeasterly winds of the winter monsoon; see ocean currents.
\BIndian paintbrush\b \JScrophulariaceae\j
\BIndian pipe\b \JMonotropaceae\j
\BIndian South Equatorial Current\b A warm surface ocean current that flows westwards in the central Indian Ocean and forms the northern limb of the South Indian Gyre and the southern limb of the North Indian Ocean circulation; see ocean currents.
\Bindicator\b An organism, species or community characteristic of a particular habitat, or indicative of a particular set of environmental conditions.
\Bindicator species\b A species, the presence or absence of which is indicative of a particular habitat, community or set of environmental conditions; index species.
\BIndicatoridae\b Honeyguides; family containing 15 species of small Old World arboreal birds (Piciformes) distributed from Africa to Borneo; feed on insects, honey and beeswax; lay eggs in nests of other hole-nesting birds; habits solitary, non-migratory, monogamous; newly hatched young use sharp hooked bill to kill other young in nest.
\Bindifferent species\b A species exhibiting no obvious affinity for any particular community; a species of low \Jfidelity\j; companion species.
\Bindigenous\b Native to a particular area; used of an organism or species occurring naturally in an environment or region.
\Bindividual distance\b The minimal distance that an animal endeavours to maintain between itself and other individuals of the species.
\Bindividualism\b A symbiosis in which the two symbionts are intimately associated, appearing to form a single organism not resembling either of the partners; \Bindividuation.\b
\Bindole acetic acid\b The most important \Jauxin\j of higher plants.
\BIndo-Malaysian subkingdom\b A subdivision of the Palaeotropical \Jkingdom\j
\BIndostomidae\b Monotypic family of tiny (to 30 mm) freshwater teleost fishes inhabiting shallow weedy lakes or streams of northern Burma and Thailand; body slender with armour of bony plates; dorsal fin with 5 isolated fin spines; formerly placed with sticklebacks (Gasterosteiformes) but now assigned to a separate order, Indostomiformes.
\Bindri\b \JIndriidae\j
\BIndriidae\b Indriid lemurs; family containing 4 species of mainly arboreal prosimian lemurs found only in Madagascar; hindlimbs longer than forelimbs with feet partly webbed; tail long or short; habits diurnal to nocturnal, herbivorous; solitary or in small groups.
\Binduction\b 1: The determination of the developmental fate of one cell mass by another. 2: A hereditary transformation mediated by foreign DNA in a multicellular organism.
\Binductive method\b A scientific method involving the formulation of universal statements, such as hypotheses or theories, from singular statements, such as empirical observations or experimental results; See also \Jdeductive method\j
\Binduration\b The process of hardening, as of sediments or rocks rendered hard by compaction, heat or pressure; \Bindurate.\b
\Bindustrial melanism\b An increase in the frequency of melanistic (dark pigmented) morphs as a response to changes in selection, in habitats blackened by industrial pollution.
\Binert\b Inactive; physiologically quiescent.
\Binfauna\b The total animal life within a sediment; endobenthos; See also \Jepifauna\j
\Binfection\b The process of invasion of a host by a parasite or microorganism; the pathological condition resulting from the growth of infectious organisms within a host; \Binfect.\b
\Binfectious disease\b Any disease transmitted without physical contact.
\Binferior ovary\b \JEpigyny\j
\Binfertile\b Non-reproductive; not fertile; \Binfertility.\b
\Binfestation\b Invasion by parasites or pests.
\Binfiltration\b The process by which water seeps into a soil, influenced by soil texture, aspect and vegetation cover.
\Binflorescence\b The arrangement and sequence of development of flowers on a flowering shoot; includes capitulum (head), catkin, corymb, cyme, panicle, raceme, spadix, spike.
\Binfradian rhythm\b A biological rhythm with a period less than 24 hours.
\Binfrahaline\b Used of fresh water having a salinity of less than 0.5 parts per thousand.
\Binfralittoral\b 1: The depth zone of a lake permanently covered with rooted or adnate macroscopic vegetation; often divided into upper (with emergent vegetation), middle (with floating vegetation) and lower (with submerged vegetation) zones. 2: The upper subdivision of the marine littoral zone, typically dominated by algae having a lower limit at the depth at which illumination is at about 1% of the surface level; sometimes used for the depth zone between low tide and 100 m; see marine depth zones.
\Binfralittoral fringe\b The transitional marine zone immediately below the eulittoral, between the intertidal and sublittoral zones; see marine depth zones.
\Binfrared radiation\b That part of the solar radiation \Jspectrum\j above the wavelength 780 nm.
\BInfusoria\b \JCiliophora\j
\Bingesta\b The total intake of substances into the body; \Bingest.\b
\Bingestion\b The action of taking in food material; feeding.
\BIngolfiellidea\b Small suborder of primitive amphipod crustaceans that live interstitially in marine bottom sediments or subterranean ground waters; typically having an elongate vermiform body lacking side plates.
\Binheritance\b The transmission of genetic information from ancestors or parents to descendants or offspring.
\Binhibition\b Any process that acts to restrain reactions or behaviour.
\Bink cap\b \JCoprinaceae\j
\Binnate\b Inherited; present at birth; used of behaviour that is instinctive and not learned.
\Binoculation\b The introduction or insertion of a pathogen into a host organism by a vector; or of an organism into an experimental culture.
\Binoculum\b The individual or group of individuals comprising the founders of a colony or newly established population.
\Binorganic\b Pertaining to, or derived from, non-biological material; used of non-carbon-chain compounds; See also \Jorganic\j
\BInozoida\b The sole order of \JPharetronidia\j
\Binquilinism\b A symbiosis in which one organism (the inquiline) lives within another without causing harm to its host; also used for the relationship between a species living within the burrow, nest or other domicile of another species; \Binquilinous.\b
\BInsecta\b Insects; a class of uniramian arthropods, by far the largest and most diverse of all classes of living organisms with about 1 million recognized species representing perhaps only 10-20 per cent of the world fauna; body of adult typically divided into head, thorax and abdomen; body length about 0.2-280 mm; head bearing pre-oral unjointed mandibles, one pair of antennae and 2 pairs of maxillae (the second fused to form labium); thorax with 3 pairs of legs on pro- meso- and metathoracic segments; the mesothorax and metathorax may also bear wings; respiration takes place through tracheae; insects exhibit an immense variety of life history strategies and are of great ecomonic importance as pests, pollinators, parasites and vectors of disease; divided into 2 subclasses, Apterygota (wingless insects) and Pterygota (winged insects), and 28 extant orders; Hexapoda.
\Binsecticide\b A chemical used to kill insects; used generally for any chemical agent used to destroy invertebrate pests.
\BInsectivora\b Diverse order of small eutherian mammals comprising 8 families, Erinaceidae (hedgehogs), Talpidae (moles), Tenrecidae (tenrecs), Chrysochloridae (golden moles), Solenodontidae, Soricidae (shrews), Macroscelididae (elephant shrews) and Tupaiidae (tree shrews); widespread distribution except Australian region, southern South America and oceanic islands.
\Binsectivorous\b Feeding on insects; \Binsectivore\b, \Binsectivory.\b
\Binsemination\b The introduction of sperms into the genital tract of a female; impregnation.
\Binsessorial\b Adapted for perching.
\Binsolation\b Exposure to solar radiation.
\Binspiration\b The process by which oxygen is absorbed by plants and animals.
\Binstar\b Any intermoult stage in the development of an arthropod; See also \Jimago\j
\Binstinctive behaviour\b Relatively complex, highly stereotyped behaviour exhibited in response to an environmental stimulus and directed towards a predictable end product.
\Binsular\b Pertaining to islands; used of an organism that has a restricted or limited habitat or range.
\Binsulosity\b The percentage of the area of a lake, within the shore line, occupied by islands.
\Bintensity of infection\b The number of individuals of a particular parasite species in each infected host.
\Binterbreeding\b Mating or hybridization between different individuals, population, varieties, races or species.
\Bintercalated\b Inserted between adjacent structures or strata.
\Binterception\b That part of total precipitation retained on the surface of vegetation before reaching the ground and returned to the atmosphere by evaporation.
\Bintercross\b The breeding or mating of heterozygotes; See also \Jincross\j
\Binterdemic\b Between local interbreeding populations.
\Binterface\b The contact surface between two contiguous substances or zones.
\Binterferon\b A low-molecular-weight protein formed by cells in response to a virus.
\Binterfertile\b Capable of interbreeding.
\Binterglacial\b A warm period between two Ice Ages or glaciations; see Quaternary Ice Age.
\Binterlittoral\b The shallow subtidal marine zone to a depth of about 20 m.
\Bintermediate host\b The host occupied by juvenile stages of a parasite prior to the definitive \Jhost\j and in which asexual reproduction frequently occurs.
\Bintersex\b An individual of a bisexual species possessing reproductive organs and secondary sexual characters partly of one sex and partly of the other, but which is of one sex only genetically.
\Binterspecies\b A cross between two distinct species; interspecific hybrid; \Binterspecific. \b
\Binterstade\b A climatic episode within a glacial stage during which a secondary retreat or standstill occurred; \Binterstadial\b; See also \Jstade\j
\Bintersterile\b Unable to interbreed; \Bintersterility.\b
\Binterstitial\b Pertaining to, or occurring within, the pore spaces (interstices) between sediment particles.
\Bintertidal zone\b The shore zone between the highest and lowest tides; littoral; see marine depth zones.
\Bintraspecific\b Within a species; between individuals or populations of the same species.
\Bintrazonal soil\b An immature soil showing more or less well developed characteristics that reflect the influence of some local factors, over the basic effects of climate and vegetation as soil-forming factors; transitional soil; see also \Jazonal soil\j \Jzonal soil\j
\Bintrinsic\b Originating or occurring within an individual, group or system.
\Bintrinsic rate of increase\b The potential rate of growth of a population in an infinite environment.
\Bintrogression\b The spread of genes of one species into the gene pool of another by hybridization and backcrossing.
\Bintrorse dehiscence\b Spontaneous opening of a ripe fruit from outside inwards; See also \Jextrorse dehiscence\j
\Binundatal\b Liable to flooding; used of plants that occupy sites susceptible to inundation during wet weather.
\Binvasion\b The mass movement or encroachment of organisms from one area into another; \Binvader.\b
\Binversion\b A structural change of a chromosome resulting from the reversal of a segment such that the genes occur in a reversed sequence.
\Binvertebrate\b 1: Used of those animals that lack a vertebral column. 2: Formerly one of the primary divisions in the classification of the Animal Kingdom, containing over 97 per cent of all species.
\Binviability\b A measure of the number of individuals failing to survive in one cohort or group, relative to another.
\Bionosphere\b The outer layer of the atmosphere more than 80 km above the Earth's surface, characterized by free electrically charged particles.
\BIowan glaciation\b The penultimate glaciation of the Quaternary Ice \JAge\j in North America, with an estimated duration, together with the Wisconsin glaciation, of about 70 000 years.
\BIpnopidae\b Family of little-known abyssobenthic myctophiform teleost fishes; body elongate, to 450 mm in length, subcylindrical with snout depressed; photophores absent; eyes variable, large and lensless or degenerate and covered with skin.
\BIpswichian interglacial\b The interglacial period preceding the Devensian glaciation in the British Isles; see Quaternary Ice Age.
\BIrenidae\b Leafbirds; family of colourful passerine birds found in forests of southern Asia and Indonesia; feed mainly on fruits and insects; nest in trees.
\BIridaceae\b Iris, crocus, gladiolus, freesia, montbretia; cosmopolitan family of Liliales comprising about 1500 species of perennial, mostly geophytic herbs, arising from bulbs, corms or rhizomes and dying back each year; leaves narrow and parallel-veined; seeds with fleshy endosperm containing reserves of hemicellulose, protein and oil; inflorescences usually spike-like and terminal, each flower bisexual, with 6 perianth segments united at base to form a tube, 3 stamens and a typically inferior ovary.
\Biris\b \JIridaceae\j
\BIrminger Current\b A cold surface ocean current that flows westwards and northwards around the southern coast of Greenland, derived in part from a deflection of the North Atlantic Drift; see ocean currents.
\BIron Age\b An archaeological period dating from about 3000 years B.P. in Europe; a period of human history characterized by the smelting of iron for industrial purposes.
\BIrregulares\b \JAnthocyathea\j
\Birritability\b Sensitivity; the ability to perceive and respond to stimuli; \Birritable. \b
\Birruption\b An irregular abrupt increase in population size or density typically associated with favourable changes in the environment and often resulting in the mass movement of the population.
\BIschnocera\b Suborder of chewing lice (Phthiraptera) containing about 1800 species, parasitic on placental mammals and birds.
\BIschnochitonida\b Large order of chitons distributed worldwide but especially abundant in tropical and subtropical waters; characterized by the shell valves, the first has an anterior area only, valves 2 to 7 have median and lateral areas, valve 8 has median and posterior areas; surrounding girdle well developed, often with embedded scales or bristles.
\BIschyrinioida\b Extinct order of rostroconch molluscs known only from the Ordovician.
\Bisidium\b An outgrowth on a lichen which may break off and develop into a lichen thallus as it contains both algal and fungal cells.
\Bisoalleles\b Alleles which are so similar in their phenotypic effects that special techniques are required to distinguish them.
\Bisobar\b A line on a chart or map connecting points of equal atmospheric or hydrostatic pressure.
\Bisobath\b A line on a chart or map connecting points of equal depth; bathymetric contour.
\BIsobryales\b Order of mosses (Bryidae) largely confined to the southern hemisphere; typically large perennial mat-forming plants growing on tree trunks, branches and rocks in forested habitats; exhibit extensive development of primary and secondary stems and the sporophyte is borne laterally.
\Bisochronal line\b A line on a chart or map connecting points (localities) at which a given event occurs simultaneously, as in the mean date of arrival of certain migratory species.
\BIsochrysidales\b Order of scale-covered flagellate algae (Prymnesiophyceae), most of which are marine; scales occasionally calcareous, forming coccoliths.
\BIsocrinida\b Order of stalked articulate crinoids in which true cirri radiate at intervals from the ossicles of the stalk; contains about 30 extant species in 2 families.
\Bisodeme\b A line on a map connecting points of equal population density; isodemic line.
\BIsoetales\b Quillworts; aquatic lower plants (Isoetopsida) with grass-like leaves containing air spaces spirally arranged on typically short stubby stem; heterosporous (producing megaspores and microspores).
\BIsoetopsida\b Subdivision of Lycopodiophyta, comprising the quillworts (Isoetales) and spike mosses (Selaginellales).
\BIsofilobranchia\b A superorder of bivalve molluscs comprising a single order, \JMytiloida\j
\Bisogametic\b Producing gametes that are similar in size, shape and behaviour; having gametes (isogametes) not differentiated into male and female; See also \Janisogametic\j
\Bisogamy\b The fusion of gametes of similar size, shape and behaviour; See also \Janisogamy\j
\Bisogenetic\b Of the same origin.
\Bisogenic\b \JHomozygous\j; having the same set of genes; syngenic; See also \Jallogenic\j
\Bisohaline\b A line on a chart or map connecting points of equal salinity.
\Bisohyet\b A line on a chart or map connecting points of equal rainfall.
\BIsolaimida\b Small order of free-living enoplian nematodes found in sandy soils which are infrequently cultivated; characterized by the apparent absence of cephalic chemosensory organs (amphids) and by the presence round the mouth of 6 hollow tubes and 2 whorls each of 6 sensory papillae.
\Bisolating mechanism\b Any intrinsic or extrinsic mechanism or barrier to the free exchange of genes between populations.
\Bisolation\b The separation of two populations so that they are prevented from interbreeding, whether by extrinsic (premating) or intrinsic (postmating) mechanisms.
\Bisolume\b A line on a chart or map connecting points of equal light intensity.
\Bisomerism\b 1: Repetition of similar parts. 2: The possession of equal numbers of serially homologous structures.
\Bisometric growth\b Growth in which relative proportions of the body parts remain constant with change in total body size; See also \Jallometric growth\j
\Bisomorphic\b Used of a plant having an alternation between diploid and haploid generations which are morphologically similar in appearance; homomorphic; See also \Jheteromorphic\j
\Bisomorphism\b Superficial similarity between individuals of different species or races; \Bisomorphous.\b
\BIsonidae\b Family containing 6 species of surf-dwelling atheriniform teleost fishes found primarily in the Indian Ocean and western Pacific; body deep, robust, transparent with silvery lateral stripe.
\Bisophagous\b Used of predators or parasites which are selective with regard to food or hosts but which are not restricted to a single food type or host species.
\Bisophenous\b Sharing or producing similar phenotypic effects; \Bisophenic.\b
\Bisophot\b A line on a chart or map connecting points of equal incident radiation.
\Bisopiptesis\b A line on a chart or map connecting points at which a given migratory species arrives on the same date.
\BIsopoda\b Cosmopolitan order of small to medium-sized peracaridan crustaceans found in marine, freshwater and terrestrial habitats and as parasites; body usually depressed; thoracic legs uniramous and with short coxae; young leaving brood pouch at manca stage; comprises about 4000 species in 9 suborders, including the Oniscoidea (woodlice), Asellota, Flabellifera, Epicaridea, Anthuridea, Gnathiidea, Microcerberidea, Valvifera and Phreatoicoidea.
\BIsoptera\b Termites, white ants; order of small social insects that construct nests on or in hollow trees, rotten wood, or the ground, which vary in size from a few centimetres with less than a hundred individuals to huge earth mounds measuring several metres with millions of colony members; caste structure includes morphologically distinct reproductives, soldiers and workers; adults (imagos) possess 2 pairs of long wings, compound eyes and a robust pigmented cuticle; secondary reproductives (neotenics) are typically blind, wingless and unpigmented; soldiers are usually blind, sterile and wingless with large heads and strong jaws; workers are mostly sterile and blind, with soft white cuticle (white ants); about 2000 species recognized, ubiquitous in tropics except for arid zones, rare in temperate regions; termites are of immense economic importance, damaging timber buildings, trees and crops; they are primary energy transformers of wet tropical ecosystems and form the principal diet of many predators.
\Bisoseismal\b A line on a chart or map connecting points of equal earthquake intensity.
\BIsospondyli\b Diverse assemblage of herring-like fishes, comprising the Clupeiformes, Elopiformes, Ostariophysi and Osteoglossidae.
\Bisosporous\b Having asexually produced spores of only one kind; homosporous; \Bisospory\b; See also \Jheterosporous\j
\Bisotherm\b A line on a chart or map connecting points of equal temperature.
\BIstiophoridae\b Billfishes, marlin, sailfish; family containing 10 species of large (to 4.5m) surface-living oceanic scombroid teleost fishes (Perciformes); head produced into pointed bill, jaw teeth present; dorsal and pelvic fins elongate; feed on other fishes using bill to stun prey.
\Biteration\b The procedure used in computation, in which the operations are repeated until a good fit is obtained.
\Biteroparous\b Used of organisms that have repeated reproductive cycles; \Biteroparity\b; See also \Jsemelparous\j
\Bivy\b \JAraliaceae\j
\BIxodida\b Arachnid ticks; subgroup of parasitiform mites (Acari) specialized as blood-feeding ectoparasites of terrestrial vertebrates-mammals, birds and reptiles; chelicerae modified for cutting skin; comprises about 800 recognized species.
\BIxonanthaceae\b Family of Linales containing about 28 species of trees and shrubs of tropical distribution.
\Bjacamar\b \JGalbulidae\j
\Bjacana\b \JJacanidae\j
\BJacanidae\b Jacanas; family containing 8 species of tropical freshwater charadriiform shore birds having long legs with extremely long toes for walking on floating vegetation such as lily pads; habits gregarious, dive and swim well, but flight slow; feed mostly on aquatic invertebrates and small fish; nest on clump of floating plant material.
\Bjack\b \JCarangidae\j
\Bjackal\b \JCanidae\j
\Bjack-in-the-pulpit\b \JAracaceae\j
\Bjactitation\b A method of seed dispersal in which seeds are tossed from the fruit by jerking movements of the plant.
\Bjaguar\b \JFelidae\j
\Bjasmine\b \JOleaceae\j
\Bjavelinfish\b \JAnotopteridae\j
\Bjaw worm\b \JGnathostomulida\j
\Bjawfish\b \JOpisthognathidae\j
\Bjay\b \JCorvidae\j
\Bjelly fungi\b \JEutremellales\j
\Bjellyfish\b \JScyphozoa\j
\BJenynsiidae\b Family of viviparous cyprinodontiform teleost fishes containing 3 species found in fresh waters of Argentina; anal fin of male modified as gonopodium for sperm transfer.
\Bjerboa\b \JDipodidae\j
\Bjewel beetle\b \JBuprestidae\j
\Bjigger\b \JTungidae\j
\Bjimsonweed\b \JSolanaceae\j
\Bjingle shell\b \JOstreoida\j
\BJoinvilleaceae\b Small family of Restionales comprising 2 species of coarse, erect herbs, with unbranched stems which are hollow except at the nodes and with alternate, rather grass-like leaves; native in the Pacific Islands; sometimes included in the Flagellariaceae.
\Bjojoba\b \JSimmondsiaceae\j
\Bjollytail\b \JGalaxiidae\j
\BJuglandaceae\b Walnut, hickory; family of aromatic trees containing about 60 species widely distributed in the temperate and subtropical northern hemisphere; flowers inconspicuous and wind-pollinated, ovary inferior; fruit is a nut.
\BJuglandales\b Order of Hamamelidae containing two families of aromatic trees with small wind-pollinated flowers borne in catkins.
\BJulianiaceae\b Family of Sapindales containing only 5 species of trees and shrubs, with well developed resin ducts; found in tropical America.
\BJulida\b Order comprising about 600 species of helminthomorphan diplopods (millipedes) found in Eurasia and North America; body length to 50 mm, a few species to 150 mm; typically inhabiting deciduous forest litter, sometimes caves and open ground.
\Bjumping mouse\b \JZapodidae\j
\Bjumping plant louse\b \JPsyllidae\j
\Bjumping spider\b \JSalticidae\j
\BJuncaceae\b Rushes; family of herbs or, rarely, shrubs with basal alternate leaves, each with a slender parallel-veined blade; flowers small, inconspicuous and typically wind-pollinated; widespread in distribution, particularly in the northern hemisphere.
\BJuncaginaceae\b Family of Najadales comprising about 20 species of cyanogenic, commonly rhizomatous, herbs of bogs and other wet, often saline habitats; with emergent or floating inflorescences; widespread in temperate and cold regions.
\BJuncales\b Order of Commelinidae comprising 2 families, Juncaceae (rushes) and Thurniaceae.
\BJungermanniales\b Large and diverse order of liverworts (Hepaticopsida) containing 43 families; plants typically leafy in organization, having 2 lateral rows of leaves and a ventral row of smaller underleaves; growth occurring by means of apical cell; smooth rhizoids usually present; female sex organs terminal, incorporating the apical cell; stalked sporophyte capsule apical and uniformly 4-valved.
\Bjungle\b Dense seral vegetation especially characteristic of tropical regions with a high level of precipitation.
\Bjuniper\b \JCupressaceae\j
\BJurassic\b A geological period of the Mesozoic era (\Ic.\i 210-140 million years B.P.); see geological time scale.
\BK selection\b Selection producing superior competitive ability in stable predictable environments so that the population is maintained at or near the carrying capacity of the habitat; See also \J\Ir\i selection\j
\BKainogaea\b \JCaenogaea\j
\BKainozoic\b \JCenozoic\j
\BKamchatka Current\b Oyashio \JCurrent\j; see ocean currents.
\BKamptozoa\b \JEntoprocta\j
\Bkangaroo\b \JMacropodidae\j
\Bkangaroo-paw\b \JHaemodoraceae\j
\Bkangaroo rat\b \JHeteromyidae\j
\BKansan glaciation\b A glaciation of the Quaternary Ice \JAge\j in North America with an estimated duration of 90 000 years.
\Bkapok tree\b \JBombacaceae\j
\Bkarstic\b Pertaining to irregular limestone strata permeated by streams, typically with sinks, caves and other subterranean passages.
\Bkaryogamy\b The fusion of gametic nuclei;\Bkaryogamic.\b
\Bkaryogenetic\b Heritable; not subjected to direct environmental influences.
\Bkaryokinesis\b Nuclear division; See also \Jcytokinesis\j
\Bkaryology\b The branch of cytology dealing with the study of nuclei, especially the structure of chromosomes.
\BKaryorelictida\b Order of gymnostome ciliates characterized by the primitive nature of their dual nuclear system, in which the macronucleus is diploid and non-dividing rather than polyploid; all are interstitial, usually in marine sediments, and most are carnivorous.
\Bkaryotype\b 1. The chromosome complement of a cell, individual, or group. 2: The structural characteristics of the chromosome set. 3: Those individuals having an identical complement of chromosomes.
\Bkasidoron\b Juvenile stage of fishes in the family \JGibberichthyidae\j
\Bkatabatic wind\b A dense mass of cold air flowing down an incline in response to gravity.
\Bkatatropism\b An orientation response downwards; \Bkatatropic.\b
\Bkatharobic\b Inhabiting pure water, or water of very low organic content; \Bkatharobe. \b
\Bkatydid\b \JTettigoniidae\j
\Bkelp\b \JLaminariales\j
\Bkelp fly\b \JCoelopidae\j
\Bkelpfish\b \JChironemidae\j
\BKelvin scale (K)\b A temperature scale that takes absolute zero (-273.16░C) as its starting point, zero K; each degree on the Kelvin scale is equal to one degree Celsius.
\Bkenapophyte\b A plant colonizing cleared land.
\BKentucky coffee tree\b \JCaesalpiniaceae\j
\Bkeratinophilic\b Thriving on horny (keratin-rich) substrates; \Bkeratinophile\b, \Bkeratinophily.\b
\Bkeystone predator\b The dominant predator, often the top predator in a given food web, having a major influence upon community structure.
\BKickxellales\b Order of zygomycete fungi containing mostly soil- and dung-inhabiting species.
\Bkiller whale\b \JDelphinidae\j
\Bkillifish\b \JCyprinodontidae\j
\Bkilo-(k)\b Prefix used to denote unit x 10\U3\u; see metric prefixes.
\Bkin selection\b Selection acting on one or more individuals and favouring or disfavouring the survival and reproduction of relatives (other than offspring) that possess the same genes by common descent, as in the case of selection for altruistic behaviour between genetically related individuals.
\Bkinesis\b A change in rate of random movement of an organism as a result of a stimulus; the linear or angular velocity changes in response to an alteration in the intensity of the stimulus, but no orientation of movement occurs with respect to the direction of the stimulus; \Bkinetic\b; see also \Jorthokinesis\j \Jklinokinesis\j
\BKinetofragminophora\b Class of ciliates either with a complete cover of cilia or with cilia limited to the ventral surface, characterized by the specialized cilia around the cytostome which are derived from the ends of the cilia rows on the general body surface; includes 4 subclasses which utilize a variety of habitats from free-living in marine sands to endoparasitic on other animals; most are holozoic, feeding on other ciliates, but many feed on bacteria.
\BKinetoplastida\b Order of small free-living and parasitic zooflagellates possessing 1 or 2 flagella arising from a pit or pocket and a DNA-containing nucleoid (the kinetoplastid) near the basal bodies of the flagella; reproduce by binary or multiple fission; includes \ITrypanosoma\i which causes Chagas' disease and sleeping sickness in man, and nagana in cattle.
\Bking crab\b \JXiphosura\j
\Bkingdom\b The highest category in the hierarchy of classification; the five kingdom classification of living organisms proposed by Whittaker and currently widely used is Monera, Protista, Fungi, Plantae and Animalia.
\Bkingfisher\b \JAlcedinidae\j
\BKinorhyncha\b Kinorhynchs, Echinodera; phylum of small, free-living marine invertebrates found in subtidal muds worldwide and characterized by a segmented body, the possession of a pseudocoelom and a chitinous cuticle; body divided into an eversible head, a neck of 1 segment and a trunk of 11 segments; the neck usually consists of a series of plates which retract over the head when it is withdrawn into the trunk; sexes separate; gut possessing mouth and anus; locomotion by repeated eversion of the head; comprises 2 orders, Cyclorhagida and Homalorhagida.
\BKinosternidae\b Musk turtles, mud turtles; family containing about 20 species of aquatic freshwater turtles (Testudines: Cryptodira) widespread in North, Central and South America; body length to 300 mm, shell domed with horny scutes; neck elongate, feet webbed; may produce foul-smelling secretions from cloacal glands.
\Bkinship\b Possession of a recent common ancestor; the condition of being related.
\Bkipuka\b An island of vegetation isolated by lava flows.
\Bkissing bug\b \JReduviidae\j
\Bkite\b \JAccipitridae\j
\Bkiwi\b \JApterygidae\j
\BKlebsormidiales\b Small order of predominantly freshwater green algae in which the thallus comprises unbranched filaments lacking holdfast cells.
\Bkleptobiosis\b An interspecific association found in some social organisms in which one species steals food from the stores of another species but does not live or nest in close proximity to it.
\Bkleptoparasitism\b A form of parasitism found in some social organisms in which a member of one species steals the prey or food stores of another species to feed its own progeny; \Bkleptoparasite.\b
\Bklinogeotropism\b The drooping tendency displayed by the tip of a climbing plant during \Jnutation\j; \Bklinogeotropic.\b
\Bklinokinesis\b A change in rate of random movement of an organism (kinesis) in which the rate of change of direction (frequency of turning movements) varies with the intensity of the stimulus; See also \Jorthokinesis\j
\Bklinophyte\b A terrestrial plant that is dependent upon other plants for physical support.
\Bklinotaxis\b An orientation response of a motile organism (taxis) in which the direction of movement results from a comparison of the intensity of the stimulus on each side of the body by successive deviations from side to side; \Bklinotactic\b; see also \Jtropotaxis\j \Jtelotaxis\j
\Bknephopelagic\b Pertaining to the middle pelagic zone of the sea extending from about 30 m to the lower limit of the photic zone.
\Bknephoplankton\b Planktonic organisms of the twilight zone between about 30 and 500 m depth; see also \Jphaoplankton\j \Jskotoplankton\j
\BKneriidae\b Family containing 12 species of African freshwater teleost fishes (Gonorhynchiformes) found mostly in fastrunning waters; body slender, subcylindrical, mouth ventral, protractile, teeth absent; gas bladder may function as accessory respiratory organ.
\Bknifefish\b \JGymnotidae\j
\Bknifejaw\b \JOplegnathidae\j
\Bknotweed\b \JPolygonales\j
\Bkoala\b \JPhascolarctidae\j
\Bkollaplankton\b Planktonic organisms rendered buoyant by encasement in gelatinous envelopes.
\BKomodo dragon\b The largest living lizard, reaching a length of up to 3 m; feeds on deer, pigs and other vertebrates, often as carrion; known from several Indonesian islands; Varanidae.
\Bkrait\b \JElapidae\j
\BKrameriaceae\b Family of Polygalales containing about 15 species of hemiparasitic shrubs and perennial herbs native to the New World.
\Bkremastoplankton\b Planktonic organisms that possess modified appendages or surface structures to reduce rates of sinking.
\Bkrill\b \JEuphausiacea\j; commonly used for \IEuphausia superba\i which is an abundant food species of baleen whales, found in the Southern Ocean.
\Bkrotovina\b A former animal burrow in one soil horizon that has been filled with organic material or material from another horizon.
\Bkrummholz\b A discontinuous belt of stunted forest or scrub typical of windswept alpine regions close to the tree line; See also \Jelfin forest\j
\I\BK\b\i\B-selected species\b A species characteristic of a relatively constant or predictable environment, typically with slow development, relatively high competitive ability, late reproduction, large body size and iteroparity; See also \J\Ir\i-selected species\j
\BKuroshio Current\b A warm surface ocean current that flows northwards and eastwards in the North Pacific, fed from the North Equatorial Current and forming the western limb of the North Pacific Gyre; see ocean currents.
\BKuroshio Extension\b A warm surface ocean current that flows eastwards in the North Pacific forming the northern limb of the North Pacific Gyre.
\BKurtidae\b Humphead; family comprising one brackish and one freshwater species of perciform teleost fishes found in India, Australia, New Guinea and China; body deep, to 600 mm length; single dorsal fin present, caudal deeply forked; eggs carried by male on supraoccipital crest.
\BKutorginida\b Extinct order of lamp shells (Brachiopoda) with biconvex, calcareous shells; known from the Lower Cambrian.
\BKy\b Abbreviation denoting 1000 years.
\Bkymatology\b The study of waves and wave motion.
\BKyphosidae\b Family containing over 30 species of marine teleost fishes (Pericformes) with relatively short heads and a small mouth; many feed on plants; widespread in warm to temperate waters.
\BLabiatae\b \JLamiaceae\j
\Blabile\b Plastic; readily modified.
\BLaboulbeniales\b Large order of parasitic pyrenomycete fungi found on insects, mites and diplopods; transmitted from one generation to the next by spores passed on by physical contact.
\BLabrador Current\b A cold surface ocean current that flows southwards off the east coast of Canada; see ocean currents.
\BLabridae\b Wrasses; diverse family containing about 400 species of tropical and temperate marine teleost fishes (Perciformes); body form variable, often elongate, colourful, length to 300 mm, few larger forms to 3 m; mouth protractile; single dorsal fin consisting of spinose and soft-rayed sections, commonly use pectoral fins instead of caudal fin for swimming; sexual dimorphism common.
\BLabroidei\b Suborder of mainly tropical and warm temperate coastal marine teleost fishes (Perciformes) comprising about 500 species in 3 families Labridae (wrasses), Scaridae (parrotfishes) and Odacidae.
\Blaburnum\b \JFabaceae\j
\BLabyrinthodontia\b Extinct subclass of primitive amphibians known from the Palaeozoic and Triassic; attaining a maximum body length of several metres.
\BLabyrinthulamycota\b Slime nets; a phylum of Protoctista also classified as a phylum of Protozoa, the \JLabyrinthulata\j
\BLabyrinthulata\b Slime nets; phylum of protozoans in which the trophic stage typically consists of mobile cells contained within an anastomosing network of ectoplasmic extensions produced at the cell surface; nutrients are absorbed through these extensions which occur on algae, angiosperms and organic detritus in marine and estuarine waters; reproduction involves the production of biflagellate zoospores.
\BLacertidae\b Family of Old World terrestrial lizards (Sauria); typically agile forms, with well developed legs and tails capable of autotomy; habits mainly diurnal, insectivorous, some forms frugivorous; reproductive oviparous, one species viviparous; containing about 210 species; distributed through Palaearctic, Ethiopian and Oriental regions.
\Blacewing\b \JNeuroptera\j
\BLacistemataceae\b Small family of Violales containing about 20 species of tanniferous shrubs and small trees with unbranched multicellular hairs; native to tropical America.
\BLactoridaceae\b Primitive family of flowering plants (Magnoliales) containing a single species of shrubs, \ILactoris fernandeziana\i, endemic to one of the Juan Fernandez Islands off the coast of Chile.
\Blacustrine\b Pertaining to, or living in, lakes or ponds; \Blacustral.\b
\Bladybird\b \JCoccinellidae\j; ladybug.
\BLaemodipodea\b \JCaprellidea\j
\BLagenidiales\b Order of aquatic oomycete fungi comprising about 65 species, most of which are obligate parasites of algae or invertebrates.
\BLagerberg-Raunkiaer cover scale\b A scale for estimating cover of a plant species, comprising 4 categories of percentage ground cover, 1 (0-10%), 2 (11-30%), 3 (31-50%), 4 (51-100%).
\BLagomorpha\b Cosmopolitan order of small terrestrial herbivorous mammals comprising about 60 species in 2 families, Ochotonidae (pikas) and Leporidae (hares, rabbits); incisor teeth chisel-like, separated from cheek teeth by wide space (diastema); ears typically elongate, tail short or absent, hindlimbs strong for hopping locomotion; habits often nocturnal or crepuscular; may inhabit simple to complex burrows; formerly known as the Duplicidentata.
\Blair-flora\b The plants inhabiting ground manured by animals.
\Blake\b A large body of fresh or saline standing water with negligible current, having a narrow peripheral beach largely devoid of vegetation as a result of wave action.
\BLamarckism\b Inheritance of acquired characters; the theory that changes in use and disuse of an organ result in changes in size and functional capacity and that these modified characters acquired by organisms in response to environmental factors are transmitted to the offspring.
\BLamellibranchia\b \JBivalvia\j
\BLamiaceae\b Mint, thyme, catnip, lavender, horehound, balm, deadnettle, rosemary, sage; large cosmopolitan family containing about 3200 species of aromatic herbs or shrubs commonly with epidermal glands containing ethereal oils; stems often square and leaves frequently hairy and arranged in opposite pairs; flowers bisexual, typically with a 5-toothed, cleft calyx, a 2-lipped, 5-lobed corolla, 2 or 4 stamens, and a superior ovary; fruit composed of 4 single-seeded nutlets; formerly known as the Labiatae.
\BLamiales\b Order of Asteridae containing 4 families of plants producing iridoid compounds, alkaloids or aromatic oils.
\Blamina\b A thin layer; the smallest recognizable unit in a bedded sediment.
\Blaminar flow\b The streamlined movement of water, in which water particles appear to move in smooth paths, and one layer of water slides over another; See also \Jturbulence\j
\BLaminariales\b Kelp; order of often large brown algae, common in the lower intertidal and sublittoral zones of temperate and polar seas; exhibiting alternation between a filamentous gametophyte and a sporophyte differentiated into holdfast, stipe and blade.
\BLamnidae\b Mackerel sharks; cosmopolitan family of large (6-9 m) pelagic lamniform elasmobranch fishes; coastal and oceanic, very active and offensive, feeding on fishes, marine mammals, birds and squid; contains 5 species including great white shark and mako, frequently recorded in attacks on people and boats; also porbeagle and salmon sharks.
\BLamniformes\b Order of pelagic marine, coastal to oceanic, galeomorph elasmobranch fishes (sharks); nasoral groove and barbels absent; mouth large, teeth small; feed on a variety of fishes, marine mammals and reptiles, and invertebrates; reproduction ovoviviparous; contains about 15 species in 7 families; includes the mako, great white, thresher, mackerel and megamouth sharks.
\Blamp shell\b \JBrachiopoda\j
\Blamprey\b \JPetromyzoniformes\j
\BLamprididae\b Opah or moonfish; family containing a single species of mesopelagic marine teleost fishes widespread in tropical and temperate waters feeding on squid, small fishes and crustaceans; body oval, compressed, to 1.8 m in length; teeth absent; dorsal and anal fins elongate, retractile; pectorals long and curved.
\BLampridiformes\b Order of pelagic marine teleosts having uniquely protrusible upper jaw; contains 35 species in 10 families, including opah, ribbonfishes, oarfishes, tapetails and tube-eye.
\BLampyridae\b Fireflies, glow worms; family of mostly nocturnal small beetles (Coleoptera) typically with luminous organs near the tip of the abdomen which are used to produce mating signals; larvae found in soil and litter, predatory on various invertebrates; contains about 2000 species.
\Blancefly\b \JLonchaeidae\j
\Blancelet\b \JCephalochordata\j
\Blancetfish\b \JAlepisauridae\j
\Bland breeze\b A light wind blowing off the land at night when the sea surface is warmer than the land; See also \Jsea breeze\j
\Bland-bridge\b A more or less continuous connection between adjacent landmasses, forming a potential route for migration and dispersal.
\Blangur\b \JCercopithecidae\j
\BLaniidae\b Shrikes; family containing about 65 species of small to medium-sized passerine birds found in variety of brush, grassland and open habitats worldwide; bill stout, compressed, hooked; wings and tail long; habits solitary, aggressive, some species migratory; feed on insects and other invertebrates that are frequently impaled on thorns; cup-shaped nest located in tree.
\Blantern tree\b \JElaeocarpaceae\j
\Blanterneye\b \JAnomalopidae\j
\Blanternfish\b \JMyctophidae\j
\BLanthanotidae\b Earless monitor; family containing a single species of lizard (Squamata) found in Borneo; can burrow and swim, feeding on various invertebrates and small fishes; body elongate with short limbs, tail not autotomous.
\Blapidicolous\b Living under or among stones; \Blapidicole.\b
\BLapidognatha\b Araneomorph spiders; largest of the 3 suborders of spiders (Araneae) comprising about 75 families and some 33 000 species; abdomen unsegmented, spinnerets located posteriorly; chelicerae move at right angles to the body axis.
\BLardizabalaceae\b Small family of Ranunculales containing about 30 species of mostly twining woody vines native principally to southeast Asia but also to Chile.
\BLaridae\b Gulls, terns; cosmopolitan family containing about 85 species of small to large charadriiform seabirds; coloration mostly black and/or white; habits gregarious, monogamous, migratory, nesting on ground, on cliffs or in trees; feed on variety of aquatic animals and carrion.
\Blark\b \JAlaudidae\j
\Blarkspur\b \JRanunculaceae\j
\Blarva\b A stage in development between hatching and attainment of adult form or maturity.
\BLarvacea\b \JAppendicularia\j
\Blarvicidal\b Lethal to larvae.
\Blarviparous\b Producing eggs that are hatched internally with release of free-living larvae; \Blarvipary\b; see also \Joviparous\j \Jovoviviparous\j, \Jviviparous\j
\Blarvivorous\b Feeding on larvae; \Blarvivore\b, \Blarvivory.\b
\Blasion\b Fouling; a dense growth of aquatic organisms, particularly on submerged objects projecting into free water.
\Blatebricolous\b Living in holes; \Blatebricole.\b
\BLaterite soil\b A zonal soil, highly weathered, having a reddish brown clay subsoil, low in minerals and soluble constituents, formed in forested warm temperate to tropical regions; Latosol.
\Blaterization\b A soil-forming process occurring in tropical regions in which the minerals are converted to clay and pronounced leaching results in the accumulation of hydroxides of aluminium and iron in the deeper layers; \Blaterite.\b
\BLatimeriidae\b Coelacanth; monotypic family of marine tassel-finned fishes found off the Comoro Islands in the Indian Ocean at a depth of 150-400 m; length to 2.75 m, body bearing cosmoid scales; swim bladder fat-filled.
\BLatosol\b Laterite \Bsoil\\Jb\j
\BLatridae\b Trumpeters; family containing 10 species of marine perciform teleost fishes found in cool temperate waters of the southern hemisphere; body oval, compressed, to 1 m length, dorsal fin elongate with many short fin spines.
\BLauraceae\b Laurels, bay laurel, avocado pear; large family of aromatic evergreen trees or shrubs (Laurales) widespread in subtropical and tropical regions; flowers generally small with a pistil consisting of a simple carpel with a single ovule; fruit typically fleshy.
\BLaurales\b One of the more archaic orders of flowering plants (Magnoliidae) comprising about 2500 species of mostly woody plants, commonly found in warm moist regions; flowers perigynous or epigynous, typically containing a single functional ovule; pollen grains mostly inaperturate or biaperturate.
\BLaurasia\b The northern supercontinent formed by the break up of \JPangaea\j in the Mesozoic (\Ic.\i 150 million years B.P.)\j, \Jand comprising North America, Greenland, Europe and Asia, excluding India; Eurasia; See also \JGondwana\j
\Blaurel\b \JLauraceae\j
\Blaurophilous\b Thriving in sewers and drains; \Blaurophile\b, \Blaurophily.\b
\Blaurophyte\b A sewer or drain plant.
\Blavender\b \JLamiaceae\j
\Blaw\b An empirical generalization; a statement of a biological principle that appears to be without exception at the time it is made, and has become consolidated by repeated successful testing.
\Blayer\b Stratum; a horizontal zone of vegetation; four such zones are recognized by plant ecologists - tree layer, shrub (bush) layer, field (herb) layer, and ground (moss) layer.
\BLD\B\D50\d\b\b Lethal dose, 50%; the dose level required to kill half the organisms in a test population per unit time.
\Bleaching\b The removal of readily soluble components, such as chlorides, sulphates and carbonates, from soil by percolating water; See also \Jflushing\j
\Blearning\b The production and accumulation of adaptive changes in individual behaviour as a result of experience.
\Bleatherback turtle\b \JDermochelyidae\j
\Bleatherjacket\b \JTipulidae\j
\BLebiasinidae\b Pencil fishes; family containing 50 species of mostly small colourful tropical South American freshwater characiform teleost fishes; body spindle-shaped, dorsal and anal fins small; complex courtship behaviour exhibited by some forms; typically surface-living in weedy habitats with still or slow moving water; extremely popular amongst aquarists.
\BLecanicephalidea\b Order of tapeworms parasitizing elasmobranch fishes; characterized by a scolex divided into an anterior portion which is either cushion-like or armed with retractable tentacles and a posterior portion which usually has 4 simple suckers.
\BLecithoepitheliata\b Order of freshwater, terrestrial and marine free-living turbellarians found throughout the world; characterized by a complex pharynx and ovovitellaria, organs that produce both oocytes and yolk cells.
\Blecithotrophic\b Pertaining to developmental stages that feed upon yolk, and to eggs rich in yolk.
\BLecythidales\b Brazil nut tree; small order of Dilleniidae comprising about 400 species of woody plants commonly with rather large flowers; best developed in tropical rainforests especially in South America; comprises the family Lecythidaceae.
\BLeeaceae\b Family of Rhamnales containing about 70 species of erect herbs or shrubs found in the Palaeotropical region; flowers usually small, perfect and borne in large cymose inflorescences.
\Bleech\b \JHirudinea\j
\Bleeward\b Pertaining to the side facing away from a wind, ice, or water current.
\Blegume\b A pod; a dry dehiscent fruit developed from a single carpel and containing one or more seeds; splits along ventral and dorsal sutures on ripening, to form 2 valves; typical of members of the \JFabales\j
\BLeguminosae\b Older name for the Fabaceae, the only family of the \JFabales\j
\Bleimocolous\b Living in moist grassland or meadowland; \Bleimocole.\b
\Bleimonapophyte\b A plant introduced into grassland or meadowland.
\Bleimophyte\b A wet-meadow plant.
\BLeiognathidae\b Ponyfishes; family containing 20 species of Indo-Pacific, bottom-living, coastal marine, brackish and freshwater teleost fishes (Perciformes); body compressed, to 300 mm in length, skin covered with copious mucus; head naked, eyes large, mouth highly protrusible.
\BLeiopelmatidae\b Family of primitive frogs (Anura) comprising 4 species from New Zealand and western North America; eggs laid onto damp ground, developing into froglets before hatching.
\BLeitneriales\b Order of Hamamelidae containing a single North American species of tanniferous shrubs with resin canals and small wind-pollinated flowers.
\Blek\b 1: An assembly area for communal courtship display. 2: A communal prenuptial display, specifically those displays involving ritualised contests between competitors, often for the use of symbolic sites; \Blekking.\b
\Blemming\b \JCricetidae\j
\BLemnaceae\b Duckweed; small family of Arales containing about 30 species of small free-floating, thalloid plants without roots or with short unbranched roots, widely distributed in still-water habitats; reproduce mainly by vegetative budding, rarely producing inflorescences.
\Blemon\b \JRutaceae\j
\Blemon shark\b \JCarcharhinidae\j
\BLemurian realm\b The zoogeographical region comprising the island of Madagascar; Malagasy region.
\BLemuridae\b Lemurs; family containing 15 species of mostly arboreal prosimians found only in Madagascar and Comoro Islands; limbs long and slender, tail well developed; habits diurnal or nocturnal, feeding on variety of plant material and insects.
\BLemuroidea\b A superfamily of the mammalian suborder Strepsirhini, comprising the lemurs (Lemuridae) and lorises (Lorisidae).
\BLennoaceae\b Family of Lamiales containing only 5 species of fleshy root-parasites lacking chlorophyll and commonly provided with stalked, glandular hairs; native to the New World.
\BLentibulariaceae\b Bladderwort, butterwort; cosmopolitan family of Scrophulariales containing over 200 species of insectivorous herbs of aquatic or wet habitats, with submerged photosynthetic organs and traps formed from modified stems or leaves; flowers irregular and bisexual, usually with a 2-lipped corolla, 2 stamens and superior ovaries.
\Blentic\b Pertaining to static, calm or slow-moving aquatic habitats; See also \Jlotic\j
\Blentil\b \JFabaceae\j
\Bleopard\b \JFelidae\j
\Blepidophagous\b Feeding on scales; used of fishes that feed on the external scales of other fishes; \Blepidophage\b, \Blepidophagy.\b
\BLepidopleurida\b Order of primitive chitons (Mollusca) distributed worldwide but containing only about 50 species; characterized by the shell valves; the first has a single area, valves 2 to 8 have central and lateral areas and valve 8 has an additional medial projection.
\BLepidoptera\b Butterflies, moths; large order of holometabolous insects comprising about 138 000 species in 5 suborders, Zeugloptera, Dacnonympha, Exoporia, Monotrysia and Ditrysia; adults typically with slender coiled sucking proboscis (maxillae); mandibles reduced, non-functional; body and wings covered with scales; the membranous fore-and hindwings coupled together as single functional unit, wings rarely reduced or absent; larvae (caterpillars) usually phytophagous, occasionally scavengers, rarely predatory or parasitic.
\Blepidopterid\b Used of flowers adapted for pollination by butterflies and moths.
\Blepidopterophilous\b Pollinated by butterflies and moths; \Blepidopterophily.\b
\BLepidosauria\b Subclass of Reptilia comprising about 5600 extant species in 2 orders, Rhynchocephalia (tuatara) and Squamata (lizards, snakes, amphisbaenians).
\BLepidosirenidae\b South American lungfish; monotypic family of freshwater fishes found in stagnant weedy backwaters of the Amazon basin; body elongate, cylindrical, length to 1.25 m; pectoral and pelvic fins short and filamentous; swim bladders paired functioning as lungs; larvae with 4 pairs of feathery external gills; adults aestivate during the dry season.
\BLepisosteidae\b Gars; family containing 7 species of medium-sized (to 1.5 m) fishes found in rivers, lakes and occasionally coastal marine waters of Central America, Cuba, and eastern North America; body very elongate bearing heavy ganoid scales; jaws prolonged with needle-like teeth; swim bladder vascularized aiding aerial respiration; larvae with adhesive organ on ventral surface of snout.
\BLeporidae\b Hares, rabbit; \JLagomorpha\j
\Bleporin\b \JAnostomidae\j
\BLepospondyli\b Extinct group of amphibians known from the Palaeozoic.
\Bleptocephalus\b A type of larval stage found in a variety of marine bony fishes; that of the common eel is transparent, with a leaf-like body and tiny eyes.
\BLeptochariidae\b Monotypic family of small (to 0.75 m) shallow-water carcharhiniform sharks of the tropical and temperate eastern Atlantic Ocean; feed on fishes, crustaceans and cephalopods; reproduction viviparous.
\BLeptodactylidae\b Diverse family of mainly terrestrial Neotropical frogs (Anura), few species aquatic or arboreal; reproductive strategies variable, ranging from fully aquatic eggs and larvae to terrestrial eggs and direct development; contains about 650 species distributed mostly in South America but extending into West Indies, Central America and southern United States.
\BLeptolinida\b Alternative name for the \JHydroida\j
\Bleptology\b The study of minute structures or particles.
\BLeptomedusae\b Suborder of predominantly marine cnidarians (Hydroida) in which the polyps are typically colonial with a horny rather than calcareous exoskeleton; free medusae tall and bell-shaped with gonads usually on the stomach.
\BLeptomitales\b Water moulds; order of oomycete fungi comprising about 20 species of saprophytes usually found on plant remains in stagnant water or waterlogged soils.
\BLeptomyxida\b Order of Acarpomyxa containing multinucleate or similar uninucleate amoeboid organisms of diverse form, including reticulate sheets, non-reticulate fans, branched amoebae and unbranched slug-like amoebae; found in freshwater and soil habitats.
\Bleptopel\b Large organic molecules or aggregates of colloidal proportions suspended in water.
\Bleptophyll\b A Raunkiaerian leaf size \Jclass\j for leaves having a surface area less than 25 mm\U2\u.
\BLeptoscopidae\b Sandfishes; family containing 3 species of small (to 90 mm) slender, sand-burrowing teleost fishes (Perciformes) found in cool coastal waters around Australia and New Zealand.
\BLeptosomatidae\b Coural; family containing a single species of coraciiform bird found in scrub and forest habitats of Madagascar and the Comoro Islands; bill stout, feeds on insects and lizards.
\BLeptostraca\b Order containing about 25 species of typically benthic marine phyllocaridan crustaceans; head and most of thorax enclosed by large bivalve carapace hinged along the mid-dorsal line; eyes stalked; long setae on thoracic legs form a ventral brood chamber.
\BLeptotyphlopidae\b Family containing about 65 species of small (to 300 mm) worm-like burrowing snakes widespread in tropical and subtropical regions; feed mainly on insects and worms; reproduction oviparous.
\BLessepsian migration\b Migration between the Red Sea and the Mediterranean by way of the Suez Canal.
\Blestobiosis\b A symbiosis between social insects in which colonies of a small species inhabit the nests of a larger species and prey on its brood or rob the food stores.
\Blethal\b Pertaining to, or causing, death by direct action.
\Blethal trait\b Any inherited character that causes the death of an organism before it can reproduce.
\BLethrinidae\b Emperors; family containing 20 species of Indo-Pacific and west African coastal marine perciform teleost fishes; body perch-like, to 1 m in length; mouth weakly protractile, lips fleshy; single dorsal fin present.
\Blettuce\b \JAsterales\j
\BLeucettida\b Order of calcinian sponges varying in form from encrusting to massive, lobed or branching; choanocyte chambers tubular to spherical; widely distributed to a maximum depth of about 500 m.
\Bleucism\b Paleness, as of coloration.
\BLeucosoleniida\b Order of calcaronian sponges typically consisting of a cluster of upright tubes, lined with choanocytes and with terminal oscula, united by a basal system of stolon-like tubes; found from the intertidal to over 2400 m.
\Blevée\b A sediment bank.
\Bliana\b 1: \JGnetidae\j 2: A woody, free-hanging, climbing plant.
\BLias\b A geological epoch of the early Jurassic period (\Ic.\i 210-175 million years B.P.); see geological time scale.
\BLiceales\b Diverse order of Myxogastromycetidae (plasmodial slime moulds) characterized by the absence of lime from the fruiting body which typically lacks a true capillitium and columella (stalk).
\BLiceida\b The slime mould order \JLiceales\j, treated as an order of the protozoan group Myxogastria.
\Blichen\b A type of thalloid lower plant formed as an association between a fungus (the mycobiont) and an alga or blue-green bacterium (the phycobiont); thallus may be encrusting, leafy or even shrubby according to species.
\Blichenicolous\b Living in or on a lichen; \Blichenicole.\b
\Blichenism\b The symbiotic relationship between a fungus and an alga that comprise a lichen.
\Blichenology\b The study of lichens.
\Blichenometry\b A method for dating rocks based on a knowledge of the growth rates of encrusting lichens; \Blichenometric.\b
\Blichenophilous\b Thriving on, or having an affinity for, lichens or lichen-rich habitats; \Blichenophile\b, \Blichenophily.\b
\Blife cycle\b 1: The sequence of events from the origin as a zygote, to the death of an individual. 2: Those stages through which an organism passes between the production of gametes by one generation and the production of gametes by the next.
\Blife form\b The characteristic structural features and method of perennation of a plant species; See also \JRaunkiaerian life forms\j
\Blife history\b The significant features of the life cycle through which an organism passes, with particular reference to strategies influencing survival and reproduction.
\Blife span\b Longevity; the maximum or mean duration of life of an individual or group.
\Blightfish\b \JGonostomatidae\j
\Blignicolous\b Growing on or in wood; \Blignicole.\b
\Bligniperdous\b Used of organisms that destroy wood.
\Blignivorous\b Feeding on wood; \Blignivore, lignivory.\b
\Blignophilic\b Thriving on or in wood; \Blignophile\b, \Blignophily.\b
\Blignum vitae\b \JZygophyllaceae\j
\Blilac\b \JOleaceae\j
\BLiliaceae\b Lilies; asparagus, aspidistra, bluebell, daffodil, hyacinth, day lily, lily of the valley, merry bells, narcissus, spider plant, tulip; large family of perennial herbs generally arising from a rhizome, bulb or corm and dying back to the ground each year, usually with basal leaves which are typically narrow and parallel-veined; flowers mostly insect-pollinated and usually trimerous with a superior ovary and many seeds; comprising nearly 4000 species, widely distributed particularly in dry temperate to subtropical regions.
\BLiliales\b Cosmopolitan order of monocotyledons (Liliidae) comprising about 8000 species in 15 families; mostly autotrophic herbs often with rhizomes, corms or bulbs, and commonly with trimerous flowers having 6 stamens and adapted for insect pollination.
\BLiliidae\b Subclass of monocotyledons (Liliopsida) comprising only 2 orders of terrestrial, epiphytic or aquatic herbs often with rhizomes, corms and bulbs; commonly mycotrophic and sometimes lacking chlorophyll; also includes some woody forms; leaves usually alternate, simple and entire, mostly without a petiole; flowers characteristically showy, with septal nectaries and adapted for pollination by insects.
\BLiliopsida\b Monocotyledons; class of Magnoliophyta; herbaceous or, sometimes, woody plants lacking typical secondary growth, vascular bundles scattered in stem or in 2 or more rings; vessels often confined to roots or absent; root system adventitious; leaves usually parallel-veined; embryo typically with a single cotyledon; consists of 65 families in 5 subclasses, Alismatidae, Arecidae, Commelinidae, Liliidae and Zingiberidae.
\Blily of the valley\b \JLiliaceae\j
\BLimacomorpha\b Superorder of pentazonian diplopods (millipedes) containing a single order, Glomeridesmida.
\Blime\b 1: \JRutaceae\j 2: \JTiliaceae\j
\Blimicolous\b Inhabiting mud; \Blimicole.\b
\Blimiting factor\b Any environmental factor, or group of related factors, which exist at suboptimal level and thereby prevent an organism from reaching its full biotic potential.
\Blimivorous\b Feeding on mud; \Blimivore\b, \Blimivory.\b
\BLimnanthaceae\b Family of Geraniales containing 11 species of small annual herbs producing mustard oils, native to North America.
\Blimnetic\b Pertaining to lakes or to other bodies of standing fresh water; often used with reference only to the open water of a lake away from the bottom; \Blimnic.\b
\Blimnetic zone\b The surface zone of a lake above the compensation depth.
\BLimnichthyidae\b Family containing 6 species of small (to 70 mm) Indo-Pacific tropical marine teleost fishes (Perciformes) found in shallow coastal waters burrowing in sandy sediments; body slender with pointed snout overlapping lower jaw; dorsal and anal fins elongate, lacking fin spines.
\Blimnicolous\b Living in lakes; \Blimnicole.\b
\Blimnion\b All lakes, ponds, pools and other bodies of standing fresh water.
\Blimnobiology\b The study of organisms living in lakes, ponds and other standing freshwater bodies; limnology.
\Blimnobiont\b A freshwater organism; \Blimnobiontic.\b
\Blimnobios\b The total life of fresh waters; that part of the Earth's surface occupied by freshwater organisms; see also \Jgeobios\j \Jhalobios\j, \Jhydrobios\j
\BLimnocharitaceae\b Water poppy; family of Alismatales containing about 12 species of perennial aquatic herbs, either free-floating or rooted and emergent; native to tropical and subtropical regions.
\Blimnocrene\b A pool of spring-water with no outflow.
\Blimnocryptophyte\b A marsh or pond plant with perennating organs below the surface.
\Blimnodic\b Pertaining to salt marshes.
\Blimnodophilous\b Thriving in salt marshes; \Blimnodophile limnodophily.\b
\Blimnodophyte\b A salt-marsh plant.
\Blimnology\b The study of lakes, ponds, and other standing waters, and their associated biota; \Blimnological.\b
\BLimnomedusae\b Suborder of predominantly freshwater cnidarians (Hydroida) in which the polyps may be solitary or colonial and the exoskeleton thin or lacking; medusae with hollow tentacles and the gonads on the stomach or radial canals.
\Blimnophilous\b Thriving in lakes or ponds; \Blimnophile\b, \Blimnophily.\b
\Blimnophyte\b A marsh or pond plant.
\Blimnoplankton\b Planktonic organisms of freshwater lakes and ponds.
\BLimoida\b File shells; order of about 125 species of widely distributed, marine, bottom-living, pteriomorphian bivalves characterized by shell and hinge structure, and by single posterior shell-closing muscle.
\Blimophagous\b Feeding on mud; \Blimophage\b, \Blimophagy.\b
\BLinaceae\b Common flax; family of about 220 species of often cyanogenic herbs and shrubs widely distributed in temperate and subtropical regions; flowers regular, bisexual and usually with 5 sepals and petals, 5, 10 or more stamens and staminodes, and superior ovaries.
\BLinales\b Order of Rosidae containing five families of woody or herbaceous plants, with most species belonging to the Erythroxylaceae and Linaceae.
\Blinden\b \JTiliaceae\j
\Blineage\b A line of common descent; line.
\Blingcod\b \JHexagrammmidae\j
\BLinguatulida\b Alternative name for the \JPentastomida\j
\BLingulida\b Small order of inarticulate brachiopods comprising about 20 species, one of which, \ILingula\i, has existed unchanged for 400 million years; pedicle elongate, foramen absent; intertidal to 130 m in tropical and warm temperate regions inhabiting U-shaped burrows in sandy sediments.
\BLiniphiidae\b Money spiders; large family of dark-coloured spiders (Araneae) which construct sheet webs on vegetation; adults hang to the underside of the web, running out over it to catch prey.
\Blinkage\b The presence of specific genes on the same chromosome such that the traits are not independently assorted; the greater the proximity of these genes the smaller the chance of their separation by crossing over, and the stronger the linkage.
\BLinnaean classification\b The system of hierarchical classification and binomial nomenclature established by Linnaeus.
\BLinophrynidae\b Family of tiny (to 80 mm) deep-sea anglerfishes (Lophiiformes) found over a depth range from 100 to 3000 m; female body rounded, mouth large, teeth long and fang-like; male parasitic on female.
\Blion\b \JFelidae\j
\Blipid\b A diverse class of hydrocarbon compounds including sterols, carotenes, xanthophylls, waxes, phosphoglycerides and acylglycerols; serving a variety of structural and storage functions.
\BLipogenyidae\b Monotypic family of small (to 400 mm) eel-like notacanthiform teleost fishes found in western North Atlantic to about 1500 m depth; body compressed with blunt snout and small mouth devoid of teeth, dorsal and anal fins spinose.
\BLiposcelidae\b Cosmopolitan family of psocopteran insects, comprising about 145 species many of which cause damage to a variety of stored products; body characteristically flattened; includes the familiar book louse which causes damage to old papers and dried natural history material.
\BLipotyphla\b Suborder of placental mammals comprising hedgehogs and moon rat (Erinaceidae), shrews (Soricidae), moles (Talpidae), solenodon (Solenodontidae), tenrecs (Tenrecidae) and golden mole (Chrysochloridae).
\Blipoxenous\b Used of a parasite that leaves its host after feeding; \Blipoxeny.\b
\Blipstick tree\b \JBixaceae\j
\Bliptocoenosis\b An assemblage of dead organisms and their biogenic products.
\BLissamphibia\b Subclass of amphibians comprising all living forms; 3 orders are recognized, Caudata (salamanders), Anura (frogs, toads) and Gymnophiona (caecilians); contains about 3140 living species in 36 families; cosmopolitan distribution, but frequently absent from oceanic islands.
\BLissocarpaceae\b Small family of Ebenales containing only 2 species of small trees, native to tropical South America.
\Blitchi\b \JSapindaceae\j
\Blithic\b Pertaining to rock.
\Blithification\b The physiochemical process that produces rock from sedimentary deposits.
\BLithistida\b Order of tetractinomorph sponges found mostly in tropical and warm temperate seas at depths of 30 to 2000 m; possessing spicules (desmas) which interlock or articulate with one another to form a rigid skeleton.
\BLithobiida\b Diverse order of mostly temperate anamorphan chilopods comprising about 1450 species in 4 families; eyes composed of small clusters of ocelli, antennae filiform; trunk 18-segmented, bearing 15 pairs of legs; tergal plates alternating large and small.
\BLithobiomorpha\b \JLithobiida\j
\Blithocarp\b A fossil fruit.
\Blithodomous\b Used of an organism that lives in holes in rock, or that bores into rock.
\Blithology\b The study of rocks and rock forming processes; petrology.
\Blithophagic\b 1: Used of organisms that erode or bore into rock; \Blithophage\b, \Blithophagy.\b 2: Eating small stones, as in some birds.
\Blithophilous\b Thriving in stony or rocky habitats; \Blithophile\b, \Blithophily. \b
\Blithophyl\b A fossil leaf.
\Blithophyte\b A plant growing on rocks or stones.
\Blithosere\b An ecological succession originating on an exposed rock surface; See also \Jsere\j
\BLithosol\b A very stony shallow azonal soil without pronounced horizons, and with incomplete surface layers comprising imperfectly weathered rock fragments; skeletal soil.
\Blithosphere\b The rigid crustal plates of the Earth.
\Blithostratigraphy\b The organization and classification of rock strata according to their lithological character; \Blithostratigraphic.\b
\Blithotomous\b Used of an organism that burrows into rock.
\Blithoxyle\b Fossilized wood.
\BLitobothridea\b Small order comprising 4 species of tapeworms parasitic in thresher sharks; characterized by a scolex comprising a single apical sucker, and by a segmented body with each proglottis containing a single set of reproductive organs.
\BLitopterna\b Extinct order of hoofed ungulates known from the Eocene to the Pleistocene of South America.
\Blitter\b 1: Recently fallen plant material which is only partially decomposed and in which the organs of the plant are still discernible, forming a surface layer on some soils. 2: Those animals produced at a multiple birth.
\BLittle Ice Age\b An interval characterized by expanding mountain glaciers (\Ic.\i 4000-2000 years B.P.); Medithermal period.
\Blittoral\b 1: Pertaining to the shore. 2: The shore of a lake to a depth of about 10 m. 3: The intertidal zone of the seashore; sometimes used to refer to both the intertidal zone on the seashore and the adjacent continental shelf to a depth of about 200 m; subdivided into supralittoral, eulittoral (intertidal zone), infralittoral and circalittoral; see marine depth zones.
\Blive-bearer\b \JPoeciliidae\j
\Bliverwort\b \JHepaticopsida\j
\Bliving fossil\b A species that has persisted to the present time with little or no change over a long period of geological time; a species with characters shared only with an otherwise extinct group.
\Blizard\b \JSauria\j
\Blizard fish\b \JSynodontidae\j
\BIlama\b \JCamelidae\j
\BL-layer\b The surface litter layer of a soil profile comprising loose fragmented material in which the original plant structures are still readily discernible; see soil horizon.
\Bloach\b 1: \JCobitidae\j 2: \JHomalopteridae\j
\Bloam\b A friable soil comprising a mixture of clay, silt, sand and organic matter.
\BLoasaceae\b Family of Violales containing about 200 species of mostly herbs commonly producing mineralized and sometimes stinging hairs; occurring mostly in the New World.
\BLobata\b Order of pelagic ctenophores found at various depths from polar to tropical seas; characterized by a body that is compressed in the tentacular plane but expanded each side of the mouth into a pair of oral lobes, and by the lack of tentacular sheaths.
\BLobeliaceae\b Lobelia; family of herbs and small trees often treated as part of the family \JCampanulaceae\j
\BLobosa\b Class of amoeboid protozoans with lobose pseudopodia comprising 2 subclasses, Gymnamoeba and Testacealobosa.
\BLobotidae\b Tripletail; family containing 4 species of marine, brackish and freshwater perciform teleost fishes widespread in warm coastal waters; body deep, perch-like, with rounded dorsal, anal and caudal fins; length to 1 m.
\Blochmodophilous\b Thriving in dry thickets; \Blochmodophile\b, \Blochmodophily.\b
\Blochmodophyte\b A plant inhabiting dry thickets.
\Blochmophilous\b Thriving in thickets; \Blochmophile\b, \Blochmophily.\b
\Blochmophyte\b A plant inhabiting thickets.
\Bloculicidal dehiscence\b Spontaneous opening of a ripe fruit along the centre line.
\BLoculoanoteromycetidae\b Subclass of loculoascomycete fungi in which the ascocarp is determinate in growth and flask shaped with the asci forming a compact layer; contains 2 orders, Chaetothyriales and Verrucariales.
\BLoculoascomycetes\b Class of ascomycotine fungi characterized by a fruiting body (ascocarp) produced by cell division or by interweaving of vegetative hyphae; sexual fusion of nuclei occurs within cells of inner portion (locule) of the ascocarp; contains 7 orders grouped into 4 subclasses, Loculoedaphomycetidae, Loculoanoteromycetidae, Loculoparenchemycetidae and Loculoplectascomycetidae.
\BLoculoedaphomycetidae\b Subclass of loculoascomycete fungi in which the ascocarp is determinate in growth, the asci form a layer and are separated by sterile hyphae or cells (pseudoparaphyses); comprises 3 orders, Hysteriales, Melanommatales and Pleosporales.
\BLoculoparenchemycetidae\b Subclass of loculoascomycete fungi in which the ascocarp is determinate in growth, the asci form a compact layer and are typically separated by the cells of the locule; contains 2 orders, Asterinales and Dothideales.
\BLoculoplectascomycetidae\b Subclass of loculoascomycete fungi containing a single order, \JMyriangiales\j
\Blocus\b The position of a given gene on a chromosome; \Bloci.\b
\Blocust\b \JCaelifera\j (Orthoptera).
\Bloess\b A fine unconsolidated wind-blown sediment.
\BLoganiaceae\b Family of Gentianales containing about 500 species of mainly tropical or subtropical woody or herbaceous plants commonly accumulating bitter substances; flowers typically with 4 or 5 sepals, petals and stamens, and a superior ovary; strychnine is obtained from seeds of one species of the largest genus, \IStrychnos.\i
\Blomentum\b A dry dehiscent fruit developed from a single carpel; contains one or more seeds released by fracture of valves on maturity.
\BLonchaeidae\b Lanceflies; cosmopolitan family containing about 500 species of small blueblack flies (Diptera) in which body has a metallic sheen; widespread in forested habitats; larvae feed mostly on decaying plant material.
\Blongevity\b The average life span of the individuals of a population under a given set of conditions.
\Blong-horned beetle\b \JCerambycidae\j
\Blongneck eel\b \JDerichthyidae\j
\Blongshore\b Used of currents or movement parallel to the coastline.
\Blong-tailed tit\b \JAegithalidae\j
\Bloon\b \JGaviidae\j
\Blooper\b The caterpillar larva of geometrid moths typically showing a looping locomotion; includes the inch worms.
\Bloosejaw\b \JMalacosteidae\j
\Bloosestrife\b \JPrimulaceae\j
\BLophiidae\b Goosefishes; family containing about 25 species of bottom-living anglerfishes (Lophiiformes) widespread on continental slopes; body naked, length to 1.2 m, head and anterior body broad, depressed, bearing spines and ridges; mouth large, teeth long and pointed.
\BLophiiformes\b Anglerfishes; order of mostly deep-water teleost fishes comprising about 215 species in 15 families, including also goosefishes, frogfishes, batfishes and sea devils; dorsal fin ray (illicium) often greatly extended bearing a lure (esca) to attract prey; sexual dimorphism may be pronounced with males much smaller than females; in some families males ectoparasitic on females.
\Blophophilous\b Thriving on hill tops; \Blophophile\b, \Blophophily.\b
\BLophophorata\b Lophophorates; a diverse assemblage of coelomate invertebrates characterized by two longitudinal coelomic compartments divided by a septum; includes 3 extant phyla, Brachiopoda, Bryozoa and Phoronida.
\Blophophyte\b A hill-top plant.
\BLophotidae\b Crestfishes; family containing 3 species of little-known mesopelagic lampridiform teleost fishes; body ribbon-like, to 1.3 m length, bearing tiny deciduous scales; anal fin absent, dorsal elongate, pelvics present or absent; a dark brown ink can be discharged from a sac opening into the cloaca.
\BLoranthaceae\b Showy mistletoe; large family of Santalales containing about 900 species of brittle, evergreen shrublets hemiparasitic on branches of trees; found in tropical and subtropical regions; flowers usually with inferior ovary, producing a berry as the fruit.
\BLoricariidae\b Family of herbivorous South American fresh and brackish water catfishes (Siluriformes); body heavily armoured with bony plates; mouth ventral, suctorial; dorsal and adipose fins often with stout spine; comprises 400 species; popular amongst aquarists, used to control algae in aquarium tanks.
\BLoricifera\b Recently discovered phylum of microscopic (up to 400 \Fm\nm) bilaterally symmetrical animals found in the interstices of marine sediments; body comprising an eversible head, neck and thorax all of which are retractible into a loricate abdominal region.
\BLorisidae\b Lorises; family containing 5 species of slow-moving arboreal prosimians found in central Africa, India and southeast Asia; body typically slender, limbs subequal length, tail short to rudimentary; habits nocturnal, feeding on variety of small animals and plant material; often hang suspended beneath branch of tree.
\Blotic\b Pertaining to fast running-water habitats, such as rivers and streams; See also \Jlentic\j
\Blotus lilies\b \JNelumbonaceae\j
\Blouse\b \JPhthiraptera\j
\Blousewort\b \JScrophulariaceae\j
\Blow tide\b Low water; the minimum height of the falling tide.
\Blow water (LW)\b The lowest surface water level reached by the falling tide; low tide.
\Blower high water (LHW)\b The lower of two high waters during any tidal day where there are marked inequalities of tidal height.
\Blower low water (LLW)\b The lower of two low waters during any tidal day where there are marked inequalities of tidal height.
\Blowest astronomical tide\b The lowest low water produced only by the gravitational effects of the sun and moon.
\BLowestoft glaciation\b Anglian \Jglaciation\j
\BLowiaceae\b Family of Zingiberales comprising only 6 species of perennial herbs with silica cells next to the vascular bundles; with malodorous flowers presumably pollinated by flies; native to southern China, Malaysia and the Pacific islands.
\BLucanidae\b Stag beetles; family containing 1200 species of often large beetles (Coleoptera) with enlarged, modified mandibles in the males which may be used for fighting; adults feeding on nectar or non-feeding; larvae feeding on decaying wood.
\BLucernariidae\b \JStauromedusae\j
\Blucicolous\b Living in open habitats with ample light; \Blucicole\b; See also \Jumbraticolous\j
\Bluciferous\b Light-producing; bioluminescent
\Blucifugous\b Intolerant of light; \Blucifugal\b; See also \Jluciphilous\j
\BLuciocephalidae\b Pikehead; monotypic family of predatory freshwater perciform teleost fishes from the Malay Archipelago; length to 180 mm, dorsal and anal fins positioned posteriorly, mouth large and protractile; utilize atmospheric oxygen through accessory respiratory structure, the suprabranchial organ.
\Bluciphilous\b Thriving in open, well-lit habitats; \Bluciphile\b, \Bluciphily\b; See also \Jlucifugous\j
\Bluffa\b \JCucurbitaceae\j
\Blugworm\b \JArenicolidae\j (Capitellida).
\Blumachelle\b An accumulation of shells in a sediment.
\BLumbricina\b Suborder of oligochaete worms (order Haplotaxida) containing the earthworms and related freshwater forms; clitellum comprising multiple layers of cells; testis in segments X and/or XI usually with single pair of male pores; ovaries in segment XIII with female pores on XIV; body length may exceed 4 m; contains about 3000 species in 15 families.
\BLumbriculida\b Order of freshwater oligochacte worms comprising a single family; body robust with 4 pairs of simple chaetae per segment; pharynx eversible; distribution mainly northern hemisphere, many species restricted to Lake Baikal.
\Bluminescence\b The emission of light by biochemical processes without the production of heat; See also \Jphosphorescence\j
\Blumpfishes\b \JCyclopteridae\j; lumpsuckers
\Blunar day\b The time interval between consecutive moonrises; 24.8 hour; See also \Jsolar day\j
\Blungfish\b 1: \JCeratodontidae\j (Australian lungfish). 2: \JLepidosirenidae\j (South American lungfish). 3: \JProtopteridae\j (African lungfish).
\Blungwort\b \JBoraginaceae\j
\Blupin\b \JFabaceae\j
\BLusitanian\b Having affinities with the Iberian peninsula.
\Bluticolous\b Inhabiting mud; \Bluticole.\b
\BLutjanidae\b Snappers; family containing 225 species of demersal and mid-water, tropical marine teleost fishes (Perciformes) found in coastal and shelf waters; body elongate to moderately deep, compressed, to 1 m in length; upper jaw protrusible; single dorsal fin present.
\BLycaenidae\b Blues, coppers, hair-streaks; large family of often brilliant metallic-coloured, small to medium-sized butterflies (Lepidoptera) found mainly in the tropics and subtropics; caterpillars frequently associated with ants.
\BLychniscosida\b Small order of hexasterophoran sponges which are typically stalked and cup-shaped, or formed as an ovoid mass of anastomosing tubes.
\BLycoperdales\b Puff balls, earthstars; widely distributed order of gasteromycete fungi producing epigeal, more or less globose, fruiting bodies; spores released by dehiscence or by rupturing.
\Blycophore\b First larval stage of a cestodarian tapeworm, possessing 10 hooks.
\BLycopodiophyta\b Division of small to mediumsized plants possessing true roots, stems and leaves; stem solid and lacking long internodes; needle or scale-like leaves each with single vein; sporangia embedded in leaf bases or in axils; contains aquatic terrestrial and epiphytic species; comprises 2 subdivisions, Lycopodiopsida and Isoetopsida.
\BLycopodiopsida\b Clubmoss; terrestrial or epiphytic plants with needle or scale-like leaves arranged spirally on stem; roots borne adventitiously on stem; sporangium bearing leaves may resemble vegetative leaves or may be aggregated to form cones.
\BLycosidae\b Wolf spiders, hunting spiders; family of medium-sized to large spiders (Araneae) which run over the ground to capture prey; some burrow or make funnel-shaped webs.
\Blygophilous\b Thriving in dark or shaded habitats; \Blygophile, lygophily.\b
\BLymantriidae\b Tussock moths; widely distributed family containing about 2000 species of medium-sized moths; typically lacking a proboscis; antennae usually bipectinate in both sexes; larvae often hairy and brightly coloured; includes the gypsy moth and other species that cause serious damage to foliage of trees.
\Blynx\b \JFelidae\j
\Blyrebird\b \JMenuridae\j
\Blysocline\b The oceanic depth zone between the carbonate dissolution depth (about 4000 m) and the carbonate compensation depth (about 5000 m), representing the major facts change between well preserved and poorly preserved calcareous elements of the ocean floor sediment.
\BLyssacinosida\b Order of hexasterophoran sponges which are typically cup-shaped, vase shaped or tubular with a stalk that is either fixed to a hard substratum or anchored in loose sediment; found in all oceans to depths greater than 6000 m.
\BLythraceae\b Purple loosestrife, crape myrtle, water willow; family of Myrtales containing about 500 species of mostly herbs widespread in tropical regions; characterized by flowers with usually 4-8 sepals, petals and stamens.
\BMacaronesia\b A biogeographical area encompassing the islands off the coast of N.W. Africa and Europe, including the Azores, Canaries, Cape Verde Islands and Madeira.
\Bmacaw\b \JPsittacidae\j
\Bmaceration\b The fragmentation and separation of parts of a specimen for microscopic examination, often by chemical treatment with strong acids.
\BMachaeridia\b Extinct class of echinoderms known from the Ordovician to the Devonian; body enclosed in an elongate, bilaterally symmetrical shell composed of calcite plates.
\Bmackerel\b \JScombridae\j
\Bmackerel shark\b \JLamnidae\j
\Bmacrobenthos\b The larger organisms of the benthos, exceeding 1 mm in length; see also \Jmeiobenthos\j \Jmicrobenthos\j
\Bmacrobiota\b Large soil organisms, exceeding about 40-50 mm in length; see also \Jmesobiota\j \Jmicrobiota\j
\BMacrocephenchelyidae\b Monotypic family of little-known Indo-Pacific marine anguilliform teleost fishes (eels); body smooth, strongly compressed posteriorly, to 500 mm length; dorsal, caudal and anal fins continuous; snout short and blunt.
\Bmacroclimate\b 1: The climate of a major geographical region. 2: The conditions of temperature, precipitation, relative humidity, sunshine and other meteorological factors, recorded about 1.5 m above ground level to avoid topological, vegetational and soil inflences; See also \Jmicroclimate\j
\BMacrodasyida\b Order of gastrotrichs found in sandy sediments of marine and brackish water habitats; characterized by pharyngeal pores, and a typically strap-shaped body bearing several adhesive tubes anteriorly.
\Bmacroevolution\b Major evolutionary events or trends such as the origin of higher groups, above species level; See also \Jmicroevolution\j
\Bmacrogamete\b The larger of two anisogametes, usually regarded as the ovum or female gamete; See also \Jmicrogamete\j
\Bmacronutrients\b Those nutrients required in relatively large amounts for optimal growth; See also \Jmicronutrients\j
\Bmacrophagous\b Feeding on relatively large food particles or prey; \Bmacrophage\b, \Bmacrophagy\b; See also \Jmicrophagous\j
\Bmacrophanerophyte\b \JMegaphanerophyte\j
\Bmacrophyll\b A Raunkiaerian leaf size \Jclass\j for leaves having a surface area between 18 225 and 164 025 mm\U2\u.
\Bmacrophyte\b A large plant, used especially of aquatic forms such as kelp; \Bmacrophytic.\b
\Bmacrophytophagous\b Feeding on higher plant material only; \Bmacrophytophage\b, \Bmacrophytophagy.\b
\Bmacroplankton\b Large planktonic organisms 20-200 mm in diameter.
\BMacropodidae\b Kangaroos, wallabies; family containing 50 species of small to large (over 2.5 m) terrestrial or arboreal diprotodont marsupials found in Australia, Tasmania and New Guinea; hindlimbs much larger than forelimbs for hopping (ricochetal) locomotion; tail often long and stout; marsupium opening anteriorly; mostly herbivorous.
\BMacrorhamphosidae\b Snipefishes; family containing 11 species of tropical and warm temperate marine gasterosteiform teleost fishes; body deep and compressed, to 300 m in length, bearing bony lateral plates; snout elongate with tiny apical mouth; first dorsal fin with 4-8 spines.
\BMacroscelididae\b Elephant shrews; family containing 15 species of small (length to 200 mm) African mammals (Insectivora); tail elongate, hindlimbs much longer than forelimbs, locomotion saltatorial.
\Bmacroscopic\b Of relatively large size; used of a structure or occurrence visible to the naked eye, or with the aid of a hand lens; See also \Jmicroscopic\j
\Bmacrosmatic\b Used of an organism possessing a highly developed sense of smell; See also \Jmicrosmatic\j
\Bmacrospore\b The larger of two kinds of haploid spores produced by vascular plants, regarded as the female spore; See also \Jmicrospore\j
\BMacrostomida\b Order of free-living turbellarians found interstitially or on the surface of plants and rocks in marine and freshwater habitats; characterized by a simple pharynx, straight gut, paired excretory ducts, and by the absence of yolk glands and of flagella on the sperm.
\Bmacrothermophilous\b Thriving in the tropics; thriving in warm habitats; \Bmacrothermophile\b, \Bmacrothermophily.\b
\BMacrouridae\b Rattails, grenadiers; family containing about 250 species of primarily bottom-living deep-sea gadiform teleost fishes characterized by a long tapering tail lacking caudal fin; pelvics thoracic; barbel usually present, gas bladder lacking connection to inner ear; photophores often present; body length to 900 mm.
\BMacrura\b The long-tailed decapod crustaceans, including the shrimp-like and lobster-like forms; formerly used as a suborder but now replaced by the suborder Dendrobranchiata and part of the Pleocyemata.
\BMacrurocyttidae\b Family of small (to 150 mm) marine zeiform teleost fishes from South America and the Philippines; body strongly compressed, mouth and eyes large; scales small and thin, dorsal fin tall and spinose.
\Bmadder\b \JRubiaceae\j
\BMadeira vine\b \JBasellaceae\j
\Bmadescent\b Becoming moist.
\Bmadid\b Wet or moist.
\BMadreporaria\b \JScleractinia\j
\Bmadrone\b \JEricaceae\j
\Bmafic\b Pertaining to rocks rich in magnesium and iron.
\BMagelonida\b Order of detritus-feeding polychaete worms that inhabit fragile mucuslined burrows in soft sediments; body threadlike, divided into 2 distinct regions; prostomium fused to peristomium, bearing long tentacular palps; pharynx eversible, unarmed; contains about 45 species in a single family, sometimes included in the order Spionida.
\Bmaggot\b Grub-like larval stage of dipterous insects.
\Bmagnetic anomaly\b A reversal in the magnetic polarity in rocks or sediments indicating a reversal of the Earth's magnetic field.
\Bmagnetotropism\b Orientation in response to a magnetic field; \Bmagnetotropic.\b
\BMagnoliaceae\b Magnolia, tulip tree; family of archaic flowering plants (Magnoliales) containing about 210 species found mostly in warm regions; flowers often large with poorly differentiated sepals and petals; stamens typically ribbon-shaped blades with embedded pollen sacs.
\BMagnoliales\b Order of rather archaic flowering plants (Magnoliidae), mostly occurring in tropical or moist warm temperate regions; plants woody, with simple leaves, commonly producing isoquinoline alkaloids; flowers typically without clearly differentiated sepals and petals, often pollinated by beetles.
\BMagnoliidae\b A subclass of dicotyledons (Magnoliopsida) comprising those forms that have retained one or more of a suite of primitive characters, the most important of which is the possession of pollen with a single germinal aperture, or a simple pistil and numerous stamens; contains 8 orders, Aristolochiales, Illiciales, Laurales, Magnoliales, Nymphaeales, Papaverales, Piperales and Ranunculales.
\BMagnoliophyta\b Flowering plants, angiosperms; the dominant land vegetation of the Earth with over 220 000 species; characterized by aggregation of sexual reproductive structures with specialized shoots (flowers) which typically comprise 4 kinds of modified leaves; sepals, petals, stamens (male organs) and carpels (female organs); ovules are enclosed within an ovary and mature into seeds in a fruit; pollen grains are produced by the stamens and germinate on the receptive stigma of the carpel, producing a pollen tube that delivers 2 sperm nuclei into the embryo sac of the ovule; flowering plants extend through the fossil record from the Lower Cretaceous to the present.
\BMagnoliopsida\b The dicotyledons; the largest class of flowering plants containing about 170 000 woody or herbaceous species; leaves usually net-veined and differentiated with a stalk (petiole) and an expanded blade; embryo typically has 2 cotyledons, although there are exceptions.
\Bmagpie\b \JCorvidae\j
\Bmahogany\b \JMeliaceae\j
\Bmaidenhair tree\b \JGinkgoatae\j
\Bmaize\b \JPoaceae\j
\Bmako shark\b \JLamnidae\j
\BMalacobothrii\b Alternative name for the \JDigenea\j
\Bmalacology\b The study of molluscs.
\Bmalacophilous\b Pollinated by snails; \Bmalacophily.\b
\BMalacopterygii\b Little-used grouping of lower fishes; characterized by soft-rayed fins lacking spines, pectoral fins set low on body and pelvics set far back.
\BMalacosteidae\b Loosejaws; family containing 10 species of luminescent deep-sea stomiiform teleost fishes found from surface to depth of 4000 m; body elongate, naked, to 300 mm in length; jaws very long with massive gape; membrane absent between the sides of the lower jaw; photophores minute, distributed over head and body.
\BMalacostraca\b The higher crustaceans; diverse class of crustaceans with a segmented body divided into 3 functional regions, head (5 segments), thorax (8 segments) and abdomen (6 or 7 segments); contains about 21 000 species in 3 subclasses, Eumalacostraca, Hoplocarida and Phyllocarida; includes crabs, lobsters, shrimps, hoppers, slaters, woodlice and many other groups.
\BMalacotylea\b Alternative name for \JDigenea\j
\BMalapteruridae\b Electric catfishes; family of nocturnal Old World freshwater teleost fishes (Siluriformes) comprising only 2 species, found in quiet backwaters of central and western Africa; body robust, to 1.2 m in length, naked, eyes small; anal and adipose fins small; 3 pairs of barbels present; produce powerful electric shocks to stun prey.
\Bmalaxation\b The act of chewing; mastication.
\Bmale\b The sperm-producing form of a bisexual or dioecious organism; symbolized $$$; See also \Jfemale\j
\BMalesherbiaceae\b Small family of Violales containing about 25 species of herbs or half shrubs native to dry habitats in the Andes.
\BMallophaga\b Chewing lice; order of small wingless hemipterodean insects that live exclusively as obligate ectoparasites of birds and mammals; body depressed, mouthparts specialized for chewing; eggs attached to hair or feathers; some may be of economic importance in domestic animals.
\Bmallow\b \JMalvaceae\j
\BMalm\b A geological epoch of the late Jurassic period (\Ic.\i 160-140 million years B.P..
\Bmalnutrition\b A deficiency condition in which one or more necessary nutrients is available in an insufficient amount for normal growth and maintenance.
\BMalpighiaceae\b Barbados cherry; family of Polygalales containing about 1200 species of woody plants commonly provided with pickshaped unicellular hairs and with pentamerous flowers; found mostly in warm regions, especially of South America.
\BMaluridae\b Thornbills, chats, wrens; diverse family containing about 100 species of small passerine birds found in forest, grassland and open arid habitats of Australia, New Guinea and New Zealand; coloration cryptic or bold; habits solitary to gregarious, arboreal to terrestrial, non-migratory; feed largely on insects, seeds and fruit; domed nest of grass, on or off the ground.
\BMalvaceae\b Hollyhock, hibiscus, cotton, mallow; large, cosmopolitan family of herbs or soft shrubs generally covered with stellate hairs; cotton is the seed hairs of \IGossypium\i species; flowers usually with 5 sepals, 5 free petals and numerous stamens and carpels, joined into rings.
\BMalvales\b Order of Dilleniidae probably derived from the Theales, containing 5 families of mostly trees and shrubs producing mucilage in special cells or canals.
\Bmamba\b \JElapidae\j
\BMammalia\b Mammals; class of warm-blooded vertebrates characterized by mammary glands, epidermal hair, enucleate red blood cells, muscular diaphragm, 3 middle ear bones, a single pair of bones (dentary) forming lower jaw articulating directly with cranium, left aortic arch only present in adults; habits primarily terrestrial but also includes aquatic, fossorial, arboreal and aerial forms; comprises the Prototheria (egg-laying mammals) and Theria (viviparous mammals).
\Bmammalology\b The study of mammals.
\Bmammoth\b Extinct Pleistocene elephants (\JElephantidae\j) found in steppe and tundra habitats; tusks elongate and strongly curved; often with long hair.
\BMammutidae\b \JMastodontidae\j
\Bmanakin\b \JPipridae\j
\Bmanatee\b \JTrichechidae\j
\Bmanca\b Juvenile stage found in some peracaridan crustaceans in which the last pair of thoracic limbs is lacking.
\BMandibulata\b A former subphylum of arthropods comprising 6 classes, Crustacea, Insecta, Chilopoda, Diplopoda, Pauropoda and Symphyla; the Crustacea is now regarded as an independent subphylum or phylum, the 5 remaining classes (plus the Onychophora) comprising the Uniramia.
\Bmandrill\b \JCercopithecidae\j
\Bmango\b \JAnacardiaceae\j
\Bmangrove\b 1: A tidal salt-marsh community dominated by trees and shrubs, particularly of the genus \IRhizophora\i, many of which produce adventitious aerial roots. 2: \JCombretaceae\j 3: \JRhizophorales\j
\BManidae\b Pangolins, scaly anteaters; family containing 7 species of nocturnal, terrestrial or arboreal mammals (Pholidota) found in Ethiopian and Oriental regions; body covered with armour of large overlapping scales; mouth tubular with long protrusible sticky tongue, teeth absent; limbs bearing strong claws; feed mainly on ants and termites.
\Bmannikin\b \JEstrildidae\j
\Bmanometabolous\b Used of a pattern of development in some insects in which a minor or very gradual metamorphosis occurs without a resting stage; \Bmanometaboly.\b
\Bmanta ray\b \JMobulidae\j
\Bmantis\b \JMantodea\j
\Bmantis shrimp\b \JStomatopoda\j (Hoplocarida).
\BMantodea\b Mantises, praying mantis; order comprising about 1800 species of medium to large (10-140 mm) predatory orthopterodean insects in which body shape is highly adapted for camouflage; head very mobile, eyes large; forelegs large, spinose, raptorial for grasping prey; forewings slender and leathery, hindwings membranous with broad fan; wings often reduced in female; most feed on insects and spiders seized by rapid strike of forelimbs, the mantis waiting motionless for the prey to arrive; in some species female eats male headfirst during copulation; distribution mainly tropical and subtropical.
\Bmaple\b \JAceraceae\j
\Bmaquis\b Scrub woodland; stunted woodland typically found on poor soil in deforested, semi-arid regions.
\BMarantaceae\b Prayer plant, peacock plant, never never plant; family of Zingiberales comprising about 400 species of perennial herbs with few leaves, and with flowers modified into a complex mechanism for insect pollination; found throughout the tropics; stamens all petaloid, one bearing a single marginal pollen sac.
\BMarattiopsida\b Subdivision of tropical terrestrial ferns (Filicophyta) in which the massive, thick-walled sporangia within a cluster (sorus) are fused; fronds often fleshy and undivided, unroll circinately; fronds fall off leaving swellings on rhizome; plants with mucilage ducts.
\BMarcgraviaceae\b Family of Theales containing about 100 species of lianas or glabrous epiphytic shrubs with clinging roots; flowers often pollinated by hummingbirds; native to tropical America.
\BMarchantiales\b Order of liverworts (Hepaticopsida); typically large plants organized as a dorsoventrally flattened, linear thallus which commonly bears ventral scales and possesses both smooth and tuberculate rhizoids; sporophyte capsule releases spores by dehiscence or disintegration.
\Bmare's tail\b \JHippuridaceae\j
\Bmargin shell\b \JNeogastropoda\j
\Bmariculture\b Cultivation, management and harvesting of marine organisms in their natural habitat or in specially constructed channels or tanks.
\Bmarigold\b \JAsterales\j
\Bmarine\b Pertaining to the sea.
\Bmarine humus\b The products of organic decomposition that accumulate in solution or suspension in the sea.
\Bmaritime\b Living in the sea; having a special affinity for the sea.
\Bmarlin\b \JIstiophoridae\j
\Bmarmoset\b \JCallitrichidae\j
\Bmarmot\b \JSciuridae\j
\Bmarsh\b An ecosystem of more or less continuously waterlogged soil dominated by emersed herbaceous plants, but without a surface accumulation of peat.
\BMarsileales\b Water ferns; small order of ferns (Filicopsida) growing underwater, on muddy shores or in ditches; creeping rhizomes rooted in mud, producing long stalked fronds; heterosporous, producing micro and megasporangia inside hard nut-like structures attached to leaf stalks.
\Bmarsupial\b \JMetatheria\j; Marsupialia.
\Bmarsupial mole\b \JNotoryctidae\j
\Bmarsupial mouse\b \JDasyuridae\j
\BMarsupicarnivora\b Order of carnivorous and omnivorous marsupials comprising 5 families, Didelphidae (opossums), Thylacinidae (Tasmanian wolf), Dasyuridae (native cats, marsupial mice), Myrmecobiidae (numbat) and Notoryctidae (marsupial mole); includes terrestrial, arboreal, semiaquatic and fossorial forms.
\Bmarten\b \JMustelidae\j
\BMartyniaceae\b Unicorn plants; small family of herbs typically clothed in sticky hairs; showy flowers arranged in terminal inflorescence; fruit a capsule with the persistent style forming a horn or hooked process; known mainly from tropical and subtropical America.
\Bmason wasp\b \JEumenidae\j
\Bmast year\b A year in which seed production is exceptionally high, usually followed by a period of several years during which relatively few seeds are produced.
\BMastacembelidae\b Spiny eels; family of nocturnal burrowing, fresh and brackish water teleost fishes (Perciformes) found in tropical Africa and southern Asia; body eel-like with many free spines in front of long dorsal fin; snout bearing fleshy tentacle.
\Bmastication\b The act of chewing.
\BMastigomycotina\b Subdivision of fungi characterized by the production of motile flagellate zoospores during the life cycle; thallus unicellular to mycelial; cosmopolitan in aquatic habitats and soil; also found as parasites; comprises 3 classes distinguished by flagellar type, Chytridiomycetes, Hyphochytridiomycetes and Oomycetes, each of which is sometimes treated as a distinct phylum of the Protoctista.
\BMastigophora\b True protozoan flagellates; subphylum of Sarcomastigophora characterized by 1 to many flagella although 2 or 4 are the commonest numbers; about one third of the species are symbionts or parasites of other animal hosts, free-living forms are abundant in both aquatic and terrestrial habitats; this subphylum comprises 3 classes, the zooflagellates (Zoomastigophora), the phytoflagellates (Phytomastigophora) and the dinoflagellates (Dinoflagellata), the last 2 groups typically possess chloroplasts and are now commonly regarded as algae.
\Bmastigopus\b Late (megalopal) larval stage of sergestoid shrimps (Decapoda).
\BMastodontidae\b Mastodon; extinct family of elephant-like animals (Hyracoidea) known from the Lower Miocene at least to the end of the Pleistocene; bodies shorter and heavier than modern elephants; tusks usually present in both upper and lower jaws.
\Bmaternal\b Pertaining to, or derived from, the female parent; See also \Jpaternal\j
\Bmaternal inheritance\b Inheritance in which characters or traits in the offspring are determined by cytoplasmic factors, such as mitochondria or chloroplasts, that are carried by the female gamete.
\Bmaternal sex determination\b The condition in which the sex of the offspring is determined by the idiotype of the female gamete.
\Bmating\b Pairing of unisexual individuals for purposes of reproduction; \Bmate.\b
\Bmatromorphic\b Resembling the female parent; See also \Jpatromorphic\j
\Bmaturation\b The attainment of sexual maturity; differentiation of the gametes; the increasing complexity or precision of behaviour patterns during growth to sexual maturity, not learned from prior experience.
\Bmatutinal\b Pertaining to the morning; used of plants that flower in the morning.
\BMaxillopoda\b Group of crustaceans containing the Mystacocarida, Cirripedia, Copepoda, Branchiura and Ostracoda; sometimes regarded as a level of organization.
\BMayacaceae\b Small family of Commelinales comprising 3 species of freshwater herbs, either free-floating or submerged and rooted in the substratum; flowers aerial each with 3 sepals, petals, stamens and carpels; found in tropical and warm temperate America and Africa.
\Bmayfly\b \JEphemeroptera\j
\Bmeadow\b An area of closed herbaceous vegetation dominated by grasses.
\Bmeadow beauty\b \JMelastomataceae\j
\Bmeadow sweet\b \JRosaceae\j
\Bmealybug\b \JCoccoidea\j (Homoptera).
\Bmean\b Average; equal to the sum of the observations divided by the number of observations.
\Bmean high water (MHW)\b The average height of all high waters recorded at a given place.
\Bmean high water neap (MHWN)\b The average height of all high waters recorded at a given place during \Jquadrature\j
\Bmean high water spring (MHWS)\b The average height of all high waters recorded at a given place during \Jsyzygy\j
\Bmean higher high water (MHHW)\b The average height of all higher high \Jwaters\j recorded at a given place.
\Bmean low water (MLW)\b The average height of all low waters recorded at a given place.
\Bmean low water neap (MLWN)\b The average height of all low waters recorded at a given place during \Jquadrature\j
\Bmean low water spring (MLWS)\b The average height of all low waters recorded at a given place during \Jsyzygy\j
\Bmean lower low water (MLLW)\b The average height of all lower low \Jwaters\j recorded at a given place.
\Bmean range\b The difference in height between mean low water and mean high water.
\Bmean sea level (MSL)\b The average height of the surface of the sea determined from all stages of the tide.
\Bmean tide level (MTL)\b The average of the observed heights of high water and low water.
\Bmean water level (MWL)\b The mean surface level determined by averaging the height of the water at a given place at hourly intervals over a prolonged period of time.
\Bmechanical weathering\b The breakdown of parent rock material without chemical changes, as part of the soil-forming process.
\Bmechanotropism\b Orientation in response to a mechanical stimulus; \Bmechanotropic.\b
\BMecoptera\b Scorpion flies, snow fleas; order of mostly diurnal holometabolous insects that inhabit moist forests feeding on nectar or preying on other insects; head prolonged into rostrum, mouthparts mandibulate; wings narrow, membranous, subequal, occasionally reduced or absent; legs long and slender; larvae caterpillar-like; about 450 species in 3 suborders, Protomecoptera, Eumecoptera and Neomecoptera.
\BMedeolariales\b Monotypic order of discomycete fungi containing a single species parasitic on the stems of the North American plant \IMededa virginiana\i; characterized by its unorganized ascocarp.
\BMediterranean climate\b A climate characterized by hot dry summers and mild wet winters.
\BMedithermal period\b An interval characterized by expanding mountain glaciers (\Ic.\i 4000-2000 years B.P.); Little Ice Age; see also \JAltithermal period\j \JAnathermal period\j
\Bmedusa fish\b \JCentrolophidae\j
\BMedusagynaceae\b Family of Theales containing a single species of glabrous trees native to the Seychelles.
\BMedusandraceae\b Family of Santalales containing a single tree species native to rainforests of tropical Africa.
\Bmega- (M)\b Prefix meaning large, great, greater than usual; used to denote unit x 10\U6\u.
\BMegachiroptera\b Suborder of Old World fruit bats (Chiroptera) comprising a single family Pteropodidae; these bats lack the echolocation mechanism of Microchiroptera.
\BMegadermatidae\b False vampires; family containing 5 species of carnivorous microchiropteran bats found in Australian, Oriental and Ethiopian regions; typically feeding on small vertebrates including fishes, amphibians, reptiles and mammals, sometimes on insects.
\Bmegafauna\b Large animals visible to the naked eye.
\Bmegaflora\b Large plants visible to the naked eye.
\BMegagaea\b A zoogeographical area comprising the Palaearctic, Nearctic, Ethiopian and Oriental Regions; see also \JArctogaea\j \JNeogaea\j, \JNotogaea\j, \JPalaeogaea\j
\Bmegagamete\b The larger of two anisogametes, usually regarded as the ovum or female gamete; macrogamete; See also \Jmicrogamete\j
\BMegalomycteridae\b Family of deep-sea lampridiform teleost fishes containing 5 species characterized by extremely large olfactory organs giving rise to the common name, large-nose fishes.
\BMegalonychoidea\b Ground sloths; extinct superfamily of ground-dwelling edentates known from the Oligocene to the Pleistocene 5 digits on each limb, often with very long claws; teeth simple and reduced.
\Bmegalopa\b Late larval stage of many malacostracan crustaceans in which at least one pair of swimming pleopods is present.
\BMegalopidae\b Tarpon; family containing 2 species of large (to 2.5 m) marine teleost fishes (Elopiiformes), highly prized as game fish by anglers.
\Bmegaloplankton\b Largest of the planktonic organisms, typically greater than 10 mm in diameter.
\BMegaloptera\b Dobsonflies, alderflies; suborder containing about 300 species of primitive neuropteran insects in which the adults have 2 pairs of large wings but perform slow, clumsy flight; adults probably non-feeding; larvae aquatic, active predators with abdominal gills; sometimes treated as an order distinct from the Neuroptera.
\Bmegaphanerophyte\b A tall \Jphanerophyte\j with renewal buds more than 30 m above ground level; macrophanerophyte.
\Bmegaphyll\b A Raunkiaerian leaf size \Jclass\j for leaves having a surface area greater than 164 025 mm\U2\u.
\Bmegaplankton\b Planktonic organisms of the largest size group, 200 mm to 2 m.
\BMegapodiidae\b Family containing 12 species of medium-sized pheasant-like birds (Galliformes), with very large strong feet; found in wooded areas of the Indo-Pacific from Australia to Polynesia; habits gregarious, monogamous; feed on seeds, fruit and small invertebrates; eggs laid in mounds of rotting vegetation or in sand, incubated by the heat of the nest.
\Bmegascopic\b Used of a structure or occurrence observable with the naked eye, or with the aid of a hand lens; See also \Jmicroscopic\j
\Bmegaspore\b The larger of two kinds of haploid spores produced by vascular plants; regarded as the female spore; See also \Jmicrospore\j
\Bmegasporogenesis\b The production of megaspores in vascular plants.
\Bmegatherm\b A plant favouring warm habitats, and with a requirement for a minimum temperature of 18░C in the coldest month; \Bmegathermic\b; see also \Jhekistotherm\j \Jmesotherm\j, \Jmicrotherm\j
\Bmeiobenthos\b Small benthic organisms that pass through a 1 mm mesh sieve but are retained by a 0.1 mm mesh; see also \Jmacrobenthos\j \Jmicrobenthos\j
\Bmeiofauna\b The small interstitial animals that pass through a 1 mm mesh sieve but are retained by a 0.1 mm mesh.
\Bmeiosis\b Reduction division; two successive divisions of a diploid nucleus preceding the formation of the haploid gametes or meiospores, each of which contains one of each pair of the homologous chromosomes of the parent cell; \Bmeiotic.\b
\Bmeiospore\b A haploid cell produced by meiosis that forms the gametophyte by mitotic division.
\Bmeiotherm\b A plant thriving in cool temperate habitats; \Bmeiothermous.\b
\Bmeiotic parthenogenesis\b \JParthenogenesis\j in which meiosis is preserved and diploidy is reinstated either by fusion of haploid nuclei within a single gamete or by the formation of a restitution nucleus.
\BMelamphaidae\b Circumtropical family containing 30 species of small (to 150 mm) bathypelagic beryciform teleost fishes; body moderately deep, rounded, bearing large cycloid scales; head cavernous; teeth minute, setiform; caudal fin with 3-4 procurrent spines.
\BMelanconiales\b Order of coelomycete fungi containing about 1000 species in a single family most of which are saprobic on plant material or parasitic; produce fruiting bodies bearing conidia on upper surface with sterile stromatic tissue restricted to basal part.
\BMelanesia\b A geographical area and an ethnological unit, sometimes considered as a distinct biogeographical unit separate from Polynesia; comprising the continental islands of the West Pacific south of the Equator, and some islands of volcanic origin; includes New Guinea, New Caledonia, Fiji, Vanuatu, Bismarck archipelago and the Solomon Islands.
\Bmelangeophilous\b Thriving in or on black loam; \Bmelangeophile\b, \Bmelangeophily.\b
\Bmelanism\b An increase in the amount of black or dark pigment in an, organism, population or group; melanic; See also \Jindustrial melanism\j
\BMelanocetidae\b Family containing 10 species of small (to 130 mm) bathypelagic anglerfishes (Lophiiformes); body rounded, naked, mouth large bearing sharp curved teeth in female; male free-living, smaller than female with small mouth lacking teeth; lure absent in male.
\BMelanogastrales\b Small order of gasteromycete fungi found in terrestrial or occasionally marine habitats; usually saprophytic or sometimes mycorrhizal; fruiting bodies typically produced underground.
\BMelanommatales\b Large order of loculoedaphomycetid fungi containing saprobic and lichenized forms as well as parasites of other plants and fungi; includes forms in which the sterile pseudoparaphyses (which separate the asci) are trabeculate and the ascospores are symmetrical.
\BMelanonidae\b Family containing 3 species of little-known pelagic gadiform teleost fishes; 2 dorsal fins and single long anal fin present; photophores absent.
\BMelanosporales\b Order of pyrenomycete fungi typically found in soil, often in association with other fungi; characterized by globose ascocarp with semitransparent walls and deliquescent asci.
\BMelanostomiatidae\b Black dragonfishes; family containing 90 species of luminescent pelagic marine teleost fishes found from surface to depth of 4500 m; body elongate, black, naked, to 350 mm in length; photophores minute, numerous on head and body; barbel present below mouth.
\BMelanostomiidae\b \JMelanostomiatidae\j
\BMelanotaeniidae\b Rainbowfishes; family containing 20 species of small (to 100 mm) colourful fresh and brackish water atheriniform teleost fishes from Australia and New Guinea; body deep, compressed, anterior dorsal fin spinose.
\BMelastomataceae\b Meadow beauty, purple glory tree; large family of Myrtales containing about 4500 species of mostly herbs and shrubs characterized by subparallel-veined leaves and specialized stamens; widespread in tropical and subtropical regions, especially of South America; flowers normally with 4-5 sepals, 4-5 petals, and 8-10 stamens.
\BMeleagridae\b Turkeys; family containing 2 species of large terrestrial gallinaceous birds found in forests of eastern United States and Mexico; habits gregarious, polygamous; feeding on insects, variety of seeds and other plant material; nest solitary, in hollow in ground; important as domesticated fowl.
\BMeliaceae\b Mahogany; family of Sapindales containing about 550 species of mostly trees and shrubs with bitter bark and spirally pinnate leaves; found mainly in warm regions; flowers usually with stamens forming a tube, and a superior ovary.
\BMelianthaceae\b Family of Sapindales containing 8 species of shrubs and trees native to Africa.
\BMeliolales\b Black mildews; order of pyrenomycete fungi widely distributed throughout moist tropical regions; forming dark-coloured mycelium over surface of leaves and stems of higher plants and feeding by means of specialized hyphae which form haustoria penetrating the host cells.
\BMeliphagidae\b Honeyeaters; family containing about 170 species of small colourful passerine birds found in forest to open arid habitats of Australia, New Zealand, New Guinea, southern Africa and many oceanic islands; bill variable, short to long, straight or curved, tongue divided distally and frilled; habits gregarious, arboreal, aggressive; feed on insects, nectar and fruit; cup or domed nest placed in tree.
\Bmeliphagous\b Feeding on honey; \Bmeliphage\b, \Bmeliphagy.\b
\BMelittidae\b Diverse family of solitary, non-parasitic bees (Hymenoptera) which dig nests in soil or build nests in pre-existing cavities, especially in wood; adults and larvae feed on nectar and pollen; some larvae spin cocoons.
\Bmelittology\b The study of bees.
\Bmelittophilous\b 1: Thriving in association with bees; used of an organism that spends part of its life cycle in association with bees. 2: Pollinated by bees; \Bmelittophile\b, \Bmelittophily.\b
\Bmelliferous\b Honey-producing.
\Bmellisugous\b Feeding on honey; honey sucking.
\Bmellivorous\b Feeding on honey; \Bmellivore\b, \Bmellivory.\b
\BMeloidae\b Blister beetles; family of often brightly coloured beetles (Coleoptera) usually found on flowers; adults producing a chemical (cantharidin) which causes skin blisters; larvae feeding on eggs of other insects and on food stores in bees' nests; contains about 3000 species, most common in warm dry regions.
\BMembracidae\b Treehoppers; family of mostly host-specific insects (Homoptera) feeding on the sap of trees and shrubs; nymphs gregarious and often attended by ants as they produce honeydew; contains about 2400 species abundant in subtropical and tropical regions.
\BMendelian character\b Any character that is inherited in accordance with Mendel's second law of independent \Jassortment\j
\BMendelian inheritance\b The inheritance of characters through nuclear chromosomes.
\BMendelism\b Inheritance in accordance with the chromosome theory of heredity.
\BMendel's laws\b First law: that in sexual organisms the two members of an allele pair or pair of homologous chromosomes separate during gamete formation and that each gamete receives only one member of the pair; law of segregation. Second law: that the random distribution of alleles to the gametes results from the random orientation of the chromosomes during meiosis; law of independent assortment.
\BMendonciaceae\b Family of Scrophulariales containing about 60 species of twining shrubs with jointed twigs; native to South America and tropical Africa.
\Bmenhaden\b \JClupeidae\j
\BMenidae\b Moonfish; family of small (to 200 mm) Indo-Pacific marine teleosts fishes (Perciformes) found mostly in deep water off coastal reefs; body deep and strongly compressed, upper profile almost straight, ventral profile deeply convex; fin spines absent; first pelvic fin ray elongate.
\BMeniscotheriidae\b Extinct family of ungulates known from the Palaeocene to the Eocene.
\BMenispermaceae\b Moonseed; family of vines or climbing shrubs commonly containing poisonous terpenoids; includes about 400 species mostly from the subtropics and tropics; flowers usually with 2 or 3 petals, and numerous stamens and carpels; fruit a drupe.
\Bmenotaxis\b A directed response of a motile organism at a constant angle to the stimulus source; \Bmenotactic.\b
\Bmensuration\b The act of measuring; quantitative estimation.
\BMenuridae\b Lyrebirds; family containing 2 species of ground-living passerine birds found in dense forests of southeastern Australia; wings short and rounded, tail long and very ornate with lyre-shaped outer feathers, legs long and stout; habits solitary, secretive, monogamous, run well but fly poorly; feed on ground invertebrates.
\BMenyanthaceae\b Buckbean; cosmopolitan family of Solanales containing about 35 species of aquatic or semiaquatic herbs that produce iridoid compounds; flowers bisexual, with 5 sepals, petals and stamens and a superior ovary.
\Bmeraspis\b Second larval stage of trilobites in which the pygidium was located behind the cephalon but trunk segmentation was absent.
\Bmerdicolous\b Living on or in dung; \Bmerdicole.\b
\Bmerdivorous\b Feeding on dung and faecal matter; \Bmerdivore\b, \Bmerdivory.\b
\Bmeridional\b Southern; pertaining to, or situated in, the south.
\Bmeristic variation\b Variation in the number of structures or parts.
\BMerliida\b Order of sclerosponges containing mostly encrusting forms known from depths of 5 to 160 m in the Atlantic and Indo-Pacific Oceans; when present the basal skeleton comprises mostly calcite.
\BMerlucciidae\b Hakes; family containing 12 species of moderately deep water gadiform teleost fishes having widespread distribution, but most abundant in Atlantic and eastern Pacific Oceans; tail elongate, tapering; 1-2 dorsal fins and single anal fin present; photophores and barbels absent.
\Bmermaid's wine glass\b \JDasycladales\j
\BMermithida\b Small order of enoplian nematodes found only as parasites of insects, slugs and snails; characterized by an exceptionally long and thin body and by the arrangement of oesophageal glands in 2 rows.
\BMerocheta\b Superorder of helminthomorphan diplopods comprising a single order Polydesmida, the largest order of millipedes.
\Bmerogamy\b A mode of reproduction in protistans involving gametes that are smaller than the vegetative cell and are produced by multiple fission; \Bmerogamete\b; See also \Jhologamy\j
\Bmeromictic\b Used of a lake that is permanently stratified due to the presence of a density gradient (pycnocline) resulting from chemical stratification; See also \Jmictic\j
\Bmeroparasite\b A partial or facultative parasite that can survive in the absence of the host; See also \Jholoparasite\j
\Bmeropelagic\b Used of aquatic organisms that are only temporary members of the pelagic community; See also \Jholopelagic\j
\BMeropidae\b Bee eaters; family containing 24 species of small colourful birds (Coraciiformes) that feed on insects caught on the wing; possessing slender pointed bills, often decurved; wings long and pointed; nest in burrows in banks; often migratory and widely distributed in tropical and warm temperate parts of the Old World from Europe to Australia.
\Bmeroplankton\b Temporary members of the planktonic community; \Bmeroplanktonic\b; See also \Jholoplankton\j
\BMerostomata\b Class of large aquatic arthropods (Chelicerata) comprising 2 orders, Xiphosura (king crabs) and the extinct Eurypterida (water scorpions); prosoma covered by a carapace, abdomen with gills and a tail spine.
\Bmerry bells\b \JLiliaceae\j
\BMertensian mimicry\b Mimicry in which a moderately offensive form is the model and a fatally offensive form is the mimic; See also \Jmimicry\j
\Bmesarch succession\b An ecological succession beginning in a habitat with a moderate amount of water; see also \Jhydrarch succession\j \Jxerarch succession\j
\BMesaxonia\b Superorder of ungulates in which the body weight is carried on the third digit; comprising a single order, Perissodactyla.
\Bmesic\b Pertaining to conditions of moderate moisture or water supply; used of organisms occupying moist habitats.
\Bmesic-supralittoral\b The wettest part of the \Jsupralittoral\j zone of the seashore, occasionally washed by splashing waves; splash zone.
\BMesitornithidae\b Family containing 3 species of small terrestrial forest-dwelling birds from Madagascar tentatively assigned to the order Gruiformes; legs short and strong, wings small; efficient runners; flight weak, probably flightless.
\Bmesobenthos\b Those organisms inhabiting the sea-bed in the archibenthal zone, between 200 and 1000 m depth.
\Bmesobiota\b Soil organisms of intermediate size, from about 40-50 mm in length to a size just visible with the aid of a hand lens; see also \Jmacrobiota\j \Jmicrobiota\j
\Bmesocosm\b A medium-scale enclosed experimental facility, used especially for assessing the impact of pollutants on natural ecosystems.
\BMesogastropoda\b An order of prosobranch molluscs containing about 10 000 species of marine, freshwater and terrestrial snails including conches, cowries, fig shells, frog shells, heteropods, periwinkles, triton shells, tun shells, violet snails, wentletraps and winkles; characterized by a primitively conical, spiral shell usually with right-handed coiling and typically lacking mother-of-pearl (nacre), and by an asymmetrical mantle cavity in which the water current enters from the anterior left side and a single gill is typically present on the left side; usually with internal fertilization.
\Bmesohaline\b Pertaining to brackish water having a salinity between 3 and 10 parts per thousand or sea water having a salinity between 30 and 34 parts per thousand; see also \Joligohaline\j \Jpolyhaline\j
\Bmesohalobous\b Pertaining to planktonic organisms living in brackish water with a salinity between 5 and 20 parts per thousand.
\Bmesohydrophyte\b A plant thriving under damper conditions than a true mesophyte; \Bmesohydrophytic.\b
\Bmesohylile\b Pertaining to moist forest habitats.
\BMesolithic\b An archaeological period \Ic.\i 10 000-4000 years B.P.; Middle Stone Age.
\Bmesolithion\b Organisms inhabiting cavities in rock.
\Bmesomorphic\b Possessing intermediate characters or traits.
\BMesonychidae\b Extinct family of condylarth mammals known from the Palaeocene to the Oligocene; upper cheek teeth triangular, adapted for shearing; may have fed on carrion.
\Bmesopelagic\b The pelagic zone of intermediate depth, 200-1000 m; see marine depth zones.
\Bmesophanerophyte\b A medium-sized \Jphanerophyte\j with renewal buds 8-30 m above ground level.
\Bmesophilic\b 1: Thriving under intermediate or moderate environmental conditions; sometimes restricted to conditions of moderate moisture, or to moderate temperature; \Bmesophile\b, \Bmesophily.\b 2: Used of microorganisms having an optimum for growth between 20 and 45░C.
\Bmesophyll\b A Raunkiaerian leaf size \Jclass\j for leaves having a surface area between 2025 and 18 225 mm\U2\u; sometimes subdivided into notophyll (2025-4500 mm\U2\u) and mesophyll (4500-18 225 mm\U2\u).
\Bmesophyte\b A plant thriving under intermediate environmental conditions of moderate moisture and temperature, without major seasonal fluctuations; \Bmesophytic\b; see also \Jhydrophyte\j \Jhygrophyte\j, \Jxerophyte\j
\Bmesophythmile\b Pertaining to the floor of a lake at depths between 6 and 25 m.
\BMesophytic\b The period of geological time during the first appearance of the angiosperms; see also \JAphytic\j \JArchaeophytic\j, \JCaenophytic\j, \JEophytic, Palaeophytic\j
\Bmesoplankton\b Planktonic organisms of intermediate body size, 0.2-20 mm.
\Bmesopleustophyte\b Any large plant floating freely between the surface and the floor of a lake.
\Bmesopsammon\b Those organisms living in the interstitial spaces of a sandy sediment.
\Bmesosaprobic\b Pertaining to a polluted aquatic habitat having reduced oxygen concentration and a moderately high level of organic decomposition; \Bmesosaprobe.\b
\BMesosauria\b Extinct order of lightly built, anapsid reptiles adapted to life in fresh water; known from Late Carboniferous and Early Permian.
\BMesotardigrada\b Order of tardigrades (water bears) found in Japanese thermal springs (65░C); head lacking cephalic appendages but lateral cirri present; legs bearing 6-10 simple claws.
\BMesothelae\b Suborder of spiders (Araneae) having a segmented abdomen bearing midventral spinnerets; chelicerae move parallel to body axis; contains about 12 species typically inhabiting trapdoor burrows in the ground.
\Bmesotherm\b A plant favouring intermediate temperature conditions, with a minimum of 22░C in the warmest month and a range of 6-18░C in the coldest month; \Bmesothermic\b; see also \Jhekistotherm\j \Jmegatherm\j, \Jmicrotherm\j
\Bmesothermophilous\b Thriving in temperate regions; \Bmesothermophile\b, \Bmesothermophily. \b
\Bmesotraphent\b Used of an aquatic plant characteristic of water bodies with intermediate nutrient concentrations; see also \Jeutraphent\j \Joligotraphent\j
\Bmesotrophic\b 1: Having intermediate levels of primary productivity; pertaining to waters having intermediate levels of the minerals required by green plants; see also \Jdystrophic\j \Jeu
\BMesozoa\b Small phylum of ciliated, multicellular animals found as endoparasites in various marine invertebrates; characterized by a solid, two-layered body lacking skeletal, muscular, nervous, digestive and excretory elements; all are obligate parasites and their simple organization may be secondary, a result of parasitic adaptation; found on both sides of the Atlantic, and on the west coast of America.
\BMesozoic\b A geological era (\Ic.\i 245-65 million years B.P.) comprising Cretaceous, Jurassic and Triassic periods; see geological time scale.
\Bmesquite\b \JMimosaceae\j
\Bmessenger RNA\b RNA that carries the code for a protein from the DNA in the nucleus to the ribosomes, and acts as a template for the synthesis of that protein; mRNA.
\BMetabasidiomycetidae\b Small subclass of tropical to temperate phragmobasidiomycete fungi in which the fruiting bodies are mainly gelatinous to waxy; comprises about 110 species.
\Bmetabolism\b 1: The totality of the synthetic and degradative biochemical processes of living organisms. 2: In ecological energetics, sometimes used as equivalent to \Jrespiration\j
\Bmetabolous\b Used of a pattern of development that includes a metamorphosis.
\Bmetachrosis\b The ability to change colour.
\Bmetagynic\b Used of a hermaphroditic organism that matures first as a male, followed by the transition to a functional female condition; \Bmetagyny.\b
\Bmetalimnion\b The zone of steep temperature gradient (thermocline) between the epilimnion and the hypolimnion in a lake; \Bmetalimnetic.\b
\Bmetallophyte\b A plant confined to substrates with very high levels of heavy metals.
\BMetameria\b A grouping of segmented animals, including the annelids and arthropods, exhibiting \Jmetamerism\j
\Bmetamerism\b The division of the body along an anteroposterior axis into a series of segments, each segment containing representatives of all the organ systems of the body; \Bmetameric.\b
\Bmetamorphic rock\b Rock formed by the restructuring of pre-existing rocks under the effects of high temperature and pressure; see also \Jigneous rock\j \Jsedimentary rock\j
\Bmetamorphosis\b A marked structural transformation during the development of an organism, often representing a change from larval stage to adult; \Bmetamorphic.\b
\Bmetanauplius\b Late nauplius larval stage of crustaceans, with more than 3 pairs of limbs present but no functional thoracic limbs.
\BMetaphyta\b A kingdom including all the multicellular plants.
\Bmetaphyte\b A multicellular plant; a plant with completely differentiated tissues.
\Bmetaplasia\b 1: An evolutionary state characterized by maximum vigour and diversification of organisms; see also \Janaplasia\j \Jca
\Bmetastasis\b 1: A change of state, form, position, or function. 2: The transportation of pathogenic organisms or cancerous cells around the host body.
\BMetatheria\b Marsupials; infraclass of viviparous mammals (Theria) comprising the single superorder Marsupialia with 4 extant orders, Marsupicarnivora, Peramelina, Paucituberculata and Diprotodontia; young typically develop within abdominal pouch (marsupium); uteri separate, vaginae paired, yolk sac placenta usually present, penis bifurcate; found in Australian and Neotropical regions, with single Nearctic species; Marsupialia.
\Bmetathetely\b The retention of some juvenile characters by an insect adult that has developed through the normal number of moults; \Bmetathetelic.\b
\Bmetatrophic\b Used of organisms that utilize organic nutrients as the source of both carbon and nitrogen.
\BMetazoa\b A kingdom including all the multicellular animals; \JEumetazoa\j
\Bmetazoan\b A multicellular animal; \JEumetazoa\j
\Bmeteorological tide\b The change in water level resulting from meteorological factors, largely barometric pressure and wind; \Bmeteorologic tide.\b
\Bmeteorology\b The study of weather or local atmosphere conditions; \Bmeteorological\b; See also \Jclimatology\j
\Bmethanogenic\b Methane-producing, as of certain autotrophic and chemolithotrophic bacteria.
\Bmetochy\b A neutral \Jsymbiosis\j in which a guest organism freely inhabits the nest of a host species without demands upon the resources of the colony.
\Bmetoecious\b Used of a parasite that is not host-specific; See also \Jametoecious\j
\Bmetoxenous\b Used of a parasite that occupies different hosts at different stages of the life cycle.
\Bmetric prefixes\b Standard prefixes used in conjunction with the metric units of the International System; see page 236.
\BMetzgeriales\b Small order of liverworts (Hepaticopsida); plants usually thallose with a flattened axis and lateral expansions, typically with smooth rhizoids; sex organs found dorsally on leading axes or on specialized reduced branches but not involving apical cells.
\Bmezereon\b \JThymelaeaceae\j
\BMiacidae\b Extinct family of early carnivores (Fissipedia) known from the Palaeocene and Eocene; typically small, with long bodies and short legs; probably arboreal forest-dwellers.
\Bmicelle\b The individual particles of the dispersed phase of a colloid in which the dispersion medium is a liquid.
\BMichurinism\b The theory that the genetic constitution of the scion can be modified by grafting.
\Bmicro- (\b\Fm\n\B)\b 1: Prefix meaning small, short. 2: Used to denote unit x 10\U-6\u; see metric prefixes.
\Bmicroaerophilic\b 1: Thriving in a free oxygen concentration significantly less than that of the atmosphere; \Bmicroaerophile\b, \Bmicroaerophily.\b 2: Used of an environment in which the partial pressure of oxygen is significantly below normal atmospheric levels but which is not fully \Janaerobic\j
\BMicroascales\b Small order of plectomycete fungi containing a single family of typically saprophytic forms found in soil, dung and organic debris; characterized by dark, hairy or appendaged ascocarps which contain evanescent asci arranged singly or in short chains in the inner tissues.
\Bmicrobenthos\b Microscopic benthic organisms less than 0.1 mm in length; see also \Jmacrobenthos\j \Jmeiobenthos\j
\Bmicrobiology\b The study of microorganisms.
\Bmicrobiota\b Microscopic soil organisms not visible with the aid of a hand lens; see also \Jmacrobiota\j \Jmesobiota\j
\Bmicrobivorous\b Feeding on microorganisms, in particular bacteria; \Bmicrobivore\b, \Bmicrobivory.\b
\BMicrocerberidea\b Suborder of minute interstitial isopod crustaceans having an elongate slender body form, found in subterranean waters of Central America, the Mediterranean region, and from Africa to India.
\BMicrochiroptera\b Cosmopolitan suborder of mainly small bats that use echolocation for navigation; many are insectivorous, but other diets include fruit, nectar, vertebrates and blood.
\Bmicroclimate\b The climate of the immediate surroundings or habitat, differing from the \Jmacroclimate\j as a result of the influences of local topography, vegetation and soil; bioclimate.
\BMicrodesmidae\b Wormfishes; family containing 30 species of eel-like tropical or subtropical marine gobioid teleost fishes found burrowing in muddy estuarine habitats or on coral reefs; body length to 300 mm, single dorsal fin present; median fins may be continuous with caudal.
\Bmicroevolution\b Minor evolutionary events usually viewed over a short period of time, consisting of changes in gene frequencies, chromosome structure or number within a population over a few generations; See also \Jmacroevolution\j
\Bmicrofauna\b 1: Small animals not visible to the naked eye. 2: A localized group of animals. 3: The animals of a microhabitat.
\Bmicroflora\b 1: Small plants not visible to the naked eye. 2: A localized flora. 3: The plants of a microhabitat.
\Bmicrofossil\b A microscopic fossil.
\Bmicrogamete\b The smaller of two anisogametes, usually regarded as the sperm or male gamete; See also \Jmacrogamete\j
\Bmicrogametogenesis\b The development of microgametes (spermatozoa).
\Bmicrohabitat\b A small specialized habitat.
\BMicrohylidae\b Diverse family containing about 230 species of narrow-mouthed frogs (Anura) with characteristic larval morphology; tadpoles have single median spiracle; beak, barbels and denticles absent; most forms have aquatic eggs and larvae, some have attenuated development or direct development from terrestrial eggs; distributed worldwide, except for Australian and Palaearctic regions.
\Bmicromelittophilous\b Pollinated by small bees; \Bmicromelittophily\b.
\Bmicromyiophilous\b Pollinated by small flies; \Bmicromyiophily\b.
\Bmicron\b Micrometre; a derived metric unit of length, equal to 10\U-6\u m; (\Fm\nm).
\BMicronesia\b An assemblage of many small oceanic islands within the warmer part of the western Pacific Ocean; a recognized geographical and ethnological area which is sometimes considered to be a distinct biogeographical unit, separate from Polynesia.
\Bmicronutrients\b Trace elements; nutrients required in minute quantities for optimal growth; See also \Jmacronutrients\j
\Bmicroorganisms\b Organisms of microscopic or ultramicroscopic size; commonly includes bacteria, blue-green algae, yeasts, some lichens and fungi, protistans, viroids and viruses.
\Bmicropalaeontology\b The study of microscopic fossils-those fossils ranging in size from 1 or 2 cm to a few microns, that must be studied by light or electron-microscopy.
\Bmicrophagous\b Feeding on relatively minute particles or on very small prey; \Bmicrophage\b, \Bmicrophagy\b; See also \Jmacrophagous\j
\Bmicrophanerophyte\b A small \Jphanerophyte\j with renewal buds 2-8 m above ground level.
\Bmicrophilic\b Thriving only within a narrow range of temperature; \Bmicrophile\b, \Bmicrophily\b.
\Bmicrophyll\b A Raunkiaerian leaf size \Jclass\j for leaves having a surface area between 225 and 2025 mm\U2\u.
\Bmicrophyte\b A microscopic plant; \Bmicrophytic\b.
\Bmicrophytic\b Used of a plant community comprising only lichens or algae.
\Bmicroplankton\b Small planktonic organisms. 20-200 \Fm\nm in diameter.
\Bmicropredator\b An organism that feeds on a prey organism which is larger than itself and to which it attaches temporarily.
\Bmicropterigidae\b Family of primitive, small, metallic-coloured moths (Zeugloptera) with functional mandibles; adults feed on pollen.
\Bmicroscopic\b Used of an organism or occurrence that cannot be observed without the use of a microscope; See also \Jmacroscopic\j
\Bmicrosere\b An ecological succession within a microhabitat, often failing to reach a stable climax.
\Bmicrosmatic\b Used of an organism possessing a poorly developed sense of smell; See also \Jmacrosmatic\j
\BMicrospora\b Microsporidians; phylum of intracellular parasitic protozoans occurring in nearly every major animal group, especially arthropods; characterized by the lack of mitochondria and by the production of tiny unicellular spores equipped with an internal, coiled polar filament which is extruded as part of the infection mechanism; includes 2 subclasses, Microsporea and Rudimicrosporea; also treated as a class, Microsporida, of the protoctistan phylum Cnidosporida.
\BMicrosporales\b Small order of freshwater green algae in which the thallus comprises an unbranched uniseriate filament and vegetative reproduction occurs by fragmentation.
\Bmicrospore\b The smaller of two kinds of haploid spores produced by vascular plants, regarded as the male spore; See also \Jmegaspore\j
\BMicrosporea\b Subclass of sporulating microsporidian protozoans that produce spores consisting of the sporoplasm, spore wall and extrusion apparatus; includes 2 orders based on the degree of development of the extrusion apparatus, Microsporidia and Minisporidia.
\BMicrosporida\b \JMicrospora\j; treated as a class of the protoctistan phylum Cnidosporida.
\BMicrosporidia\b Order of \JMicrosporea\j typically with marked development of the extrusion apparatus and a variety of spore sizes and shapes.
\Bmicrosporogenesis\b The production of microspores in vascular plants; the production of the male gametophyte (pollen).
\Bmicrotherm\b A plant favouring relatively cold habitats with a minimum temperature of 6░C in the coldest month and a range of 10-22░C in the warmest month; \Bmicrothermic\b; see also \Jhekistotherm\j \Jmegatherm\j, \Jmesotherm\j
\Bmicrothermic\b Used of organisms requiring only a minimum of heat, or favouring relatively low temperatures; \Bmicrotherm.\b
\Bmicrothermophilous\b Thriving in boreal regions; \Bmicrothermophile\b, \Bmicrothermophily. \b
\Bmicrowhipscorpion\b \JPalpigradi\j
\Bmicrozoophilous\b Pollinated by small animals; \Bmicrozoophily.\b
\BMictacea\b Order of peracaridan crustaceans lacking an epipod on the thoracic legs and lacking a carapace and functional eyes; known from one deep-sea species and one cavernicolous species from marine caves on Bermuda.
\Bmictic\b Pertaining to patterns of water circulation in a lake; see also \Jamictic\j \Jdimictic\j, \Jholomictic\j, \Jmeromictic, monomictic, polymictic\j
\Bmidden\b A refuse heap; used especially in archaeology.
\Bmidge\b \JChironomidae\j (\JNematocera\j).
\Bmid-ocean ridge\b A topographical feature of the ocean floor comprising rifts and mountain ridges representing the sites of ocean floor upwelling and spreading.
\Bmignonette\b \JResedaceae\j
\Bmigration\b 1: Periodic or seasonal movement, typically of relatively long distance, from one habitat or climate to another; any general movement that affects the range of distribution of a population or individual; \Bmigrate\b; See also \Jdispersion. 2: Movement of a pathogen within the host body. 3: Gene flow; exchange of genetic information between populations\j
\Bmigrule\b A unit step or agent of migration.
\Bmildew\b Any fungal disease in which the fungal mycelium is visible as pale patches on the leaves of the host plant.
\Bmilkfish\b \JChanidae\j
\Bmilkweed\b \JAsclepiadaceae\j
\Bmilkwort\b \JPolygalaceae\j
\Bmillennial\b Pertaining to periods of thousands of years; see also \Jdecennial\j \Jsecular\j
\Bmillennium\b A unit of time equal to 1000 years or 1 millicron.
\BMilleporina\b Fire coral; order of Hydrozoa in which the polyps are colonial and form a massive calcareous skeleton; medusae are free-swimming and formed in special cavities in the colony; found in coral reefs in tropical seas; known as fossils from the Cretaceous to Recent times.
\BMillericrinida\b Order of deep-sea stalked articulate crinoids in which the cirri are absent, the stalk elongate and slender, and the attachment is by a terminal calcareous disk; 5 arms are present and may be branched; the group is largely extinct with only 8 living species.
\Bmillet\b \JPoaceae\j
\Bmilli (m)\b Prefix meaning thousand, thousandth; used to denote unit x 10\U-3\u; see metric prefixes.
\Bmillipede\b \JDiplopoda\j
\Bmimesis\b \JMimicry\j; \Bmimetic.\b
\Bmimetic polymorphism\b Polymorphism in which the various morphs resemble other unpalatable or venomous species in order to deceive the operator (predator).
\Bmimic\b To imitate; any organism that imitates another.
\Bmimicry\b The close resemblance of one organism (the mimic) to another (the model) to deceive a third (the operator); mimesis; see also \Jaggressive mimicry\j \JBatesian mimicry\j, \JMertensian mimicry\j, \JMüllerian mimicry\j
\BMimidae\b Mockingbirds; family containing about 30 species of medium-sized passerine birds found in a variety of forest, woodland and arid habitats of the New World from Canada to Argentina; habits solitary, arboreal to terrestrial, feeding mostly on insects and fruit; cup-shaped nest of grass and twigs, on or off the ground.
\BMimosaceae\b Acacia, mimosa, mesquite; large family of Fabales containing about 2000 species of sometimes spiny, mostly woody leguminous plants with mostly bipinnately compound leaves; widespread in tropical to subtropical regions especially in dry areas; flowers regular, with 4-10, or many stamens; formerly known as the subfamily Mimosoideae of the family Leguminosae.
\BMindel glaciation\b A glaciation of the Quaternary Ice \JAge\j in the Alpine area, with an estimated duration of 90 000 years.
\BMindel-Riss interglacial\b An interglacial period in the middle of the Quaternary Ice \JAge\j in the Alpine area.
\Bmineral replacement\b A mode of fossilization in which organic material is removed and replaced by minerals.
\Bminerotrophic\b Used of organisms nourished by minerals.
\BMinisporidia\b Order of \JMicrosporea\j typically with tiny rounded spores with only a minimal development of the extrusion apparatus.
\Bmink\b \JMustelidae\j
\Bminke whale\b \JBalaenopteridae\j
\Bminnow\b \JCyprinidae\j
\Bmint\b \JLamiaceae\j
\BMiocene\b A geological epoch within the Tertiary period (\Ic.\i 26-5 million years B.P.); see geological time scale.
\Bmiracidium\b Free-swimming ciliated larval stage of a digenean trematode parasite that hatches from the egg and infects the molluscan intermediate host and develops asexually into the redia q.v.
\BMirapinnidae\b Hairyfish; family of bizarre lampridiform teleost fishes known from a single immature specimen collected in the North Atlantic; body length to 55 mm, with dense hair-like covering; pelvic fins large, fan like; pectorals small; caudal fin with overlapping lobes.
\Bmire\b An ecosystem in which the vegetation is rooted in wet peat; a collective term for various bogs and fens.
\BMischococcales\b Order of mostly freshwater algae (Xanthophyceae) comprising unicellular forms with a distinct cell wall but lacking contractile vacuoles and an eyespot.
\Bmiscible\b Used of liquids that can be mixed together in any ratio without separation; \Bmiscibility.\b
\BMisodendraceae\b Family of Santalales containing 10 species of dioecious shrubs which are hemiparasitic on the branches of Nothofagus trees in temperate forested regions of South America.
\BMisophrioida\b Order of primitive marine copepod crustaceans containing about 16 species of near-bottom living planktonic predators or scavengers restricted mainly to the deep sea but also known from shallow water and marine caves; characterized by a carapace covering the first leg-bearing thoracic segment.
\Bmistletoe\b \JViscaceae\j
\Bmite\b \JAcari\j
\Bmite harvestmen\b Suborder comprising about 50 species of small (up to 3 mm) litter-dwelling harvestmen (Opiliones) that superficially resemble true mites (Acari) except that the abdomen is segmented.
\Bmitosis\b The process of chromosome division and separation that takes place in a dividing cell, producing daughter cells of equivalent chromosomal composition to the parent cell; typically 4 main stages are recognized, prophase, metaphase, anaphase and telophase; \Bmitotic.\b
\Bmitospore\b A diploid spore produced by mitosis.
\BMitrastemonaceae\b Family of Rafflesiales containing only 2 species of chlorophyll-less endoparasites the vegetative body of which resembles a fungal mycelium penetrating the roots of its host.
\Bmitre shell\b \JNeogastropoda\j
\BMitsukurinidae\b Goblin shark; monotypic family of rare deep-water bottom-dwelling lamniform elasmobranch fishes; body length to 2.5 m, head flattened, snout elongate and blade-like, eyes very small.
\Bmixed layer\b A layer of water well mixed by wave action or thermocline convection.
\Bmixis\b The fusion of gametes; karyogamy and karyomixis.
\Bmixolimnion\b The upper low-density region of periodic free circulation above the \Jmonimolimnion\j in the meromictic lake.
\Bmixosaur\b One of the earliest of the ichthyosaurs, without the well developed caudal fin of later forms.
\Bmixotrophic\b Used of organisms that are both autotrophic and heterotrophic; \Bmixotroph\b, \Bmixotrophy.\b
\Bmnemotaxis\b A directed response of a motile organism to a memory stimulus; \Bmnemotactic.\b
\Bmoa\b \JDinornithidae\j
\Bmobbing\b A collective attack by a group of animals, on a predator that is too large or aggressive to be repelled by individual effort.
\BMobulidae\b Manta rays, devil rays; family of large, tropical and subtropical marine, myliobatiform elasmobranch fishes containing 10 species; body disk much broader than long, distinctly demarkated from head; pectoral fins forming pair of vertical lobes in front of head; tail filamentous distally, caudal fin absent; mouth broad with many minute teeth; feed on small pelagic fishes and crustaceans filtered by gill plates.
\Bmoccasin\b \JViperidae\j
\BMochokidae\b Family of crepuscular African freshwater catfishes (Siluriformes) found in slow-moving rivers and swamps; some swim actively in an inverted posture beneath vegetation; body naked, dorsal fin short with stout spine; 3 pairs of barbels present; contains about 150 species; popular in aquarium trade; also known as the Synodidae.
\Bmockingbird\b \JMimidae\j
\BMoeritherioidea\b Extinct suborder of small primitive elephant-like mammals (Proboscidea) known from the Upper Eocene to the Oligocene; exhibited early stage of tusk evolution.
\BMolidae\b Sunfishes, trunkfishes; family containing 3 species of large (to 4 m) surface-living oceanic tetraodontiform teleost fishes; body deep, compressed; mouth small with jaw teeth fused to form beak; dorsal and anal fins tall.
\BMollicutes\b A group containing the smallest self-replicating prokaryotes, characterized by the lack of a peptidoglycan cell wall so that they are bound only by a plasma membrane; all but one species are parasitic; mycoplasms.
\BMolluginaceae\b Common carpetweed; small family of Caryophyllales containing about 100 species of sometimes saponiferous herbs found mainly in warm regions, especially in Africa.
\BMollusca\b Large phylum of unsegmented animals with a ventral gliding surface or foot and a dorsal mantle bearing more-or-less imbricating calcareous scales primitively, or a solid calcareous shell in more advanced forms; posterior mantle cavity containing a pair of respiratory gills (ctenidia) and the excretory and genital openings; mouth typically possessing a radula; head commonly with sensory tentacles and eyes; most internal organs contained within dorsal visceral mass, protected by shell secreted by the mantle; molluscs are widespread in marine, freshwater and terrestrial habitats, mostly free-living but occasionally parasitic; comprising nearly 50 000 species in 8 classes, Bivalvia, Caudofoveata, Cephalopoda, Gastropoda, Monoplacophora, Polyplacophora, Scaphopoda and Solenogastres.
\Bmolluscicide\b A chemical used to kill snails, slugs and other molluscs.
\BMolossidae\b Free-tailed bats; family containing about 80 species of insectivorous microchiropteran bats found in both Old and New World.
\BMolpadiida\b Order of littoral to abyssal holothurians comprising about 85 species that burrow in soft sediments with their respiratory posterior end at the surface; test robust, tapering posteriorly, tentacles digitate or claw-like, respiratory trees present, tube-feet absent.
\BMomotidae\b Motmots; small family containing 9 species of colourful Neotropical forest birds (Coraciiformes) that feed on a variety of invertebrates and small vertebrates caught mainly on the wing; typically nest in burrows in banks.
\Bmonacmic\b Exhibiting one abundance peak pet year; see also \Jdiacmic\j \Jpolyacmic\j
\Bmonandrous\b Used of a female that mates with a single male; \Bmonandry\b; See also \Jpolyandrous\j
\Bmonaxenic\b Used of a mixed culture of an organism with one prey species; see also \Jaxenic\j \Jdixenic\j
\BMonera\b The major kingdom of \Jprokaryotes\j in which the genetic material comprises a single long molecule of DNA arranged as the chromonema, and the main site of metabolic activity is the plasma membrane; reproduction essentially asexual, neither meiosis nor mitossis is exhibited; comprises 3 divisions, Bacteria. Cyanophycota and Prochlorophycota.
\Bmoneran\b Pertaining to the prokaryotic organisms of the kingdom Monera; See also \Jprotistan\j
\Bmoney spider\b \JLiniphiidae\j
\Bmongoose\b \JViverridae\j
\BMoniliformida\b Order of archiacanthocephalan thorny-headed worms found worldwide as parasites of mammals and occasionally birds; characterized by a cylindrical proboscis with long, straight rows of hooks, each with a simple root.
\BMoniligastrida\b Order of primitive oligochaete worms typically found in damp primary forests of southeast Asia, from Japan to southern India; body may exceed 1 m length; comprises a single family with about 115 species.
\BMonimiaceae\b Large family of woody plants (Laurales) containing about 450 species native to subtropical and tropical regions, particularly in the southern hemisphere; characterized by having flowers in cymes, with sepals and petals frequently not differentiated.
\Bmonimolimnion\b The perennially stagnant high-density, usually saline, deep-water layer in a meromictic \Jlake\j; See also \Jmixolimnion\j
\Bmonitor lizard\b \JVaranidae\j
\Bmonkey hopper\b \JCaelifera\j
\Bmonkey puzzle tree\b \JAraucariaceae\j
\Bmonkfish\b \JSquatinidae\j
\BMonoblepharidales\b Order of chytridiomycete fungi comprising about 20 species of microscopic saprobes living in temperate freshwater habitats or in tropical and subtropical soils; characterized by a mycelium-like thallus and sexual reproduction by fusion of a non-motile oosphere and motile male planogametes; also treated as a class of the protoctistan phylum Chytridiomycota, under the name Monoblepharida.
\Bmonocarpic\b Producing a single fruit, or having only one fruiting period, during the life cycle; See also \Jpolycarpic\j
\BMonocentridae\b Pine-cone fishes; family containing 2 species of small (to 230 mm) pelagic Indo-Pacific beryciform teleost fishes; body compressed, bearing armour of heavy scales; eyes large, teeth setiform; ventral surface of lower jaw with luminous organ containing symbiotic bacteria.
\BMonocheta\b Superorder of helminthomorphan diplopods (millipedes) comprising a single order, Stemmiulida.
\Bmonochronic\b Occurring only once.
\BMonocleales\b Small order of liverworts (Hepaticopsida) found in South and Central America, the Caribbean and New Zealand; organized as a dichotomously branching thallus with mostly smooth rhizoids on its ventral surface, some rhizoids having rudimentary pegs; sporophyte capsule produced on long, massive stalk releasing spores by dehiscence.
\Bmonoclinous\b Used of a flower having both male and female organs; hermaphrodite; perfect; \Bmonocliny\b; See also \Jdiclinous\j
\BMonocotyledoneae\b Monocotyledons; one of the great divisions of flowering plants in which the embryo typically has one cotyledon; now known as the \JLiliopsida\j
\Bmonoculture\b The cultivation or culture of a single crop or species to the exclusion of others.
\BMonocyathea\b Extinct class of usually solitary, marine animals (Archaeocyatha) known from the Lower and Middle Cambrian.
\BMonodactylidae\b Moonfish; family containing 5 species of small (to 200 mm) coastal marine and brackish-water teleost fishes (Perciformes) found in western Africa and the Indo-Pacific; body very deep and compressed, dorsal and anal fins elongate, pelvics vestigial.
\Bmonodomic\b Used of colonies of social insects that occupy only one nest; See also \Jpolydomic\j
\BMonodontidae\b Family of odontocete mammals comprising the narwhal and the beluga or white whale, found in cold waters of north polar seas; in the male narwhal the left incisor of the upper jaw develops into a long (up to 2.5 m) spiral tusk; feed on large invertebrates and fishes.
\Bmonoecious\b 1: Used of individuals having both male and female reproductive organs; hermaphrodite. 2: Used of a bisexual plant species having separate male and female flowers (unisexual) on the same individual; ambisexual; monecious; \Bmonoecism\b, \Bmonoecy\b; see also \Jdioecious\j \Jtrimonoecious\j, \Jtrioecious\j
\Bmonoestrous\b Having a single breeding period in a sexual season; see also \Janoestrus\j \Jdioestrus\j, \Jpolyoestrous\j
\Bmonogamous\b Pertaining to the condition in which a single male and female form a prolonged and more or less exclusive breeding relationship; \Bmonogamic\b, \Bmonogamy\b; See also \Jpolygamous\j
\BMonogenea\b Subclass of trematodes comprising about 1100 species, mostly ectoparasitic on the gills and skin of fishes but also found on amphibians, reptiles and crustaceans; characterized by a direct life cycle involving only one host and without intermediate multiplication by larval stages, and by an anterior holdfast (prohaptor) of one or more suckers and a well developed posterior holdfast (opisthaptor) with suckers, clamps or hooks; most species are oviparous, producing typically operculate eggs containing a ciliated oncomiracidium larva.
\Bmonogenetic\b 1: Pertaining to a symbiont having only one host throughout its life cycle; see also \Jdigenetic\j \Jtrigenetic. 2: Used of asexually reproducing organisms\j, \Jor of asexual reproduction\j
\Bmonogenic\b Producing only male or only female offspring; \Bmonogeny\b; see also \Jallelogenic\j \Jamphogenic\j, \Jarrhenogenic\j, \Jthelygenic\j
\Bmonogenous\b Pertaining to asexual reproduction or asexually reproducing organisms.
\BMonognathidae\b Family containing 6 species of small (to 100 mm) bathypelagic gulper-eels (Anguilliformes) found in tropical and subtropical waters; upper jaws absent, tail long and tapering; pectoral fins small or absent.
\BMonogonata\b Large class of rotifers characterized by a single germovitellarium, by a maximum of 2 toes on the foot and by a small male with a single testis; comprises 3 orders, Collothecaceae, Flosculariaceae and Ploima.
\Bmonogoneutic\b Producing only one brood per year or season; \Bmonogoneutism\b; see also \Jdigoneutic\j \Jtrigoneutic\j, \Jpolygoneutic\j
\Bmonogony\b Asexual reproduction; monogenesis.
\Bmonogyny\b 1: The mating of a male with only one female. 2: The presence of a single queen in a colony of social insects; \Bmonogynous\b; see also \Joligogyny\j \Jpolygyny\j
\BMonohysterida\b Order of chromadorian nematodes found in marine, fresh-and brackish-water habitats, and in soil; loosely characterized by simple and spiral to circular amphids; typically possessing neck setae; generally the cephalic sensory organs are combined so that the second and third circlets form a single whorl of 10 setae.
\BMonomastigales\b Order of \JPrasinophyceae\j known from both freshwater and marine habitats; characterized by a covering of organic scales over the cell surface and flagella.
\Bmonometrosis\b The founding of a colony of social organisms by a single fertile female, as from a queen in some social insects; \Bmonometrotic\b; See also \Jpleometrosis\j
\Bmonomictic\b Used of a lake having a single period of free circulation or overturn per year, with consequent disruption of the thermocline; may be either cold monomictic or warm monomictic; See also \Jmictic\j
\Bmonomorphic\b 1: Pertaining to a population or taxon showing no genetically fixed discontinuous variation, therefore comprising a single discrete morph; see also \Jdimorphic\j \Jpolymorphic
\BMononchida\b Order of enoplian nematodes found in soil and freshwater habitats throughout the world; mostly predatory on soil microorganisms; characterized by small cup-like chemosensory organs (amphids) positioned on the head just behind the lateral lips and by the arrangement of head sensilla in one whorl of 6 and another of 10.
\Bmonophagous\b Utilizing only one kind of food feeding upon a single species or food plant; host-specific; \Bmonophage\b, \Bmonophagy\b; see also \Joligophagous\j \Jpolyphagous\j
\Bmonophyletic\b Derived from the same ancestral taxon; used of a group sharing the same common ancestor; \Bmonophyly\b; See also \Jpolyphyletic\j
\BMonoplacophora\b Small class of primitive shelled molluscs found in the sea from 200 m to abyssal depths, characterized by a single, typically conical shell formed by the dorsal mantle and up to 8 paired foot retractor muscles and up to 6 pairs of gills around the foot; includes \INeopilina\i.
\Bmonoplanetic\b Having a single motile stage during a life cycle; \Bmonoplanetism\b; see also \Jdiplanetic\j \Jpolyplanetic\j
\Bmonoploid\b Having a single set of chromosomes with a basic chromosome number; equivalent to the lowest haploid number of a polyploid series; \Bmonoploidy\b; See also \Jploidy\j
\BMonoraphideae\b Order of pennate diatoms (Pennales) possessing a fully developed raphe on one of the valves; also treated as a suborder, Monoraphidineae.
\BMonorhina\b A group of jawless fishes possessing a single nostril between the eyes; includes the lampreys.
\Bmonospermy\b The penetration of an ovum by a single sperm during normal fertilization; \Bmonospermic\b; see also \Jdispermy\j \Jpolyspermy\j
\Bmonotokous\b Having only one offspring per brood; fruiting only once during a life cycle; see also \Jditokous\j \Joligotokous\j, \Jpolytokous\j
\Bmonotopic\b Occurring or arising in a single locality or geographical area; \Bmonotopy\b; See also \Jpolytopic\j
\BMonotremata\b The egg-laying mammals; \JPrototheria\j; including the modern duck-billed platypus (Ornithorhynchidae) and spiny anteater (Tachyglossidae).
\BMonotropaceae\b Indian pipe; small family of Ericales containing about 12 species of strongly mycotrophic herbs which have reduced leaves, lack chlorophyll and depend on their associated fungus for food, water and minerals.
\Bmonotropism\b Orientation movement in one direction only; \Bmonotropic.\b
\BMonotrysia\b Suborder of small to minute lepidopteran insects comprising about 950 species, in which the adult proboscis is rudimentary; larvae mainly leaf or seed-pod miners.
\Bmonoxenous\b Used of a parasite utilizing a single host species during its life cycle; \Bmonoxeny\b; see also \Jdixenous\j \Jheteroxenous\j, \Joligoxenous\j, \Jtrixenous\j
\Bmonozygotic\b Used of twins derived from a single fertilized egg; such twins are thus genetically identical and of the same sex; identical (twins); See also \Jdizygotic\j
\Bmonsoon\b A seasonal climatic pattern in which a cool dry period alternates with a hot wet period.
\BMonsoon Current\b A warm surface ocean current that flows eastwards in the northern part of the Indian Ocean produced by the southwesterly winds of the summer monsoon; North East Monsoon Drift; see ocean currents.
\BMonstrilloida\b Order of bizarre marine copepods (Crustacea) which live as parasites inside polychaetes and echinoderms during early development, then emerge as non-feeding, planktonic adults, lacking mouthparts and a gut.
\Bmonstrosity\b Any abnormal, malformed, or markedly aberrant individual.
\Bmontane\b Pertaining to mountainous regions; the cool moist upland habitat below the tree line, dominated by evergreen trees.
\Bmontbretia\b \JIridaceae\j
\Bmonticolous\b Living in mountainous habitats; \Bmonticole.\b
\Bmoor\b An open elevated region of wet acidic peat typically dominated by heathers, sedges and some grasses.
\Bmoose\b \JCervidae\j
\Bmor\b A forest soil type characterized by a discrete humus layer separated from the underlying mineral soil, typically highly acidic; a raw humus produced under cool moist conditions; See also \Jmull\j
\BMoraceae\b Fig, breadfruit, mulberry; large family of Urticales widespread in subtropical and tropical regions; mostly woody plants producing milky latex and often with mineralized cell walls; fruits typically produced in infructescences with a fleshy receptacle, often edible.
\Bmoray eel\b \JMuraenidae\j
\Bmorel\b \JPezizales\j
\Bmores\b Groups of organisms having similar ecological requirements and behavioural attributes.
\Bmoribund\b Dying; close to death.
\BMoringaceae\b Small family of Capparales containing about 10 species of xerophytic, deciduous trees found from Africa to India; fruit a long pod splitting into to 3 valves to release large, 3-winged seeds.
\BMoringuidae\b Spaghetti eels; family containing 10 species of marine anguilliform teleost fishes of the western Atlantic and Indo-Pacific; body very slender, smooth, cylindrical; dorsal and anal fins small, pectorals reduced or absent; sexual dimorphism pronounced.
\BMormonilloida\b Small order containing 2 widely distributed species of marine planktonic copepod crustaceans; characterized by a median ventral genital aperture in the female and by the lack of the fifth swimming legs.
\BMormoopidae\b Family containing 8 species of insectivorous bats (Microchiroptera) in which there is no nose leaf, but the nostrils form part of a fleshy pad with the lips; found in Central and South America.
\BMormyridae\b Elephant fishes; family containing about 100 species of mostly small (to 0.5 m) primitive teleost fishes found in African freshwater habitats; body elongate, eyes reduced, caudal musculature electrogenic; habits benthic or pelagic, commonly crepuscular.
\Bmorning glory\b \JConvolvulaceae\j
\Bmorph\b A form; any of the individuals of a polymorphic group; any phenotypic or genetic variant; any local population of a polymorphic species exhibiting distinctive morphology or behaviour.
\Bmorphocline\b A graded series of character states of a homologous character.
\Bmorphogenesis\b 1: The totality of the process of embryological development and growth. 2: The evolution of morphological structures; \Bmorphogenetic.\b
\Bmorphology\b 1: The study of form and structure of organisms, rocks and sediments. 2: The form and structure of an organism, with special emphasis on external features; \Bmorphologic\b, \Bmorphological.\b
\Bmorphometry\b The measurement of external form and structure; the characterization of form for quantitative analysis; \Bmorphometric\b.
\Bmorphoplankton\b Planktonic organisms rendered buoyant by anatomical specializations such as oil droplets or gas vesicles, or in which the rate of sinking is reduced by structural features or diminutive body size.
\Bmorphosis\b Variation in morphogenesis of an individual induced by environmental changes.
\Bmortality\b Death rate as a proportion of the population expressed as a percentage or as a fraction; often used in a general sense as equivalent to death; See also \Jnatality\j
\Bmorwong\b \JCheilodactylidae\j
\Bmos\b A community or assemblage of species living together but without mutual interdependence.
\Bmosaic\b An organism comprising tissues of two or more genetic types; usually used with reference to plants.
\Bmosquito\b \JCulicidae\j (Nematocera).
\Bmoss\b \JBryopsida\j
\Bmoss animal\b \JBryozoa\j
\Bmoss campion\b \JCaryophyllaceae\j
\Bmoss rose\b \JPortulaceae\j
\BMotacillidae\b Wagtails, pipits; widely distributed family containing about 50 species of passerine birds found in open grassland; body and tail elongate, bill slender; feed mainly on insects; nest on the ground.
\Bmoth\b \JLepidoptera\j
\Bmotile\b With the capacity for movement; exhibiting movement; \Bmotility.\b
\Bmotmot\b \JMomotidae\j
\Bmould\b 1: A fungus which produces a furry or velvet-like mycelium or spore mass over the surface of its host, as in the bread mould (\JMucorales\j). 2: A cavity or space in a sediment remaining after the organic material of an organism has been removed by the action of soil water.
\Bmouldering\b Decomposition of organic matter under conditions of low oxygen resulting in the formation of carbon-rich residues; see also \Jdecay\j \Jputrefaction\j
\Bmoultinism\b A polymorphism in which different strains have a different number of larval stages.
\Bmountain ash\b \JRosaceae\j
\Bmountain beaver\b \JAplodontidae\j
\Bmountain laurel\b \JEricaceae\j
\Bmouse\b 1: \JMuridae\j (Old World mice). 2: \JCricetidae\j (New World mice).
\Bmousebird\b \JColiidae\j
\Bmousefish\b \JGonorhynchidae\j
\Bmouse-tailed bat\b \JRhinopomatidae\j
\BMozambique Current\b A warm surface ocean current that flows southwards through the Mozambique Channel; see ocean currents.
\BmRNA\b Messenger \JRNA\j
\Bmucilaginous\b Comprising or resembling mucilage.
\Bmucivorous\b Feeding on plant juices or mucilage; \Bmucivore\b, \Bmucivory.\b
\Bmuck\b Highly decomposed plant material typically darker and with higher mineral content than peat.
\BMucorales\b Bread mould; large order of zygomycete fungi containing forms saprobic on dung or organic debris, and parasites of invertebrates, other fungi and plants; also treated as a class of the phylum Zygomycota.
\Bmud\b Fine sediment particles of diameter less than 0.002 mm; fine-grained, slimy, marine or lacustrine detrital sediment; see sediment particle size.
\Bmud lobster\b \JThalassinidea\j
\Bmud plantain\b \JPontederiaceae\j
\Bmud puppy\b \JProteidae\j
\Bmud salamander\b \JAmbystomatidae\j
\Bmud turtle\b \JKinosternidae\j
\Bmudminnow\b \JUmbridae\j
\Bmudsnail\b \JNeogastropoda\j
\BMugilidae\b Mullets, grey mullets; family containing 70 species of coastal marine, brackish and freshwater teleost fishes (Perciformes) widespread in tropical to temperate waters; body stout, to 0.9 m in length, with blunt-snouted head; anterior dorsal fin composed of 4 strong spines; lateral line usually absent; feed by sucking up mud containing algae, invertebrates and detritus.
\BMugiloidei\b Suborder of perciform teleosts comprising a single family Mugilidae (mullets).
\BMugiloididae\b Sandperches; family containing 25 species of Indo-Pacific tropical marine teleost fishes (Perciformes) found in shallow water, burrowing in sand or concealed amongst stones or coral; body elongate, to 300 mm in length, head and mouth large, jaws protractile; 2 dorsal fins contiguous; Parapercidae.
\Bmulberry\b \JMoraceae\j
\Bmull\b A forest soil type in which the organic matter is intermixed with mineral soil without a discrete humus layer; See also \Jmor\j
\Bmullein\b \JScrophulariaceae\j
\BMüllerian mimicry\b Imitative similarity, typically based on warning coloration amongst a number of mimic species all of which are unpalatable or otherwise offensive to a predator (the operator); See also \Jmimicry\j
\BMüler's larva\b Free-swimming larval stage of some polyclad turbellarians (Platyhelminthes); possessing 8 ciliated lobes or lappets.
\BMullidae\b Goatfishes, red mullets; family containing 60 species of bottom-dwelling tropical and warm-temperate, shallow marine and estuarine teleost fishes (Perciformes); body elongate, strongly convex dorsally, flattened ventrally, length to 600 mm; 2 large chin barbels present; 2 short dorsal fins.
\Bmultiparous\b 1: Producing 2 or more offspring in a single brood; pluriparous; see also \Jbiparous\j \Juniparous. 2: Having produced more than one previous brood\j
\Bmultiple alleles\b Two or more different forms of a gene occupying a specific locus.
\Bmultiple fission\b A variant of binary \Jfission\j found in some protistans in which a subsequent division commences before the earlier one is complete.
\Bmultistratal\b Pertaining to vegetation composed of several horizontal layers; See also \Junistratal\j
\BMultituberculata\b Extinct order of probably herbivorous, rodent-like mammals (Prototheria) known from the late Jurassic to the Eocene; regarded as a side branch from the main lineage of mammalian evolution.
\BMultivalvulida\b Order of \JMyxosporea\j characterized by having spores with more than 2 shell valves.
\Bmultivoltine\b Having several broods or generations per year; See also \Jvoltine\j
\Bmune\b A group of organisms having similar ecological requirements and a characteristic behavioural response.
\BMuraenesocidae\b Pike congers; family containing 15 species of tropical and warm temperate anguillform teleost fishes found mainly in shallow sandy marine habitats; body smooth, to 2 m length; jaws bearing strong canine-like teeth; eyes, pectoral fins and gill openings well developed; dorsal, caudal and anal fins continuous.
\BMuraenidae\b Moray eels; family containing 100 species of nocturnal predatory or scavenging anguilliform teleost fishes widespread on reefs and rocky bottoms of shallow tropical and temperate seas; body smooth, to 3 m length, compressed; dorsal and anal fins continuous with caudal; pelvic and pectoral fins absent; jaws and teeth well developed.
\BMuraenolepididae\b Family of little-known Southern Ocean gadiform teleost fishes containing only 3 species; body length to 200 mm; dorsal, caudal and anal fins continuous; pelvics jugular.
\Bmural\b Pertaining to, or growing on, walls; rupestral.
\BMuridae\b Old World rats, mice; large cosmopolitan family of myomorph rodents comprising about 450 species in 100 genera; habits diverse, may be terrestrial, arboreal, fossorial or semiaquatic; herbivorous or insectivorous.
\BMusaceae\b Banana, plantain; small family of Zingiberales comprising about 35 species of coarse, tree-like perennial herbs dying back to the ground after flowering; leaves with a petiole and expanded simple blade; flowers strongly nectariferous and adapted for pollination by birds and bats, producing a fleshy fruit; confined to tropical and subtropical regions of the Old World; flowers finger-shaped, arranged in racemes with brightly coloured bracts, each with 6 petals and stamens and an inferior ovary.
\Bmuscarian\b Used of flowers that attract flies by a putrid odour.
\BMusci\b True mosses; large class of bryophytes characterized by a typically filamentous protonema from which arise buds that develop into the gametophyte; spore capsule opening by means of a lid; usually known as the \JBryopsida\j
\BMuscicapidae\b Flycatchers; diverse family containing about 300 species of Old World passerine birds widespread in forest and grassland habitats; feeding on insects caught on the wing, on the ground, or gleaned from trees; bill often strong and hooked; habits solitary to gregarious, arboreal to terrestrial, monogamous or polygamous; nest in tree, bank or rock crevice.
\Bmuscicolous\b Living on or in mosses or moss-rich communities; \Bmuscicole.\b
\BMuscidae\b Houseflies, stable fly; cosmopolitan family of small to large flies (Diptera) comprising over 3000 species many of which are pests of livestock and may be vectors of disease; the larvae feed mostly on decaying plant and animal material or dung, and some are parasitic.
\Bmuscology\b The study of mosses; bryology.
\Bmushroom\b \JAgaricales\j
\Bmusk\b \JScrophulariaceae\j
\Bmusk turtle\b \JKinosternidae\j
\Bmuskeg\b A grassy bog habitat, with scattered, stunted conifers.
\Bmuskmelon\b \JCucurbitaceae\j
\BMusophagidae\b Touracos; family containing 18 species of arboreal birds found in African forests; feed mainly on seeds and fruit; regarded by some authorities as suborder of Cuculiformes (cuckoos).
\BMuspiceida\b Small order of enoplian nematodes found as parasites in vertebrates; typically lacking amphids and cephalic sensory papillae; digestive tube reduced.
\Bmussel\b \JMytiloida\j
\Bmussel\b, \Bpearly freshwater\b \JUnionoida\j
\Bmussel shrimp\b \JOstracoda\j
\Bmustard tree\b \JSalvadoraceae\j
\BMustelidae\b Weasels, stoats, otters, badgers, mink; family of mostly small terrestrial, arboreal or semiaquatic carnivorous mammals (Carnivora) widespread in Holarctic, Neotropical, Ethiopian and Oriental regions; body typically elongate with short limbs and long tail; contains about 65 species including also martens, sable, skunk, ermine, wolverine and polecat.
\Bmutagen\b Any agent that produces a mutation or enhances the rate of mutation; \Bmutagenic\b, \Bmutagenesis.\b
\Bmutant\b Any organism, gene, or character that has undergone a mutational change.
\Bmutation\b 1: A sudden heritable change in the genetic material, most often an alteration of a single gene by duplication, replacement or deletion of a number of DNA base pairs. 2: An individual that has undergone such a mutational change; mutant.
\BMutica\b A mammalian cohort comprising the single order Cetacea (whales).
\BMutillidae\b Cow killers, velvet ants; family of wasps (Hymenoptera) in which the female is brightly coloured and wingless, and the male dark with wings; females parasitize bees, wasps, beetles or other insects, typically laying eggs on relatively immobile stages of the host enclosed in a cell, cocoon or puparium.
\Bmutualism\b A symbiosis in which both organisms benefit, frequently a relationship of complete dependence; interdependent association.
\Bmycelium\b The mass of filamentous hyphae that comprises the vegetative stage of many fungi.
\Bmycetogenic\b Produced by fungi.
\Bmycetology\b The study of fungi; mycology.
\Bmycetophagous\b Feeding on fungi; \Bmycetophage\b, \Bmycetophagy.\b
\BMycetophilidae\b Fungus gnats; family containing about 2000 species of small fragile flies (Diptera); larvae feed mostly on fungi or decaying vegetation and are economically important as pests of mushroom crops.
\Bmycetozoan\b A slime mould; \JMyxomycota\j
\Bmycobiont\b The fungal partner of a lichen (algal/fungal symbiosis); See also \Jphycobiont\j
\Bmycobiota\b The fungal flora of an area or habitat.
\Bmycocriny\b The decomposition of organic material by the action of fungi.
\Bmycology\b The study of fungi.
\Bmycophagous\b Feeding on fungi; \Bmycophage\b, \Bmycophagy.\b
\Bmycoplasma\b Any organism in the class \JMollicutes\j
\Bmycorrhiza\b The close physical association between a fungus and the root system of a plant, which enables the roots to take up nutrients more efficiently than if uninfected.
\Bmycotic\b Produced by the agency of fungi; \Bmycosis.\b
\Bmycotrophic\b Used of plants that live in a symbiosis with a fungus and are nutritionally dependent upon it, as in those plants with mycorrhizal associations; \Bmycotrophy.\b
\BMyctophidae\b Lanternfishes; cosmopolitan family of small to medium-sized (to 150 mm) pelagic deep-sea myctophiform teleost fishes; body compressed, eyes and mouth large; photophores numerous on ventral surface of head and body; adipose fin present; contains about 240 species, some locally abundant, many exhibiting diurnal migration between surface and 500-1000 m.
\BMyctophiformes\b Order of pelagic and benthic teleost fishes found in littoral to abyssal marine habitats, comprising about 400 species in 16 families, including lanternfishes, lizard fishes, barracudinas, lancetfishes, daggertooths, pearleyes; body commonly bearing photophores, adipose fin present, pelvics abdominal; many species hermaphroditic.
\Bmygalomorph spider\b \JOrthognatha\j
\Bmyiophilous\b Pollinated by flies; \Bmyiophily.\b
\BMyliobatidae\b Eagle rays; family containing 20 species of medium to large, tropical and subtropical, marine and estuarine elasmobranch fishes; body disk much broader than long and distinctly demarkated from head; pectoral fins produced anteriorly as subrostral lobe; tail filamentous distally, caudal fin absent; mouth bearing series of grinding plates; feed on benthic molluscs and crustaceans dug up using pectoral fins.
\BMyliobatiformes\b Stingrays, eagle rays, devil rays; order of small to large (to 6 m) benthic or epipelagic, marine, brackish or freshwater, ray-like elasmobranch fishes; body disk strongly depressed, may be much broader than long, tail slender to whip-like; single dorsal fin present or absent; mouth small; reproduction viviparous; comprises about 150 species in 7 families.
\BMymaridae\b Fairy flies; family of extremely tiny hymenopterous insects (Apocrita) with narrow, hair-fringed wings exhibiting reduced venation; all are egg parasites of other insects.
\BMyobatrachidae\b Family containing about 95 species of mainly terrestrial frogs (Anura) from Australia, a few species arboreal or aquatic; eggs and larvae typically aquatic, but other reproductive strategies include gastric brooding, retention of tadpoles in lateral pouches, and direct development.
\BMyocastoridae\b Coypu; a monotypic family of large semiaquatic hystricomorph rodents native to the southern Neotropical region, but recently established in the Holarctic; body robust, limbs short, feet webbed; excavate burrows in earth banks, feeding mainly on aquatic vegetation.
\BMyodocopa\b Class of benthic, epibenthic and planktonic marine ostracod crustaceans found from the surface to abyssal depths; contains 600 species in 2 orders, Myodocopida and Halocyprida.
\BMyodocopida\b Order of mostly marine myodocopan ostracods, typically benthic and mesoplanktonic, occasionally abyssopelagic; contains about 380 species in 5 families.
\BMyoida\b Order of marine and freshwater heterodont bivalves which are generally burrowing, filter feeders possessing well developed siphons; shell morphology variable, 2 shell-closing muscles present, hinge often degenerate; includes the soft-shelled clams, piddocks and shipworms.
\BMyomorpha\b Large, cosmopolitan suborder of small terrestrial and arboreal mammals (Rodentia) comprising 9 families and including rats, mice, dormice, voles, jerboas, gerbils, hamsters, lemmings, and many others.
\BMyoporaceae\b Emu bushes; family of Scrophulariales containing about 125 species of shrubs and small trees producing iridoid compounds and with scattered small secretory cavities; widely distributed in southern hemisphere; flowers with 5 fused sepals, a 5 lobed tubular corolla, 4 stamens and a superior ovary.
\Bmyria-\b 1: Prefix used to denote unit x 10\U4\u. 2: Prefix meaning many, innumerable.
\BMyriangiales\b Order of mostly tropical loculoascomycete fungi in which the asci are scattered through the poorly differentiated inner tissue of the ascocarp; most are external saprobes on plants, some parasitic on plants and animals.
\BMyriapoda\b Heterogeneous assemblage of arthropods comprising the centipedes (Chilopoda), millipedes (Diplopoda), Pauropoda and Symphyla; trunk segments not differentiated into thorax and abdomen; sometimes treated as a subphylum or class of \JUniramia\j
\BMyricales\b Wax myrtle, sweet fern; small order of Hamamelidae comprising a single family (Myricaceae) of about 50 species of aromatic shrubs or small trees bearing small flowers in catkins.
\BMyristicaceae\b Family of primitive plants (Magnoliales) containing mostly trees producing aromatic oils and hallucinogenic compounds, widespread in tropical regions; flowers usually tiny, unisexual, with stamens united as a column; includes the nutmeg tree.
\BMyrmecobiidae\b Numbat; monogeneric family of small (to 400 mm) terrestrial marsupial anteaters; tongue long, sticky, and protrusible; marsupium absent.
\Bmyrmecochorous\b Dispersed by the agency of ants; \Bmyrmecochore\b, \Bmyrmecochory.\b
\Bmyrmecoclepty\b A symbiosis between ant species in which the guest species steals food directly from the host species.
\Bmyrmecodomatia\b Plant structures inhabited by ants or termites.
\Bmyrmecodomus\b Used of a plant affording shelter to ants.
\Bmyrmecology\b The study of ants.
\Bmyrmecolous\b Living in ant or termite nests; \Bmyrmecocole.\b
\BMyrmecophagidae\b Anteaters; family of Neotropical insectivorous mammals (Edentata) containing a single terrestrial, and two mainly arboreal, species; head elongate, oral region tubular; teeth absent, tongue elongate, protrusible and sticky; forelimbs powerful with large claws for breaking open nests of ants and termites.
\Bmyrmecophagous\b Feeding on ants or termites; \Bmyrmecophage\b, \Bmyrmecophagy.\b
\Bmyrmecophilous\b 1: Thriving in association with ants; used of organisms that spend part of their life cycle in ant or termite nests; \Bmyrmecophile\b, \Bmyrmecophily\b; See also \Jmyrmecophobous. 2: Pollinated by ants or termites\j
\Bmyrmecophobous\b Used of organisms that repel ants or termites; \Bmyrmecophobe\b, \Bmyrmecophoby\b; See also \Jmyrmecophilous\j
\Bmyrmecophyte\b A plant having specialized structures for sheltering ants or termites, or having a mutual interdependence with ants or termites.
\Bmyrmecosymbiosis\b A symbiosis between an ant and its host plant; \Bmyrmecosymbiotic.\b
\Bmyrmecotrophic\b Pertaining to plants and animals that provide food for ants.
\Bmyrmecoxenous\b Used of plants that provide both food and shelter for ants and termites; \Bmyrmecoxeny.\b
\BMyrmeleontidae\b Ant lions; family containing about 600 species of generally nocturnal flying, neuropteran insects often with a long abdomen and highly patterned wings; larvae typically lie in wait for prey insects, some constructing conical pitfall traps.
\BMyrothamnaceae\b Family containing 2 species of glabrous, aromatic shrubs found in Africa and Madagascar having leaves that fold up and turn blackish during the dry season but expand and turn green again after rain.
\BMyrsinaceae\b Large family of Primulales containing about 1000 species of woody plants containing yellow to brown resinous material in ducts or cavities; widespread in tropical and subtropical regions; flowers typically arranged in umbels or panicles.
\BMyrtaceae\b Myrtle, eucalyptus, gum tree; large family containing about 3000 species of shrubs or trees producing ethereal oils in scattered cavities; found in tropics, subtropics and in temperate Australia; flowers typically perfect, borne in cymes and with 4-5 sepals and petals, large numbers of stamens and an inferior ovary.
\BMyrtales\b Large order of Rosidae containing over 9000 species of trees, shrubs and herbs; largest families are the Melastomataceae and Myrtaceae.
\Bmyrtle\b \JMyrtaceae\j
\BMysidacea\b Opossum shrimps; order of predominantly marine shrimp-like peracaridan crustaceans containing about 780 species, epibenthic or pelagic, littoral to abyssal; includes a few freshwater and cavernicolous forms; typically with a pair of conspicuous statocysts in the tail fan.
\Bmysis\b The late zoeal phase of larval development found in many shrimp-like malacostracan crustaceans.
\BMystacinidae\b Family containing a single species of omnivorous bat (Microchiroptera) from New Zealand; body with thick fur; wings tucked into pockets when at rest.
\BMystacocarida\b Class of minute crustaceans inhabiting the interstitial spaces in shallow marine sediments; characterized by larval-type cephalic appendages and by a slender trunk bearing 4 pairs of limb buds; contains 9 species in a single order, Mystacocaridida.
\BMystacocaridida\b Sole order of the \JMystacocarida\j
\BMysticeta\b Baleen whales; suborder of large marine mammals (Cetacea) in which teeth are absent and upper jaw carries a filter curtain of long baleen plates; skull bilaterally symmetrical; blowhole paired; found in all oceans but more common at high latitudes; most are migratory; feed mainly on crustaceans; comprises 3 families, Balaenidae (right whales), Eschrichtiidae (grey whale), Balaenopteridae (rorquals).
\BMytiloida\b Mussels; an order of typically marine or estuarine pteriomorphian bivalves which are commonly sedentary as adults, attached by byssus threads to the substratum; characterized by their gill structure and by stiff ciliated disks uniting the gill filaments.
\BMyxiniformes\b Hagfishes; order of agnathan vertebrates (Cephalaspidomorphi); body eel-like, naked, with copious mucous secretion; paired fins and dorsal fin absent; eyes reduced; up to 16 pairs of gill openings; feed on dead or moribund fish and invertebrates; comprises about 30 species in a single family, Myxinidae; also known as the Hyperotreti.
\BMyxogastria\b Subclass of plasmodial slime \Jmoulds\j, \Jmore commonly treated as the \JMyxogastromycetidae\j in the class Myxomycetes.
\BMyxogastromycetidae\b Subclass of plasmodial slime \Jmoulds\j (Myxomycetes) exhibiting two plasmodial types, a large phaneroplasmodium which has well developed margins, polarity and grows better in drier conditions producing either many fruiting bodies or a single massive one, and a microscopic protoplasmodium which gives rise to a single small sporangium; fruiting body arises from elongate column of protoplasm which swells apically.
\BMyxomycetes\b Plasmodial slime \Jmoulds\j treated as a class of the Myxomycota and classified with the fungi; comprises 3 subclasses, Ceratiomyxomycetidae, Myxogastromycetidae and Stemonitomycetidae.
\BMyxomycota\b 1: Slime moulds; group of primitive organisms with an amoeba-like colonial stage in the life cycle; treated as fungi, comprising cellular slime \Jmoulds\j (Acrasiomycetes) and plasmodial slime \Jmoulds\j (Myxomycetes\j, \JPlasmodiophoromycetes and Protosteliomycetes). 2: Plasmodial slime \Jmoulds\j, treated as a phylum of Protoctista.
\BMyxophaga\b Small suborder of minute (0.5-2.5 mm) beetles (Coleoptera) comprising about 60 species in 4 families.
\BMyxosporea\b Class of \JMyxozoa\j containing mostly parasites of marine and freshwater fishes; possessing 1-6 polar capsules and usually 2, but up to 6, valves; comprises 2 orders, Bivalvulida and Multivalvulida.
\BMyxosporida\b \JMyxozoa\j; treated as a class of the protoctistan phylum Cnidosporida.
\Bmyxotrophic\b Used of an organism obtaining nutrients through the ingestion of partices; \Bmyxotrophy.\b
\BMyxozoa\b Phylum of sporulating parasitic organisms commonly classified in the Protozoa but representing primitive multicellular organisms as they have spores composed of several specialized cells; spores comprise generative cells (sporoplasms), capsule cells containing coiled polar filaments and valve cells that develop into shell valves; known as parasites of invertebrates and lower vertebrates; also treated as a class, Myxosporida, of the protoctistan phylum Cnidosporida.
\BMyzopodidae\b Family containing a single species of bat (Microchiroptera) from Madagascar bearing adhesive suckers on all 4 limbs.
\BMyzostomata\b Class of small aberrant annelid worms comprising about 120 species in 7 families all of which are parasitic on or in echinoderms, mostly crinoids, but also ophiuroids and asteroids; body oval or flattened, lacking external segmentation, head indistinct, pharynx muscular and unarmed, parapodia uniramous.
\Bnaiad\b \JUnionoida\j
\BNajadaceae\b Water nymph; cosmopolitan family comprising about 35 species of submerged annual herbs found in fresh or brackish water with small, unisexual flowers borne singly in axils.
\BNajadales\b Order of Alismatidae containing 10 families of aquatic or semiaquatic herbs; leaves commonly basal and sheathing; flowers inconspicuous, without differentiated sepals and petals, pollinated by wind or water.
\Bnamatophilous\b Thriving in brooks and streams; \Bnamatophile namatophily.\b
\Bnamatophyte\b A plant inhabiting a stream or brook.
\Bnanander\b A dwarf male.
\BNandidae\b Leaffishes; family containing 10 species of small (to 200 mm) predatory freshwater teleost fishes (Perciformes) that feed voraciously on other small fishes by rapid extension of the jaws whilst floating leaf-like at the water surface; body deep, mouth large and highly protrusible.
\Bnanism\b The condition of being stunted or smaller than normal, or of having restricted growth; dwarfism; See also \Jgigantism\j
\Bnano- (n)\b Prefix denoting unit x 10\U-9\u; nanno-.
\Bnanofossils\b Very small marine fossils, usually algae, typically close to the resolution limit of a light microscope and studied by electron microscopy.
\Bnanophanerophyte\b A dwarf \Jphanerophyte\j with renewal buds less than 2 m above ground level.
\Bnanophyll\b A Raunkiaerian leaf size \Jclass\j for leaves having a surface area between 25 and 225 mm\U2\u.
\Bnanoplankton\b Minute planktonic organisms with a body diameter between 2 and 20 \Fm\nm; nanoplankton; formerly used for those organisms that passed through a 0.03-0.04 mm mesh silk bolting cloth.
\BNarcinidae\b Family of small (to 0.75 m) torpediniform fishes; body disk circular to wedge-shaped, tail stout, dorsal fins large; eyes small to vestigial; mouth highly protractile; contains about 15 species found from the littoral to depths of 100 m, rarely to 1000 m.
\Bnarcissus\b \JLiliaceae\j
\BNarcomedusae\b Suborder of marine cnidarians (Trachylina) in which the polyp generation is reduced or absent; medusae with scalloped margin, solid tentacles and gonads on the stomach wall; mouth opening directly into stomach.
\Bnarcotropism\b Orientation movements resulting from the effects of narcotics; \Bnarcotropic.\b
\BNarkidae\b Family of small (less than 0.5 m) torpediniform fishes; body disk ovoid to circular; tail bearing lateral folds; dorsal fins present or absent; mouth small, protractile; eyes small to vestigial; contains 10 species found from the littoral zone to 200 m.
\Bnarwhal\b \JMonodontidae\j
\BNassellarida\b Order of radiolaria (Polycystina) in which the capsular membrane is perforated at one pole and the skeleton has a bilateral symmetry.
\BNassulida\b Order of hypostomatan ciliates with reduced circumoral ciliature (the hypostomial frange); common in aquatic and soil habitats
\Bnastic\b Pertaining to plant movement in response to a diffuse stimulus, and to structural curvature resulting from differential growth of opposite surfaces; \Bnasty.\b
\Bnasturtium\b \JTropaeolaceae\j
\BNatalidae\b Family of agile, long-legged, insectivorous bats (Microchiroptera) containing 8 species found mostly in Central and South America; nose simple, without a leaf.
\Bnatality\b Birth rate; the number of offspring produced per female or head of the population per unit time; the production of new individuals by birth, germination or fission; See also \Jmortality\j
\BNatantia\b The shrimp-like decapod crustaceans; formerly used as a suborder but now divided between the suborders Dendrobranchiata (Penaeidea) and Pleocyemata (Caridea and Stenopodidea).
\Bnatatorial\b Adapted for swimming; \Bnatant.\b
\Bnative\b Indigenous; living naturally within a given area; used of a plant species that occurs at least partly in natural habitats and is consistently associated with certain other species in these habitats.
\Bnative cat\b \JDasyuridae\j
\Bnatural classification\b A hierarchical classification based on hypothetical phylogenetic relationships such that the members of each category in the classification share a single common ancestor.
\Bnatural history\b The study of nature, natural objects and natural phenomena.
\Bnatural selection\b The non-random and differential reproduction of different genotypes acting to preserve favourable variants and to eliminate less-favourable variants; viewed as the creative force that directs the course of evolution by preserving those variants or traits best adapted in the face of natural competition.
\Bnaturalized\b Used of an alien or introduced species that has become successfully established.
\Bnauplius\b Earliest larval stage of crustaceans; typically with 3 pairs of functional limbs, lacking compound eyes but usually with a simple median eye.
\BNautiloidea\b Pearly nautilus; a subclass of cephalopod molluscs characterized by a chambered, external, spiral shell containing gas for buoyancy and by the numerous adhesive cirri or tentacles arranged around the mouth; also possessing 4 gills in the mantle cavity and pinhole camera-like eyes without lenses; contains a few living species but has an extensive fossil record dating from the Upper Cambrian.
\Bnealogy\b The study of young and immature organisms.
\Bneandertals\b Group of homonids that lived in the mid-Palaeolithic about 100 000-35 000 years B.P., before and during the last Ice Age, known from fossils found in Europe, North Africa and western Asia; they share many features with modern man and are placed in the same species, but as a separate subspecies, \IHomo sapiens neandertalensis\i.
\Bneanic\b 1: Adolescent; pertaining to the larval phase that precedes the adult condition. 2: Used of characters which first appeared, in evolution, in early ontogenetic stages; See also \Jephebic\j
\Bneap tide\b The tide of minimum range occurring at the time of first and third quarters of the moon, when the gravitational attraction of the sun and the moon act at right angles to each other during \Jquadrature\j; See also \Jspring tide\j
\BNearctic region\b A zoogeographical \Jregion\j comprising North America, Greenland and northern Mexico; subdivided into Alleghany, Californian, Canadian and Rocky Mountain subregions.
\BNebraskan glaciation\b A glaciation of the Quaternary Ice \JAge\j in North America with an estimated duration of 100 000 years.
\Bnecrocoenosis\b An assemblage of dead organisms.
\Bnecrocoleopterophilous\b Pollinated by carrion beetles; \Bnecrocoleopterophily.\b
\Bnecrogenous\b 1: Growing on, or inhabiting, dead bodies. 2: Used of organisms or factors that premote decay.
\Bnecrology\b The study of decomposition, fossilization and other processes affecting plant and animal remains after death.
\Bnecrophagous\b Feeding on dead material; saprophytic; \Bnecrophage, necrophagy.\b
\Bnecrophoresis\b The transport of dead individuals away from a colony, as in some social insects.
\Bnecrophytophagous\b Feeding on dead plant material; \Bnecrophytophage, necrophagy.\b
\Bnecrotrophic symbiosis\b A symbiosis established between two living organisms in which one symbiont continues to use the other as a food source even after complete or partial death has occurred.
\Bnectariferous\b Nectar-producing.
\BNectariniidae\b Sunbirds; family containing about 115 species of small active Old World passerines found in moist to arid wooded habitats, from Africa to Australia; male plumage often colourful; bill slender, curved, serrated, tongue tubular; habits solitary to gregarious, arboreal, non-migratory; feed on insects, nectar and fruit; nest pouch-like, suspended in tree.
\Bnectarivorous\b Feeding on nectar; \Bnectarivore, nectarivory.\b
\Bnectism\b Swimming by means of cilia.
\Bnectobenthic\b Swimming off the sea bed.
\Bnectochaete\b A free-swimming posttrochophore larval stage in some polychaetes in which body segmentation is apparent and chaetae-bearing parapodia are present.
\Bnectocalyx\b Medusa-shaped zooid lacking a manubrium in colonial hydrozoan coelenterates (Siphonophora).
\BNectonematoida\b Class of exclusively marine horsehair worms found as parasites in the body cavities of a variety of decapod crustaceans; characterized by a double row of swimming hairs along each side of the body.
\Bneedlefish\b \JBelonidae\j
\Bneidioplankton\b Planktonic organisms possessing some form of swimming apparatus.
\Bnekrophytophagous\b Feeding on dead plant material; \Bnekrophytophage\b, \Bnekrophytophagy. \b
\Bnektobenthic\b Swimming off the sea bed.
\Bnektobenthos\b Organisms typically associated with the benthos that swim actively in the water column at certain periods; \Bnektobenthic.\b
\Bnekton\b Those actively swimming pelagic organisms able to move independently of water currents; typically within the size range 20 mm to 20 m; \Bnektonic\b; See also \Jplankton\j
\BNelumbonaceae\b Lotus lilies; small family of aquatic plants (Nymphaeales) with floating or emergent leaves and a large solitary flower raised above water no long peduncle.
\BNemaliales\b Large diverse order of algae containing erect filamentous or pseudoparenchymatous forms; found in both marine and freshwater habitats.
\Bnematicide\b A chemical used to kill nematode worms.
\BNemathelminthes\b Phylum comprising the \JNematoda\j and \JNematophora\j; often treated as separate phyla
\BNematocera\b Suborder of mainly slender-bodied delicate flies (Diptera) comprising about 32 000 species and including crane flies, sand flies, mosquitoes, blackflies, gnats and midges.
\BNematoda\b Nematodes, roundworms, eelworms; a phylum of about 12 000 species of unsegmented, bilaterally symmetrical worm-like organisms which are extremely abundant in marine and freshwater habitats, in soil, and as parasites of plants and animals; characterized by the possession of a cuticle secreted by hypodermal cells, a pseudocoelom, a terminal mouth surrounded by lips and 3 rings of sensilla (6 + 6 + 4), and a subterminal anus; sexes usually separate, female system opening through a ventromedial vulva, male system opening through anus, male often provided with cuticular sex organs (spicules); 3 juvenile stages during development; much of classification is based on the degree of cephalization as indicated by the numbers of sense organs; comprises 2 classes, Adenophorea and Secernentea; Nemata.
\Bnematology\b The study of nematodes; \Bnematodology.\b
\BNematomorpha\b Gordian worms, horsehair worms; phylum of elongate, pseudocoelomate worms found as parasites of arthropods when juvenile but emerging into aquatic habitats as ephemeral free-living adults; the adults lack a functional digestive tract and are probably dependent on food reserves built up during parasitic phase; characterized by a single layer of longitudinal body wall muscles and by the opening of the genital ducts through a cloaca, shared with the anus; comprises a marine class, the Nectonematoida, and a freshwater class, the Gordioida.
\BNemertea\b Ribbon worms; phylum of unsegmented, bilaterally symmetrical, acoelomate worms found mainly in intertidal or subtidal marine habitats living either on the substrate or burrowing in soft sediments, occasionally found in freshwater or damp terrestrial situations; characterized by an eversible muscular proboscis, ciliated epidermis and gut epithelium, and an alimentary system with mouth and anus; typically predatory carnivores or scavengers, some can reach lengths of several metres; mostly dioecious and oviparous with rare exceptions; Nemertini.
\BNemertodermatida\b Order of turbellarian flatworms comprising only 5 species found free-living in subtidal sediments and as parasites in holothurians; characterized by the possession of sperm with a single flagellum and of a statocyst with 2 statoliths.
\BNemichthyidae\b Snipe eel; family containing 10 species of bathypelagic anguilliform teleost fishes; body slender, naked, compressed, dorsal fin very long and continuous with anal, pectorals present; jaws markedly prolonged, often divergent.
\Bnemoricolous\b Living in open woodland; \Bnemoricole.\b
\Bnemorose\b Living in open woodland.
\BNeobatrachia\b Suborder of aquatic, terrestrial and arboreal anurans (Amphibia) containing the majority of modern frogs; distribution worldwide, especially diverse in the tropics; reproductive strategies very varied; comprises about 2700 species.
\BNeoceratiidae\b Monotypic family of tiny (to 60 mm) deep-sea anglerfishes (Lophiiformes); female with very large mouth bearing long slender, articulating teeth; lure absent; male parasitic on female, with vestigial eyes and small teeth.
\Bneo-Darwinism\b The modern theory of evolution that combines both natural selection and population genetics, in which the Darwinian concept of spontaneous variation is explained in terms of mutation and genetic recombination.
\BNeoechinorhynchida\b Order of eoacanthocephalan thorny-headed worms found as parasites of marine and freshwater fishes, amphibians and turtles, and utilizing crustaceans, molluscs and insects as intermediate hosts; characterized by the lack of spines on the trunk.
\BNeogaea\b A zoogeographical area originally comprising both Nearctic and Neotropical regions; now generally used to refer to the Neotropical region only; Neogea; see also \JArctogaea\j \JMegaea\j, \JNotogaea\j, \JPalaeogaea\j
\BNeogastropoda\b Order of advanced prosobranch snails containing about 5000 carnivorous and scavenging species, most of which are marine, and including augurs, basket shells, cone shells, crown conches, dogwhelks, dove shells, false conches, margin shells, mitre shells, mudsnails, olive shells, pagoda shells, tulip shells, volutes and whelks; characterized by a highly variable shell with a pronounced canal for the anterior incurrent siphon; shell lacking mother-of-pearl layer, operculum chitinous; mantle cavity with a single gill.
\BNeogene\b A division of the Tertiary period comprising the Pliocene and Miocene epochs (\Ic.\i 26-1.6 million years B.P.); see geological time scale.
\BNeognathae\b Superorder of neornithine birds containing about 23 Recent orders and comprising all living groups except Impennes (penguins) and Palaeognathae (ratites, tinamous).
\BNeogregarinida\b Order of gregarines which reproduce by multiple fission (merogony) within their insect hosts as well as by gamete and sporozoite formation.
\Bneoichnology\b The study of tracks, burrows and other trace structures made by living organisms; See also \Jpalaeoichnology\j
\Bneo-Lamarckism\b Inheritance of acquired characters; the theory that characters acquired by organisms as a response to environmental factors are assimilated into the genome and transmitted to the offspring.
\BNeolampadoida\b Small order of irregular echinoids with non-petaloid ambulacra found in tropical seas.
\BNeolithic\b An archaeological period \Ic.\i 4000-2500 years B.P.; a period of human history characterized by the use of polished stone tools; the late Stone Age; New Stone Age.
\BNeoloricata\b Subclass of \JPolyplacophora\j containing all living chitons, and some fossils.
\BNeomeniamorpha\b Order of solenogastres characterized by a typically blunt body shape and by a variable mantle covering; Neomeniida.
\Bneontology\b The study of living organisms; See also \Jpalaeontology\j
\BNeoophora\b Subclass of turbellarian flatworms found mainly in marine and freshwater habitats; with divided ovary.
\BNeopilina\b Living representative of the primitive class of molluscs, \JMonoplacophora\j
\BNeoptera\b Infraclass of pterygote insects in which the wings can be folded onto the body at rest; contains the majority of extant insects in 3 superorders, Orthopterodea, Hemipterodea and Holometabola.
\BNeopterygii\b Large group of bony fishes including the Holostei and Teleostei.
\BNeorhabdocoela\b Order of free-living and parasitic turbellarians found in freshwater and marine habitats; characterized by the bulbous, complex pharynx, a straight gut without branchings or diverticula and separate yolk glands and ovaries.
\BNeornithes\b Subclass of Aves comprising all 9000 species of Recent birds; 4 superorders recognized, Odontognathae (fossil), Palaeognathae (ratites, tinamous), Impennes (penguins) and Neognathae.
\BNeoscopelidae\b Family of pelagic myctophiform teleost fishes containing 5 species widespread in tropical and subtropical seas from surface to 1000 m or more; body compressed, eyes small to large, photophores usually present.
\BNeoselachii\b Sharks and rays; group of elasmobranch fishes containing all living species in 4 superorders, Squalomorphii, Batoidea, Squatinimorphii and Galeomorphii.
\BNeostethidae\b Family containing 15 species of tiny (to 35 mm) fresh- and brackish-water cyprinodontiform teleost fishes from southeastern Asia; body slender, translucent; pelvic fins reduced or absent in female, specialized as copulatory organ in male; reproduction oviparous, fertilization internal.
\Bneoteny\b \JPaedomorphosis\j produced by retardation of somatic development, such that sexual maturity is attained in an organism retaining juvenile characters; \Bneotenic.\b
\BNeotropical kingdom\b One of six major phytogeographical \Jareas\j characterized by floristic composition; comprises Andean, Caribbean, Juan Fernandez, Venezuela, and Guianan and Pampas regions.
\BNeotropical region\b A zoogeographical \Jregion\j comprising South America, West Indies and Central America south of the Mexican plateau; subdivided into Antillean, Brazilian, Chilean, and Mexican subregions.
\BNeozoic\b The period of geological time from the end of the Mesozoic (\Ic.\i 65 million years B.P.) to the present.
\BNepenthaceae\b East Indian pitcher plants; family of insectivorous, tanniferous shrubs, often climbing or epiphytic, with leaf blade carrying an open pitcher at the end of a distal tendril.
\BNepenthales\b Order of Dilleniidae containing about 200 species of insectivorous perennial herbs or shrubs with leaves modified as traps or pitchers; comprises Droseraceae, Nepenthaceae and Sarraceniaceae.
\Bnepheloid layer\b The turbid layer of bottom ocean water carrying very fine suspended particulate matter.
\BNepidae\b Water scorpions; family of aquatic heteropteran bugs which live submerged in still waters, breathing through a tubular tail extending to the surface; front legs raptorial and used for grasping prey.
\Bnepotism\b Showing favouritism to a relative.
\BNerillida\b Order of minute (to 1.5 mm) polychaete worms containing 30 species in a single family, found in marine, brackish and freshwater sediments; body transparent, lacking distinct segmentation; pharynx eversible and armed; parapodia uniramous.
\Bneritic\b Pertaining to the shallow waters overlying the continental shelf; See also \Joceanic\j
\Bneritopelagic\b Inhabiting shallow coastal waters over the continental shelf.
\Bneritoplankton\b Plankton of shallow continental shelf waters.
\Bnervicolous\b Living on or in the veins of leaves; \Bnervicole.\b
\Bnest epiphyte\b An epiphyte with a twisted growth form which accumulates humus within the tangle.
\Bnest odour\b The distinctive odour of a nest by which its inhabitants are able to distinguish the nest from others, and from the surrounding environment.
\Bnest parasitism\b Symbiosis between two termite species in which colonies of one species live in, and feed on, the walls of the nests of a second (host) species.
\Bnet photosynthesis\b Apparent photosynthesis measured as the net uptake of carbon dioxide into the leaf; equal to gross photosynthesis less respiration.
\Bnet precipitation\b That part of total precipitation that actually reaches the ground; calculated as total precipitation less interception (that part of precipitated water intercepted by plant surfaces).
\Bnet primary production\b The total assimilation of organic matter by an autotrophic individual or population less that consumed by the catabolic processes of respiration; See also \Jgross primary production\j
\Bnet production\b The total assimilation of organic matter by an individual, population or trophic unit less that consumed by respiration; often referred to simply as \Jproduction\j See also \Jgross production\j
\Bnet secondary production\b The total assimilation of organic matter by a primary \Jconsumer\j individual or population less that consumed by the catabolic processes of respiration; gross secondary production.
\BNettastomatidae\b Duckbill eels; family containing 20 species of tropical and temperate deep-sea anguilliform teleost fishes; body smooth, soft, skeleton weakly developed, tail filiform, gill openings small, jaws slender and prolonged; pectoral fins absent.
\Bnettle\b \JUrticaceae\j
\BNeuradaceae\b Small family of Rosales containing about 10 species of densely hairy, prostrate annual plants native to deserts in Africa and the Middle East.
\BNeuroptera\b Order of primitive holometabolous insects typically having 2 pairs of subsimilar membranous wings and chewing mouthparts; comprises about 4500 species in 3 suborders, Megaloptera (alderflies, dobsonflies), Raphidioidea (snakeflies) and Plannipennia (lacewings, dusty wings, spongilla flies, owl flies, ant lions).
\BNeuropterodea\b \JHolometabola\j
\Bneuston\b Small to medium-size organisms that live on (epineuston) or under (hyponeuston) the surface film of water bodies; \Bneustont\b, \Bneustonic\b; See also \Jpleuston\j
\Bneustonology\b The study of neuston - those organisms living at the air/water interface of water bodies.
\Bneustophagous\b Feeding on organisms living at the surface film of a water body (neuston); \Bneustophage\b, \Bneustophagy.\b
\Bneuter\b Of neither sex; with imperfectly developed or non-functional reproductive organs.
\Bnever never plant\b \JMarantaceae\j
\BNew World monkey\b \JCebidae\j
\BNew World pitcher plant\b \JSarraceniaceae\j
\BNew Zealand lemonwood\b \JPittosporaceae\j
\Bnewt\b \JSalamandridae\j
\Bniche\b The ecological role of a species in a community; conceptualized as the multidimensional space, of which the coordinates are the various parameters representing the condition of existence of the species, to which it is restricted by the presence of competitor species; sometimes used loosely as an equivalent of microhabitat in the sense of the physical space occupied by a species; see also \Jfundamental niche\j \Jrealized niche\j
\Bnidus\b 1: A nest, domicile, breeding place, or point of origin. 2: The focus or primary site of an infection.
\Bnight lizard\b \JXantusiidae\j
\Bnightingale\b \JTurdidae\j
\Bnightjar\b \JCaprimulgidae\j
\Bniphic\b Pertaining to snow.
\BNippotaeniidea\b Small order of tapeworms comprising 3 species parasitic in freshwater teleost fishes; characterized by a rounded scolex with an apical sucker, a small subcylindrical body, a single set of reproductive organs in each proglottis and a covering of minute spines over the entire body surface.
\Bnidicolous\b Living in a nest; used also of young animals, especially birds, that remain in the nest for a prolonged period after birth; \Bnidicole\b; See also \Jnidifugous\j
\Bnidification\b Nest building.
\Bnidifugous\b Used of young animals, especially birds, that leave the nest soon after birth; \Bnidifuge\b; See also \Jnidicolous\j
\BNidulariales\b Widespread order of gasteromycete fungi usually found on dung and plant debris; producing small, sessile fruiting bodies which are typically nest-shaped; includes cannonball fungi (\ISphaerobolus\i) and bird's-nest fungus (\ICyathus\i).
\Bnit\b An egg belonging to a phthirapteran louse, especially the human head and body lice.
\Bnitration\b The oxidation of nitrite to nitrate, especially by aerobic soil microorganisms.
\Bnitrification\b The oxidation of ammonia to nitrite, and nitrite to nitrate, by aerobic microorganisms.
\Bnitrogen cycle\b The biogeochemical cycle of nitrogen involving fixation, nitrification, decomposition by putrefaction and denitrification.
\Bnitrogen fixation\b The reduction of gaseous nitrogen to ammonia or other inorganic or organic compounds by microorganisms or lightning.
\Bnitrophilous\b Thriving in soil rich in nitrogenous compounds; \Bnitrophile\b, \Bnitrophily.\b
\Bnitrophyte\b A plant thriving in soil rich in nitrogenous compounds.
\Bnitrozation\b The oxidation of ammonia to nitrite by aerobic soil microorganisms.
\Bnival\b Pertaining to snow.
\Bnivation\b Erosion of the land surface by the action of snow.
\Bniveoglacial\b Pertaining to the combined action of snow and ice.
\Bnivicolous\b Living in snow or snow-covered habitats; \Bnivicole.\b
\BNoctilionidae\b Fish-eating bats; family containing 2 species of large bats (Microchiroptera) with long legs and large feet equipped with well developed claws; includes an insectivorous and a piscivorous species, both from tropical America.
\BNoctilucales\b Order of typically large, motile, marine phagotrophic dinoflagellates, including the bioluminescent \INoctiluca.\i
\Bnoctilucent\b Used of bioluminescent organisms emitting light during darkness.
\BNoctuidae\b Cutworms, armyworms; family of small to very large mostly nocturnal moths (Lepidoptera) containing about 25 000 species; larvae feeding on leaves, flowers, buds or boring into plant stems and fruits, and many causing serious damage to crops.
\Bnocturnae\b Pertaining to night-flying insects; See also \Jdiurnae\j
\Bnocturnal\b 1: Active during the hours of darkness. 2: Lasting only one night; see also \Jcrepuscular\j \Jdiurnal\j
\BNolanaceae\b Family of Solanales containing about 65 species of herbs or small shrubs with internal phloem in small strands; native to western South America and the Galapagos; flowers typically with 5 fused sepals, a 5-lobed bell-shaped corolla and a superior ovary; fruit usually a nutlet.
\Bnomad\b 1: A wandering organism. 2: A pasture plant.
\Bnomadic\b Pertaining to the habit of wandering from place to place, usually within a well defined territory; \Bnomadism.\b
\BNomeidae\b Driftfishes; family containing 15 species of meso- and bathypelagic stromateoid teleost fishes (Perciformes); length to 1 m, mouth small; juveniles live in association with jellyfish and siphonophores.
\Bnomenclature\b The system of scientific names applied to taxa, or the application of these names; \Bnomenclatural.\b
\Bnomocolous\b Living in pasture; \Bnomocole.\b
\Bnomophilous\b Thriving in pastures; \Bnomophile\b, \Bnomophily.\b
\Bnon-available water\b The amount of water still remaining in the soil when a plant reaches the permanent wilting point.
\BNon-calcic Brown soil\b A zonal soil with a light red or reddish brown acidic A-horizon over a light brown to red B-horizon, formed in subhumid climates under a mixture of forest prairie transitional vegetation; Shantung soil.
\Bnoosphere\b That part of the biosphere altered or influenced by the activities of man.
\Bnormoxic\b Used of a habitat having the normal atmospheric level of oxygen; \Bnormoxicity\b; see also \Janoxic\j \Joligoxic\j
\BNorth Atlantic Drift\b A north-easterly continuation of the Gulf Stream current into the eastern North Atlantic; see ocean currents.
\BNorth Atlantic Gyre\b The major clockwise circulation of surface ocean water in the North Atlantic Ocean; see ocean currents.
\BNorth Equatorial Countercurrent\b A warm surface ocean current that flows eastwards in the tropical Pacific Ocean; see ocean currents.
\BNorth Equatorial Current\b A major warm surface ocean current that flows westwards in the North Pacific and forms the southern limb of the North Pacific Gyre; see ocean currents.
\BNorth Pacific Gyre\b The major clockwise circulation of surface ocean water in the North Pacific; see ocean currents.
\BNorthern coniferous forest biome\b The circumboreal forest belt across North America and Eurasia bordering to the north with the Tundra \Jbiome\j, also found on high mountains at lower latitudes; characterized by long cold winters with deep snow, short warm summers, podzol soils; dominated by evergreen needle-leaved trees and dense mats of lichens, mosses and low shrubs, deer, rodents and seasonal swarms of insects; taiga.
\BNorway lobster\b \JAstacidea\j
\Bnosogenic\b Pathogenic; disease-producing.
\Bnosology\b The study and classification of disease.
\Bnosophyte\b A pathogenic plant.
\BNostocales\b Order of blue-green algae (Cyanophycota) found in freshwater, soil and marine habitats and as symbionts in lichens; characterized by a filamentous organization lacking true branching.
\BNotacanthidae\b Spiny eels; family containing 9 species of notacanthiform teleost fishes with elongate cylindrical body, length to about 1.2 m, blunt snout and small mouth; dorsal and anal fins as series of spines lacking external fin membrane; gill openings well developed.
\BNotacanthiformes\b Small order of eel-like deep-sea teleost fishes comprising about 25 species; body tapering posteriorly with weak skeleton, caudal fin reduced or absent, pelvics united, snout elongate; development includes leptocephalus larval stage.
\BNotaspidea\b Umbrella shell; order of opisthobranch molluscs comprising about 150 species that feed on sponges, ascidians and other invertebrates; characterized by the radula teeth formula, by their discarding outgrown teeth and by the production of an acidic secretion when disturbed.
\Bnoterophilous\b Thriving in mesic habitats; \Bnoterophile, noterophily.\b
\BNothosauria\b Extinct suborder of marine reptiles (Sauropterygia) with long necks and limbs adapted for swimming, known from the Triassic.
\BNotodontidae\b Prominents; family of large robust moths (Lepidoptera) comprising over 2000 species widespread in temperate and tropical regions; larvae of some species are economically important pests causing damage to the foliage of a variety of fruit and forest trees.
\BNotogaea\b A zoogeographical area originally comprising both Australian and Neotropical regions, now generally used to refer to the Australian region only; Notogea; see also \JArctogaea\j \JMegagaea\j, \JNeogaea\j, \JPalaeogaea\j
\BNotonectidae\b Water boatmen; family of aquatic hemipteran insects, comprising about 200 species, that characteristically swim upside down.
\Bnotophyll\b A leaf size category added to the Raunkiaerian leaf size \Jclass\j for leaves having a surface area between 2025 and 4500 mm\U2\u.
\BNotopteridae\b Featherbacks; family containing 6 species of primitive nocturnal teleost fishes found mainly in weedy lentic freshwater habitats of the Old World tropics; body compressed, to 0.8 m length, anal fin continuous with caudal; dorsal and pelvic fins reduced or absent.
\BNotoryctidae\b Marsupial mole; family of small (to 200 mm) blind fossorial mammals comprising a single genus and 2 species found in arid sandy habitats of Australia; marsupium opens posteriorly; burrow actively close to sand surface, feeding on insects and earthworms.
\BNotostigmata\b \JOpilioacariformes\j
\BNotostraca\b Tadpole shrimps; sole order of calmanostracan crustaceans inhabiting temporary freshwater bodies in arid areas; typically with a shield-shaped carapace covering head and thorax, and slender abdomen; feed on detritus or as predators; contains only 11 extant species within a single family, Triopidae.
\BNototheniidae\b Cod icefishes, Antarctic cods; family containing 50 species of Southern Ocean, bottom-dwelling teleost fishes (Perciformes) abundant in Antarctic waters; body elongate, robust, to 1 m length; mouth protractile; 2 dorsal fins and 2-3 lateral lines present; blood may contain a glycoprotein antifreeze; red blood cells absent in some forms.
\BNotothenioidei\b Suborder of southern hemisphere marine teleost fishes (Perciformes) found primarily in cold Antarctic waters, comprising about 100 species in 4 families; many have blood antifreeze as protection against subzero temperatures.
\BNotoungulata\b Extinct order of ungulates known mainly from the Oligocene of South America; characterized by their unusual ear structure.
\Bnucivorous\b Feeding on nuts; \Bnucivore\b, \Bnucivory\b.
\Bnucleotide\b A subunit of the DNA and RNA molecules, comprising phosphoric acid, a purine or pyrimidine base and a sugar.
\BNuculoida\b Nut shells; order of primitive protobranch bivalves found in marine sediments; characterized by 2 more or less equal shell-closing muscles.
\BNuda\b Class of ctenophores lacking tentacles, comprising a single order, the Beroida.
\Bnudation\b The production of an area of bare ground by natural or artificial means.
\BNudibranchia\b Sea slugs; large cosmopolitan order of exclusively marine slug-like opisthobranch molluscs which lack a shell and are usually bilaterally symmetrical; most are carnivores with specialized diets, many are brightly coloured and have an elaborate body form covered with papillae, tufts or finger-like processes.
\Bnumbat\b \JMyrmecobiidae\j
\Bnumerical taxonomy\b Classification based on the numerical comparison of large numbers of equally weighted characters, scored consistently for all the groups under consideration, and in which individuals are grouped solely on the basis of observable similarities.
\BNumididae\b Guinea fowl; family containing 7 species of medium-sized gallinaceous birds (Galliformes) found in forests of Africa and Madagascar; habits solitary, monogamous, feeding on insects, seeds, and plant material; nest in hollow on the ground.
\Bnunatak hypothesis\b The theory that apparent anomalies of modern plant distribution patterns can be explained in terms of survival through periods of glaciation in ice-free areas (nunataks) surrounded by ice.
\Bnuptial flight\b The mating flight of social insects.
\Bnurse shark\b \JGinglymostomatidae\j
\Bnut\b A dry indehiscent fruit derived from more than one carpel but containing only a single seed; the wall of the fruit (pericarp) is usually woody; includes acorn and hazelnut.
\Bnut shell\b \JNuculoida\j
\Bnutation\b A rhythmic or rotational movement of the growing tip of a plant.
\Bnutrition\b Ingestion, digestion and/or assimilation of food by plants and animals; \Bnutritive.\b
\BNyctaginaceae\b Garden four-o'clock, bougainvillea; family of Caryophyllales containing about 300 species of herbs or woody plants, widespread in tropical and subtropical regions; characterized by individual flowers typically surrounded by bracts which may be large and showy, but lacking petals.
\Bnyctanthous\b Flowering only during the night; \Bnyctanthic\b, \Bnyctanthy\b; See also \Jhemeranthous\j
\BNycteribiidae\b Bat flies; family of small fragile wingless flies (Diptera) that are blood-feeding ectoparasites of bats.
\BNyctibiidae\b Pottoos; family of cryptically coloured, nocturnal insectivorous birds (Caprimulgiformes) with small bills, large gapes and no rictal bristles; nest in tree crevices.
\Bnyctigamous\b Used of flowers that open at night and close during the day; \Bnyctigamy.\b
\Bnyctinasty\b Orientation movements of plants during the night; \Bnyctinastism\b, \Bnyctinastic.\b
\Bnyctipelagic\b Pertaining to organisms that migrate into surface waters at night.
\Bnyctiperiod\b A period of darkness; a dark phase in a light/dark cycle; See also \Jphotoperiod\j
\Bnyctitropism\b An orientation response occurring at night; \Bnyctitropic.\b
\Bnymph\b A stage in the development of exopterygote insects, between hatching and the reorganization involved in attaining the adult stage.
\BNymphaeaceae\b Water lilies; family of aquatic plants containing about 50 species having a cosmopolitan distribution; leaves floating, flowers large and aerial, borne singly on long peduncles.
\BNymphaeales\b Water lilies; an ancient order of aquatic herbs found in still waters; tissues with conspicuous air passages; flowers solitary; comprises 5 families, Barclayaceae, Cabombaceae, Ceratophyllaceae, Nelumbonaceae and Nymphaeaceae.
\BNymphalidae\b Large family of small to large, colourful butterflies (Lepidoptera) with reduced, non-functional forelegs and long, hair-like scales; eggs ribbed, caterpillars with spines; contains about 5000 species including the admirals, emperors, fritillaries and tortoiseshell butterflies.
\Bnymphiparous\b Giving birth to offspring at the nymphal stage of development.
\BNyssaceae\b Sour gum, dove tree; small family of Cornales containing 8 species of trees and shrubs found in eastern North America and eastern Asia.
\Boak\b \JFagaceae\j
\Boarfish\b \JRegalecidae\j
\Boats\b \JPoaceae\j
\BObik Sea\b An epicontinental sea joining the Arctic Sea and the Tethys Sea during the Eocene epoch (\Ic.\i 54-38 million years B.P.).
\Bobligate\b Essential; necessary; unable to exist in any other state or relationship; See also \Jfacultative\j
\Bobligate anaerobe\b An organism surviving only in the absence of molecular oxygen.
\Bobliterative shading\b A graded coloration of a body which neutralizes relief giving the appearance of a flat surface.
\BObolellida\b Extinct order of inarticulate lamp shells (Brachiopoda) known only from the Cambrian.
\Boccidental\b Western; westerly.
\Bocean currents\b See chart on page 263 for major ocean surface currents.
\BOceania\b The islands of the Pacific and surrounding seas.
\Boceanic\b Pertaining to the open ocean waters beyond the edge of the continental shelf; See also \Jneritic\j
\Boceanic climate\b A climate characteristic of continental margins and islands in which the annual temperature range is less than the average for that latitude because of the proximity of an ocean or sea.
\Boceanic eddy\b A body of water rotating within the main current system, or deflected from the main current into adjacent areas.
\Boceanic island\b A volcanic island formed independently of continental land masses; See also \Jcontinental island\j
\Boceanodromous\b Used of organisms that migrate only within the oceanic province; see also \Janadromous\j \Jcatadromous\j, \Jpotamodromous\j
\Boceanography\b The study of the oceans.
\Boceanophilous\b Thriving in oceanic habitats; \Boceanophile\b, \Boceanophily.\b
\Boceanophyte\b An oceanic plant.
\Bocelot\b \JFelidae\j
\BOchnaceae\b Small family of tropical, mostly glabrous, evergreen trees or shrubs, especially common in Brazil; typically with regular, bisexual flowers having 5 sepals, 5 petals, 5, 10 or many stamens and a superior ovary.
\BOchotonidae\b Conies, pika; family containing 14 species of lagomorph mammals found in mountainous regions of the northern hemisphere; ears short; forelimbs with 5 digits, hindlimbs with 4; tail not visible externally.
\Bochthophilous\b Thriving on banks; \Bochthophile\b, \Bochthophily.\b
\Bochthophyte\b A plant living on banks.
\Bocotillo\b \JFouquieriaceae\j
\BOctocorallia\b \JAlcyonaria\j; octocorals.
\BOctodontidae\b Bush rats; family containing 7 species of rat-like ground-dwelling or burrowing rodents (Hystricomorpha) known only from South America; tail hairy, typically with apical tuft.
\BOctopoda\b Octopuses; order of carnivorous cephalopod molluscs with a short sac-like body, and 8 arms more or less connected by webbing; shell usually absent; funnel lacking a valve.
\Boctopus\b \JOctopoda\j
\BOdacidae\b Family of colourful marine teleost fishes resembling wrasses in which the jaws form a parrot-like beak; contains 8 species found in cool coastal waters of Australia and New Zealand.
\BOdobenidae\b Walrus; now treated as part of the family Otariidae.
\BOdonata\b Dragonflies, damselflies; order of large paleopterous insects comprising 3 suborders, Zygoptera (damselflies), Anisozygoptera and Anisoptera (dragonflies); adults with powerful predatory mouthparts, large compound eyes, and short slender antennae; the wings are long and slender, of similar size and distally rounded; larvae typically aquatic with strong hinged labrum (mask) for grasping prey; larvae feed on aquatic larvae, tadpoles, worms and small fishes; adults predatory on flying insects taken in flight or at rest.
\BOdontaspididae\b Sand tiger sharks; family containing 4 species of inoffensive pelagic or benthic lamniform elasmobranch fishes, cosmopolitan in tropical and warm temperate seas from surface to 1000 m, feeding mostly on bony fishes, but also crustaceans and cephalopods; body length to 3.5 m.
\BOdontoceta\b Toothed whales; suborder of carnivorous marine and freshwater mammals (Cetacea) comprising 6 extant families, Platanistidae (freshwater dolphins), Delphinidae (dolphins), Phocoenidae (porpoises), Monodontidae (belugas), Physeteridae (sperm whales) and Ziphiidae (beaked whales); teeth typically present, baleen absent, skull asymmetrical, blowhole single.
\BOdontognathae\b Superorder of neornithine birds known as fossils from the Cretaceaous period; probably possessed teeth in both jaws; includes the large aquatic form, \IHesperornis\i.
\BOdontostomatida\b Order of spirotrich ciliates with a laterally compressed, typically wedge-shaped body and reduced ciliature; found in polysaprobic freshwater habitats.
\Bodour trail\b A chemical trace (trail pheromone) deposited by one animal for another to follow.
\Boecology\b \JEcology\j; \Boecological.\b
\BOedogoniales\b Order of green algae (Chlorophycota) found attached to various substrata in freshwater habitats; characterized by a thallus comprising filaments of uninucleate cells, each with a reticulate chloroplast, and by the production of zoospores with a ring of flagella; also treated as a class of the protoctistan phylum, Chlorophyta.
\BOegophiurida\b Order of primitive ophiuroidean echinoderms represented by a single living species from Indonesia, but with an extensive fossil record from the Palaeozoic.
\BOestridae\b Warble flies, botflies; family of robust flies (Diptera) the larvae of which are subcutaneous parasites of mammals, especially ungulates and rodents; several species are important pests of livestock.
\Boestrus\b The period of maximum sexual receptivity, or heat, in female mammals, usually also the time of the eggs; estrus.
\BOgcocephalidae\b Batfishes; family containing about 55 species of bizarre bottom-living anglerfishes (Lophiiformes) widespread on soft offshore sediments; body depressed, to 400 mm length, disk-shaped anteriorly, dorsal and lateral surfaces spinose or rugose; pectoral fins set on elbow-like bases; glandular lure located beneath rostrum; mouth small.
\BO-horizon\b The upper soil horizon having more than 20% organic matter; subdivided into litter layer (L-or Ol-layer), fermentation layer (F-or Of-layer), and humified layer (H-or Oh-layer); see soil horizons.
\Boil\b A triacylglycerol that is liquid at room temperature and which typically functions as an energy storage compound.
\Boilfish\b \JComephoridae\j
\Bokapi\b \JGiraffidae\j
\BOlacaceae\b Family of Santalales containing about 250 species of evergreen woody plants, widespread in tropical and subtropical regions; many are hemiparasitic, attaching to roots of other plants; flowers usually green or white, with sepals reduced to narrow lobes, 4-6 petals and up to twice as many stamens.
\BOld World monkey\b \JCercopithecidae\j
\BOleaceae\b Olive, lilac, ash, forsythia, jasmine, privet, syringa, fringe tree; family of Scrophulariales containing about 600 species of woody plants nearly cosmopolitan in distribution but best developed in Asia and Malaysia; flowers usually perfect and regular, with 4 sepals and petals, 2 stamens and a superior ovary.
\Boleaginous\b Producing or containing oil.
\Boleander\b \JApocynaceae\j
\Boleaster\b \JElaeagnaceae\j
\BOligacanthorhynchida\b Order of archiacanthocephalan thorny-headed worms found worldwide as parasites of mammals and, rarely, birds, and utilizing insects or occasionally snakes as intermediate hosts; characterized by a large trunk which is not pseudosegmented, a subspherical proboscis and the presence of protonephridial glands.
\Boligoaerobic\b Pertaining to organisms that grow in conditions of low oxygen concentration.
\BOligocene\b A geological epoch within the Tertiary period (c. 38-26 million years B.P.); see geological time scale.
\BOligochaeta\b Earthworms, pot worms, freshwater ringed worms; class of clitellate annelids comprising 3 orders, Lumbriculida, Moniligastrida and Haplotaxida; body length 1 mm to 4 m, parapodia absent, chaetae sparse; head simple without sensory appendages; typically hermaphroditic but ensuring cross fertilization by copulation.
\Boligogyny\b 1: The mating of a single male with a few females. 2: The presence of a few queens within a single colony of social insects; \Boligogynous\b; see also \Jmonogyny\j \Jpolygyny\j
\Boligohalabous\b Used of planktonic organisms living in sea water of less than 5 parts per thousand salinity.
\Boligohaline\b 1: Used of organisms that are tolerant of only a moderate range of salinities; see also \Jeuryhaline\j \Jholeuryhaline, polystenoh
\BOligohymenophora\b Class of ciliates with cilia on general body surface arranged in uniform rows when present; the oral ciliary apparatus is distinct from the somatic cilia and consists, in part, of a well defined undulating membrane; widely distributed, free-living and symbiotic.
\Boligolectic\b Used of insects that collect pollen from only a few different types of flowers.
\BOligonephridia\b \JHemipterodea\j
\Boligonitrophilous\b Thriving in habitats having a low nitrogen content; \Boligonitrophile\b, \Boligonitrophily.\b
\Boligopelic\b Used of an area, substrate or habitat containing only small amounts of clay.
\Boligophagous\b Utilizing only a small variety of food species; \Boligophage\b, \Boligophagy\b; see also \Jmonophagous\j \Jpolyphagous\j
\BOligopygoida\b Extinct order of irregular echinoids known only from the Eocene; genital plates fused, ambulacra petaloid.
\Boligosaprobic\b Pertaining to polluted habitats having a high oxygen concentration, low levels of dissolved organic matter, and a low level of organic decomposition; \Boligosaprobe.\b
\Boligothermic\b Tolerating relatively low temperatures; See also \Jpolythermic\j
\Boligotokous\b Having only a few offspring per brood; see also \Jditokous\j \Jmonotokous\j, \Jpolytokous\j
\Boligotraphent\b Used of an aquatic plant characteristic of water bodies having low nutrient concentration; see also \Jeutraphent\j \Jmesotraphent\j
\BOligotrichida\b Large order of free-living spirotrich ciliates with reduced body ciliature and often with a lorica; contains the tintinnids which are abundant in the marine pelagic environment.
\Boligotrophic\b 1: Having low primary productivity; used of substrates or water bodies low in nutrients. 2: Used of any organism requiring only a small nutrient supply, or restricted to a narrow range of nutrients. 3: Used of a lake in which the hypolimnion does not become depleted of oxygen during the summer; see also \Jdystrophic\j \Jeutrophic\j, \Jmesotrophic. 4: Pertaining to insects that visit only a small variety of plant species\j
\Boligoxenous\b Used of a parasite utilizing a few host species during the life cycle; \Boligoxeny\b; see also \Jdixenous\j \Jheteroxenous\j, \Jmonoxenous\j, \Jtrixenous\j
\Boligoxic\b Used of a habitat having reduced levels of molecular oxygen; \Boligoxicity\b; see also \Janoxic\j \Jnormoxic\j
\BOliniaceae\b Small family of Myrtales containing 8 species of tanniferous shrubs or trees confined to tropical and southern Africa and to St Helena.
\Bolive\b \JOleaceae\j
\Bolive shell\b \JNeogastropoda\j
\Bolm\b \JProteidae\j
\Bolynthus\b Hollow vase-like stage in the development of some calcareous sponges.
\BOlyridae\b Family of small (to 100 mm) Old World freshwater catfishes (Siluriformes) found in streams of India and Burma, comprising a single genus and 3 species; body elongate, naked, eyes reduced; 4 pairs of barbels present; dorsal fin lacking spine, caudal forked with long upper lobe; gas bladder partially enclosed in bony capsule.
\Bombratropism\b An orientation response to rain; \Bombratropic.\b
\Bombrocleistogamic\b Used of a flower that remains closed because of rain and within which self-pollination occurs; \Bombrocleistogamy.\b
\Bombrophilous\b Thriving in habitats having abundant rain; \Bombrophile\b, \Bombrophily\b; See also \Jombrophobic\j
\Bombrophobic\b Intolerant of prolonged rain; \Bombrophobe\b, \Bombrophoby\b; See also \Jombrophilous\j
\Bombrophyte\b 1: A plant growing in situations exposed to direct rainfall. 2: An epiphyte that absorbs rainwater by aerial assimilation through specialized structures.
\Bombrotiphic\b Pertaining to temporary pools of water formed from melting snow or rain.
\Bombrotrophic\b Pertaining to organisms that obtain nutrients largely from rainwater; \Bombrotrophy.\b
\BOmmatomorpha\b Superorder of helminthomorphan diplopods (millipedes) comprising a single order, Polyzoniida.
\Bomnicolous\b Living on a wide variety of substrata; \Bomnicole.\b
\Bomnivorous\b Feeding on a mixed diet of plant and animal material; \Bomnivore\b, \Bomnivory.\b
\BOmosudidae\b Hammerjaw; monotypic family of predatory pelagic myctophiform teleost fishes found in warm seas from surface to 1300 m; body compressed, naked, length to 250 mm; mouth very large bearing strong sharp teeth; eyes well developed; photophores absent.
\BOnagraceae\b Fuchsia, evening primrose, sundrop, water purslane, willow herb; family of Myrtales containing about 650 species of herbs or shrubs found mainly in temperate and subtropical regions; flowers bisexual, typically with 4 sepals, 0-4 petals, 8 stamens in 2 whorls and an inferior ovary.
\BOncoceratida\b Extinct order of thick-shelled cephalopod molluscs (Nautiloidea) known from the Ordovician to the Carboniferous.
\Boncosphere\b First larval stage of tapeworms, possessing 6 hooks.
\BOncothecaceae\b Family of Theales containing a single glabrous, tanniferous evergreen tree species; known from New Caledonia.
\BOneirodidae\b Family containing 35 species of small (to 200 mm) deep-sea anglerfishes (Lophiiformes); found at depths of 300-3000 m; body typically naked, or with sparse spines in female; males free-living, lacking teeth; feed mainly on crustaceans.
\BOniscoidea\b Pill bugs, slaters, sow bugs, woodlice; suborder of isopod crustaceans adapted to terrestrial habitats, containing about 3500 species distributed worldwide; eyes sessile, thoracic legs ambulatory; abdominal limbs (pleopods) modified for reproduction and aerial respiration; many able to roll into a ball (conglobation).
\BOniscomorpha\b Superorder of pentazonian diplopods (millipedes) in which the body comprises only 12 or 13 segments and is modified for enrolment into a compact ball; posterior legs of male specialized for clasping female; gut coiled or sinuous; comprises 2 orders, the largely northern hemisphere Glomerida and southern hemisphere Sphaerotheriida.
\Bontogeny\b The course of growth and development of an individual to maturity; \Bontogenetic. \b
\BOnychophora\b Phylum of primitive terrestrial tracheate arthropods typically found in humid forest litter; body cylindrical, 15-150 mm in length, metamerically segmented; head bearing single pair of antennae, eyes at base of antennae; mandibles present; legs sac-like, unsegmented, annulate (lobopods); sexes separate, oviparous to viviparous; habits largely nocturnal, feeding on small invertebrates; contains about 70 species; also treated as subphylum of \JUniramia\j
\Boocyte\b The cell that produces eggs (ova) by meiotic division; See also \Jspermatocyte\j
\Boogamy\b The fertilization of large non-motile eggs by motile sperms; usually applied to algae.
\Boogenesis\b Female gametogenesis; the formation, development, and maturation of female gametes (ova); ovogenesis.
\Boogonium\b The typically unicellular, female reproductive organ in which oospheres are produced in some algae and fungi.
\Boology\b The study of eggs.
\BOomycetes\b Class of fungi (Mastigomycotina) containing parasitic or saprobic forms characterized by motile zoospores with a posteriorly directed whiplash flagellum and an anteriorly directed tinsel flagellum; usually without cross walls; cell walls composed mostly of cellulose; comprises 4 orders, Saprolegniales, Leptomitales, Lagenidiales and Peronosporales; sometimes classified as a phylum, Oomycota, of the Protoctista.
\BOomycota\b \JOomycetes\j, treated as a phylum of the Protoctista.
\Boophagous\b Feeding on eggs; \Boophage\b, \Boophagy.\b
\Boosphere\b The female gamete prior to fertilization.
\Boospore\b The fertilized female gamete.
\Booze\b A fine-grained pelagic deposit comprising at least 30% undissolved sand or silt-sized skeletal remains of marine organisms, the remainder being amorphous clay-sized material; see also \Jcoccolith ooze\j \Jdiatomaceous ooze\j, \Jforaminiferal ooze\j, \Jglobigerina ooze, pteropod ooze, radiolarian ooze, siliceous ooze\j
\Bopah\b \JLampridae\j
\BOpalinata\b Subphylum of Sarcomastigophora; protozoans with a uniform covering of short flagella arranged in oblique rows over the body and with 2 to many nuclei, reproducing by binary or multiple fission and by the production of flagellated sexual gametes; all species are found in the intestine or rectum of cold-blooded vertebrates; comprises a single order, Opalinida.
\BOpheliida\b Order of deposit-feeding polychaete worms found in soft sediments from littoral to abyssal depths, comprising about 140 species in 2 families; prostomium and peristomium naked, pharynx eversible, unarmed; parapodia biramous.
\BOphichthidae\b Snake eels, worm eels; large family of littoral to bathyal anguilliform teleost fishes; body smooth, to 2 m length, slender, tail pointed (snake eels) or fringed with fin (worm eel); some snake eels totally devoid of fins; contains about 270 species; many burrow tail first in sandy or muddy sediments.
\BOphidia\b Alternative name for the \JSerpentes\j; snakes.
\BOphidiidae\b Cusk eels, brotulas; family of coastal to deep-water marine and freshwater gadiform teleost fishes; body elongate, tail tapering, length to 1.5 m; some species ovoviviparous with internal fertilization; contains 35 species, including the brotulas which are sometimes treated as a separate family, Brotulidae.
\BOphiocistioidea\b Extinct class of free-living echinozoans with a dome-shaped test lacking arms; known from the Ordovician to the Devonian.
\BOphioglossopsida\b Subdivision of small to medium-sized, mostly terrestrial ferns (Filicophyta) with a distinct fertile portion of frond held erect; stems fleshy, subterranean and mycorrhizal, fronds fleshy to membranous and do not unroll circinately; sporangia massive with 2000-5000 spores.
\Bophiology\b The study of snakes.
\Bophiophagous\b Feeding on snakes; \Bophiophage\b, \Bophiophagy.\b
\Bophiopluteus\b The \Jpluteus\j larval stage of a brittle star.
\Bophiotoxicology\b The study of snake venoms.
\BOphiurida\b Largest of 3 extant orders of ophiuroidean echinoderms comprising about 2000 species found at all depths from intertidal to deep sea; arms unbranched with vertebral articulation that permits lateral but limited vertical movement, spines typically simple; contains the majority of living ophiuroids.
\BOphiuroidea\b Brittle stars, snake stars, basket stars; subclass of asterozoan echinoderms comprising about 2000 extant species in 3 orders, Oegophiurida, Phrynophiurida and Ophiurida; arms slender, tapering only gradually and distinctly offset from central disk; typically 5-radiate, although arms may be branched in some species; tube-feet without suckers, anus absent; sexes usually separate, fertilization external, development involving vitellaria and ophiopluteus larvae, but may be direct; asexual reproduction by fission may occur in some groups; most species feed as scavengers or utilize suspended matter; brittle stars range from intertidal to deep-sea and may be extremely abundant, forming a major component of the benthos.
\BOpiliaceae\b Family of Santalales containing about 50 species of mostly evergreen woody plants which are hemiparasitic on roots of other plants; widespread in tropical and subtropical regions.
\BOpilioacariformes\b Monofamilial suborder of primitive mites (Acari); Notostigmata.
\BOpiliones\b Harvestmen; order of typically small-bodied long-legged arthropods (Arachnida) that are frequently predators of other small arachnids, molluscs and worms, or scavenge dead plant and animal material; cephalothorax and abdomen compact, joined by broad waist; legs mostly elongate but may be short in some species; single pair of tracheae present; female with long ovipositor; comprises about 4500 species in 30 families.
\BOpisthobranchia\b Subclass of gastropod molluscs containing about 2000 species of mainly marine, bottom-living or littoral forms; characterized by detorsion of the body, which may exhibit secondary bilateral symmetry, by reduction or loss of the shell and the mantle cavity with its associated structures, by a typically flat and creeping foot and by a head primitively covered with a cephalic shield and bearing paired tentacles and rhinophores; mostly hermaphrodites, with internal fertilization; comprises 9 orders, the largest of which is the Nudibranchia (sea slugs).
\BOpisthocomidae\b Hoatzin; monotypic family of medium-sized tree-dwelling birds found in forests of nothern South America; flight weak; feet strong for climbing; habits gregarious, monogamous, feeding on leaves and fruit; nest solitary, typically in tree over water; young with claws on wings.
\BOpisthocomiformes\b Order of neognathous birds comprising a single family, Opisthocomidae (hoatzin).
\BOpisthognathidae\b. Jawfishes; family containing 30 species of shallow-water, tropical marine perciform teleost fishes; body elongate, to 500 mm in length; mouth large bearing strong jaw teeth; dorsal and anal fins long; some forms inhabit burrows in sandy sediments; males sometimes incubate eggs orally.
\BOpisthoproctidae\b Barreleyes; family containing 11 species of small (to 150 mm) bizarre deep-sea salmoniform teleost fishes characterized by projecting tubular eyes providing binocular vision; photophores often present within the orbit.
\BOpisthorchiida\b Order of digenetic trematodes with 3 hosts in the life cycles; eggs develop into miracidia, sporocysts and rediae in prosobranch snails, cercariae infect fishes and form encysted metacercariae and the adult fluke is found in another vertebrate; characterized by a single pair of flame cells in the miracidium larva.
\BOplegnathidae\b Knifejaws, parrotfishes; family of Indo-Pacific shallow marine perciform teleost fishes comprising 4 species; teeth fused into parrot-like beak used to scrape food from hard surfaces; body deep, compressed, to 900 mm in length; single dorsal fin present.
\Bopophilous\b Thriving or feeding on sap; \Bopophile\b, \Bopophily.\b
\Bopophyte\b A parasitic plant.
\Bopossum\b \JDidelphidae\j
\Bopossum shrimp\b \JMysidacea\j
\Bopportunistic species\b A species adapted for utilizing variable, unpredictable or transient environments, typically with a high dispersal ability and a rapid rate of population growth; r-selected species.
\Boptimal\b Most favourable; used of the levels of environmental factors best suited for growth and reproduction of organisms; See also \Jpessimal\j
\Boptimal foraging theory\b That selection favours a strategy in which a predator utilizes prey in a manner that optimizes net energy gain per unit feeding time.
\Boptimal yield\b The maximum sustainable rate of increase of a population under a given set of environmental conditions.
\Borange\b \JRutaceae\j
\Borang-utan\b \JPongidae\j
\BOrbiniida\b Order of errant marine polychaete worms comprising about 200 species in 2 families; typically burrowing deposit feeders found at all depths from littoral to abyssal; prostomium conical, without appendages; pharynx usually eversible and unarmed; parapodia biramous lacking acicula and cirri.
\Borb-web spider\b \JAraneidae\j
\Borchid bee\b \JApidae\j
\BOrchidaceae\b Orchids; well defined family of monocotyledons comprising 15 000 to 20000 species of strongly mycotrophic terrestrial or often epiphytic herbs; cosmopolitan in distribution but most abundant and diverse in tropical forests; characterized by numerous, often bizarre specializations for pollination by particular species of insects; usually green and commonly with crassulacean acid metabolism; producing from a thousand to several millions of tiny seeds with a minute undifferentiated embryo which require association with an appropriate fungus for successful germination.
\BOrchidales\b Order of Liliidae comprising 4 families of strongly mycotrophic herbs, sometimes without chlorophyll; leaves parallel-veined or sometimes reduced to scales, flowers basically trimerous and adapted for pollination by insects; producing abundant tiny seeds with a minute undifferentiated embryo and no endosperm.
\BOrdovician\b A geological period within the Palaeozoic (\Ic.\i 504-441 million years B.P.); see geological time scale.
\BOrectolobidae\b Wobbegongs; family containing 7 species of large (to 3.5 m) orectolobiform elasmobranch fishes found on coral and rocky reefs of the western Pacific Ocean; body and head depressed, nostrils with long barbels; mouth terminal, teeth strongly differentiated; feed on fishes, crustaceans and cephalopods, occasionally offensive to man; reproduction ovoviviparous.
\BOrectolobiformes\b Carpet sharks; circumtropical order of marine or brackish-water galeomorph elasmobranch fishes, primarily benthic, occasionally pelagic; mouth terminal or subterminal, teeth undifferentiated; dorsal fins without spines; feed on bottom invertebrates and small fishes; reproduction oviparous or ovoviviparous, egg cases without spiral flanges; comprising about 30 species in 7 families; mostly inoffensive, a few species dangerous if provoked.
\BOreosomatidae\b Oreos; cosmopolitan family containing 10 species of deep-water zeiform teleost fishes; body compressed, to 400 mm length, scales cycloid or ctenoid, mouth and eyes large.
\Borgadocolous\b Living in open woodland; \Borgadocole.\b
\Borgadophilous\b Thriving in open woodlands; \Borgadophile\b, \Borgadophily.\b
\Borgadophyte\b A plant inhabiting open woodland.
\Borganic\b Pertaining to or derived from living organisms, or to compounds containing carbon as an essential component; See also \Jinorganic\j
\Borganism\b Any living entity; plant, animal, fungus, protistan, or prokaryote; \Borganismal\b, \Borganismic.\b
\Borganogenesis\b The formation of organs during development; \Borganogeny.\b
\Borgasm\b Intense sexual excitement or climax.
\BOribatei\b Diverse subgroup of acariform mites (Acari) containing about 145 families; commonly part of the soil fauna these mites are also widespread amongst lichens, mosses, and algae; most are fungivorous, none is parasitic; Cryptostigmata.
\BOribatida\b \JOribatei\j
\Boriental\b Eastern; easterly.
\BOriental region\b A zoogeographical \Jregion\j comprising India, Sri Lanka, Malay peninsula, Sumatra, Philippines, Borneo, Djawa (Java) and Bali; subdivided into Indian, Indo-Chinese, Indo-Malayan and Sri Lankan subregions.
\Boriole\b 1: \JOriolidae\j 2: \JIcteridae\j
\BOriolidae\b Orioles; family containing about 25 species of colourful Old World passerine birds found in tropical forests from Africa to Australia; habits solitary, arboreal, feeding on fruit and insects; cup-shaped nest of twigs placed in tree.
\Bornithichite\b A fossilized track or footprint of a bird.
\BOrnithischia\b Order of Mesozoic dinosaurs possessing a bird-like pelvis; included both tetrapodal and bipedal forms; all were herbivorous.
\Bornithocoprophilous\b Thriving in habitats rich in bird droppings; \Bornithocoprophile\b, \Bornithocoprophily.\b
\BOrnithogaea\b The zoogeographical region comprising New Zealand and Polynesia.
\Bornithogenic\b Pertaining to sediments rich in bird droppings.
\Bornithology\b The study of birds; \Bornithological.\b
\Bornithophilous\b Pollinated by birds; \Bornithophily.\b
\BOrnithopoda\b A suborder of ornithischian dinosaurs characterized by their bipedal gait; included the hadrosaurs and iguanodonts.
\BOrnithorhynchidae\b Platypus; monotypic family of egg-laying mammals (Monotremata) found in streams and lakes of Tasmania and eastern Australia; body covered with soft fur; feet webbed bearing strong claws; jaws toothless in adult, prolonged and strongly depressed to form large duck-bill; excavate burrows in banks for protection and as brood chamber; feed mainly on aquatic invertebrates.
\BOrobanchaceae\b Family of Scrophulariales containing about 150 species of herbaceous root parasites that lack chlorophyll; commonly producing iridoid compounds and orobanchin; widespread in northern hemisphere.
\Borogeny\b The process of mountain formation; \Borogenic\b, \Borogenesis.\b
\Borographic\b Pertaining to relief factors such as hills, mountains, plateaux, valleys and slopes.
\Borographic desert\b A rain shadow desert on the leeward side of a mountain range.
\Borographic rain\b Rainfall produced by supersaturation of an air mass forced upwards by a mountain range; see also \Jconvective rain\j \Jfrontal-cyclonic rain\j
\Borohylile\b Pertaining to an alpine or subalpine forest community or habitat.
\Borophilous\b Thriving in subalpine, or in mountainous regions; \Borophile\b, \Borophily.\b
\Borophyte\b A subalpine plant; \Borophytic.\b
\Borphan\b Of, or relating to, a virus that has no known association with disease.
\Bortet\b The original organism from which a clone was derived; see also \Jramet\j \Jgenet\j
\BOrthida\b Extinct order of articulate lamp shells (Brachiopoda) known from the Cambrian to the Permian.
\BOrthognatha\b Mygalomorph spiders; diverse suborder of mainly tropical spiders (Araneae) comprising about 1800 species and including various trapdoor, funnel web and purse web groups, and a family of large tarantulas; abdomen unsegmented, spinnerets located posteriorly; chelicerae move parallel to body axis.
\Borthoheliotropism\b An orientation response towards sunlight; \Borthoheliotropic.\b
\Borthokinesis\b A change in the rate of random movement of an organism (kinesis) in which the rate of locomotion (linear velocity) varies with the intensity of the stimulus; See also \Jklinokinesis\j
\BOrthonectida\b Class of mesozoans found as endoparasites in marine brittle stars, bivalve molluscs and polychaete worms; characterized by the alternation of an asexually reproducing stage and a free-swimming sexual stage.
\BOrthonychidae\b Rail babblers; family containing about 20 species of ground-dwelling passerine birds found in forest and open habits of Australia and New Guinea; wings short, legs and feet large and robust; habits solitary, secretive, non-migratory, feeding on insects; nest on ground or in burrow.
\Borthophototropism\b An orientation response towards light; \Borthophototropic.\b
\BOrthopsida\b Extinct order or regular echinoids with simple ambulacral plates, known from the Jurassic and Cretaceous.
\BOrthoptera\b Grasshoppers, crickets, locusts, katydids; order of orthopterodean insects comprising about 20 000 species found in almost all terrestrial habitats from subterranean burrows to tree canopies, and forests to deserts; body length 5-120 mm, hindlimbs usually specialized for jumping; forewings leathery or parchment-like, hindwings forming membranous fan, or may be reduced; many species produce sounds (stridulate) by rubbing together forewings, hindlimbs or hindlimbs against forewings; most are phytophagous, some omnivorous, a few predatory; as crop pests the group is of immense economic importance.
\BOrthopterodea\b Superorder of neopteran insects that retain primitive mandibulate mouthparts; wings variously modified or absent; contains 10 extant orders, Blattaria (cockroaches), Mantodea (mantises), Isoptera (termites), Grylloblattaria, Orthoptera (grasshoppers, locusts), Phasmoptera (stick insects), Dermaptera (earwings), Embiidina, Plecoptera (stoneflies) and Zoraptera.
\BOrthotrichales\b Order of dull tuft-or mat-forming mosses (Bryidae) that grow on rocks or tree trunks; stems with terminal sporophytes; leaves mostly papillae.
\Borthotropism\b Orientation or growth in a straight line; \Borthotropic.\b
\BOrycteropodidae\b Aardvark; monotypic family of insectivorous mammals (Tubulidentata) found in open grassland and brushland of Ethiopian region; body sparsely covered with bristly hairs, limbs stout with strong nails for digging, tongue long and protrusible; habits nocturnal, solitary, semifossorial, feeding mainly on ants and termites.
\Boryctology\b The study of fossils; palaeontology.
\BOryziatidae\b Ricefishes; family containing 7 species of fresh-and brackish-water cyprinodontiform teleost fishes found in southeastern Asia; body elongate, exhibiting weak sexual dimorphism; reproduction oviparous, fertilization external.
\BOsmeridae\b Smelts; family of marine and freshwater salmoniform teleost fishes found in the Arctic, and northern Atlantic and Pacific Oceans; body elongate, silvery, compressed and rather fragile, to 400 mm in length, cycloid scales thin; adipose fin present; contains 10 species which are anadromous or migrate upstream for spawning; locally abundant, smelts are important commercially as food-fish.
\Bosmoconformer\b An organism having a body fluid of the same osmotic concentration as the surrounding medium; See also \Josmoregulator\j
\Bosmophilic\b Thriving in a medium of high osmotic concentration; \Bosmophile\b, \Bosmophily.\b
\Bosmoregulation\b Control of the volume and composition of body fluids.
\Bosmoregulator\b An organism that maintains the osmotic concentration of its body fluid at a level independent of the surrounding medium; See also \Josmoconformer\j
\Bosmosis\b Diffusion of a solvent through a differentially permeable membrane from a region of low solute concentration to one of high solute concentration; \Bosmotic.\b
\Bosmotaxis\b A directed reaction of a motile organism to a change or gradient of osmotic pressure; \Bosmotactic.\b
\Bosmotic water\b Water held in close contact by clay particles that is less available to soil organisms than capillary \Jwater\j
\Bosmotrophic\b Used of organisms that are capable of absorbing organic nutrients directly from the external medium; \Bosmotrophy.\b
\Bosmotropism\b An orientation response to an osmotic stimulus; \Bosmotropic.\b
\Bosphresiology\b Study of the sense of smell.
\Bosprey\b \JPandionidae\j
\BOstariophysi\b Group of bony fishes possessing Weberian ossicles; includes the Cypriniformes, Gonorhynchiformes and Siluriformes.
\BOsteichthyes\b Bony fishes; group comprising all true bony fishes, about 18 000 species in 450 families; skull with sutures, teeth fused to bone; swim bladder frequently present functioning as lung or hydrostatic organ; internal fertilization rare.
\BOsteoglossidae\b Bonytongues; family containing 6 species of primitive freshwater teleost fishes from tropical South America, Africa, southeast Asia and Australia; body elongate, to 4.5 m in length; anal and dorsal fins long, pelvics posterior to pectorals; gas bladder richly vascularized and serving as accesssory respiratory organ; parental care may involve nest building or oral incubation.
\Bosteology\b Study of the structure and development of bones.
\BOsteostraci\b Extinct order of jawless vertebrates with a fish-like body and a flattened head covered by a bony plate with a series of gill openings; known from the Silurian to the Devonian.
\BOstraciontidae\b Boxfishes; family containing about 25 species of tropical shallow marine tetraodontiform teleost fishes commonly found on sea-grass beds; body enclosed within body carapace, length to 600 mm, fins small and paddle-like; may release toxin when alarmed.
\BOstracoda\b Mussel shrimps; class of small aquatic crustaceans containing about 5700 species inhabiting marine, brackish and freshwater habitats from littoral to abyssal zones, and occasionally terrestrial; body entirely enclosed in hinged bivalved carapace ranging in length from 0.1 to 30 mm; comprises 3 subclasses, Myodocopa, Podocopa and Palaeocopa; contains at least 10 000 fossil species stretching through the fossil record from the Cambrian to Recent times.
\BOstreoida\b Oysters, scallops, jingle shells, saddle oysters, window-pane shells; order of pteriomorphian bivalve molluscs with variable, often unequal, shell valves; characterized by 1 or 2 unequal shell-closing muscles, and by the lack of ventral fusion of the mantle, which has tentaculate margins.
\Bostrich\b \JStruthionidae\j
\BOstropales\b Order of predominantly saprophytic discomycete fungi found on decaying wood in warm climates; characterized by sessile, flask-shaped fruiting bodies and filiform ascospores.
\BOtariidae\b Sealions, fur seals, walruses; family of aquatic mammals (Carnivora) widespread in cold marine waters, comprising about 15 species; fore- and hindlimbs modified as flippers; ear pinnae present; feeding mostly on fishes but diet may include squid, other molluscs and other large invertebrates.
\BOtididae\b Bustards; family containing 24 species of medium-sized to large terrestrial gruiform birds found in open grassland habitats of Africa through Asia to Australia; neck and legs long, wings broad; habits cursorial, gregarious, feeding on variety of animals and plants, nesting in hollow on ground.
\Botter\b \JMustelidae\j
\Botter shrew\b \JTenrecidae\j
\Boutbreeding\b Mating or crossing of individuals that are either less closely related than average pairs in the population, or from different populations; See also \Jinbreeding\j
\Bovariicolous\b Living in ovaries; \Bovariicole.\b
\Bovary\b 1: The egg-producing reproductive organ of animals. 2: The swollen basal part of the carpel in flowering plants, containing one or more ovules.
\Bovenbird\b \JFurnariidae\j
\Bovergrazing\b Grazing which exceeds the recovery capacity of the community and thus reduces the available forage crop or causes undesirable changes in the community composition.
\Boverstorey\b The topmost layer of a forest community, formed by the tallest trees of the canopy.
\Boverturn\b Thorough water circulation in the sea or a lake, often occurring seasonally and caused by density differentials resulting from changes of temperature.
\Bovigerous\b Egg-bearing; used of a female carrying eggs; berried.
\Boviparous\b Egg-laying; producing eggs that are laid and hatch externally; \Boviparity\b; see also \Jlarviparous\j \Jovoviviparous\j, \Jviviparous\j
\Boviposition\b The act or process of depositing eggs.
\Bovoviviparous\b Producing fully formed eggs that are retained and hatched inside the maternal body with the release of live offspring; \Bovoviviparity\b; see also \Jlarviparous\j \Joviparous\j, \Jviviparous\j
\Bovum\b An unfertilized egg cell; a female gamete; \Bova.\b
\BOweniida\b Order of tubicolous, suspension- or deposit-feeding, polychaete worms comprising a single family of about 30 species; body elongate, prostomium and peristomium rudimentary, fused; pharynx unarmed, non-eversible.
\Bowl\b 1: \JTytonidae\j 2: \JStrigidae\j
\Bowl-fly\b \JAscalaphidae\j (Neuroptera).
\BOxalidaceae\b Carambola, oxalis, wood sorrel; widespread family of Geraniales containing about 900 species of herbs or shrubs, often with tubers or bulbs, commonly accumulating oxalates; flowers typically regular, with 5 sepals and petals. 10 stamens and a superior 5-celled ovary.
\Boxodic\b Pertaining to a peat bog community.
\BOxyaenidae\b Extinct family of mustelid-like carnivores (Creodonta) which flourished during the Eocene.
\Boxygenated\b With adequate available oxygen; aerobic; See also \Jdeoxygenated\j
\Boxygenotaxis\b A directed response of a motile organism towards (positive) or away from (negative) an oxygen stimulus; \Boxygenotactic.\b
\Boxygenotropism\b An orientation movement induced by an oxygen gradient stimulus; \Boxygenotropic.\b
\Boxygeophilous\b Thriving in humus-rich habitats; \Boxygeophile\b, \Boxygeophily.\b
\Boxygeophyte\b A plant growing in humus.
\Boxygeophytic\b Pertaining to plant communities in humus-rich habitats.
\Boxylophilous\b Thriving in humus or humus-rich habitats; \Boxylophile\b, \Boxylophily. \b
\Boxylophyte\b A plant growing in a humus-rich habitat; \Boxylophytic.\b
\BOxymonadida\b Order of zooflagellates characterized by the arrangement of flagella in 2 pairs in the motile stages; all species are commensal or symbiotic usually in insect digestive systems, rarely in vertebrate digestive systems.
\Boxyphilous\b Thriving in acidic habitats; \Boxyphile\b, \Boxyphily\b; See also \Joxyphobous\j
\Boxyphobous\b Thriving in alkaline habitats; intolerant of acidic conditions; \Boxyphobe, oxyphoby\b; See also \Joxyphilous\j
\Boxyphyte\b A plant growing under acidic conditions.
\Boxytaxis\b A directed response of a motile organism to an oxygen stimulus; \Boxytactic.\b
\Boxytropism\b 1: An orientation response to an oxygen gradient stimulus; \Boxytropic.\b 2: An orientation response to an acid stimulus.
\BOyashio Current\b A cold surface ocean current that flows southwards in the northwest Pacific, Oya Shio; Kamchatka Current; see ocean currents.
\Boyster\b \JOstreoida\j
\Boystercatcher\b \JHaematopodidae\j
\Bpaca\b \JDasyproctidae\j
\BPachycephalidae\b Whistlers; family containing about 45 species of arboreal passerine birds found in a variety of forest and open arid habitats of the Indo-Pacific region; bill typically compressed and hooked, wings short and rounded; habits solitary to gregarious, non-migratory; feed largely on insects, commonly caught on the wing; sometimes classified in the Muscicapidae.
\Bpaddlefish\b \JPolyodontidae\j
\Bpaddleworm\b \JPhyllodocida\j
\Bpaedogenesis\b Precocious sexual maturation in an organism that is still at a morphologically juvenile stage.
\Bpaedomorphosis\b The retention of juvenile characters of ancestral forms by adults, or later ontogenetic stages, of their descendants; superlarvation; \Bpaedomorphic\b; see also \Jneoteny\j \Jprogenesis\j
\Bpaedoparthenogenesis\b Parthenogenetic reproduction occurring in larvae.
\Bpaedophagous\b Feeding on embryos and the young stages of other species; \Bpaedophage, paedophagy.\b
\BPaenungulata\b Superorder of herbivorous mammals (Ferungulata) comprising the hyraxes (Hyracoidea), elephant-like forms (Proboscidea), Pantodonta, Dinocerata, Embrithopoda, sea cows (Sirenia) and Pyrotheria.
\BPaeoniaceae\b Peony; small isolated family in the Dilleniales containing about 30 species of mainly Eurasian herbs or soft shrubs which commonly have large showy flowers with 5 sepals, 5 petals, many stamens and a superior ovary.
\Bpagoda flower\b \JVerbenaceae\j
\Bpagoda shell\b \JNeogastropoda\j
\Bpagophilous\b Thriving in foothills; \Bpagophile, pagophily.\b
\Bpagophyte\b A plant inhabiting foothills.
\Bpair bonding\b The formation of a close and lasting association between a male and female animal, used particularly with reference to the cooperative rearing of young.
\BPalaeacanthocephala\b Large, diverse class of thorny-headed worms found as parasites of fishes, amphibians, reptiles, birds and mammals, often utilizing crustaceans as intermediate hosts; characterized by a retractable proboscis with hooks arranged in alternating rows, and a double-walled proboscis receptacle; comprises 2 orders, Echinorhynchida and Polymorphida.
\BPalaeanodonta\b Extinct suborder of primitive edentates found in North America from the Palaeocene to the Oligocene; cheek teeth peg-like without enamel but canines well developed.
\BPalaearctic region\b A zoogeographical \Jregion\j comprising Europe, North Africa, western Asia, Siberia, northern China, Japan; Palearctic region; subdivided into European, Mediterranean, Siberian and Manchurian subregions.
\Bpalaeoagrostology\b The study of fossil grasses.
\Bpalaeoalgology\b The study of fossil algae.
\Bpalaeobiology\b Study of the biology of extinct organisms.
\Bpalaeobotany\b Study of the plant life of the geological past.
\BPalaeocene\b A geological epoch within the Tertiary period (\Ic.\i 65-54 million years B.P.); see geological time scale.
\Bpalaeoclimatology\b Study of the climate during periods of past geological time; \Bpalaeoclimate.\b
\BPalaeocopa\b Subclass of marine ostracod crustaceans comprising a single order, Palaeocopida.
\BPalaeocopida\b Sole order of marine palaeocopan ostracods, comprising a single family, Punciidae, with only 2 species.
\Bpalaeodendrology\b The study of fossil trees.
\BPalaeodonta\b Extinct suborder of small artiodactyls found in North America during the Eocene and Oligocene.
\Bpalaeoecology\b Study of the ecology of fossil communities.
\BPalaeogaea\b A zoogeographical area originally comprising the Palaearctic, Ethiopian, Oriental and Australian regions; see also \JArctogaea\j \JNeogaea\j, \JMegagaea\j, \JNotogaea\j
\BPalaeogene\b A division of the Tertiary period (\Ic.\i 65-26 million years B.P.) comprising the Palaeocene, Eocene and Oligocene epochs; see geological time scale.
\BPalaeognathae\b Superorder of mainly large, flightless, terrestrial birds comprising 5 extant orders, Struthioniformes (ostrich), Rheiformes (rheas), Casuariformes (emus, cassowaries), Apterygiformes (kiwis) and Tinamiformes (tinamous); also includes the subfossil Dinornithiformes (moas), Aepyornithidae (elephant birds) and Dromornithidae; distribution confined to southern hemisphere; the flightless orders are commonly referred to as ratites.
\Bpalaeoichnology\b The study of trace fossils; See also \Jneoichnology\j
\Bpalaeolimnology\b Study of the geological history and development of inland waters.
\BPalaeolithic\b An archaeological period from about 10 000 to 3.5 million years B.P.; a period of human history characterized by the use of stone tools; the early, older or chipped Stone Age.
\BPalaeoloricata\b Extinct order of primitive chitons (Polyplacophora) found from the Cambrian to the Cretaceous.
\BPalaeonemertea\b Order of anoplan nemerteans with either 2 or 3 layers of musculature in the body wall and with the main components of the nervous system located in the inner longitudinal muscle layer or external to the muscle layers; Palaeonemertini.
\Bpalaeontology\b The study of fossils; paleontology; See also \Jneontology\j
\Bpalaeopalynology\b The study of fossil spores and pollen.
\BPalaeophytic\b The period of geological time between the development of the algae and the first appearance of gymnosperms, during which pteridophytes were abundant; Pteridophytic; see also \JAphytic\j \JArchaeophytic\j, \JCaenophytic\j, \JEophytic, Mesophytic\j
\Bpalaeosol\b A soil formed under past environmental conditions.
\BPalaeotheriidae\b Extinct family of horse-like mammals (Perissodactyla) known from the Eocene and Oligocene.
\BPalaeotropical kingdom\b One of 6 major phytogeographical \Jareas\j, characterized by its floristic composition; comprises African, Indo-Malaysian and Polynesian subkingdoms.
\BPalaeotropical Region\b Ethiopian \Jregion\j
\BPalaeozoic\b A geological era (\Ic.\i 570-245 million years B.P.) comprising the Cambrian, Ordovician, Silurian, Devonian, Carboniferous and Permian periods; see geological time scale.
\Bpalaeozoology\b Study of the animal life of the geological past.
\Bpaleo-\b See palaeo-.
\BPaleoheterodonta\b Subclass of freshwater and marine bivalve molluscs characterized by a generally equal-valved shell, a dentate hinge, 2 shell-closing muscles and a broad ventral mantle opening which forms inhalent and exhalent current apertures only rarely drawn out into siphons; comprises the orders Trigonioida and Unionoida.
\BPaleoptera\b Infraclass of primitive winged insects comprising 2 extant orders, Ephemeroptera (mayflies) and Odonata (dragonflies, damselflies); eyes large, antennae inconspicuous; the large wings have a rich venation and frequently exhibit surface corrugation or fluting; these insects are unable to fold the wings flat against the body; developmental stages are usually aquatic.
\BPalinura\b Spiny lobsters, crawfish; infraorder of pleocyematan decapod crustaceans; third maxilliped leg-like, not chelate; abdomen well developed; includes many species of commercial importance.
\Bpalm\b \JArecales\j
\BPalmae\b Palms; former name for the Arecaceae, sole family of the \JArecales\j
\BPalmariales\b Small order of red algae including the commercially important \IPalmaria palmata\i, which is used for human \Iconsumption\i and as cattle feed.
\Bpalmigrade\b \JPlantigrade\j
\BPalpigradi\b Microwhipscorpions; order of small (to 3 mm) agile terrestrial arthropods (Arachnida) comprising a single family of about 60 species typically found in the soil beneath stones; chelicerae long and slender, chelate; abdomen bearing terminal flagellum
\Bpaludification\b The process of bog expansion resulting from the rising water table produced as drainage is impeded by the accumulation of peat.
\Bpalustrine\b Pertaining to wet or marshy habitats; \Bpalustral.\b
\Bpalynology\b The study of pollen and spores.
\Bpan\b A soil horizon of highly compacted material, or one of high clay content.
\BPAN\b Peroxiacetyl nitrate, an atmospheric pollutant produced from automotive and industrial fumes under strong radiation.
\BPancarida\b Superorder of eumalacostracan crustaceans comprising a single order, \JThermosbaenacea\j
\BPandaceae\b Family of Euphorbiales containing 26 species of dioecious trees or shrubs, native to tropical Africa, Asia and New Guinea; flowers usually unisexual, regular and pentamerous; fruit commonly a drupe.
\BPandanales\b Screw pine; order of Arecidae comprising a single family, Pandanaceae, of about 500 species of trees, shrubs and woody climbers confined to the Old World and best developed in the tropics; stem often appears dichotomously branched and may have prop roots; leaves usually with an elongate and spiny blade; flowers small and unisexual.
\BPandionidae\b Osprey; monotypic family of fish-eating raptors (Falconiformes) cosmopolitan in freshwater and coastal marine habitats; capture fish with powerful feet, diving from 20-50 m; habits solitary, monogamous, nesting in trees, rocks or on the ground.
\BPangaea\b The single supercontinent formed about 240 million years B.P. comprising the present continental landmasses joined together, which began to break up about 150 million years B.P. (some authorities date the break up closer to 200 million years B.P.); see also \JGondwana\J \JLaurasia\j, \JTethys\j
\BPangasiidae\b Family containing 25 species of large (to about 3 m) southeast Asian freshwater catfishes (Siluriformes); body elongate, compressed; dorsal fin short with 1-2 spines, adipose fin small; 2 pairs of barbels present.
\Bpangolin\b \JManidae\j
\Bpanicle\b An inflorescence comprising several racemose parts; a compound raceme commonly found in grasses.
\Bpanmixis\b Unrestricted random mating; the free interchange of genes within an interbreeding population; \Bpanmictic.\b
\Bpanspermia\b The theory that life did not originate on Earth but was introduced from elsewhere in the Universe.
\Bpansy\b \JViolaceae\j
\BPanthalassa\b The single large ocean surrounding \JPangaea\j
\BPantodonta\b Extinct order of ungulates (Ferungulata) known from the Palaeocene through to the Oligocene.
\BPantodontidae\b Butterfly fish; monotypic family of small (to 100 mm) primitive teleost fishes inhabiting tropical west African fresh waters; dorsal and anal fins located posteriorly, pectorals large, pelvics with long fin rays; typically surface-dwelling, insectivorous, capable of jumping short distances.
\BPantopoda\b \JPycnogonida\j
\BPantotheria\b Extinct infraclass of primitive, egg-laying mammals (Theria) including the ancestors of all marsupial and placental mammals; mostly insectivorous with shrew-like appearance; known from the Jurassic.
\Bpantropical\b Extending or occurring throughout the tropics and subtropics.
\BPapaveraceae\b Poppies; family of herbs or softwooded shrubs with milky or coloured latex; flowers large typically with 2 sepals, 4 petals, many stamens and a superior ovary producing a nut or capsule containing many oily seeds; includes the opium poppy, \IPapaver somniferum.\i
\BPapaverales\b Order of dicotyledons (Magnoliidae) comprising 2 families of herbs or shrubs which produce isoquinoline alkaloids in specialized glands (laticifers) or cells; the fruit is typically a dry capsule opening by valves or pores.
\Bpapaya\b \JCaricaceae\j
\BPapilionidae\b Swallowtails; family of medium-sized to very large butterflies (Lepidoptera) of cosmopolitan distribution but most abundant in tropical regions; comprises about 500 species and includes the largest known butterflies, the birdwings.
\Bpapyrus\b \JCyperaceae\j
\Bparabiosis\b 1: The temporary suspension of physiological activity. 2: Utilization of the same nest by colonies of different species of social insects which nevertheless keep their broods separate; \Bparabiotic.\b
\Bparachrosis\b The process of colour change.
\BParacrinoidea\b Extinct class of echinoderms (Pelmatozoa) with a box-like test and uniserial branchioles; known only from the Ordovician.
\BParacryphiaceae\b Family of Theales containing a single tree species with unicellular hairs, known only from New Caledonia.
\BParadisaeidae\b Birds of paradise; family containing 40 species of colourful and ornate passerine birds found in forests of New Guinea; often with elaborate plumes, crests, and other modified long feathers; habits solitary, arboreal, monogamous to polygamous; males with elaborate courtship behaviour; feed on insects, small vertebrates and fruits; cup-shaped nest placed in tree.
\Bparaheliotropism\b Movement of leaves to avoid or minimize exposure to sunlight; \Bparaheliotropic.\b
\BParalepididae\b Barracudinas; small family of myctophiform teleost fishes distributed worldwide in the deep sea; body slender, pointed anteriorly, with single mid-dorsal fin, contains about 50 species.
\Bparalimnion\b The littoral zone of a lake from the water margin to the deepest level of rooted vegetation; \Bparalimnetic.\b
\Bparallel evolution\b The independent acquisition in two or more related descendant species of similar derived character states evolved from a common ancestral condition; parallelism; See also \Jconvergent evolution\j
\Bparallelogeotropism\b An orientation response that brings the main axis of the body to the vertical; \Bparallelogeotropic.\b
\Bparallelotropism\b Orientation or growth in a straight line; \Bparallelotropic.\b
\Bparameter\b Any measurable factor.
\BParamyxea\b Class of Ascetospora containing a single species parasitic in the intestinal cells of larval polychaetes; spore production is similar to that in the myxosporidia although no polar capsules are developed.
\Bparapatric\b Used of populations whose geographical ranges are contiguous but not overlapping, so that gene flow between them is possible; \Bparapatry\b; see also \Jallopatric\j \Jdichopatric\j, \Jsympatric\j
\BParapercidae\b \JMugiloididae\j
\BParapithecidae\b Extinct family of anthropoid primates (Cercopithecoidea) known from the Eocene and Oligocene in Asia and Africa; short-faced, with jaws like those of tarsiers.
\BParascyllidae\b Collared carpet sharks; family of small (to 1 m) bottom-dwelling orectolobiform elasmobranch fishes found in the western Pacific Ocean; body cylindrical, mouth subterminal, nostrils with short barbels; caudal fin lacking ventral lobe.
\Bparasematic\b Pertaining to markings, structures or behaviour intended to deter, distract or mislead a predator.
\Bparasexual\b Pertaining to organisms that achieve genetic recombination by means other than the regular alternation of meiosis and \Jkaryogamy\j; See also \Jeusexual\j
\Bparasite\b Any organism that is intimately associated with, and metabolically dependent upon, another living organism (the host) for completion of its life cycle, and which is typically detrimental to the host to a greater or lesser extent.
\Bparasitic castration\b Reproductive death of a host organism resulting from a parasitic infection.
\Bparasitic male\b A dwarf male that lives a parasitic existence attached to the body of its female, typically having well developed reproductive organs but an otherwise degenerate body form.
\Bparasitic slime moulds\b A group of organisms with a plasmodial (multinucleate and lacking cell walls) trophic stage capable of amoeboid movement between host cells; comprising about 35 species all of which are intracellular parasites of algae, fungi or vascular plants; life cycle includes biflagellate zoospores; several species cause diseases of economically important plants, such as clubroot of cabbage and powdery scab of potatoes; classified as a phylum of Protoctista (Plasmodiophoromycota), as a class of fungal slime moulds (Plasmodiophoromycetes), or as a class of rhizopod protozoans (Plasmodiophorea).
\BParasitica\b Parasitic wasps, gall wasps, fig wasps, chalcid wasps; diverse division of hymenopteran insects (suborder Apocrita) comprising over 100 000 species that are parasites or parasitoids of other arthropods, mainly insects and spiders, or plant tissues; female typically inserts egg into host with ovipositor; none of the parasitic wasps is eusocial; Terebrantia.
\BParasitiformes\b Suborder of medium-sized to large mites (Acari) comprising 3 subgroups, Mesostigmata, Holothyrina and Ixodida (arachnid ticks); ecologically very diverse, found in forest litter, moss and wood, feeding as predators, saprophages, fungivores or as parasites.
\Bparasitism\b An obligatory relationship between individuals of two different species, in which the parasite is metabolically dependent on the host, and in which the host is typically adversely affected but rarely killed; \Bparasitic.\b
\Bparasitoid\b An organism with a mode of life intermediate between parasitism and predation; usually a species of hymenopteran in which the larva feeds within the living body of another organism eventually causing the death of the host.
\Bparasitology\b The study of parasites and parasitism.
\Bparatenic host\b A host that is not essential for the completion of a parasite's life cycle but is used as a temporary habitat or as a means of reaching the definitive \Jhost\j; See also \Jintermediate host\j
\Bparathermotropism\b Movement of leaves to avoid or minimize the heating effects resulting from exposure to sunlight; \Bparathermotropic.\b
\Bparatrophic\b Feeding in the manner of a parasite; parasitic; \Bparatrophism\b, \Bparatrophy.\b
\BParazenidae\b Monotypic family of small (to 140 mm) marine zeiform teleost fishes reported from Japan and Cuba; body moderately compressed, mouth and eyes large; scales ctenoid.
\BPareiasauridae\b Extinct group of primitive herbivorous reptiles (Cotylosauria) with limbs rotated in towards body: known from the Permian.
\Bparenchymella larva\b Flagellated larval stage of demosponges.
\Bparent material\b The inorganic deposit which has been modified by weathering, translocation or other pedogenic process, to give rise to different soil types.
\BParidae\b Chickadees, titmice; family containing about 60 species of small acrobatic passerine birds found in forest and open woodland habitats of the northern hemisphere, Africa and Indonesia; bill typically short and stout; habits gregarious, arboreal, feeding mostly on insects, seeds and fruit; nest in tree hole or crevice.
\BParomomyidae\b Extinct family of early primates that flourished during the Palaeocene; probably herbivorous, ground-dwelling, and about the size of a shrew.
\Bparsimonious\b The condition of being economic or frugal in use or application; \Bparsimony.\b
\Bparsley\b \JApiaceae\j
\Bparsnip\b \JApiaceae\j
\Bparthenocarpy\b The development of fruit without seeds, typically resulting from lack of fertilization; \Bparthenocarpic.\b
\Bparthenogamete\b A gamete capable of parthenogenetic development.
\Bparthenogenesis\b The development of an individual from a female gamete without fertilization by a male gamete; see also \Jacyclic parthenogenesis\j \Jameiotic parthenogenesis\j, \Jandrocyclic parthenogenesis\j, \Janholocyclic parthenogenesis, arrhenotoky, automictic parthenogenesis, cyclic parthenogenesis, haploid parthenogenesis, holocyclic parthenogenesis, meiotic parthenogenesis, thelytoky\j
\Bparthenospore\b A spore produced from an unfertilized female gamete.
\Bparturition\b The act of giving birth.
\BParulidae\b Wood warblers; family containing about 125 species of small New World passerine birds found in variety of forest, woodland and open habitats; plumage often colourful; bill short, slender to robust; habits arboreal or terrestrial, some species migratory; feed on insects, fruit, nectar; nest on or off the ground.
\Bpascual\b Pertaining to, or inhabiting, pasture.
\Bpasculomorphosis\b Change in the structure of plants as a result of grazing by animals.
\BPasseridae\b Sparrows; family containing 27 species of small passerine birds found in variety of woodland and open habitats of the Old World, but also introduced and now widespread in many parts of New World and Australia; bill short, conical; habits gregarious, terrestrial, non-migratory; feed on seeds and insects; nest usually a loose mass of twigs and grass in a crevice or burrow.
\BPasseriformes\b Perching birds; the largest order of neognathous birds comprising about 70 families and over 5000 species; body form and habits extremely diverse; group includes great variety of flycatchers, swallows, larks, babblers, warblers, thrushes, wrens, shrikes, creepers, finches, sparrows, buntings, starlings and crows.
\BPassifloraceae\b Passion flower; large family of Violales containing about 650 species of vines climbing by axillary tendrils, best developed in tropical America and Africa; flowers often large and typically with 5 sepals and petals, many thread-like appendages forming a central corona, 5 stamens, 3 styles and a superior ovary.
\Bpassion flower\b \JPassifloraceae\j
\Bpassive chamaephyte\b A type of \Jchamaephyte\j in which the erect vegetation shoots persist through unfavourable seasons in a procumbent position.
\Bpassive uptake\b The absorption of ions by diffusion or other physical process not involving the expenditure of metabolic energy.
\BPastonian interglacial\b An interglacial period of the Quaternary Ice \JAge\j in the British Isles.
\BPataecidae\b Prowfishes; family containing 5 species of small (to 200 mm) Australian marine scorpaeniform teleost fishes; body strongly compressed, naked, sometimes papillose; dorsal fin very long, may be contiguous with caudal.
\BPaterinida\b Extinct order of inarticulate lamp shells (Brachiopoda) with phosphatic shells; known from the Cambrian to the Ordovician.
\Bpaternal\b Pertaining to, or derived from, the male parent; See also \Jmaternal\j
\Bpaternal sex determination\b The condition in which the sex of the offspring is determined by the idiotype of the male parent.
\Bpathogenic\b Producing or capable of producing disease; \Bpathogen\b, \Bpathogenicity. \b
\Bpathology\b The study of disease.
\Bpatobiontic\b Used of an organism that spends its entire life cycle in the forest litter; \Bpatobiont.\b
\Bpatocolous\b Used of an organism that inhabits the forest litter for only part of its normal life cycle; \Bpatocole.\b
\Bpatoxenous\b Used of an organism that occurs in the forest litter only by accident; \Bpatoxene.\b
\Bpatromorphic\b Resembling the male parent; See also \Jmatromorphic\j
\BPaucituberculata\b Order of small shrew-like South American marsupials comprising a single extant family, Caenolestidae; rat opossums.
\Bpaurometabolous\b Used of a pattern of development displaying a gradual metamorphosis in which changes are inconspicuous.
\BPauropoda\b Pauropods; class of minute (0.5-1.5 mm) blind arthropods comprising about 500 species in 2 suborders, Hexamerocerata and Tetramerocerata; body with 9-11 pedigerous segments, tergites bearing 5 pairs of long setae; antennae branched, mouthparts reduced, blood vascular system absent; typically found in soil or litter habitats, feeding on fungi or decaying plant material.
\BPavlovales\b Small order of mostly marine flagellate algae (Prymnesiophyceae) lacking scales.
\Bpawpaw\b \JAnnonaceae\j
\BPaxillosida\b Order of primitive, intertidal to abyssal, sediment-dwelling asteroidean echinoderms characterized by a series of columnar ossicles on the aboral surface (paxillae) that form a barrier to exclude sediment from the upper surface; comprises about 400 extant species.
\BPBBs\b Polybrominated biphenyls; class of compounds related to PCBs.
\BPCBs\b Polychlorinated biphenyls; chlorinated hydrocarbons used in industry which occur as persistent pollutants, particularly in aquatic ecosystems.
\Bpea\b \JFabaceae\j
\Bpea weevil\b \JBruchidae\j
\Bpea wilt\b \JHypocreales\j
\Bpeach\b \JRosaceae\j
\Bpeacock plant\b \JMarantaceae\j
\Bpeafowl\b \JPhasianidae\j
\Bpeanut\b \JFabaceae\j
\Bpeanut worm\b \JSipuncula\j
\Bpear\b \JRosaceae\j
\Bpearl oyster\b \JPterioida\j
\Bpearl perch\b \JGlaucosomidae\j
\Bpearleye\b \JScopelarchidae\j
\Bpearlfish\b \JCarapidae\j
\Bpearly nautilus\b \JNautiloidea\j
\Bpeat\b An accumulation of unconsolidated partially decomposed plant material found in more or less waterlogged habitats of fen (alkaline peat), bog (acid peat) and swamp.
\Bpeat moss\b \JSphagnopsida\j
\Bpebble\b A sediment particle between 4 and 64 mm in diameter; medium gravel; see sediment particle size.
\Bpeccary\b \JTayassuidae\j
\Bpeck order\b A dominance hierarchy, used especially of birds.
\BPecora\b Infraorder of advanced ruminants (Artiodactyla) containing the chevrotains (Tragulidae), deer and giraffe (Cervoidea) and sheep, cattle and antelopes (Bovoidea); stomach 4-chambered; 2 functional digits in each limb; mostly with horns.
\BPectobothrii\b Alternative name for the \JMonogenea\j
\Bped\b A unit of soil structure formed by natural processes, such as an aggregate, block or crumb.
\Bpedalfer\b An acid soil type found in humid regions rich in aluminium and iron compounds, but low in carbonates; See also \Jpedocal\j
\BPedaliaceae\b Sesame; family of Scrophulariales containing about 80 species of terrestrial or sometimes aquatic herbs and shrubs, mostly tropical in distribution especially in arid areas or along sea coasts.
\BPeditidae\b Springhaas; monotypic family of burrowing nocturnal rodents (Sciuromorpha); rabbit-like body, with long ears and a long tail; hindlimbs long for hopping locomotion, forelimbs short and clawed for digging; found in central and southern Africa.
\BPediculidae\b Family of sucking lice (Anoplura) comprising 2 species parasitic on New World monkeys, gibbons, great apes and man; includes the human head and body lice.
\BPedinomonadales\b Small order of uniflagellate \JPrasinophyceae\j lacking organic scales over cell and flagellar surfaces.
\Bpediophilous\b Thriving in uplands; \Bpediophile\b, \Bpediophily.\b
\Bpediophyte\b A plant of an upland community.
\BPedipalpi\b A group of arachnids comprising the tailless whip scorpions (Amblypygi) and whip scorpions (Uropygi); sometimes treated as an order.
\Bpedocal\b An alkaline soil type found in arid regions characterized by a high calcium carbonate content; See also \Jpedalfer\j
\Bpedology\b Study of the structure and formation of soils; soil science.
\Bpedon\b 1: Those organisms that live on or in the substratum of an aquatic habitat. 2: The smallest vertical column of soil containing all the soil horizons at a given location.
\Bpedosphere\b That component of the biosphere comprising the soil and soil organisms.
\BPegasidae\b Sea moths; family of tropical Indo-Pacific shallow marine gasterosteiform teleost fishes; body broad, depressed, armoured with bony rings; length to 140 mm; snout elongate; pectoral fins wing-like.
\Bpelagic\b Pertaining to the water column of the sea or lake; used of organisms inhabiting open waters; \Bpelagial\b See also \Jbenthic\j
\Bpelagic sediment\b A deep-ocean sediment containing no significant terrigenous component.
\Bpelagophilous\b Thriving in the open surface waters of the sea; \Bpelagophile\b, \Bpelagophily.\b
\Bpelagophyte\b A plant living at the sea surface.
\Bpelargonium\b \JGeraniaceae\j
\BPelecanidae\b Pelicans; small family containing 8 species of large water birds, cosmopolitan in tropical and temperate coastal habitats and large lakes; feed on fish caught in large pouch like bill, by plunging from flight; nest in colonies in trees or on ground.
\BPelecaniformes\b Order of medium to large neognathous water birds, found in marine and freshwater coastal habitats worldwide; comprises 6 families including pelicans, gannets, cormorants and frigate birds.
\BPelecanoididae\b Diving petrels; small family containing 4 species of oceanic sea birds (Procellariformes) found throughout the cold southern oceans; resembling the auks of northern seas; highly efficient divers, using wings underwater and feeding mainly on fish and crustaceans; nest in burrows or crevices.
\BPelecypoda\b \JBivalvia\j
\Bpelican\b \JPelecanidae\j
\BPellicieraceae\b Family of Theales comprising a single species of glabrous mangrove trees native to the shores of the Pacific Ocean from Costa Rica to Colombia.
\BPelmatozoa\b Subphylum of echinoderms typically exhibiting radial symmetry; attached by stalk (pelma) and with a globular body protected by a plated test; ambulacra extending onto arms; includes the Homalozoa and Crinozoa.
\BPelobatidae\b Spadefoot toads; family of toadlike terrestrial or fossorial anurans containing about 50 species widely distributed from North America, Europe, North Africa to the Oriental region; eggs and larvae aquatic in ponds and occasionally in streams; adults lacking ribs; possess digging tubercles on hindfeet.
\BPelobiontida\b Order of elongate, multinucleate naked amoebae (Gymnamoeba) which feed by ingesting plant material at the posterior end; lack a contractile vacuole, mitochondria and a flagellate phase; found in black bottom muds of ponds and ditches.
\Bpelochthophilous\b Thriving on mud-banks; \Bpelochthophile, pelochthopily.\b
\Bpelochthophyte\b A mud-bank plant.
\BPelodryadidae\b Family of Australo-New Guinean tree frogs (Anura); most species arboreal, a few terrestrial; body length to about 140 mm, tips of digits bearing expanded disks for adhesion; eggs and larvae aquatic.
\BPelodytidae\b Family containing 2 species of European toads (Anura) with long, leaping hindlimbs; related to the spadefoot toads (Pelobatidae).
\Bpelogenous\b Mud-producing or clay-producing.
\BPelomedusidae\b Small family containing 14 species of side-necked turtles (Pleurodira) inhabiting lakes and rivers of Africa, Madagascar and South America; head fully retractile; omnivorous, feeding mostly in shallow water.
\Bpelophilous\b Thriving in habitats rich in clay; \Bpelophile, pelophily.\b
\Bpelophyte\b A plant living in clay or muddy soil.
\Bpelopsammic\b Pertaining to or comprising both clay and sand.
\BPelycosauria\b Extinct order of synapsid reptiles containing both carnivorous and herbivorous species; many carried large, sail-like dorsal fins; known from the Upper Carboniferous and Lower Permian.
\BPenaeaceae\b Small family of Myrtales containing about 20 species of tanniferous evergreen shrubs native to Cape Province of South Africa.
\BPenaeidea\b Shrimps, prawns; infraorder of dendrobranchiate decapod crustaceans typically with a long abdomen, the first segment of which is not overlapped by the pleura of the second; includes many commercially important species.
\Bpencil fish\b \JLebiasinidae\j
\Bpencil urchin\b \JCidaroida\j
\Bpenguin\b \JSpheniscidae\j
\BPenicillata\b Subclass of diplopods (millipedes) comprising a single order, Polyxenida.
\Bpenicillium\b \JEurotiales\j
\BPeninoida\b Order of rare echinoids (Diadematacea) containing only about 15 species, found on the continental slope and outer shelf.
\BPennales\b Pennate diatoms; order of primarily freshwater algae found in the plankton and in damp terrestrial situations; characterized by a basically bilateral symmetry and by a slit between the valves, called a raphe, through which slime is exuded; may exhibit a gliding locomotion; sexual reproduction involves nonflagellate male gametes; also treated as a class of the phylum Bacillariophyta.
\BPennatulacea\b Sea pens, sea pansies; order of complex octocorals adapted for living on soft substrata in both warm and cold seas; the colony comprises an elongate axial polyp (oozoid) giving rise to dimorphic secondary polyps, some of which are specialized as siphonozooids pumping water into the colony to maintain its turgor pressure.
\Bpentacrinoid\b A stalked, larval stage of a sea lily (Crinoidea), attached at the base and with a distal crown showing the rudiments of developing arms and the 5-radial symmetry.
\BPentamerida\b Extinct order of thick-shelled, articulate brachiopods known from the Cambrian to the Devonian.
\BPentaphragmataceae\b Family of Campanulales containing about 30 species of perennial herbs lacking alkaloids and a latex system; native to southeast Asia.
\BPentaphylacaceae\b Family of Theales comprising a single species of evergreen shrubs or small trees native to southeast Asia; flowers hermaphrodite, pentamerous, with porous anthers; fruit capsular.
\BPentastomata\b Sole class in the arthropod subphylum \JPentastomida\j
\Bpentastome\b \JPentastomida\j
\BPentastomida\b Subphylum of vermiform blood-feeding arthropods, endoparasitic in the lungs and nasal passages of reptiles, birds and mammals; body divided into head and annulate abdomen, appendages confined to 4 chitinous hooks on ventral surface of head; mouthparts, circulatory and respiratory systems absent; sexes separate; larval stage with 2 pairs of non-jointed appendages and one or more piercing stylets; contains about 55 species in 2 orders, Cephalobaenida and Porocephalida; phylogenetic affinities uncertain, some workers assign the group to the Crustacea on the basis of sperm morphology.
\BPentatomidae\b Shield bugs; family of phytophagous and predatory hemipteran insects comprising about 5000 species, including several economically important agricultural pests; body typically shieldshaped.
\BPentazonia\b Subclass of diplopods (millipedes) comprising 2 superorders, Limacomorpha and Oniscomorpha.
\BPentoxylales\b Extinct group of shrubby or tree-like gymnosperms known from the Jurassic.
\Bpeony\b \JPaeoniaceae\j
\Bpepo\b A type of \Jberry\j with a hard outer layer derived from the outer fruit wall (epicarp) or from non-carpellary tissue.
\Bpepper\b \JPiperaceae\j
\Bpepper root\b \JBrassicaceae\j
\BPeracarida\b Superorder of eumalacostracan crustaceans in which the carapace is usually reduced or absent and the eggs are retained in a ventral brood pouch; diverse in morphology, life history and ecology; contains about 12 000 species in 7 extant orders, Amphipoda, Cumacea, Isopoda, Mictacea, Mysidacea, Spelaeogriphacea and Tanaidacea.
\BPeramelidae\b Family of short-haired terrestrial bandicoots from Australia, Tasmania and New Guinea; marsupium opening posteriorly, forelimbs shorter than hindlimbs; habits nocturnal, insectivorous.
\BPeramelina\b Bandicoots; order of insectivorous terrestrial marsupials found in Australia and New Guinea, comprising 2 families, Peramelidae and Thylacomyidae; marsupium opens posteriorly; chorio-allantoic placenta present but without villi.
\Bperch\b \JPercidae\j
\Bperching bird\b \JPasseriformes\j
\BPercichthyidae\b Family containing about 40 species of marine, brackish and freshwater perch-like teleost fishes (Perciformes) widespread in tropical and temperate regions; sometimes included in the family Serranidae; length to about 2 m; important as sport and food-fishes.
\BPercidae\b Perches, darters; diverse family of primarily northern hemisphere freshwater teleost fishes (Perciformes); body usually elongate, with 2 dorsal fins; length to 900 mm but often much less; feeding planktotrophic, insectivorous or piscivorous; reproduction oviparous; contains 160 species, some popular with anglers, others fished commercially.
\BPerciformes\b Large and diverse order of marine, brackish and freshwater teleost fishes comprising about 7000 species in 150 families; strong fin spines usually present, body scales often ctenoid or absent; adipose fin absent, pelvic fins thoracic or jugular; swim bladder lacking pneumatic duct.
\Bpercolation\b Downward movement of water through porous sediments.
\BPercophididae\b Family containing 20 species of deep-water, bottom-dwelling perciform teleost fishes most frequent in the Indian and Pacific Oceans but also present in the Atlantic; body elongate, to 250 mm length, head depressed with large eyes, lower jaw prolonged; 2 dorsal fins present.
\BPercopsidae\b Trout-perches; family of small (to 200 mm) North American freshwater teleost fishes (Percopsiformes) containing only 2 species; body slender, compressed, silvery; dorsal and anal fins with 1-2 spines, adipose fin present, caudal fin deeply forked.
\BPercopsiformes\b Order of North American freshwater teleost fishes comprising about 8 species and including trout-perches, pirate perch and cave fishes.
\Bperegrine\b Foreign, non-native; used of organisms transported into an area from outside.
\Bperegrine falcon\b \JFalconidae\j
\Bperennation\b The survival of plants from year to year with an intervening period of reduced activity.
\Bperennial\b Used of plants that persist for several years with a period of growth each year; see also \Jannual\j \Jbiennial\j
\Bperfect\b 1: Pertaining to a hermaphrodite or bisexual flower. 2: Pertaining to fungi or fungal life cycle stages that produce sexual spores.
\Bpergelicolous\b Living in geloid \Jsoils\j having a crystalloid content below 0.2 parts per thousand; \Bpergelicole\b; see also \Jgelicolous\j \Jhalicolous\j, \Jpergelicolous\j
\Bpergelicolous\b Living in geloid \Jsoils\j having a crystalloid content below 0.2 parts per thousand; \Bpergelicole\b; see also \Jgelicolous\j \Jhalicolous\j, \Jpergelicolous\j
\Bperianth\b The structure surrounding the inner, reproductive parts of a flower; typically comprising an outer whorl (the calyx) of sepals and an inner whorl (the corolla) of petals but sometimes comprising undifferentiated elements called tepals.
\Bpericontinental sea\b A shallow sea covering a modern continental shelf, typically less than 200 m in depth; See also \Jepeiric sea\j
\BPeridiniales\b Large order of predominantly marine thecate dinoflagellates which are typically photosynthetic; some neritic species become so adundant as to discolour the water, producing red tides.
\BPeridiscaceae\b Small family of Violales comprising 2 species of trees from tropical South America.
\Bperigean tides\b The tides of increasing amplitude occurring at the time the moon is nearest the Earth.
\Bperigyny\b The arrangement of the parts of a flower so that the sepals, petals and stamens are inserted at about the same level as the ovary; see also \Jepigyny\j \Jhypogyny\j
\Bperiodicity\b The periodic or rhythmic occurrence of an event; also the duration of a single phase of such an oscillation.
\Bperiphyton\b A community of plants, animals and associated detritus adhering to and forming a surface coating on stones, plants and other submerged objects; \Bperiphyte, periphytic.\b
\BPeriptychidae\b Extinct family of primitive ungulates known from the Palaeocene.
\BPerischoechinoidea\b Subclass of primitive regular echinoids (Echinoidea) containing a single extant order, \JCidaroida\j, but with many fossil forms known from the Ordovician onwards.
\BPerissodactyla\b Odd-toed ungulates; order of large terrestrial herbivorous mammals (Ferungulata) in which the central digit of each foot is dominant and carries most of the weight (mesaxonic); lateral digits present or absent; horns of bone absent; stomach simple; includes 3 families, Equidae (horses), Tapiridae (tapirs) and Rhinocerotidae (rhinoceroses).
\BPeritricha\b Large subclass of sessile oligohymenophoran ciliates typified by an inverted bell-shaped body on a long contractile stalk with a prominent ring of cilia around the distal (oral) end; generally found on an aquatic or semiterrestrial host.
\BPerkinsea\b Class of apicomplexan protozoans containing a single species parasitic in American oysters; propagating by flagellate zoospores.
\Bpermafrost\b Permanently frozen subsoil.
\Bpermeability\b 1: The condition of having pores or spaces that permit the passage of fluid molecules. 2: A measure of the freedom of entry of new members into a community or society.
\Bpermeant\b An organism that frequently moves from one community to another.
\BPermian\b A geological period of the Palaeozoic (\Ic.\i 290-245 million years B.P.); see geological time scale.
\Bpermineralization\b A process of fossilization by the infiltration and subsequent precipitation of dissolved minerals into the pore spaces of bones, shells and other skeletal parts.
\BPeronosporales\b Downy mildews, white rusts, potato blight; order of mainly terrestrial oomycete fungi comprising about 500 species, many of which parasitize flowering plants; characterized by a mycelial thallus with narrow hyphae lacking cross walls.
\Bperpelic\b Used of plants that live in areas of pure or abundant clay.
\Bperpsammic\b Used of plants that live in areas of pure or abundant sand.
\Bpersimmon\b \JEbenaceae\j
\Bperturbation\b A disturbance; any departure of a biological system from a steady state.
\BPeru Current\b The northerly extension of the cold Humboldt Current off the Peruvian coast, divided into an inner coastal current and an outer oceanic current by a tongue of warm water from the South Equatorial Countercurrent; see ocean currents.
\Bpessimal\b Least favourable; used of the levels of environmental factors that are close to the tolerance limits of an organism; See also \Joptimal\j
\Bpesticide\b A chemical agent that kills insects and other animal pests.
\Bpeta-(P)\b Prefix used to denote unit x 10\U15\u; see metric prefixes.
\BPetauridae\b Family containing about 20 species of small to medium-sized (to 1 m) arboreal marsupial phalangers found in Australia, Tasmania and New Guinea; marsupium opens anteriorly; tail prehensile; habits nocturnal or crepuscular, mainly herbivorous.
\Bpetricolous\b Growing within rock; \Bpetricole.\b
\Bpetrification\b A process of fossilization in which tissues are preserved by impregnation with carbonate or silicate minerals; \Bpetrified.\b
\Bpetrimadicolous\b Used of an organism living in the surface film of water on rocks; \Bpetrimadicole.\b
\Bpetrobiontic\b Living on or amongst rocks or stones; \Bpetrobiont.\b
\Bpetrochthophilous\b Thriving on rock-banks; \Bpetrochthophile\b, \Bpetrochthophily.\b
\Bpetrochthophyte\b A rock-bank plant.
\Bpetrocolous\b Living in rocky habitats; \Bpetrocole.\b
\Bpetrodophilous\b Thriving in boulder fields; \Bpetrodophile\b, \Bpetrodophily.\b
\Bpetrodophyte\b A plant inhabiting rocky or stony habitats.
\BPetromyzoniformes\b Lampreys; order of jawless vertebrates (Cephalaspidomorphi) with eel-like, naked body; paired fins absent; possessing 7 pairs of external gill openings; adults typically feed on blood of other fishes, but some non-parasitic species do not feed before reproducing; ammocoete larval stage found in fresh water, adults freshwater or anadromous; contains about 30 species in single family, Petromyzonidae.
\Bpetrophilous\b Thriving on rocks or in rocky habitats; \Bpetrophile\b, \Bpetrophily. \b
\Bpetrophyte\b A rock plant.
\BPetrosaviaceae\b Family of Triuridales comprising only 2 species of small mycotrophic herbs lacking chlorophyll; leaves reduced to alternate scales; single ring of vascular bundles present in stem; native to southeast Asia.
\BPetrosiida\b Order of ceractinomorph sponges widely distributed at depths down to 185 m in tropical and warm temperate seas; characterized by a reticulate skeleton of spicule tracts in which the spicules dominate the spongin.
\Bpetunia\b \JSolanaceae\j
\BPezizales\b Large order of discomycete fungi distributed worldwide predominantly on soil, dung and plant debris; characterized by cupshaped, saddle or sponge-shaped apothecia containing asci and interspersed sterile filaments (paraphyses) within a fertile layer (hymenium); the asci open by an operculum or rarely a longitudinal split and eject ascospores forcibly; includes morel.
\BpF\b Back-pull; a measure of the suction force of a soil.
\BpH\b The negative logarithm of the hydrogenion (H\U+\u) concentration, giving a measure of acidity on a scale from 0 (acid) through 7 (neutral) to 14 (alkaline).
\BPhacidiales\b Widely distributed order of discomycete fungi typically found as parasites of plants; characterized by the development of apothecia within surrounding sterile tissue (stroma) which ruptures at maturity to expose the fertile hymenium layer; spores violently ejected and disseminated by wind.
\BPhaeocalpida\b Order of Phaeodaria in which the shell is small and porcelain-like with one large opening and numerous small pores.
\BPhaeocystida\b Order of Phaeodaria in which the skeleton consists of either free spines or spines radiating from a common junction point.
\BPhaeodaria\b Class of Actinopoda in which the skeleton, when present, consists of hollow spines and is composed of silica and organic material; a thick capsular membrane is present in the vegetative stages which has only 3 apertures; typically found in deeper oceanic waters where they feed on small protozoans caught and digested externally.
\BPhaeodendrida\b Order of Phaeodaria in which the skeleton consists of two valves bearing long branching spines.
\BPhaeogromida\b Order of Phaeodaria in which the skeleton is a small diatomaceous or alveolar shell with one large opening.
\BPhaeogymnocellida\b Order of naked Phaeodaria lacking a skeleton or surrounded by skeletons from other protozoans.
\BPhaeophyceae\b Brown algae; large class containing over 1500 species of predominantly marine seaweeds inhabiting intertidal and sublittoral zones; ranging in form from filamentous to large parenchymatous blades; characterized by their photosynthetic pigments which include chlorophylls \Ia\i and \Ic\i, \Fb\n -carotene, fucoxanthin and violaxanthin; reproduction mostly sexual involving biflagellate sperm; also treated as a phylum of the Protoctista under the name Phaeophyta.
\BPhaeophyta\b The brown algae treated as a phylum of the Protoctista; \JPhaeophyceae\j
\BPhaeosphaerida\b Order of Phaeodaria in which the skeleton consists of a large latticed shell with wide polygonal meshes.
\BPhaethontidae\b Tropic birds; family containing 3 species of oceanic sea birds; feed on fish caught by diving; nest on cliffs.
\Bphage\b Bacteriophage; a virus of bacteria.
\Bphagocytosis\b The ingestion of solid particulate matter by a cell.
\Bphagotrophic\b Feeding by ingesting organic particulate matter; used of cells in the blood or body fluid that ingest foreign particles; \Bphagotroph, phagotrophy.\b
\BPhalacrocoracidae\b Cormorants; family containing 33 species of medium-sized water birds (Pelecaniformes), cosmpolitan in coastal marine and freshwater habitats; feed on fishes caught by diving from water surface; breed in colonies, nesting in tree or on ground.
\Bphalanger\b \JPhalangeridae\j
\BPhalangeridae\b Phalangers, cuscuses, possums; family containing 9 species of arboreal, diprotodont marsupials found in Australia and New Guinea; marsupium opens anteriorly; tail prehensile; habits nocturnal or crepuscular, mainly herbivorous.
\Bphalarope\b \JPhalaropodidae\j
\BPhalaropodidae\b Phalaropes; family containing 3 species of small, aquatic charadriiform shore birds, found in high latitudes of northern hemisphere; feed on crustaceans and insects at water surface; nest in hollows on ground, solitarily or in small colonies.
\BPhallales\b Stinkhorns; order of gasteromycete fungi in which, at maturity, part of the fruiting body autolyses into a putrid slime containing the spores, which are disseminated by flies.
\BPhallostethidae\b Family of tiny (to 25 mm) fresh and brackish-water atheriniform teleost fishes found in southeastern Asia; body slender, translucent; pelvic fins reduced or absent in females, modified as asymmetrical copulatory organ in males; reproduction oviparous.
\Bphaneric\b Pertaining to conspicuous coloration, See also \Jcryptic\j
\Bphanerogam\b A higher plant with reproductive organs conspicuous, in the form of flowers or cones; See also \Jcryptogam\j
\Bphanerogamous\b Reproducing by conspicuous means, used in particular of a plant having conspicuous flowers; \Bphanerogamy.\b
\Bphanerophytes\b Tall aerial perennial plants, mostly trees or shrubs with their renewal buds at least 250 mm above ground level; subdivided on the basis of bud height above the ground into - nanophanerophyte (up to 2 m), microphanerophyte (2-8 m), mesophanerophyte (8-30 m), megaphanerophyte (greater than 30 m); See also \JRaunkiaerian life forms\j
\BPhanerozoic\b That part of geological history in which there is abundant evidence of past life in fossil remains; the aeon comprising the Palaeozoic, Mesozoic and Cenozoic eras (\Ic.\i 570-0 million years B.P.); see geological time scale.
\Bphaoplankton\b The surface plankton of the upper photic zone; see also \Jknephoplankton\j \Jskotoplankton\j
\BPharetronidia\b Subclass of calcareous sponges comprising a single order, Inozoida, and characterized by massive reinforcement of the skeleton with additional calcite; usually found in shaded sites such as submarine caves and tunnels.
\Bpharotaxis\b 1: Navigation by means of landmarks. 2: Movement towards a specific place in response to a learned or conditioned stimulus.
\BPharyngobdellida\b Order of carnivorous hirudinean worms (Annelida) in which a pharynx is present, without jaws; found mostly in freshwater habitats.
\BPhascolarctidae\b Koala; monotypic family of arboreal, diprotodont marsupials confined to the forests of eastern Australia; length up to 0.8 m, body covered with soft fur, eyes large tail absent; marsupium opens posteriorly; habits nocturnal, herbivorous, feeding solely on eucalyptus leaves.
\BPhasianidae\b Pheasants, peafowl, jungle fowl, quails; diverse family containing about 185 species of small to large gallinaceous birds found worldwide in woodland and grassland habitats; often with colourful plumage in male and cryptic plumage in female; habits gregarious or solitary, monogamous or polygamous, feeding on seeds, fruit and insects; typically nest in hollow in ground; includes the wild ancestor of the chicken.
\Bphasmid\b \JPhasmoptera\j
\BPhasmoptera\b Stick insects, leaf insects, walkingsticks, phasmids, spectres; order of phytophagous, nocturnal, arboreal or arbusticolous orthopterodean insects found mainly in wet tropical habitats; contains about 2500 species; camouflage and mimicry highly developed; body commonly elongate and twiglike or flattened and leaf-like, length up to 300 mm; forewings parchment-like or leathery, hindwings forming broad fan, but may be reduced or absent; legs subsimilar; Phasmatodea.
\Bpheasant\b \JPhasianidae\j
\Bpheasant shell\b \JArchaeogastropoda\j
\Bphellophilous\b Thriving on stony or rocky ground; \Bphellophile, phellophily.\b
\Bphellophyte\b A plant living on gravel or a loose stony substratum.
\BPhenacodontidae\b Extinct family of protoungulates, comprising the best known of the condylarths from the Palaeocene to the Eocene; early forms possessed claws, late forms showed more ungulate features including hooves and an elongate third digit.
\Bphenetic\b Pertaining to overall similarity based on characters selected without regard to evolutionary history.
\Bphenetic method\b A method of classification based on the criteria of overall morphological, anatomical, physiological or biochemical similarity or difference, with all characters equally weighted and without regard to phylogenetic history; phenetics; See also \Jcladistic method\j
\Bphengophilous\b Thriving in, or having an affinity for, light; \Bphengophile\b, \Bphengophily\b; See also \Jphengophilous\j
\Bphengophobous\b Intolerant of light; \Bphengophobe\b, \Bphengophoby\b; See also \Jphengophilous\j
\Bphenodeme\b A local interbreeding population characterized by observed structural and functional properties (phenotype); See also \Jdeme\j
\Bphenology\b Study of the temporal aspects of recurrent natural phenomena, and their relation to weather and climate.
\Bphenometry\b The quantitative measurement of plant growth, mass and leaf area; \Bphenometric.\b
\Bphenotype\b The sum total of observable structural and functional properties of an organism; See also \Jgenotype\j
\Bpheromone\b A chemical messenger secreted by an organism that conveys information to another individual, often eliciting a specific response.
\Bphi grade scale\b A logarithmic transformation of the Udden grade scale of sediment particle size categories; see sediment particle size.
\Bphilodendron\b \JAracaceae\j
\Bphilopatric\b Exhibiting a tendency to remain in the native locality; used of species or groups that show little capacity to spread or disperse; \Bphilopatry.\b
\Bphilothermic\b Thriving in a warm climate; \Bphilotherm\b, \Bphilothermy.\b
\BPhilydraceae\b Small family of Liliales containing only 5 species of erect perennial herbs from Australia, the Pacific islands and southeastern Asia; flowers with a perianth of 4 petaloid members and a solitary stamen; seeds containing starch, protein and oil.
\BPhlebobranchia\b Order of solitary, occasionally colonial, tunicates (Ascidiacea) having internal longitudinal folds in the branchial sac; gonads located in loop of intestine; free-living larva present, but asexual reproduction also occurs by budding and strobilation; cosmopolitan distribution and found at all depths from littoral to deep water.
\BPhlebotamidae\b Sand flies; family of small hairy flies (Diptera) found in moist shady habitats; feed by sucking blood of vertebrates and known to act as vectors of disease.
\Bphlox\b \JPolemoniaceae\j
\Bphobotaxis\b An avoidance reaction of a motile organism; \Bphobotactic.\b
\BPhocidae\b Hair seals; cosmopolitan family of marine mammals (Pinnipedia) containing about 20 species and including grey, hooded, harp, monk, crabeater, Ross, leopard, Weddell, and elephant seals, and the sole freshwater Baikal seal; feed primarily on fishes, squid and crustaceans; ear pinnae absent.
\BPhocoenidae\b Porpoises; family containing 6 species of marine mammals (Odontoceta) found in coastal and estuarine waters of the Pacific, Atlantic, and Indian Oceans; head profile lacking distinct beak; feed on squid, crustaceans and fishes.
\BPhoenicopteridae\b Flamingos; family containing 6 species of large, long-legged wading birds cosmopolitan in tropical freshwater and marine shallow lakes and lagoons; bill characteristically bent downwards at midlength; feed on plankton and other suspended organic matter filtered out by sweeping movements of bill, with head inverted; breed in colonies, nesting on mounds in mud flats.
\BPhoenicopteriformes\b Order of long-necked, long-legged wading birds comprising a single family, Phoenicopteridae.
\BPhoeniculidae\b Small family of birds, the wood hoopoes, usually included within the family \JUpupidae\j
\Bpholad\b \JPiddock\j
\Bpholadophyte\b A plant living in hollows, intolerant of high light intensity.
\BPholididae\b Gunnels; family containing 14 species of intertidal and shallow marine blennioid teleost fishes (Perciformes), found mostly in rocky habitats; body slender, compressed, to 300 mm in length; dorsal fin long, continuous with caudal and anal; pectorals reduced or absent.
\BPholidoskepia\b Order of solenogastres (Mollusca) characterized by a layer of solid, scale-like calcareous bodies in the mantle and by the absence of true stalked epidermal papillae.
\BPholidota\b Order of placental mammals comprising a single family, Manidae (pangolins).
\Bphoresy\b A symbiosis in which one organism is merely transported on the body of an individual of a different species.
\BPhoridae\b Scuttle flies; family containing over 3000 species of small flies (Diptera) which often have reduced wings and run actively; larvae are specialised predators or parasitoids or live in decaying matter.
\BPhoronida\b Horseshoe worms; phylum or class of tubicolous marine coelomates comprising about 10 species characterized by a tentaculate lophophore surrounding the mouth serving respiratory, food collecting and protective functions; gut U-shaped, anus opening outside lophophore; hermaphrodite or with separate sexes, asexual propagation common; planktonic larval stage termed an actinotroch; adults found on hard and soft substrata, or in association with cerianthid anemones; intertidal to 400 m.
\Bphorophyte\b The host plant of an \Jepiphyte\j
\Bphosphorescence\b The emission of light in darkness by the release of absorbed radiation; also the light so produced; See also \Jbioluminescence\j
\Bphotic zone\b The surface zone of the sea or a lake having sufficient light penetration for photosynthesis; see also \Jdysphotic zone\j \Jeuphotic zone\j
\Bphotoautotrophic\b Used of organisms, such as green plants, that obtain metabolic energy from light by a photochemical process; \Bphotoautotroph\b, \Bphotoautotrophy\b; See also \Jchemoautotrophic\j
\Bphotocleistogamic\b Used of a plant in which self-pollination occurs within flowers that remain closed because of insufficient illumination; \Bphotocleistogamy. \b
\Bphotoepinasty\b Upward curvature induced by light; \Bphotoepinastic\b; See also \Jphotohyponasty\j
\Bphotohoramotaxis\b The directed reaction of a motile organism to colour, or to a light-pattern stimulus; \Bphotohoramotactic.\b
\Bphotohyponasty\b Downward curvature induced by light; \Bphotohyponastic\b; See also \Jphotoepinasty\j
\Bphotokinesis\b A change in random movement of an organism in response to a light stimulus; \Bphotokinetic.\b
\Bphotonasty\b Growth curvature in response to a diffuse light stimulus; \Bphotonastic.\b
\Bphotoperiod\b The light of a light/dark cycle; See also \Jnyctiperiod\j
\Bphotoperiodic\b Pertaining to the response of an organism to changes in daylength or to a light/dark cycle.
\Bphotophilic\b Thriving in conditions of full light; \Bphotophile\b, \Bphotophily\b; See also \Jphotophobic\j
\Bphotophobic\b Intolerant of, or avoiding, conditions of full light; \Bphotophobe\b, \Bphotophoby\b; See also \Jphotophilic\j
\Bphotophobotaxis\b A response of an organism to a temporal change in light intensity; positive when stimulated by a decrease in light intensity and negative when stimulated by an increase; \Bphotophobotactic.\b
\Bphotoplagiotropism\b Orientation at an oblique angle to incident light; \Bphotoplagiotropic.\b
\Bphotorespiration\b A metabolic process involving the uptake of oxygen and release of carbon dioxide, exhibited by many green plants when exposed to light, and which ceases in the dark.
\Bphotosynthates\b The products of carbon dioxide assimilation during photosynthesis.
\Bphotosynthesis\b The biochemical process that utilizes radiant energy from sunlight to synthesize carbohydrates from carbon dioxide and water in the presence of chlorophyll; \Bphotosynthetic\b; See also \Jchemosynthesis\j
\Bphotosynthetically active radiation (PAR)\b Radiation capable of driving the primary processes of photosynthesis, in the range of wavelengths between 380-710 nm.
\Bphototaxis\b A directed response of a motile organism towards (positive) or away from (negative) a light stimulus; \Bphototactic.\b
\Bphototropism\b An orientation response to light; \Bphototropic.\b
\BPhractolaemidae\b Monotypic family of small tropical African freshwater teleost fishes (Gonorhynchiformes) found in turbid weedy habitats; body elongate, cylindrical, becoming compressed posteriorly; mouth small but highly protractile bearing only 2 teeth on lower jaw; gas bladder functioning as accessory respiratory organ.
\BPhragmobasidiomycetes\b Heterogeneous class of basidiomycotine fungi almost all of which are saprobic; exhibiting a variety of forms of fruiting body from inconspicuous types adhering closely to the substratum to large, pigmented foliose structures; comprises 2 subclasses, Heterobasidiomycetidae and Metabasidiomycetidae.
\BPhragmophora\b Order of chaetognaths characterized by a primitive ventral transverse musculature; comprises 2 families, one with 13 pelagic species, the other containing 8 benthic species.
\Bphragmosis\b The action of closing the entrance to a nest or burrow with the body.
\Bphreatic\b Pertaining to ground water.
\Bphreaticolous\b Inhabiting ground water habitats; \Bphreaticole.\b
\Bphreatobiology\b The study of ground-water organisms.
\BPhreatoicoidea\b Small order of mainly subterranean freshwater isopod crustaceans found in Australia, New Zealand, India and South Africa.
\Bpheatophyte\b A plant that absorbs water from the permanent water table.
\Bphretophilous\b Thriving in water tanks; \Bphretophile\b, \Bphretophily.\b
\Bphretophyte\b A plant inhabiting a water tank.
\BPhrynophiurida\b Cosmopolitan order of ophiuroidean echinoderms comprising about 275 species found at all depths from littoral to deep sea; the disk and arms are covered by a thick skin, arms often coiled ventrally or branched (basket stars), spines often ornate; vertebral articulation permits vertical and lateral movement of arms.
\BPhthiraptera\b Lice; order of wingless hemipterodean insects comprising 2 groups, Anoplura (sucking lice) and Mallophaga (chewing lice), often classified as distinct orders; lacking eyes and with antennae reduced.
\Bphycobiont\b The algal partner of a lichen (an algal/fungal symbiosis); See also \Jmycobiont\j
\Bphycocoenology\b The study of algal communities.
\Bphycology\b The study of algae.
\Bphycophagous\b Feeding on algae; \Bphycophage\b, \Bphycophagy.\b
\Bphycophilic\b Thriving in algae-rich habitats; living on algae; \Bphycophile\b, \Bphycophily.\b
\BPhylactolaemata\b Class of freshwater bryozoans comprising a single order, Plumatellida, in which zooids are cylindrical, monomorphic, with crescent-shaped lophophore bearing 100 or more tentacles; colonies encrusting or gelatinous; typically found attached to tree roots and submerged vegetation.
\Bphyletic\b Pertaining to a line of direct descent, or a course of evolution.
\Bphylktioplankton\b Planktonic organisms rendered buoyant by hydrostatic means.
\BPhyllidae\b Leaf insects; family containing about 50 species of large, dorsoventrally flattened insects (Phasmoptera) found mainly in southeastern Asia and New Guinea; legs broad with flattened extensions giving entire body a leaf-like appearance.
\Bphyllobiology\b The study of leaves.
\BPhyllocarida\b Subclass of malacostracan crustaceans comprising a single order, \JLeptostraca\j
\BPhyllodocida\b Order of errant, pelagic and burrowing polychaete worms comprising about 3000 species in 26 families; pharynx cylindrical, muscular, eversible, with or without jaws; mouth surrounded by tentacular cirri; parapodia uniramous or biramous, acicula distinct; includes paddleworms, scaleworms, sea mouse, catworms and ragworms.
\BPhyllomedusidae\b Family of New World tree frogs (Anura), comprising about 40 species, found in tropical forests from Mexico to Argentina; body usually green dorsally, often brightly coloured on sides; eggs typically laid on vegetation above water, tadpoles aquatic.
\Bphyllophagous\b 1: Feeding on leaves; \Bphyllophage\b, \Bphyllophagy.\b 2: Pertaining to plants that obtain nourishment from their leaves.
\Bphyllosoma\b Zoeal larval stage of palinuran decapod crustaceans.
\Bphyllosphere\b The microhabitat of a leaf; the immediate surroundings of plant leaves that are influenced by their presence; See also \Jrhizosphere\j
\BPhyllostomatidae\b Vampire bats, leaf-nosed bats; diverse family containing about 130 species of small to large, New World bats (Microchiroptera); diets include insects, small vertebrates, fruit, nectar and blood.
\Bphyllotaxis\b The arrangement of leaves on a stem; \Bphyllotaxy.\b
\Bphylogenetic\b Pertaining to evolutionary relationships within and between groups; \Bphylogeny.\b
\Bphylogenetic relationship\b Evolutionary relationship; affinity based on recency of common ancestry.
\Bphylogenetic tree\b Evolutionary \Jtree\j
\Bphylogeny\b 1: The evolutionary history of a group or lineage. 2: The origin and evolution of higher taxa; \Bphylogenetic.\b
\Bphylum (phyla)\b A rank within the zoological hierarchy of classification; the principal category immediately below kingdom.
\BPhymosomatoida\b Order of echinoids (Echinacea) found in the Indo-Pacific and Japan, comprising only 2 extant species but having an extensive fossil record.
\BPhysarales\b Morphologically and developmentally complex order of Myxogastromycetidae characterized by a fruiting body with a dark spore mass and often containing visible lime; spores disseminated by wind.
\BPhysarida\b The slime mould order \JPhysarales\j, treated as an order of the protozoan group, Myxogastria.
\BPhyseteridae\b Sperm whales; family containing 3 species of small to very large (adult length 3-18 m) marine mammals (Odontoceta) widespread in oceanic waters; upper jaw with teeth absent or vestigial; head containing spermaceti organ giving blunt anterodorsal profile; feed mostly on squid, fishes and crustaceans.
\BPhyseteroidea\b Superfamily of whales (Odontoceta) comprising the sperm whales (Physeteridae) and the beaked and bottlenosed whales (Ziphiidae).
\Bphysiognomy\b The characteristic features or appearance of a plant community or vegetation; \Bphysiognomic.\b
\Bphysiographic\b Pertaining to geographical features of the Earth's surface; \Bphysiography. \b
\Bphysiology\b Study of the normal processes and metabolic functions of living organisms; \Bphysiological.\b
\Bphysogastry\b A condition of excessive enlargement of the abdomen, as found in some insects.
\Bphytal zone\b That part of a shallow lake bottom supporting rooted vegetation.
\Bphytobenthos\b 1: A bottom-living plant community. 2: That part of the bottom of a stream or lake covered by vegetation; See also \Jgeobenthos\j
\Bphytochemistry\b Chemotaxonomy of plants.
\Bphytochrome\b A proteinaceous pigment involved in photoperiodic responses and some other photoreactions in plants.
\Bphytocide\b A chemical used to destroy and control plants; \Bphytocidal.\b
\Bphytocoenology\b Phytosociology; the study of plant communities.
\BPhytodiniales\b Small order of unicellular freshwater dinoflagellates which typically live attached to other aquatic plants by a stalk or basal disk.
\Bphytoedaphon\b Soil flora; the plant community of the soil.
\Bphytoflagellate\b \JPhytomastigophora\j
\Bphytogenic\b Arising from, or caused by, plants.
\Bphytogeographical regions\b The major geographical divisions of the world characterized by floristic composition; the 6 commonly recognized kingdoms are - Antarctic, Australian, Boreal, Neotropical, Palaeotropical and South African; see map on page 294.
\Bphytogeography\b Study of the biogeography of plants.
\BPhytolaccaceae\b Common pokeweed; small family of Caryophyllales comprising about 125 species of often glabrous and succulent herbs best developed in subtropical and tropical areas of the New World.
\Bphytoliths\b Small particles of opaline silica found in the cell walls of some plants and studied as plant trace fossils.
\BPhytomastigophora\b Phytoflagellates; subphylum of Mastigophora commonly treated as algae, comprising all or part of the following algal groups, Euglenophycota, Cryptophyceae, Chrysophyceae, Xanthophyceae, Eustigmatophyceae, Raphidiophyceae, Prymnesiophyceae, and Chlorophyceae.
\Bphytopathology\b The study of plant disease.
\Bphytophagous\b Feeding on plants or on plant material; \Bphytophage\b, \Bphytophagy. \b
\Bphytophenology\b Study of the periodic phenomena of plants, such as flowering and leafing.
\Bphytoplankton\b Planktonic plant life; typically comprising suspended microscopic algal cells such as diatoms and desmids; \Bphytoplankter\b, \Bphytoplanktont\b; See also \Jzooplankton\j
\Bphytopleuston\b Plants free-floating in aquatic habitats.
\BPhytosauria\b Extinct order of crocodile-like reptiles (Archosauria) known from the Triassic.
\Bphytosis\b A disease caused by a plant parasite.
\Bphytosociology\b The study of vegetation, including the organization, development, geographical distribution and classification of plant communities.
\Bphytosuccivorous\b Feeding on sap; sap-sucking; \Bphytosuccivore\b, \Bphytosuccivory. \b
\Bphytotelmata\b Small pools of water in or on plants, such as the leaf bases of bromeliads or the pitchers of pitcher plants.
\Bphytotelmic\b Used of organisms that inhabit small pools of water within or upon plants.
\Bphytoteratology\b The study of malformations and monstrosities in plants; plant teratology.
\BPhytotomidae\b Plantcutters; family containing 3 species of finch-like passerine birds found in open woodland in South America; bills stout with serrated edges; feed on fruit, leaves and buds; nest in bushes.
\Bphytotoxic\b Poisonous to plants; \Bphytotoxicity.\b
\BPicathartidae\b Small family of passerine birds, the bald crows, usually included in the family \JTimaliidae\j
\BPicidae\b Woodpeckers, wrynecks; family containing about 200 species of hole-nesting birds (Piciformes) found worldwide in forests, grasslands and deserts; head large, bill typically strong and straight, tongue elongate and extensible; habits solitary, monogamous, non-migratory; feed mostly on insects and fruit; nest in tree holes or ground burrows.
\BPiciformes\b Diverse cosmopolitan order of small to medium-sized hole-nesting birds comprising 6 families and including honeyguides, toucans and woodpeckers.
\Bpickerelweed\b \JPontederiaceae\j
\Bpico- (p)\b Prefix used to denote unit x 10\U-12\u; see metric prefixes.
\Bpicoplankton\b Planktonic organisms between 0.2 and 2.0\Fm\nm in diameter.
\BPicrodontidae\b Extinct family of prosimian primates known from the Palaeocene.
\Bpiddock\b Pholad; a member of the family Pholadidae in the order Myoida, containing about 100 species of mostly marine bivalves which bore into hard substrata such as chalk, shale or wood.
\BPieridae\b Whites, brimstones; family of medium-sized butterflies (Lepidoptera) with predominantly white or yellow wings; caterpillar with fine hairs, pupa supported by central silk girdle.
\Bpiezoelectric\b Pertaining to a crystalline substance the electrical property of which is changed by pressure.
\Bpiezotropism\b A growth movement in response to a compression stimulus; \Bpiezotropic. \b
\Bpig\b \JSuidae\j
\Bpigeon\b \JColumbidae\j
\Bpigfish\b \JCongiopodidae\j
\Bpika\b \JOchotonidae\j
\Bpike\b \JEsocidae\j
\Bpike conger\b \JMuraenesocidae\j
\Bpike-characin\b \JCtenoluciidae\j
\Bpikehead\b \JLuciocephalidae\j
\Bpilidium\b Ciliated planktonic larval stage of some nemertean worms.
\BPilosa\b Infraorder of edentates (Xenarthra) comprising the sloths (Bradypodoidea), ant-eaters (Myrmecophagoidea) and the extinct ground sloths (Megalonychoidea).
\Bpilot whale\b \JDelphinidae\j
\BPimelodidae\b Family containing about 300 species of nocturnal or crepuscular New World catfishes (Siluriformes) found primarily in freshwaters of South and Central America; body elongate, naked, dorsal fin with stout spine, adipose fin present; 3 pairs of barbels, one pair often elongate; important locally as food-fish and also popular in aquarium trade.
\Bpimpernel\b \JPrimulaceae\j
\BPinaceae\b Pines, firs; large family of conifers (Pinatae) from the temperate zone of the northern hemisphere; usually evergreen, resiniferous trees with needle-like leaves spirally arranged; commercially important for timber, pulp, turpentine and resin products.
\Bpill beetle\b \JByrrhidae\j
\Bpill bug\b \JOniscoidea\j
\BPilosa\b Infraorder of edentates (Xenarthra) comprising the sloths (Bradypodoidea), anteaters (Myrmecophagoidea) and the extinct ground sloths (Megalonychoidea).
\Bpilot whale\b \JDelphinidae\j
\BPimelodidae\b Family containing about 300 species of nocturnal or crepuscular New World catfishes (Siluriformes) found primarily in freshwaters of South and Central America; body elongate, naked, dorsal fin with stout spine, adipose fin present; 3 pairs of barbels, one pair often elongate; important locally as food-fish and also popular in aquarium trade.
\Bpimpernel\b \JPrimulaceae\j
\BPinaceae\b Pines, firs; large family of conifers (Pinatae) from the temperate zone of the northern hemisphere; usually evergreen, resiniferous trees with needle-like leaves spirally arranged; commercially important for timber, pulp, turpentine and resin products.
\BPinatae\b Conifers; the largest class of extant Gymnosperms; usually evergreen shrubs or trees, branches with short spur shoots and long shoots; leaves small and scale-like or linear to needle-like; mature female (pistillate) strobilus either a cone or drupe-like structure.
\BPinicae\b Subdivision of Gymnosperms (Pinophyta); evergreen or deciduous shrubs or trees which are usually resiniferous; wood (xylem) lacks vessels, and stem cortex of minor importance in mature plant; male (staminate) structures found in simple strobili, female (pistillate) structures present in compound strobili; includes classes Ginkgoatae and Pinatae.
\Bpink\b \JCaryophyllaceae\j
\Bpinnigrade\b A form of locomotion by swimming using flippers as paddles.
\BPinnipedia\b Suborder of carnivores (Ferae) comprising the sealions, walrus (Otariidae), and seals (Phocidae); digits fully webbed and modified with the limbs into paddles.
\Bpinocytosis\b Active ingestion of fluid by a cell, by invagination of the cell membrane to form vesicles; \Bpinocytotic.\b
\BPinophyta\b Gymnosperms; ancient division of seed-bearing vascular plants extending from the Devonian to Recent; plants with true roots, stems and leaves; female (pistillate) and male (staminate) reproductive structures borne in clusters or strobili, often forming cones; pollen sacs present on scales (microsporophylls) and ovules on scales (megasporophylls) of cone; pollen usually fertilizes ovule by entry through the microphyle pore at its base; no style or stigma present; extant representatives known in 3 subdivisions, Cycadicae, Gneticae and Pinicae.
\BPiperaceae\b Peppers; large family of aromatic herbs (Piperales) and occasionally vines and epiphytes, widespread in tropical regions in moist, shady habitats; includes \IPiper nigrum\i, from which pepper is made, and the betel nut tree.
\BPiperales\b Order of flowering plants (Magnoliidae); mostly herbs and shrubs with reduced flowers lacking a perianth often borne in dense spikes; ovules usually orthotropic; fruit a berry or drupe.
\BPipidae\b Family containing 15 species of aquatic toads (Anura) from tropical west Africa and South America; body length to 250 mm, hindlimbs large and webbed, ribs present. tongue absent; eggs and larvae aquatic; in one genus eggs laid in pockets on back of female, with aquatic larvae or direct development.
\Bpipit\b \JMotacillidae\j
\BPipridae\b Manakins; family containing about 50 species of small Neotropical passerine birds found in wet forest habitats; plumage often colourful; males exhibit lek courtship display; habits solitary to gregarious, arboreal, polygamous, feeding on fruit and insects; nest in trees often over water.
\Bpiranha\b \JSerrasalmidae\j
\Bpirate perch\b \JAphredoderidae\j
\BPiroplasmia\b Piroplasms; subclass of apicomplexan protozoans which are usually found as parasites of red blood cells in vertebrates and utilize ticks as vectors; characterized by the lack of conoid from the apical complex of organelles; includes \IBabesia\i; also treated as a class, Piroplasmasida, of the protoctistan phylum Apicomplexa.
\BPisces\b Fishes; group of vertebrates that includes all fishes in the broad sense; See also \JTetrapoda\j
\Bpiscicolous\b Living on or within fishes; \Bpiscicole.\b
\Bpiscivorous\b Feeding on fishes; \Bpiscivore, piscivory.\b
\BPittosporaceae\b Australian laurel, New Zealand lemonwood; family of Rosales containing about 200 species of often climbing shrubs and trees widely distributed in warm temperate and tropical regions; flowers typically small and bell-like with 5 sepals, petals and stamens, and a superior ovary.
\Bplacental mammal\b \JEutheria\j
\BPlacodermi\b Class of primitive, heavily armoured, jawed fishes (Gnathostomata) known primarily from the Devonian; body typically depressed, head covered by shield of bony plates; tail heterocercal.
\BPlacodontidae\b Family of euryapsid reptiles known from the Triassic; most were specialized shellfish-feeders; some were turtle-like in form, others resembled nothosaurs.
\BPlacozoa\b Phylum of primitive multicellular animals comprising only 2 species found free-living in the littoral zone of warmer seas; characterized by the construction of its 2 body layers, a thin dorsal epithelium of flagellate cells and a thick ventral epithelium of flagellate and glandular cells, with a network of fibre cells running between them; also characterized by the lack of bilateral symmetry of muscular and nervous systems, and of gonads; reproduction usually by binary fission or budding.
\BPlagiorchiida\b Order of digenetic trematodes characterized by a single pair of flame cells (excretory organs) in the miracidia larva and by the lack of excretory vessels in the tail of the cercaria larva.
\Bplagiotropism\b An orientation response at an oblique angle to the vertical; \Bplagiotropic. \b
\Bplaice\b \JPleuronectidae\j
\BPlanctosphaeroidea\b Class of hemichordates known only from a planktonic ciliated larva (tornaria) collected from the Bay of Biscay; adult unknown.
\Bplane\b \JPlatanaceae\j
\Bplanetic \bMotile; possessing motile or swarming stages; \Bplanetism.\b
\Bplanidium\b First instar of bee fly larvae (Diptera: Bombayliidae) parasitic on the eggs and larvae of other insects.
\Bplankter\b An individual planktonic organism.
\Bplankton\b Those organisms that are unable to maintain their position or distribution independent of the movement of water or air masses; See also \Jnekton\j
\Bplanktont\b An individual planktonic organism.
\Bplanktophilous\b Living or thriving in the plankton; \Bplanktophile\b, \Bplanktophily. \b
\Bplanktophyte\b A planktonic plant; a member of the phytoplankton.
\Bplanktotrophic\b Feeding on plankton; \Bplanktotroph\b, \Bplanktotrophy.\b
\BPlannipennia\b Large suborder of advanced \JNeuroptera\j comprising the lacewings, dustywings, spongilla flies, owl flies and ant lions.
\Bplanogamete\b A motile gamete; zoogamete; See also \Japlanogamete\j
\Bplanomenon\b All free-living organisms; those organisms not rooted or attached to a substratum; see also \Jephaptomenon\j \Jrhizomenon\j
\Bplanont\b A motile gamete, spore or zygote.
\BPlanosol\b An intrazonal soil with an eluviated surface layer over a strongly compacted eluviated claypan, formed in humid to subhumid climates.
\Bplant\b 1: Any member of the kingdom Plantae. 2: A multicellular eukaryote organism typically exhibiting holophytic nutrition, lacking locomotion, lacking obvious nervous or sensory organs, and possessing cellulose cell walls.
\Bplant hopper\b \JHomoptera\j
\BPlantae\b Plants; kingdom of eukaryotic organisms which typically use light as an energy source via photosynthetic pathways involving the green pigment chlorophyll; mostly non-motile, lacking nervous and excretory systems but possessing cell walls composed largely of cellulose; traditionally including unicellular algae, which may be motile and heterotrophic, and fungi, which lack chlorophyll and absorb their food; comprises 2 subkingdoms, the Thallobionta and the Embryobionta.
\BPlantaginales\b Plantain; order of Asteridae containing about 250 species in a single family, Plantaginaceae; mostly herbs with basal leaves; flowers wind-pollinated, or cleistogamous, borne on spikes.
\Bplantain\b 1: \JPlantaginales\j 2: \JMusaceae\j
\Bplantcutter\b \JPhytotomidae\j
\Bplanticolous\b Used of organisms that spend most of their active life on or within plants; \Bplanticole.\b
\Bplantigrade\b Walking with the entire sole of the foot in contact with the ground.
\Bplanula\b A free-swimming larval stage of cnidarians with an elongate, radially-symmetrical and ciliated body.
\Bplasmodial slime moulds\b A group of organisms with phagocytic amoeboid stages which are plasmodial (multinucleate and lacking cell walls) and move by protoplasmic streaming and by filose pseudopodia; produce sedentary fungus-like fruiting bodies containing one to many spores; flagellate stages often present; found on decaying organic matter in moist microhabitats, and feeding on bacteria, fungi and protistans; classified as a phylum of Protoctista (Myxomycota), as a class of fungal slime moulds (Myxomycetes), or as a class of rhizopod protozoans.
\BPlasmodiophorea\b Parasitic slime \Jmoulds\j treated as a class of rhizopod protozoans.
\BPlasmodiophoromycetes\b Parasitic slime \Jmoulds\j, treated as a class of the Myxomycota and classified with the Fungi.
\BPlasmodiophoromycota\b Parasitic slime \Jmoulds\j, treated as a phylum of the Protoctista.
\Bplasmogamy\b Fusion of the cytoplasm of two or more cells without nuclear fusion.
\Bplasmophagous\b Feeding on body fluid; used of a parasite that freely absorbs the cellular fluid of the host; \Bplasmophage\b, \Bplasmophagy.\b
\Bplasmotomy\b The division of a multinucleated cell into multinucleated daughter cells, without accompanying mitosis.
\Bplastogamy\b The fusion of the cytoplasm of unicellular organisms to form a plasmodium, without fusion of the nuclei.
\BPlatacanthomyidae\b Spiny dormice; family of arboreal mice with long bushy tails, found in India and southern China; generally included as a subfamily of the \JMuridae\j
\BPlatanaceae\b Plane, sycamore; family of deciduous trees containing 6 species native to the Mediterranean region through to the Himalayas, and to North America; typically with small flowers; fruits are densely hairy achenes or nutlets in globose heads.
\BPlatanistidae\b River dolphins; family containing 4 species of freshwater dolphins widespread in rivers of southern Asia, China and South America; head with long slender beak and distinct forehead bulge; feed mainly on fishes but also take large aquatic invertebrates.
\Bplate tectonics\b The concept that the Earth's crust is divided into a number of rigid plates that are in motion relative to each other; the plates are formed at the mid-ocean ridges (seafloor spreading) and typically destroyed in deep-sea trenches.
\BPlatyasterida\b Order of asteroidean echinoderms represented by a single living genus with about 50 species; the group dates from the Lower Ordovician and contains the most primitive of the true asteroids.
\BPlatycephalidae\b Flatheads; family of bottom-living marine and brackish-water scorpaeniform teleost fishes from the Indo-Pacific and eastern Atlantic; body elongate, cylindrical, to 1.2 m in length; head depressed, spinose and ridged.
\BPlatycopida\b Order of marine podocopan ostracod crustaceans with a single family, Cytherellidae, containing about 75 species of benthic burrowers and crawlers which are unable to swim; typically abundant on continental shelf and in tropical lagoons; body size between 0.5 and 1.5 mm.
\BPlatyctenida\b Order of often brightly coloured ctenophores found commonly in coastal waters of tropical and polar regions; containing sessile, creeping and planktonic forms which are often compressed in oralaboral axis and may have the anterior part of the gastrovascular system erected to form a creeping sole; comb rows often absent in adults.
\BPlatydesmida\b Order of slender helminthomorphan diplopods (millipedes) having the sternal sclerites free, the pleural and tergal sclerites fused, and a conspicuous median dorsal suture; contains about 60 species, many of which are colonial, distributed throughout the Holarctic.
\BPlatyhelminthes\b Flatworms; phylum of dorsoventrally flattened, vermiform animals exhibiting bilateral symmetry and a definite head end but lacking a coelom; other characteristics include the single-celled excretory organs (flame cells), the incomplete digestive system which necessitates the voiding of waste matter through the mouth, and the typically hermaphroditic reproductive system; comprises 3 classes, the mostly free-living Turbellaria, and the wholly parasitic Trematoda and Cestoda.
\Bplatypus\b \JOrnithorhynchidae\j
\BPlatyrhinidae\b Family containing 5 species of small (less than 1 m) rhinobatiform fishes; body disk short and broad, snout rounded, tail slender and demarcated from disk; caudal fin without ventral lobe, axis straight.
\BPlatyrrhini\b Infraorder of arboreal Neotropical primates (Haplorhini) comprising the marmosets, Callitrichidae, and the New World monkeys, Cebidae.
\BPlatysternidae\b Big-headed turtle; family containing a single species of carnivorous, freshwater turtle (Testudines) from Asia; jaws serrated, carapace flattened, head too large to be withdrawn into shell.
\Bplay\b Trial-and-error learning especially in young animals.
\BPlecoglossidae\b Ayu; monotypic family of anadromous salmoniform teleost fishes found in China and Japan; body stout; teeth feeble, flattened and moveable; adipose fin present; prized locally as food-fish, and cultured in ricefields, ponds and waterways; some are caught using tethered cormorants.
\BPlecoptera\b Stoneflies; order of orthopterodean insects found mostly in cryptic habitats under stones and other debris; wings pleated or folded, abdomen 10-segmented bearing paired cerci; larvae usually aquatic, often in running water.
\BPlectomycetes\b Class of ascomycotine fungi in which the asci are scattered through the inner tissues and are typically globose in shape; asci deliquescent or evanescent; typically the fruiting body (ascocarp) lacks an ostiole; comprises 5 orders, Ascophaerales, Elaphomycetales, Eurotiales, Gymnascales and Microascales.
\Bpleiomorphic\b Exhibiting polymorphism at different stages of the life cycle; \Bpleiomorphism\b, \Bpleiomorphous.\b
\Bpleiotropic\b Used of a gene that has more than one, apparently independent, phenotypic effect; \Bpleiotropism\b, \Bpleiotropy.\b
\Bpleioxenous\b Used of a parasite that is not host-specific, or a parasite that has several hosts during its life cycle; \Bpleioxeny.\b
\BPleistocene\b A geological epoch of the Quaternary period (\Ic.\i 1.6-0.01 million years B.P.); see geological time scale.
\BPleistocene refuge\b An area peripheral to a major ice sheet, or an elevated, ice-free area within an ice sheet (a nunatak) that has been relatively unaltered by glaciation during the Pleistocene and which has a biota once typical of the region as a whole.
\BPleocyemata\b Large suborder of decapod crustaceans in which the gills lack secondary branching; females carry eggs which typically hatch as zoea larvae; comprises 6 infraorders, Astacidea (crayfishes), Anomura (hermit crabs, squat lobsters), Brachyura (crabs), Caridea (shrimps), Stenopodidea (shrimps) and Palinura (lobsters).
\Bpleogamy\b The maturation and pollination of different flowers on an individual plant at different times; \Bpleogamic.\b
\Bpleometrosis\b The founding of a colony of social organisms by more than one original female; \Bpleometrotic\b; See also \Jmonometrosis\j
\Bpleomorphic\b Polymorphic; assuming various shapes or forms within a species or group, or during a single life cycle.
\Bpleophagous\b 1: Feeding on a variety of food substances or food species; \Bpleophage\b, \Bpleophagy\b. 2: Used of a parasite associated with a variety of hosts.
\BPleosporales\b Large order of loculoedaphomycetid fungi which may be parasitic on plants and other fungi, saprobic or lichenized.
\Bplerocercoid\b Larval stage of tetraphyllidean cestodes, typically found in copepod crustacean hosts.
\BPlesiadapidae\b Extinct family of primates with squirrel-like bodies, equal length fore- and hindlimbs, claws on the digits and chisel-like incisors; known from the Palaeocene and Eocene.
\BPlesiocidaroida\b Extinct order of small, regular echinoids with very large apical system and ambulacra; known from the Triassic.
\Bplesiomorphic\b 1: Used of ancestral or primitive characters or character states; See also \Japomorphic. 2: Having similar shape or structure; \Bplesiomorph. \\j
\BPlesiopidae\b Roundheads; family of small (to 250 mm) Indo-Pacific perciform teleost fishes found in shallow water over reefs and rocky bottoms; body stout, head rounded with large mouth.
\BPlesiopora\b Small order of free-living and tubicolous annelid worms (Oligochaeta).
\BPlesiosauroidea\b Plesiosaurs; extinct suborder of aquatic reptiles known from the Jurassic and Cretaceous; body up to 15 m long, limbs paddle-shaped, neck either short (plesiosaurs) or long (pliosaurs).
\BPlethodontidae\b Family containing about 210 species of mostly terrestrial salamanders (Caudata); lungs absent; fertilization internal, males producing spermatophores; development variable with evolutionary trend from aquatic larvae to terrestrial eggs and direct development; some forms neotenic; mainly New World distribution, but also represented in Europe.
\BPleurocapsales\b Order of unicellular or multicellular blue-green algae found in marine, freshwater and terrestrial habitats; characterized by an aggregation of cells into chains or filaments and by reproduction involving endospores or exospores.
\BPleurodira\b Side-necked turtles; suborder of testudine reptiles in which the head is withdrawn laterally under the front edge of the carapace; comprises 45 species in 2 families. Pelomedusidae and Chelidae (snake-necked turtles), distributed throughout the southern hemisphere.
\BPleurogona\b Order of ascidiacean tunicates comprising a single suborder, Stolidobranchia, in some classifications treated as a in distinct order.
\BPleuronectidae\b Plaice, halibut, dab, flounder; family of pleuronectoid flatfishes widespread in temperate and tropical waters, in which the eyes are on the right side of the head; body length to 2.5 m; contains about 100 species several of which are important as food-fishes.
\BPleuronectiformes\b Flatfishes; order of bottom-living marine and brackish-water teleost fishes characterized by a strongly compressed body with both eyes on the same side of the head; the pelagic larval stage is symmetrical, undergoing metamorphosis in adopting benthic mode of life; comprises 7 families in 3 suborders; many very important commercially, including flounders, sole, plaice, halibut, turbot, dab.
\BPleuronectoidei\b Flounders; suborder of marine and brackish-water flatfishes comprising 4 families (Citharidae, Bothidae, Pleuronectidae and Scophthalmidae) with about 300 species; median fins lacking fin spines; pectoral fins present; vomerine and palatine teeth absent; typically use body undulations for locomotion.
\BPleurostomatida\b Order of gymnostome ciliates comprising a single family of voracious carnivores widely distributed in aquatic habitats; characterized by a slit-like cytostome positioned on the edge of a laterally compressed body.
\BPleurotremata\b Older name for the sharks; \JSelachii\j
\Bpleustohelophyte\b A plant which floats at the surface of a water body but which also has emergent structures.
\Bpleuston\b Aquatic organisms that remain permanently at the water surface by their own buoyancy, normally positioned partly in the water and partly in the air; \Bpleustonic\b, \Bpleustont\b; See also \Jneuston\j
\Bpleustophyte\b A free-floating macroscopic plant.
\BPliocene\b A geological epoch within the Tertiary period (\Ic.\i 5.0-1.6 million years B.P.); see geological time scale.
\Bpliosaur\b \JPlesiosauroidea\j
\BPloceidae\b Weaver finches, sparrows; family containing about 115 species of small Old World passerine birds found in forest, grassland and open arid habitats of Africa and southeast Asia; bill conical and robust; habits gregarious, arboreal to terrestrial, monogamous to polygamous or polyandrous, feeding mainly on seeds and insects; nest colonial to solitary, woven from grasses, usually placed in tree; members of one African subfamily are nest parasites.
\Bploidy\b The number of sets of chromosomes present; see also \Jmonoploid\j \Jhaploid\j, \Jdiploid\j, \Jtriploid, tetraploid, polyploid\j
\BPloima\b Large order of monogonatan rotifers containing both marine and freshwater forms, the latter often producing resistant resting eggs which ensure the survival of the rotifers during periods of desiccation; characterized by a circumapical ciliated band on the corona and by the presence of 1 or 2 toes and pedal glands on the foot.
\Bplotophyte\b A floating plant, usually having special flotation structures.
\BPlotosidae\b Catfish eels; family containing 30 species of marine, brackish and freshwater catfishes (Siluriformes) found in coastal waters of the Indo-Pacific; body elongate and tapering, naked; first dorsal fin short with serrate spine, second long and contiguous with caudal and anal; 4 pairs of barbels present.
\Bplover\b \JCharadriidae\j
\Bplum\b \JRosaceae\j
\BPlumatellida\b Sole order of bryozoan class, \JPhylactolaemata\j
\BPlumbaginales\b Devil's herb, statice; small but cosmopolitan order of Caryophyllidae comprising the family Plumbaginaceae containing about 400 species of herbs or low shrubs, many xerophytic or maritime; characterized by flowers with 5 sepals, 5 petals, 5 stamens and a superior ovary with 5 styles.
\Bpluriparous\b 1: Producing several offspring within a single brood; multiparous; see also \Jbiparous\j \Juniparous. 2: Having produced more than one previous brood\j
\Bplurivorous\b Feeding on a variety of different food sources or food species; \Bplurivore\b, \Bplurivory.\b
\Bpluteus\b Free-swimming, planktonic larval stage of sea urchins (echinopluteus) and brittle stars (ophiopluteus) in which the long larval lobes bearing bands of cilia are supported by skeletal rods.
\Bpluvial\b 1: Pertaining to, or resulting from, the action of rain or precipitation. 2: Used of a geological period, or the climate, characterized by abundant rainfall.
\Bpluvial periods\b Periods during the \JQuaternary\j characterized by excessive rainfall and the formation of great lakes in tropical and subtropical regions.
\Bpluviofluvial\b Pertaining to the combined action or effects of rainfall and streams.
\Bpluviophilous\b Thriving in conditions of abundant rainfall; \Bpluviophile\b, \Bpluviophily\b; See also \Jpluviophobous\j
\Bpluviophobous\b Intolerant of conditions of abundant rainfall; \Bpluviophobe\b, \Bpluviophoby\b; See also \Jpluviophilous\j
\Bpneumatophore\b 1: Gas-filled apical zooid in colonial hydrozoan cnidarians (Siphonophora) that acts as a float. 2: Specialized aerial roots through which gaseous exchange can take place; found in mangroves and other plants in waterlogged or compacted soils.
\Bpneumotaxis\b The directed response of a motile organism towards (positive) or away from (negative) a stimulus of dissolved carbon dioxide or other gas; \Bpneumotactic.\b
\Bpneumotropism\b An orientation response to a stimulus of dissolved carbon dioxide or other gas; \Bpneumotropic.\b
\BPoaceae\b Grasses; cosmopolitan family of Cyperales containing about 8000 species of mostly herbs, occasionally woody plants (bamboo), which tend to accumulate silica; stems mostly round and hollow, leaves usually narrow and parallel-veined; flowers small and arranged in spikelets which are in turn arranged in spikes; pollen grains with a single pore; includes many domesticated species providing staple foods for man, such as wheat, rice, millet, maize, oats, sugarcane, sorghum, rye, barley and bluegrass; formerly known as Graminae.
\Bpoacher\b \JAgonidae\j
\Bpocket gopher\b \JGeomyidae\j
\Bpocket mouse\b \JHeteromyidae\j
\BPodargidae\b Frogmouths; family containing 13 species of solitary nocturnal birds (Caprimulgiformes) found in forest and bushland from India through to Australia; head large, bill broad and hooked with wide gape; feed on insects and small mammals; nest in trees.
\BPodaxales\b Order of gasteromycete fungi containing a single species found in warm sandy habitats, frequently on ants' nests, which are penetrated by mycelium; fruiting body produced on surface.
\BPodicipedidae\b Grebes; family containing 20 species of specialized aquatic birds; legs located posteriorly for efficient swimming and diving, but locomotion on land clumsy; sexes similar; feed on fish, aquatic invertebrates and plant material; breed on freshwater lakes and ponds, overwintering along coasts.
\BPodicipediformes\b Order of neognathous birds containing a single cosmopolitan family, Podicipedidae (grebes).
\BPodocarpaceae\b Family containing over 100 species of evergreen, resiniferous conifers (Pinatae) native mainly to tropical and subtropical mountains of southern hemisphere; leaves scale- to needle-like; mature pistillate cones small and drupe-like.
\BPodocopa\b Diverse subclass of ostracod crustaceans found in marine, freshwater and, rarely, terrestrial habitats; mostly benthic creepers and burrowers; contains 2 orders, Platycopida and Podocopida.
\BPodocopida\b Order of podocopan ostracod crustaceans found in marine, brackish and freshwater habitats; mostly benthic creepers and crawlers, some living on algae or commensal on crustaceans; includes about 30 families and more than 5000 species.
\BPodostemales\b Small order of Rosidae containing over 200 species of aquatic herbs producing tiny aerial flowers; found in fast rivers with stony beds in tropical regions; species of family Podostemaceae have a thallus-like form anchored by roots.
\BPodzol soil\b A zonal soil with acidic layer of litter and duff over a highly acidic leached A-horizon and dark brown illuvial acidic lower horizon with translocated deposits of humus and iron oxide, formed in cool temperate to temperate, humid climates, under coniferous or mixed coniferous/deciduous forest or heath.
\Bpodzolization\b A soil-forming process in regions of high precipitation, good internal soil drainage, and low calcium carbonate levels; the soil becomes more acidic and iron and aluminium sesquioxides, as well as humus colloids, are translocated down the soil profile by percolating water.
\BPoeciliidae\b Live-bearers, guppies; family containing 140 species of small viviparous fresh-and brackish-water cyprinodontiform teleost fishes widespread in South and Central America, and also found in parts of North America; anal fin of male modified as gonopodium for sperm transfer; sexual dimorphism often well developed.
\BPoecilosclerida\b Large order of ceractinomorph sponges found in all seas and from the intertidal to depths in excess of 7000 m; characterized by a skeleton of megascleres and spongin, varying in body form from encrusting to branching or massive; extensive fossil record from Cambrian to recent.
\BPoecilostomatoida\b Order of marine copepod crustaceans containing about 1350 species of free-living predatory or surface-feeding forms, commensals and parasites, typically with powerful grasping maxillipeds and short antennae in males.
\BPoeobiida\b Monotypic order of aberrant pelagic polychaete worms; body compressed, transparent, lacking segmentation; prostomium and peristomium indistinct, bearing branchiae and tentacular palps.
\BPogonophora\b Beard worms; phylum of sedentary marine worms inhabiting cylindrical tubes typically buried vertically in fine ocean sediments; depth range 20-4000 m; body extremely slender, length 50-800 mm, divided into 4 regions - head bearing tentacles, mesosoma with or without an oblique ridge (bridle), long metasoma containing gonads, and a terminal opisthosoma armed with setae; mouth, gut and anus absent, nutrients absorbed through tentacles; sexes separate; contains about 100 species in 2 classes, Frenulata and Afrenulata.
\Bpoic\b Pertaining to meadows.
\Bpoikilohaline\b Used of organisms having body fluids that conform to external changes in salinity.
\Bpoikilosmotic\b Used of organisms that have an internal osmotic pressure that conforms to the osmotic pressure of the external medium; See also \Jhomoiosmotic\j
\Bpoikilothermic\b Cold-blooded; used of an organism having no mechanism for internal temperature regulation so that body temperature fluctuates with that of the immediate environment; \Bpoikilotherm\b, \Bpoikilothermy\b; See also \Jhomoiothermic\j
\Bpoikilothermy\b The condition of being \Jpoikilothermic\j
\Bpoinsettia\b \JEuphorbiaceae\j
\Bpoison ivy\b \JAnacardiaceae\j
\Bpoison oak\b \JAnacardiaceae\j
\Bpolar\b Pertaining to the areas within the Arctic and Antarctic Circles; characteristic of regions around the geographical poles; see also \Jtemperate\j \Jtropical\j
\Bpolecat\b \JMustelidae\j
\BPolemoniaceae\b Phlox; widely distributed family of Solanales containing nearly 300 species of mostly herbs with glandular hairs producing an often mephitic odour; flowers in crowded cymes, each flower with 5 sepals, petals and stamens, and a superior ovary.
\Bpoleophilous\b Thriving in urban habitats; \Bpoleophile\b, \Bpoleophily\b; See also \Jpoleophobous\j
\Bpoleophobous\b Intolerant of urban habitats; \Bpoleophobe\b, \Bpoleophoby\b; See also \Jpoleophilous\j
\BPolioptilidae\b Gnatcatchers; family containing 13 species of small, active passerine birds found in the New World; bills long and slender for feeding on insects; live in scrub, nest in trees.
\Bpollarding\b Severe pruning in which all the younger branches of a tree are cut back almost to the trunk; See also \Jcoppicing\j
\Bpollen\b The microspores of flowering plants containing the male gametophyte.
\Bpollen rain\b The total amount of pollen and spores deposited in a given area over a specified period of time.
\Bpollen tube\b An outgrowth of the pollen grain of a seed plant which grows through compatible stigmatic tissue towards the egg, carrying the male gametes with it; representing the reduced male gametophyte generation.
\Bpollenphagous\b Feeding on pollen; \Bpollenophage\b, \Bpollenophagy.\b
\Bpollination\b Transference of pollen from the anther to the receptive area of a flower; used loosely to mean fertilization of a seed plant.
\Bpollution\b The contamination of a natural ecosystem, especially with reference to the activity of man; \Bpollutant.\b
\Bpolyacmic\b Exhibiting many abundance peaks per year; see also \Jdiacmic\j \Jmonacmic\j
\Bpolyandrous\b Used of a female that mates with several males; \Bpolyandry\b; See also \Jmonandrous\j
\Bpolybrominated biphenyls\b \JPBBs\j
\Bpolycarpic\b Producing fruit or spores more than once during a life cycle; See also \Jmonocarpic\j
\BPolychaeta\b Bristleworms; class of marine, brackish and freshwater annelid worms comprising about 8000 species in 85 families; body length from 1 mm to 3 m, segments typically with paired lobes (parapodia) bearing variety of chaetae and bristles; exhibit diverse errant, sedentary, tubiculous, pelagic and parasitic habits with associated morphological adaptations.
\Bpolychlorinated biphenyls\b \JPCBs\j
\BPolycladida\b Large order of mostly predatory turbellarians found in coastal habitats and occasionally in plankton, rarely in fresh water; characterized by a large, flattened body, a main median intestine with numerous lateral branches, and many small testes and ovaries.
\BPolycystina\b Class of Actinopoda characterized by a skeleton made of silica and by the presence of a capsular membrane in the vegetative stages, which is regularly perforated; shell architecture depends on the arrangement of axopodia; found in all oceanic waters; includes 2 orders, Nassellarida and Spumellarida.
\BPolydesmida\b Diverse order of blind helminthomorphan diplopods (millipedes); body compact, able to roll into a loose coil or spherical ball; habits commonly nocturnal and fossorial, but order also includes arboreal, troglophilic, and active ground-living carnivorous species; the largest order of millipedes.
\Bpolydomic\b Used of colonies of social insects that occupy more than one nest; See also \Jmonodomic\j
\Bpolyethism\b The division of labour within a society on the basis of morphological castes (caste polyethism) or age (age polyethism).
\BPolygalaceae\b Milkwort; cosmopolitan family containing about 750 species of herbs and woody plants often with extrafloral nectaries; flowers bisexual but irregular with 5 sepals (the 2 inner sepals being petaloid), usually 8 stamens and a superior ovary.
\BPolygalales\b Order of Rosidae consisting of 7 families of woody and herbaceous plants, the largest of which are the Malpighiaceae, Polygalaceae and Vochysiaceae.
\Bpolygamous\b 1: Pertaining to the condition in which an individual has more than one sexual partner; \Bpolygamy\b; See also \Jmonogamous. 2: Used of a plant having perfect and imperfect flowers together on the same individual\j
\BPolygonales\b Buckwheat, dock, rhubarb, knotweeds, sorrels, sulphur plant; small order of Caryophyllidae consisting of a single family, the Polygonaceae, of mostly herbaceous or woody plants chiefly from northern temperate regions; characterized by small, perfect flowers usually with 3-6 perianth segments, up to 9 stamens and a superior ovary.
\Bpolygoneutic\b Producing several broods per year or season; \Bpolygoneutism\b; see also \Jmonogoneutic\j \Jdigoneutic\j, \Jtrigoneutic\j
\BPolygordiida\b Order of deposit-feeding polychaete worms found on intertidal and subtidal coarse sediments, comprising a single family and about 15 species; body segmentation indistinct; prostomium and peristomium with pair of short tentacles; pharynx eversible; parapodia and chaetae absent.
\Bpolygyny\b 1: The mating of a single male with several females. 2: The presence of many queens within a single colony of social insects; see also \Jmonogyny\j \Joligogyny\j
\Bpolyhaline\b Pertaining to brackish water having a salinity between 10 and 17 parts per thousand; or to sea water having a salinity greater than 34 parts per thousand; see also \Jmesohaline\j \Joligohaline\j
\Bpolyhalophilic\b Thriving in a wide range of salinities; \Bpolyhalophile\b, \Bpolyhalophily.\b
\BPolyhymenophora\b Class of ciliates with sparse body ciliature but a highly developed oral ciliature comprising numerous membranelles; found most commonly as free-swimming forms in aquatic and soil habitats, although some are endocommensals; contains a single subclass, Spirotricha.
\Bpolymictic\b Used of a lake having no persistent thermal stratification, which is continually circulating with only brief periods of stability; See also \Jmictic\j
\BPolymixiidae\b Beardfishes; family containing 3 species of mesopelagic marine teleost fishes widespread in tropical and temperate seas; body deep, compressed, to 250 mm length; eyes well developed; pair of long chin barbels present.
\BPolymixiiformes\b Monofamilial order of pelagic marine teleost fishes sometimes included in the Beryciformes.
\BPolymorphida\b Order of palaeacanthocephalan thorny-headed worms that are parasites of amphibians, reptiles, birds and mammals.
\Bpolymorphism\b 1: The co-occurrence of several different forms. 2: The co-existence of two or more discontinuous, genetically determined, segregating forms in a population, where the frequency of the rarest type is not maintained by mutation alone; see also \Jdimorphic\j \Jmonomorphic\j
\BPolynemidae\b Threadfins; family containing 35 species of small to large (to 2 m), tropical and subtropical, coastal marine and brackishwater teleost fishes (Perciformes); snout pointed, mouth subterminal, 2 dorsal fins present; pectorals subdivided, with several elongate rays; feed on pelagic crustaceans and fishes.
\BPolynemoidei\b Suborder of marine and brackishwater perciform teleost fishes comprising a single family, Polynemidae (threadfins).
\BPolynesia\b An assemblage of a large number of small oceanic islands scattered over the eastern Pacific Ocean, extending northwards to include Hawaii and eastwards to Easter Island, sometimes also including New Zealand; used loosely as a geographical area and ethnological unit to include both eastern \JMelanesia\j and \JMicronesia\j
\BPolynesian subkingdom\b A subdivision of the Palaeotropical \Jkingdom\j
\Bpolynya\b An expanse of open water in the middle of sea ice.
\BPolyodontidae\b Paddlefishes; family of primitive freshwater fishes, allied to sturgeons; body elongate, mostly naked, length to 2 m, snout paddle-shaped; contains 2 species, one found in North America, the other in China.
\Bpolyoestrous\b Having a succession of breeding periods in one sexual season; see also \Janoestrus\j \Jdioestrus\j, \Jmonoestrous\j
\Bpolyoxybiotic\b Used of organisms requiring abundant free oxygen.
\Bpolyp\b The individual, soft-bodies, sedentary form of cnidarians; typically a cylindrical trunk with an apical mouth surrounded by tentacles; attached basally to substratum in solitary forms or to branching tubular system in colonial forms.
\BPolyphaga\b The largest suborder of beetles (Coleoptera) comprising about 140 families, including Staphylinidae (rove beetles), Lucanidae (stag beetles), Scarabaeidae (dung beetles), Buprestidae (jewel beetles), Elateridae (click beetles), Lampyridae (fireflies, glow worms), Cantharidae (soldier beetles), Coccinellidae (ladybird beetles), Tenebrionidae (darkling ground beetles), Meloidae (blister beetles), Cerambycidae (long-horned beetles), Bruchidae (bean and pea weevils), Chrysomelidae (leaf beetles) and Curculionidae (weevils).
\Bpolyphagous\b Feeding on a wide variety of different foods or food species; \Bpolyphage\b, \Bpolyphagy\b; see also \Jmonophagous\j \Joligophagous\j
\Bpolyphyletic\b Derived from two or more distinct ancestral lineages; used of a group comprising taxa derived from two or more different ancestors; \Bpolyphyly\b; See also \Jmonophyletic\j
\BPolyplacophora\b Chitons, coat-of-mail shells; class of marine, free-living molluscs mostly found in shallow waters and characterized by a dorsal shell consisting of 8 overlapping, calcareous plates; typically with broad, ventral foot used for movement over or attachment to the substratum, surrounded by a groove containing 6 to many pairs of gills (ctenidia); jaws lacking, radula usually consisting of regular transverse rows of teeth; all living chitons belong to the subclass, Neoloricata.
\Bpolyplanetic\b Having several motile stages and intervening resting phases during the life cycle; \Bpolyplanetism\b; see also \Jdiplanetic\j \Jmonoplanetic\j
\Bpolyploid\b Having more than two sets of homologous chromosomes; \Bpolyploidy\b; See also \Jploidy\j
\BPolypteridae\b Reedfishes, bichirs; family containing 11 species of African freshwater fishes found in weedy lakes and rivers; body elongate, subcylindrical, to almost 1 m in length, bearing robust ganoid scales; gas bladder serves as accessory respiratory organ; dorsal fin comprising many small finlets, pelvics absent; larvae with external gills; adults predatory on fishes and amphibians.
\Bpolysaccharide\b A polymer comprising monosaccharides (simple sugars) or their derivatives; function mainly as structural elements (such as cellulose in plant cell walls) or as energy storage molecules (such as starch).
\Bpolyspermy\b The penetration of two or more sperms into a single ovum at the time of fertilization; \Bpolyspermic\b; see also \Jdispermy\j \Jmonospermy\j
\Bpolystenohaline\b Used of organisms that only inhabit oceanic waters of relatively constant high salinity; see also \Jeuryhaline\j \Jholeuryhaline\j, \Joligohaline\j, \Jstenohaline\j
\Bpolythermic\b Tolerating relatively high temperatures; See also \Joligothermic\j
\Bpolytokous\b Having many offspring per brood; fruiting many times during the life cycle; see also \Jditokous\j \Jmonotokous\j, \Joligotokous\j
\Bpolytopic\b Occurring or arising independently in two or more separate localities or geographical areas; \Bpolytopism\b, \Bpolytopy\b; See also \Jmonotopic\j
\BPolytrichidae\b Subclass of mosses (Bryopsida) in which plants are differentiated into above-and below-ground portions, with erect, sparsely branching stems, a well developed conducting system and complex leaf structure; grow as individual plants up to 800 mm in height or as dense mats.
\Bpolytrophic\b Feeding on a variety of different food substances or food species; \Bpolytrophy\b.
\BPolyxenida\b Order of minute (to 4 mm) diplopods (millipedes) having thin flexible body, lacking mineralization; typically active, colonial, prefering arid habitats; contains about 90 species having primarily tropical distribution.
\BPolyzoa\b \JBryozoa\j
\BPolyzoniida\b Cosmopolitan order of helminthomorphan diplopods (millipedes) having smooth polished body typically without median suture; contains about 25 species, inhabiting moist leaf litter and humus.
\BPomacentridae\b Damselfishes; family containing about 200 species of primarily tropical marine, reef-dwelling perciform teleost fishes, also occasionally found in shallow brackish and fresh waters; small (to 350 mm) and colourful, body deep and compressed; very popular amongst aquarists.
\BPomadasyidae\b \JHaemulidae\j
\BPomatomidae\b Bluefishes; family containing 3 species of large (to 1 m) predatory, pelagic, tropical and warm temperate, perciform marine teleost fishes; body elongate and robust, jaws and teeth strong; 2 dorsal fins present; popular as sport and food-fishes.
\Bpome\b A type of fleshy false fruit (pseudocarp) such as the apple, in which the true fruit (core) is surrounded by succulent tissues derived from the enlarged receptacle of the flower.
\Bpomegranate\b \JPunicaceae\j
\BPomeranian glaciation\b A subdivision of the Weichselian \Jglaciation\j
\Bpomfret\b \JBramidae\j
\Bpomology\b The study and practice of fruit cultivation.
\Bpompano\b \JCarangidae\j
\BPompilidae\b Spider wasps; family of slender solitary wasps (Hymenoptera) often with black or metallic blue bodies and orange or yellow wings; females paralyse spiders then lay one egg on each prey which is usually left in a burrow; contains approximately 2500 species.
\Bpond\b A small natural or artificial body of standing fresh water, intermediate in size between a pool and a lake, usually with negligible current and having more or less continuous vegetation from the marginal land areas into the water.
\Bpond skater\b \JGerridae\j
\Bpond snail\b \JBasommatophora\j
\Bpondweed\b \JPotamogetonaceae\j
\BPongidae\b Great apes; family of large, primarily herbivorous, arboreal or terrestrial primates (Catarrhini) found in the Oriental and Ethiopian regions; body robust, forelimbs longer than hindlimbs; tail and ischial callosities absent; contains the orang-utan, gorilla and chimpanzee.
\BPontederiaceae\b Water hyacinth, pickerelweed, mud plantain; family of Liliales comprising about 30 species of aquatic or semiaquatic herbs with floating or emergent leaf blades; flowers with 6 stamens; widespread in warm regions and extending into the north temperate zone.
\Bpontic\b Pertaining to the deep sea.
\Bpontophilous\b Thriving in the deep sea; \Bpontophile\b, \Bpontophily.\b
\Bponyfish\b \JLeiognathidae\j
\Bpoocolous\b Living in meadows; \Bpoocole\b.
\Bpoophilous\b Thriving in meadows; \Bpoophile\b, \Bpoophily.\b
\Bpoophyte\b A meadow plant.
\Bpoplar\b \JSalicales\j
\Bpoppy\b \JPapaveraceae\j
\Bpopulation\b All individuals of one species occupying a defined area and usually isolated to some degree from other similar groups.
\Bpopulation biology\b The study of the spatial and temporal distribution of organisms.
\Bpopulation dynamics\b The study of changes within populations and the factors that cause or influence those changes.
\Bpopulation genetics\b The study of gene frequencies and selection pressures in populations.
\Bpopulation size\b The number of items or individuals in a finite population.
\Bpopulation structure\b The composition of a population according to age and sex of the individuals.
\Bporbeagle\b \JLamnidae\j
\Bporcupine\b 1: \JHystricidae\j, \JOld World porcupines. 2: \JErethizontidae\j, New World porcupines.
\Bporcupine fish\b \JDiodontidae\j
\Bpore volume\b The volume of air-filled space in a soil.
\Bporgy\b \JSparidae\j
\Bporicidal dehiscence\b Spontaneous release of the contents of a ripe fruit through pores.
\BPorifera\b Sponges; phylum of aquatic animals characterized by an internal canal system through which water is propelled by flagella borne singly on choanocyte cells typically located in special chambers; water enters inhalent spaces through ostia in the outer covering, pores in the pinacocyte-lined walls of these inhalent spaces allow the water to percolate into the mesohyl (area containing the skeletal elements and other cell types of the sponge); water leaves sponge via the choanocyte chambers, the exhalent canal system and a set of larger openings, or oscules; skeleton made up of spicules of varying shape and chemical composition.
\BPorocephalida\b Order of pentastomes containing 38 species in 2 superfamilies, one parasitic in mammals, the other in reptiles (crocodiles, monitor lizards, snakes, turtles); in mammals, pentastomes found as adults only in nasal passages of Canidae, with juveniles infesting variety of intermediate hosts including horses, camels, pigs, hares, ruminants and occasionally man; body length up to 90 mm; head flattened; hooks arranged in transverse row.
\Bporosity\b The ratio of the volume of pore space to the total volume of sediment.
\Bporosphere\b The habitat or environment provided by a porous medium such as soil, that is more or less solid but with internal spaces (interstices) and surfaces.
\BPorphyridiales\b Order of marine and freshwater red algae (Rhodophyceae) with typically single-celled thalli, or rows of cells held together by mucilage.
\Bporpoise\b \JPhocoenidae\j
\BPortuguese man o'war\b \JSiphonophora\j
\BPortulaceae\b Moss rose, bitterroot; family of Caryophyllales containing about 500 species of often succulent herbs with capsular fruits; cosmopolitan but best developed in western North America and the Andes; flowers bisexual, typically borne on cymes and with 2 sepals, 4 to many petals, 1 or 2 whorls of 5 or several stamens and, commonly, a superior ovary.
\BPosidoniaceae\b Family of Najadales consisting of 3 species of glabrous, rhizomatous herbs growing submerged in sea water or on rocks that may be exposed at low tide.
\Bpossum\b \JPhalangeridae\j
\Bpost coitum\b Occurring after mating.
\Bpot worm\b \JEnchytraeidae\j
\Bpotamic\b Pertaining to rivers, or transport by river currents.
\Bpotamicolous\b Living in rivers; \Bpotamicole.\b
\Bpotamodromous\b Used of an organism that migrates only within fresh water; see also \Janadromous\j \Jcatadromous\j, \Joceanodromous\j
\BPotamogetonaceae\b Pondweeds; cosmopolitan family of Najadales comprising about 100 species of glabrous herbs with creeping rhizomes, erect leafy branches and small, wind-pollinated flowers, found in freshwater habitats.
\Bpotamology\b The study of rivers.
\Bpotamophilous\b Thriving in rivers; \Bpotamophile\b, \Bpotamophily.\b
\Bpotamophyte\b A river plant.
\Bpotamoplankton\b Planktonic organisms of slow-moving streams and rivers.
\BPotamotrygonidae\b River rays; family containing 20 species of medium-sized myliobatiform fishes confined to freshwater habitats of tropical South America; body disk oval to circular, tail slender and filamentous with serrated dorsal spine; dorsal and caudal fins absent.
\Bpotamous\b Pertaining to the lower reaches of rivers and streams; See also \Jrhithrous\j
\Bpotato\b \JSolanaceae\j
\Bpotato blight\b \JPeronosporales\j
\Bpotter wasp\b \JEumenidae\j
\BPottiales\b Small cosmopolitan order of mosses (Bryidae) containing generally small plants that grow as tufts on soil, rock and trees; stems usually having terminal sporophyte, the apical cell of the stem with 3 cutting faces; erect spore capsule typically borne on long stalk.
\Bpottoo\b \JNyctibiidae\j
\Bpot worm\b \JEnchytraeidae\j
\Bpowdery mildew\b \JErysiphales\j
\BPraecardioida\b Extinct order of thin-shelled, bivalve molluscs known from the Ordovician to the Carboniferous.
\Bprairie dog\b \JSciuridae\j
\BPrairie soil\b A zonal soil with a dark greyish brown to black moderately acidic A-horizon grading through brown into a light-coloured parent material, formed in temperate to cool temperate humid climates under tall grass vegetation; Brunizem.
\Bpraniza\b Parasitic larval stage of gnathiidean isopods (Crustacea).
\BPrasinomonadida\b \JPrasinophyceae\j treated as an order of the protozoan class, Phytomastigophora.
\BPrasinophycales\b \JPrasinophyceae\j treated as a class of the protoctistan phylum, Chlorophyta.
\BPrasinophyceae\b Class of mostly flagellate chlorophycote green algae found in marine, brackish and freshwater habitats; characterized by a covering of polysaccharide scales over the cells and flagella; comprises 5 orders, Pedinomonadales, Monomastigales. Pyramimonadales, Pterospermatales and Chlorodendrales; also treated as a class of the protoctistan phylum Chlorophyta under the name Prasinophycales, and as an order of the protozoan class Phytomastigophora, under the name Prasinomonadida.
\BPrasiolales\b Small order of terrestrial, freshwater and marine green algae in which the body form varies from filamentous to a parenchymatous cylinder with attachment rhizoids; cells uninucleate with an axial, stellate chloroplast.
\Bpratal\b Pertaining to grassland and meadowland.
\Bpratincole\b \JGlareolidae\j
\Bpratinicolous\b Living in grassland and meadowland; \Bpratinicole.\b
\Bprawn\b \JDendrobranchiata\j and \JPleocyemata\j; shrimp.
\Bprayer plant\b \JMarantaceae\j
\Bpraying mantis\b \JMantodea\j
\BPreboreal period\b A period of the Blytt-Sernander \Jclassification\j (\Ic.\i 9000-10 000 years B.P.), characterized by birch and pine vegetation and by relatively colder and wetter conditions than in the Boreal period.
\BPrecambrian\b A geological era ending about 570 million years B.P. comprising the Proterozoic, Cryptozoic, Archaeozoic and Azoic eons; see geological time scale.
\Bprecipitation\b Rainfall; also including snow, hail and sleet.
\Bprecocial\b Used of offspring that exhibit a high level of independent activity from birth; praecocial; See also \Jaltricial\j
\Bprecocious\b Occurring particularly early in development.
\Bpredation\b The consumption of one animal (the prey) by another (the predator); also used to include the consumption of plants by animals, and the partial consumption of a large prey organism by a smaller predator (micropredation).
\Bpredator\b An organism that feeds by preying on other organisms, killing them for food; \Bpredation.\b
\Bprehensile\b Adapted for gripping.
\BPrenebraskan glaciation\b An early glaciation of the Quaternary Ice \JAge\j in North America.
\Bpreservation\b The maintenance of individual organisms, populations or species by planned management and breeding programmes; See also \Jconservation\j
\Bpresocial\b Pertaining to a social group, or the condition in which members display some degree of social behaviour but fall short of full \Jeusocial\j behaviour.
\Bprevalence of infection\b The number of individuals of a host species infected by a particular parasite species divided by the number of hosts examined, usually expressed as a percentage.
\Bprevernal\b Pertaining to early spring.
\Bprey\b An animal or animals killed and consumed by a predator.
\Bprey set\b The total range of prey items utilized by a predator.
\BPriacanthidae\b Bigeye; family containing 15 species of nocturnal predatory bottom-living tropical and subtropical marine perciform teleost fishes; body deep, compressed, usually bright red in colour; eyes large, lower jaw prolonged; pelvic fin joined to body by flap of skin.
\BPriapulida\b Small phylum of generally rare marine worms known from less than 10 species found burrowing within sediments from intertidal to abyssal depths; characterized by an unsegmented cylindrical body typically divided into an anterior portion, the introvert, which bears the mouth and is invaginable into the abdomen, an abdomen bearing the anus and urogenital pores posteriorly, and a postanal tail; sexes separate, fertilization generally external; larval stages covered by a cuticular lorica.
\Bprickleback\b \JStichaeidae\j
\Bpricklefish\b \JStephanoberycidae\j
\Bprimary consumer\b A heterotrophic organism that feeds directly on a primary producer.
\Bprimary producer\b An organism that synthesizes complex organic substances from simple inorganic substrates.
\Bprimary production\b The assimilation of organic matter by autotrophs; see also \Jgross primary production\j \Jnet primary production\j
\Bprimary sexual characters\b Those differences between the sexes that relate to the reproductive organs and gametes; See also \Jsecondary sexual characters\j
\BPrimates\b Order of arboreal and terrestrial mammals that includes lemurs, tarsiers, monkeys, gibbons, apes, and man; eyes well developed, with binocular vision; digits usually prehensile, pollex and hallux opposable; typically produce single altricial young; many exhibit strong social organization; cosmopolitan in distribution but most abundant in the tropics; comprises 2 suborders, Strepsirhini (prosimians) and Haplorhini (monkeys, apes).
\Bprimeval\b Pertaining to earliest times, or the beginning of the Universe.
\Bprimitive\b 1: Early; simple; poorly developed; unspecialized. 2: Used of characters or character states present in ancestral forms; plesiomorphic.
\BPrimociliatida\b Order of primitive gymnostome ciliates distinguished by the possession of 2 or more nuclei, all of the same kind.
\Bprimordial\b Primitive; primary; used of the earliest stage in ontogeny or development of an organ or system; original.
\Bprimrose\b \JPrimulaceae\j
\BPrimulaceae\b Primrose, pimpernel, cyclamen, cowslip, loosestrife, primula; large family of mostly herbs containing about 1000 species found in cold and temperate regions of northern hemisphere; flowers typically with a 5-part calyx, a 5-lobed corolla, 5 stamens, 1 style and a superior ovary.
\BPrimulales\b Order of Dilleniidae containing about 2100 species of herbs or woody plants in 3 families, Myrsinaceae, Primulaceae and Theophrastaceae.
\BPrionodonta\b Superorder of bivalve molluscs comprising a single order, \JArcoida\j
\BPristidae\b Sawfishes; family containing 9 species of large (to 6 m) tropical and subtropical shallow marine, brackish and freshwater elasmobranch fishes (Pristiformes) in which the snout is prolonged into a long blade bearing a series of marginal teeth; body only moderately depressed, pectoral fins weakly expanded, dorsals and caudal large; feed on fishes and bottom invertebrates using snout to forage in sediment or slash small schooling fishes; reproduction viviparous, without placenta.
\BPristiformes\b Order of large elasmobranch fishes (Batoidea) comprising a single family, Pristidae (sawfishes).
\BPristiophoridae\b Saw sharks; family containing 5 species of medium-sized (to 2 m) pristiophoriform elasmobranch fishes confined to the Indo-Pacific; body elongate and subcylindrical, head depressed with long blade-like snout bearing irregular saw-teeth and long ventral barbels; large dorsal fins without spines, anal fin absent.
\BPristiophoriformes\b Order of squalomorph sharks containing a single family, Pristiophoridae.
\Bprivet\b \JOleaceae\j
\Bproaposematic coloration\b Warning coloration as exhibited by many venomous or unpalatable animals; See also \Japosematic coloration\j
\BProboscidea\b Order of terrestrial mammals (Ferungulata) comprising the elephants and their extinct relatives; typically large body size and showing development of a trunk from the nose and upper lip; teeth reduced, upper jaw often with tusks; includes elephants and mammoths (Elephantidae), mastodons (Mammutidae) and the Deinotherioidea, Moeritherioidea and Gomphotheriidae.
\Bprocaryotic\b \JProkaryotic\j
\BProcaviidae\b Hyraxes; family of small terrestrial or arboreal mammals (Hyracoidea) comprising about 10 species; forefeet with 4 digits, soles of hindfeet bearing large elastic adhesive pads to assist in climbing; habits diurnal to nocturnal, colonial, herbivorous; distributed through Ethiopian region to Mediterranean.
\BProcellariidae\b Petrels, fulmars, shearwaters; cosmopolitan family containing about 65 species of medium-sized to large, oceanic sea birds (Procellariiformes) specialized for dynamic soaring close to sea surface; feed on fishes, squid and crustaceans; breed in colonies on islands, having a single egg per clutch.
\BProcellariiformes\b Order of neognathous sea birds specialized for soaring flight close to sea surface; comprises 4 families, and includes albatrosses, fulmars and petrels.
\BProchlorophycota\b Division of photosynthetic, alga-like, unicellular, moneran microorganisms found in association with ascidians in tropical seas; characterized by the presence of chlorophyll \Ia\i and \Ib\i but without phycobiliproteins, and by the formation of photosynthetic lamellae from pairs or stacks of thylakoids; Chloroxybacteria.
\Bprocryptic\b Pertaining to coloration and behaviour that affords protection against enemies; \Bprocrypsis\b; See also \Janticryptic\j
\BProcyonidae\b Raccoons, coatis, red panda; family of arboreal mammals (Carnivora) comprising about 15 species found in the New World and in the Palaearctic (Himalayan red panda); diets include shoots, roots, fruit, small animals and carrion.
\Bproducer\b An organism that synthesizes complex organic substances from simple inorganic substrates; primary producer.
\Bproduction\b 1: Gross production, the actual rate of incorporation of energy or organic matter by an individual or population. 2: Net production, that part of assimilated energy converted into biomass through growth and reproduction by an individual or population per unit time.
\Bproductivity\b 1: The potential rate of incorporation or generation of energy or organic matter by an individual or population; rate of carbon fixation; See also \Jproduction. 2: Often used loosely for the organic fertility or capacity of a given area or habitat\j
\Bproepisematic\b Pertaining to a character or trait that aids social recognition; See also \Jepisematic\j
\Bprofile\b The vertical sequence of distinct horizontal layers of a soil, sediment or vegetation.
\Bprofundal\b Pertaining to a deep zone of a lake below the level of effective light penetration.
\Bprogamous\b Occurring or existing before fertilization.
\Bprogenesis\b The precocious sexual maturation of an organism that is still at a morphologically juvenile stage.
\Bprogeny\b The offspring of a single mating or of an asexually reproducing individual.
\BProkaryotae\b Superkingdom comprising viruses and the typical moneran forms; predominantly single-celled microorganisms or infectious agents of cells, lacking an organized nucleus and surrounding nuclear envelope in their cells; See also \JEukaryotae\j
\Bprokaryotic\b Used of organisms lacking a discrete nucleus separated from the cytoplasm by a membrane, as in bacteria and blue-green algae; \Bprokaryote\b, \Bprocaryotic\b; See also \Jeukaryotic\j
\BProlecithopora\b Order of marine and freshwater turbellarians found on mud, algae or interstitially in sediment; characterized by a plicate or variable pharynx, a simple sac-like gut and a common genital atrium receiving both male and female systems.
\Bprominent\b \JNotodontidae\j
\Bpromiscuous\b Pertaining to the mating system in which neither sex is restricted to a single mate.
\Bpronghorn\b \JAntilocapridae\j
\Bpropagation\b 1: Vegetative increase. 2: Sexual or asexual multiplication; \Bpropagate.\b
\Bpropagule\b 1: Any part of an organism, produced sexually or asexually, that is capable of giving rise to a new individual. 2: The minimum number of individuals of a species required for colonization of a new or isolated habitat.
\Bprophylactic\b Pertaining to the prevention of a disease; \Bprophylaxis.\b
\BProplicastomata\b Small order of free-living turbellarians known only from a single species found off Greenland at a depth of 180 m; characterized by an elongate, plicate pharynx, sac-like gut and by the absence of a statocyst.
\BProrocentrales\b Small order of typically marine unicellular dinoflagellates.
\BProsauropoda\b Extinct order of large, herbivorous dinosaurs (Saurischia) which were partly bipedal; known mainly from the Triassic.
\BProscyllidae\b Family containing 7 species of small (to 1 m), tropical, bottom-dwelling, carcharhiniform cat sharks, found mostly in deep water, to depths of 600 m.
\BProseriata\b Order of predominantly marine free-living turbellarians widely distributed in intertidal habitats, as well as occurring in deeper coastal waters and interstitially; characterized by a plicate pharynx, an unbranched gut, and a distinctive type of statocyst.
\Bprosimian\b \JStrepsirhini\j
\BProsimii\b Subgroup of primates usually known as the Strepsirhini in modern classifications; formerly used for a subgroup comprising the more primitive lemurs, lorises and tarsiers.
\BProsobranchia\b Snails; subclass of gastropod molluscs found in marine, freshwater and terrestrial habitats, and occasionally as parasites; characterized by a typically twisted body enclosed in a spirally coiled shell, by the position of the mantle cavity opening above or near the head and by the muscular creeping foot which usually bears a horny or calcareous plate (operculum) to close the aperture of the shell upon retraction; comprises 3 orders, Archaeogastropoda, Mesogastropoda and Neogastropoda.
\BProsopora\b Small order of aquatic annelid worms (Oligochaeta); typically with paired testes.
\BProsotheca\b Pot worms; small order of oligochaete worms comprising a single family, the Enchytraeidae; usually included within the order Haplotaxida.
\BProstigmata\b Subgroup of acariform mites (Acari) comprising about 14000 species in 130 families; exceedingly diverse in terrestrial, freshwater and marine habitats, including fungal and algal feeders, saprophages, phytophages and predators, as well as parasites of vertebrates and invertebrates.
\BProstomatida\b Order of gymnostome ciliates possessing a polyploid macronucleus, and an apical or subapical cytostome surrounded by unspecialized ciliature.
\Bprotandrous\b Pertaining to a hermaphrodite organism that assumes a functional male condition during development before reversal to a functional female state; \Bprotandry\b; See also \Jprotogynous\j
\Bprotaspis\b Planktonic, first larval stage of trilobites, in which the body was covered by a single dorsal carapace.
\BProtea\b \JProteaceae\j
\BProteaceae\b Protea, firewheel tree, pincushion flower, silky oak; large family of over 1000 species of evergreen shrubs or trees often possessing characteristic 3-celled hairs; widespread in tropical and subtropical regions, especially South Africa and Australia; flowers usually bisexual with 4 perianth segments, 4 long stamens bearing spoon-shaped anthers, and a superior ovary; flowers grouped into large showy inflorescences.
\BProteales\b Order of Rosidae containing only 2 families of mostly woody plants, Proteaceae and Elaeagnaceae.
\BProteidae\b Mud puppies, olm; small family of aquatic salamanders (Caudata); body length to 400 mm; metamorphosis incomplete; fore and hindlimbs, lungs, and external gills present; fertilization internal, males producing spermatophores; eggs typically laid under stones in streams; contains 5 North American species and a single subterranean species from Europe.
\Bprotein\b Large complex organic molecule composed of one or more polypeptide chains each of which consists of a sequence of amino acids.
\Bprotelean\b Used of an organism that is parasitic when immature and free-living as an adult.
\BProteocephalidea\b Order of tapeworms parasitic in the gut of fishes, amphibians and reptiles, and utilizing copepod crustaceans as intermediate hosts; characterized by a scolex with 4 suckers commonly covered with minute spines, the presence of a neck and by the segmented body.
\BProteromonadida\b Small order of zooflagellates with 2 or 4 flagella, one of which is recurrent and arises from the anterior pole of the body; found as parasites in the guts of amphibians, reptiles and mammals.
\BProterozoic\b A geological period (\Ic.\i 2400-570 million years B.P.); the late Precambrian era; Algonkian, Agnotozoic; see geological time scale.
\BProteutheria\b Suborder of insectivores comprising the modern tree shrews (Tupaiidae) and a variety of extinct forms known from fossils in the Cretaceous.
\Bprothallus\b The free-living gametophyte generation of ferns and certain other lower vascular plants.
\Bprothetely\b Accelerated sexual maturation in insects resulting in the production of an imago exhibiting larval or pupal characters; \Bprothetelic.\b
\BProtista\b Kingdom of eukaryotic microorganisms comprising protozoans, some algae and fungi with flagellated spores which are classified in up to 30 separate phyla; typically possessing a true flagellum (9 + 2 undulipodium); mitochondria and plastids often present.
\Bprotistan\b Pertaining to the eukaryotic organisms of the kingdom Protista, including some algae, fungi and protozoans; formerly used only of unicellular eukaryotic organisms; See also \Jmoneran\j
\Bprotistology\b The study of protistans.
\BProtoalcyonaria\b Order of deep-water solitary octocorals that reproduce sexually and possess only one type (morph) of polyp.
\BProtobranchia\b Subclass of marine bivalve molluscs containing about 500 species typically found living in the sediment and feeding on detritus; characterized by 2 shell-closing muscles and by protobranch gills consisting of simple filaments with plate-like leaflets on both sides; comprises 2 orders, Nuculoida and Solemyoida.
\BProtococcidiida\b Small, primitive order of coccidians in which merogony is absent; found in marine annelids.
\BProtoctista\b Kingdom of eukaryotic organisms which are defined by the lack of a blastula, an embryo or spores in the life cycle and by the lack of true flagella (9+2 undulipodia).
\BProtodrilida\b Order of interstitial polychaete worms found on coarse, shallow-marine sediments, comprising about 45 species in 2 families; body depressed and ciliated; prostomium and peristomium with pair of tentacles, pharynx non-eversible; parapodia reduced.
\BProtogastrales\b Order of gasteromycete fungi containing 3 species each in a separate family; characterized by a small fruiting body with a single hymenial cavity; typically found growing on plant roots and rabbit dung.
\Bprotogynous\b Pertaining to a hermaphroditic organism that assumes a functional female condition first during development before changing to a functional male state; \Bprotogyny\b; See also \Jprotandrous\j
\BProtomedusae\b Diverse class of extinct primitive cnidarians having bodies swollen into radial pouches separated by radial grooves; known from the Precambian to Ordovician.
\BProtomycetales\b Order of hemiascomycete fungi comprising a single worldwide family of parasites causing galls or other lesions in tissues of flowering plants.
\Bprotonema\b The typically filamentous juvenile form of a moss or liverwort which develops on germination of a spore.
\Bprotonymph\b Immature stage of mites (Acari) possessing 4 pairs of legs, and relatively simple chaetotaxy and genitalia; formed from the larval stage that has only 3 pairs of legs; proteronymph.
\BProtopteridae\b African lungfish; family containing 4 species of freshwater fishes found in weedy sluggish backwaters of central Africa; body elongate, cylindrical with paired swim bladders functioning as a lung; pectoral and pelvic fins long and filamentous; larvae with 4 pairs of feathery external gills; adults aestivate in dry season.
\BProtostelia\b Subclass of slime moulds which range from uninucleate amoeboid forms to multinucleate reticulate plasmodia, found on dead plants, dung and decaying organic matter; characterized by minute, stalked fruiting bodies bearing usually 1-4 spores.
\BProtosteliomycetes\b The \JProtostelia\j treated as a group of plasmodial slime moulds (Myxomycota).
\Bprotostomes\b Group of invertebrate animals linked by embryological characters such as spiral cleavage and formation of a coelom by splitting of the mesoderm (schizocoelic); includes annelids, molluscs and arthropods.
\BPrototheria\b Subclass of egg-laying mammals comprising a single Recent order, Monotremata, with 2 living families, Ornithorhynchidae (platypus) and Tachyglossidae (echidna); primitive features include retention of cloaca, unfused uteri, shell glands, and abdominal testes; female incubates eggs, the young feeding on milk from mammary glands that lack nipples.
\BProtoungulata\b Superorder of placental mammals (Ferungulata) including the earliest known ungulates from the late Cretaceous, which began to specialize for a herbivorous diet; comprises the orders Condylarthra, Litopterna, Astrapotheria, Notoungulata and Tubulidentata.
\Bprototrophic\b 1: \JAutotrophic\j; protrophic. 2: Obtaining nourishment from a single source only; \Bprototrophism\b. 3: Used of microorganisms capable of growth on simple sugars and salts without specific additional nutrient requirements.
\BProtozoa\b Diverse group of unicellular, eukaryotic organisms typically found as free-living heterotrophs in all types of habitat and as symbionts and parasites of other organisms; typically possess a single nucleus, sometimes with 2 or many nuclei; reproduction usually by simple binary fission although more elaborate cycles involving sexual phenomena occur in many protozoan groups; some forms are sessile, attached to the substratum by a stalk, some construct lorica or test to live in, others are colonial; they may be classified within the kingdom Protista, or as a subkingdom of the kingdom Animalia; includes at least 7 phyla, Apicomplexa, Ascetospora, Ciliophora, Labyrinthulata, Microspora, Myxozoa and Sarcomastigophora.
\Bprotozoea\b The early zoeal phase of larval development found in crustaceans.
\Bprotozoology\b The study of Protozoa.
\Bprotozoophilous\b Pollinated by Protozoa or other microscopic animals, as in some aquatic plants; \Bprotozoophily.\b
\Bprovisioning\b Providing food for young.
\BProtura\b Class of primitively wingless, white insects which lack eyes and antennae and have reduced mouthparts; body elongate with 3 pairs of jointed legs on the thorax and 3 pairs of rudimentary limbs (styli) on the abdomen, contains about 120 species found worldwide under bark, stones or in rotting vegetation.
\Bprowfish\b \JPataecidae\j
\BPrunellidae\b Hedge sparrows; family containing 12 species of small Eurasian passerine birds found in woodland, meadow, and montane habitats; bill slender and pointed, wings short and rounded; habits solitary, terrestrial, often migratory, feeding on ground insects, seeds and fruit; nest on ground, in crevices or in bushes.
\BPrymnesiales\b Order of mostly marine, planktonic flagellate algae (Prymnesiophyceae) which are covered in unmineralized organic scales.
\BPrymnesiophyceae\b Haptophytes; class of mostly marine flagellate chromophycote algae typically unicellular and possessing 2 equal flagella; characterized by the presence of chlorophylls \Ia\i and \Ic\i, and xanthophyll pigments which produce a golden brown coloration; usually covered with organic scales, which may be calcified to form coccoliths around the cell; comprises 4 orders. Coccosphaerales, Isochrysidales, Pavlovales and Prymnesiales; also treated as a phylum of Protoctista under the name Haptophyta, and as an order of the protozoan class Phytomastigophora under the name Haptomonadida.
\Bpsamathophilous\b Thriving in the strandline of a sandy seashore; \Bpsamathophile\b, \Bpsamathophily.\b
\Bpsamathophyte\b A strandline plant of a sandy seashore.
\BPsamminida\b Widely distributed order of xenophyophores distinguished by the general rigidity of the body and by the absence of organic threads in the test.
\Bpsammobiontic\b Living in sand; living interstitially between or attached to sand particles.
\BPsammodrilida\b Order of small (to 9 mm) interstitial neotenic polychaete worms that inhabit mucus tubes covered with sand grains in shallow water; typically feeding on benthic diatoms; body segmentation indistinct; prostomium and peristomium fused, naked; pharynx non-eversible; parapodia reduced.
\Bpsammofauna\b Those animals associated with a sandy substratum, or living within a sandy area.
\Bpsammolittoral\b Pertaining to a sandy shore.
\Bpsammon\b Those organisms living in, or moving through, sand; the interstitial flora and fauna; See also \Jbenthos\j
\Bpsammophilous\b Thriving in sandy habitats; \Bpsammophile\b, \Bpsammophily.\b
\Bpsammophyte\b A plant growing or moving in unconsolidated sand.
\Bpsammosere\b An ecological succession commencing on an area of unconsolidated sand.
\BPsettodidae\b Family of primitive marine flatfishes (Pleuronectiformes) containing 3 species found in west Africa and the Indo-Pacific; body length to 700 mm; median fins spinous, pectorals present; vomerine and palatine teeth present; typically use caudal fin for locomotion.
\Bpseudaposematic coloration\b Warning coloration which takes the form of a bluff, as in Batesian mimicry; See also \Japosematic coloration\j
\Bpseudepisematic\b Pertaining to a character or trait aiding recognition but involving deception; See also \J\Bepisematic\b\j
\BPseudidae\b Family containing 4 species of fully aquatic frogs (Anura) found in tropical lowlands of South America; hindlimbs strong, feet webbed; tadpoles extremely large, up to 250 mm in length.
\BPseudocarchariidae\b Crocodile shark; monotypic family of small (about 1 m) and little-known lamniform elasmobranch fishes; head and snout conical, eyes large; distribution circumtropical, in oceanic waters from surface to 300 m.
\Bpseudocarp\b False fruit; a fruit incorporating tissues other than those derived from the \Jgynoecium\j
\BPseudochromidae\b Dottybacks; family of small colourful, slender-bodied Indo-Pacific perciform teleost fishes found in shallow waters over reefs and rocky bottoms; dorsal fin elongate bearing only 3 spines.
\Bpseudocopulation\b A mode of pollination in which a male insect attempts to copulate with a flower that resembles a female insect, and in the process transfers pollen from one flower to another.
\Bpseudogamy\b The activation of an egg by a male gamete that degenerates without its nucleus fusing with that of the egg.
\Bpseudomycorrhizal association\b A symbiosis between a fungus and a higher plant in which the fungus is parasitic.
\BPseudophyllidea\b Widely distributed order of tapeworms parasitic in fishes, amphibians, birds and mammals, and often utilizing crustaceans as intermediate hosts; characterized by a scolex with dorsal and ventral grooves (bothria) which may be fused along their lengths.
\BPseudoplesiopidae\b Small family of marine perciform teleost fishes with an elongate body, large eyes and rounded fins; commonly found on coral reefs between Australia and Indonesia.
\BPseudorajidae\b Family containing 4 species of small (to 0.5 m) rajiform fishes found in the tropical western Atlantic at depths of 250-1000 m; dorsal fin absent, caudal fin bearing both dorsal and ventral lobes.
\BPseudoscorpiones\b False scorpions; order of small (to 7 mm) predatory terrestrial arthoropods resembling tiny scorpions but without slender tail and sting; chelicerae large and chelate, often bearing a spinneret used to construct silk cocoons; pedipalps often with venom gland; contains about 2000 species, most abundant in tropical regions; Chelonethida.
\BPseudoscorpionida\b \JPseudoscorpiones\j
\Bpseudosematic\b Used of a character or trait that serves as a false danger signal or warning.
\BPseudotriakidae\b False cat sharks; family containing 2 species of large (to 3 m) carcharhiniform elasmobranch fishes, found in deep waters (300-1500 m) of boreal to tropical seas.
\Bpseudozoea\b Early free-swimming larval stage of some stomatopods possessing biramous antennules, 2 pairs of uniramous thoracic limbs and 4 or 5 pairs of functional pleopods.
\Bpsicolous\b Living in prairie or savannah habitats; \Bpsicole.\b
\Bpsilic\b Pertaining to savannah or prairie communities or habitats.
\Bpsilicolous\b Living in savannah or prairie habitats; \Bpsilicole.\b
\BPsilidae\b Rust flies; family containing about 200 species of small slender-bodied flies (Diptera) usually found in habitats shaded by dense vegetation; larvae feed on plant stems and roots, and some, such as the carrot rust fly, are important horticultural pests.
\Bpsilopaedic\b Used of birds that are naked when hatched; See also \Jptilopaedic\j
\Bpsilophilous\b Thriving in prairie or savannah habitats; \Bpsilophile\b, \Bpsilophily. \b
\Bpsilophyte\b A prairie or savannah plant.
\BPsilophytopsida\b \JPsilotophyta\j
\BPsilorhynchidae\b Family of tiny (to 50 mm) Indian freshwater cypriniform teleost fishes containing 3 species found in fast-flowing rivers and streams; body deep, flattened ventrally, mouth subterminal with thick lips.
\BPsilotophyta\b Whiskferns; division of simply constructed vascular plants lacking true roots and often lacking leaves; usually epiphytic; gametophytes subterranean and mycorrhizal; stems simple or dichotomously branched; sporangia large, each having 2 or 3 chambers; homosporous; consists of 2 genera in a single order, Psilotales; Psilophytopsida is an alternative name.
\BPsittacidae\b Parrots, cockatoos, macaws; large family of small to medium-sized birds with strong hooked bills and fleshy tongues; plumage often brightly coloured; habits gregarious, monogamous, sometimes nocturnal; feed mainly on fruit, also on pollen and nectar; contains about 340 species, widely distributed in tropical regions of Australia and South America.
\BPsittaciformes\b Diverse order of mainly arboreal birds comprising a single family, Psittacidae (parrots).
\BPsocoptera\b Book lice, bark lice, psocids; order containing about 2600 species of small (1-10 mm) hemipterodean insects found in diverse habitats such as leaf litter, beneath bark, stones and other debris, and in stored products where they may become pests; compound eyes larger in males than females; wing venation reduced; polymorphism common, involving reduction or loss of wings in either or both sexes; parthenogenesis obligatory or facultative; psocids feed mainly on microflora.
\BPsophiidae\b Trumpeters; family containing 3 species of medium-sized wading birds (Gruiformes) found in wet forests of South America; neck and legs long, wings small; feed on insects and plant material; nest in tree holes.
\BPsychodidae\b Sand flies; family containing about 500 species of dipteran insects; adult body small with a dense covering of hairs; mandibles typically absent; one bloodsucking group is responsible for transmitting leishmaniasis in man.
\Bpsychophilous\b Pollinated by diurnal Lepidoptera; \Bpsychophile\b, \Bpsychophily.\b
\Bpsychric\b Pertaining to low temperatures or cold habitats.
\Bpsychrocleistogamic\b Used of plants in which self-pollination takes place within flowers that remain closed because of abnormally cold conditions.
\Bpsychrokliny\b Growth behaviour influenced by low temperatures.
\BPsychrolutidae\b Family containing 7 species of small (to 60 mm) marine sculpins (Scorpaeniformes) found in the Pacific Ocean; body naked, compressed posteriorly, rounded anteriorly with large head and mouth; skin loose and spinulose.
\Bpsychrophilic\b 1: Thriving at low temperatures; \Bpsychrophile\b, \Bpsychrophily\b. 2: Used of microorganisms having an optimum for growth below 20░C.
\Bpsychrophyte\b A plant living in relatively cold polar or alpine habitats or on a cold substratum.
\BPsyllidae\b Jumping plant lice, psyllids; family containing about 1300 species of small, jumping insects (Homoptera) resembling cicadas; usually host-specific on various plants, feeding by sucking sap; nymphs live in galls or free on the plant, often producing honeydew or protective wax.
\Bptenophyllophilous\b Thriving in deciduous forest; \Bptenophyllophile\b, \Bptenophyllophily. \b
\Bptenophyllophyte\b A deciduous woodland plant.
\Bptenothalophilous\b Thriving in deciduous thickets; \Bptenothalophile\b, \Bptenothalophily. \b
\Bptenothalophyte\b A deciduous thicket plant.
\BPteraspidimorphi\b Class of eel-like, jawless vertebrates (Agnatha) which lack paired fins, possess 2 semicircular canals and lack a true bony skeleton; includes the fossil pteraspids and the hagfish (Myxiniformes).
\Bpteridology\b The study of ferns.
\BPteridophyta\b Ferns; commonly classified under the name \JFilicophyta\j; pteridophytes.
\BPteridophytic\b \JPalaeophytic\j; the age of ferns.
\BPteridospermales\b Seed ferns; extinct order of primitive seed plants (Pinophyta) that flourished during the Carboniferous.
\BPterioida\b Pearl oysters, hammer oysters; order comprising about 100 species of mainly marine pteriomorphian bivalve molluscs; characterized by detailed shell and hinge structure, and by the posterior shell closing muscle being larger than the anterior.
\BPteriomorphia\b Large subclass of mainly marine, sedentary bivalve molluscs often attached to the substratum by byssus apparatus; comprises the Eupteriomorphia, Isofilobranchia and Prionodonta.
\BPterobranchia\b Class of littoral to abyssal, tubicolous, tentaculate hemichordates; groups of individuals (zooids) termed a coenecium; body sac-like, gut U-shaped, mesosome with anteroventral mouth and up to 9 pairs of dorsal tentaculate arms; nerve chord absent, coelom confined to tentacles and metasome; development takes place without free larval stage, and asexual reproduction by budding is common.
\BPteroclididae\b Sandgrouse; family containing about 15 species of small grouse-like terrestrial columbiform birds found in grassland and deserts of Africa and Eurasia; habits gregarious, monogamous, solitary when breeding, feeding mainly on fruit and insects.
\Bpteropod ooze\b A calcareous pelagic sediment containing at least 30% calcium carbonate in the form of skeletal remains, predominantly of pteropod molluscs; See also \Jooze\j
\BPteropodidae\b Family of large tree-dwelling fruit bats found in the Old World tropics; contains about 150 species in 2 subfamilies, one frugivorous (flying foxes), the other mainly nectivorous (long-tongued fruit bats).
\Bpteropods\b Marine gastropod molluscs belonging to the orders \JGymnosomata\j and \JThecostomata\j
\BPterosauria\b Pterosaurs; extinct order of flying reptiles most widespread during the Jurassic; probably lived around sea coasts feeding on fishes.
\BPterospermatales\b Small order of marine flagellates (Prasinophyceae) characterized by the production of spheroidal cyst-like cells (phycomata) during the life cycle.
\BPterygota\b Subclass of winged or secondarily wingless insects comprising all but a tiny minority of insect species; adult, terminal, or reproductive stage typically bearing 1 or 2 pairs of wings on meso- and metathorax; in many groups the wings are modified, in either or both sexes, as for example the shield-like elytra of beetles (Coleoptera) or the balancing halteres of flies (Diptera), or may be absent; fertilization usually internal; comprises 2 infraclasses, Paleoptera and Neoptera.
\BPthiridae\b Monogeneric family of sucking lice (Anoplura) comprising 2 species, one found on gorillas, the other on man (the public or crab louse).
\BPtilichthyidae\b Quillfish; monotypic family of northeastern Pacific, blennioid teleost fishes (Perciformes); body extremely slender, naked, to 350 mm in length; dorsal fin bearing numerous (up to 90) isolated hooked spines; pelvic fins and caudal fin absent.
\BPtilonorhynchidae\b Bowerbirds; family containing 18 species of medium-sized passerine birds found in forests of Australia and New Guinea; males court females in forest clearings or in a specially constructed bower of twigs decorated with coloured objects; habits solitary to gregarious, non-migratory, monogamous to polygamous, feeding on ground invertebrates and fruit; the shallow nest is usually placed in a tree.
\Bptilopaedic\b Used of birds that are covered with down when hatched; See also \Jpsilopaedic\j
\BPtinidae\b Spider beetles; family containing about 700 species of small spider-like beetles (Coleoptera); larvae white and fleshy with tiny legs; common pests in homes and warehouses, occurring naturally in the nests of birds and mammals, and in ant nests.
\BPtychodactiaria\b Small order of deep-water solitary zoantharians resembling sea anemones; possess a definite base but no basilar muscles.
\Bpuberty\b The onset of sexual maturity.
\Bpuerulus\b Late (megalopal) larval stage of palinuroid decapod crustaceans.
\BPulmonata\b Snails; subclass of predominantly terrestrial and freshwater gastropod molluscs generally possessing a spirally coiled shell typically without an operculum; characterized by the modification of the mantle cavity into a vascularized, pulmonary cavity for aerial respiration; divided into 4 orders, Archaeopulmonata, Basommatophora, Stylommatophora and Systellommatophora.
\Bpuma\b \JFelidae\j
\Bpumpkin\b \JCucurbitaceae\j
\BPunicaceae\b Pomegranate; family of Myrtales containing only 2 species of often thorny shrubs or trees; flowers brilliant scarlet in colour, with 5-8 sepals and petals, and many stamens; forming a fruit with a tough, leathery rind enclosing many seeds, each with a fleshy aril.
\Bpunky\b \JCeratopongonidae\j
\Bpupa\b The life cycle stage during which the larval form is reorganized to produce the final, adult form; commonly an inactive stage enclosed within a hard shell (chrysalis) or silken covering (cocoon).
\Bpupate\b To change from larva to pupa.
\Bpupigerous\b Containing a pupa.
\Bpupiparous\b Producing offspring already at the pupal stage, or larvae ready to pupate.
\Bpupivorous\b Feeding on pupae; \Bpupivore\b, \Bpupivory.\b
\Bpurple glory tree\b \JMelastomataceae\j
\Bpurple loosestrife\b \JLythraceae\j
\Bputrefaction\b The decomposition of organic matter with incomplete oxidation, producing methane and other gaseous products subject to further oxidation; see also \Jdecay\j \Jmouldering\j
\Bpuya\b \JBromeliales\j
\Bpycnocline\b A zone of marked density gradient.
\BPycnogonida\b Sea spiders; class of marine chelicerate arthropods containing about 1000 species found in benthic habitats from the intertidal to abyssal depths, commonly in association with hydroids, sea anemones and algae; body typically small with long legs; feed as succivorous predators; Pantopoda.
\BPycnonotidae\b Bulbuls; family containing about 120 species of small Old World passerine birds found in woodland and scrubland habitats from Africa to southeast Asia and Japan; habits gregarious, sedentary, arboreal, nonmigratory, feeding on fruit and insects; nest in tree or bush; some species have been introduced into the New World.
\BPygasteroida\b Extinct order of irregular echinoids known from the Jurassic and Cretaceous.
\Bpygmy phalanger\b \JBurramyidae\j
\BPygopodidae\b Snake lizards; family containing about 30 species of limbless lizards (Sauria) found in Australia and New Guinea; body snake-like with large scales; length to 250 mm; forelimbs absent, hindlimbs reduced to minute flaps; habits mostly terrestrial, nocturnal and insectivorous, some species fossorial.
\BPyralidae\b Family of small to large, often slender, moths (Lepidoptera) the larvae of which are phytophages, scavengers, or rarely parasites on other insects; contains over 20 000 species including many important agricultural pests that bore into grain, or damage leaves of trees and other crops.
\BPyramimonadales\b Order of aquatic flagellates (Prasinophyceae) that are covered with one to several layers of organic scales and possess 2-4 flagella.
\BPyrenomycetes\b Class of ascomycotine fungi, characterized by unitunicate, sometimes evanescent, asci and by an ascocarp which develops from an initial coiled hypha (ascogonium); the ascogonium becomes enveloped by other hyphae which from the wall of the ascocarp.
\BPyrocystales\b Small order of pelagic marine, photosynthetic unicellular dinoflagellates many of which are intensely bioluminescent.
\BPyrolaceae\b Wintergreen; small family of Ericales containing about 45 species of strongly mycotrophic perennial herbs or half shrubs; commonly growing in acid soils in cool regions of the northern hemisphere.
\Bpyrophilous\b Thriving on ground that has recently been scorched by fire; \Bpyrophile\b, \Bpyrophily.\b
\Bpyrophobic\b Intolerant of the soil conditions produced by fire; used of a plant that is unable to re-establish itself following a fire; \Bpyrophobe\b, \Bpyrophoby.\b
\Bpyrophyte\b A plant resistant to permanent damage by fire.
\BPyrosomida\b Order of compound, barrel-shaped, pelagic tunicates (Thaliacea) in which the colony may be several metres in length and strongly bioluminescent; zooids have inhalent siphons on external wall and exhalent siphons opening into chamber of barrel, the anterior end of which is closed; colony formed by budding from primary sexually produced zooid, larval stage absent.
\BPyrotheria\b Extinct order of elephant-like South American ungulates (Ferungulata) known from the Oligocene.
\Bpyroxylophilous\b Thriving on burnt wood; \Bpyroxylophile\b, \Bpyroxylophily.\b
\Bpythmic\b Pertaining to lake bottoms.
\Bpython\b \JBoidae\j
\Bquadrat\b 1: A delimited area for sampling flora or fauna; usually taken randomly within the study area and typically consisting of a 1 metre square frame. 2: The sampling frame itself.
\Bquadrature\b The time at which the sun and moon are approximately at right angles with respect to the Earth; See also \Jsyzygy\j
\Bquadrivoltine\b Having four broods per year or per season; See also \Jvoltine\j
\Bquagga\b \JEquidae\j
\Bquail\b \JPhasianidae\j
\Bqualitative\b Descriptive; non-numerical.
\Bquantitative\b Numerical; based on counts, measurements, ratios or other values.
\BQuaternary\b A geological period of the Cenozoic (\Ic.\i 1.6 million years B.P. to present), comprising the Pleistocene and the Holocene; see geological time scale.
\BQuaternary Ice Age\b A period in the Quaternary when glaciation was much more widespread than at present; Pleistocene glaciation.
\Bqueen substance\b A pheromone or combination of pheromones produced by a queen to control the reproductive behaviour of workers and other queens; trans-9-keto-2-decenoic acid is the most potent of the set of such pheromones used by a queen.
\Bqueenright\b Used of a colony of honeybees that contains a functional queen.
\BQuestida\b Monofamilial order of polychaete worms.
\Bquiescence\b 1: A temporary resting phase characterized by reduced activity or cessation of development; \Bquiescent\b. 2: The condition of seeds that have not germinated because one or more environmental variables is unfavourable; See also \Jdormancy\j
\BQuiinaceae\b Small family of Theales, native to tropical America, containing about 40 species of mostly trees or shrubs with mucilage channels.
\Bquillfish\b \JPtilichthyidae\j
\Bquillwort\b \JIsoetales\j
\Br selection\b Selection favouring a rapid rate of population increase, typical of species that colonize short-lived environments or of species that undergo large fluctuations in population size; See also \JK selection\j
\Brace\b A subgroup of a species characterized by conspicuous physiological (physiological race), biological (biological race), geographical (geological race) or ecological (ecological race) properties.
\Bracehorse\b \JCongiopodidae\j
\Braceme\b An inflorescence in which the main axis continues to grow, producing flowers laterally the youngest flowers are apical or central; racemose inflorescence.
\Brachion\b The zone on the shore of a lake subject to pronounced wave action.
\BRadiata\b \JCnidaria\j
\Bradicicolous\b Growing on or in roots; \Bradicicole.\b
\Bradicivorous\b Feeding on roots; \Bradicivore, radicivory.\b
\BRadiolaria\b Loose assemblage of marine pelagic protozoans (Actinopoda) comprising the classes Polycystina and Phaeodaria; may also include the Acantharia.
\Bradiolarian ooze\b A pelagic siliceous sediment comprising at least 30% siliceous material, predominantly in the form of radiolarian tests. See also \Jooze\j
\Bradiotropism\b A growth effect produced by radiation; \Bradiotropic.\b
\Bradish\b \JBrassicaceae\j
\BRafflesiaceae\b Family of plants lacking chlorophyll which are endoparasitic in the roots or shoots of other plants and vegetatively resemble a fungal mycelium; flowers typically produced terminally on short fleshy shoots; includes \IRafflesia arnoldi\i from Sumatra which has the largest flower of any flowering plant.
\BRafflesiales\b Small order of Rosidae containing about 60 species of fleshy parasitic herbs lacking chlorophyll, often with only the flowers or inflorescence emerging from the host.
\Brafting\b Dispersal of terrestrial organisms across water on floating objects.
\Bragfish\b \JIcosteidae\j
\Bragweed\b \JAsterales\j
\Bragworm\b \JPhyllodocida\j
\Brail\b \JRallidae\j
\Brail babblers\b \JOrthonychidae\j
\Brain forest\b A tropical forest having an annual rainfall of at least 254 cm (100 inches).
\Brain shadow\b An area on the leeward side of a mountain or range of mountains having a significantly lower rainfall than an area on the windward side.
\Brain shadow desert\b An area of desert or arid land in the rain shadow on the leeward side of a mountain range.
\Brainbowfish\b \JMelanotaeniidae\j
\Brainfall\b The amount of water precipitated from the atmosphere over a given period of time.
\BRajidae\b Family containing about 175 species of shallow littoral to abyssal rajiform fishes: body disk subcircular to rhomboidal, tail slender: dorsal fins close to tip of tail, caudal fin small to minute.
\BRajiformes\b Skates, rays; order containing about 200 species of bottom-dwelling elasmobranch fishes (Batoidea); body strongly depressed, length to 2m, pectoral fins forming subcircular to rhomboidal disk, typically broader than long; tail slender to whip-like, dorsal and caudal fins small or absent; habits littoral to abyssal, feeding on benthic invertebrates and fishes; reproduction oviparous, egg capsules having adhesive filaments for attachment.
\BRallidae\b Rails, coots, gallinules; diverse family containing about 140 species of small to medium-sized gruiform birds found in wet and woodland habitats worldwide; most are terrestrial or aquatic with weak flight, several island species are flightless; habits solitary, secretive, often crepuscular, monogamous, feeding on variety of plant and animal material; nest on ground, on water, or in bushes.
\Bramapithecines\b Extinct group of Miocene apes that lived about 14-8 million years ago, known from fossil fragments found in Africa, the Near East and Asia; hominid affinities uncertain, having jaw and teeth features that link them to chimpanzees and gorillas as well as to man.
\Bramet\b A member or modular unit of a clone, that may follow an independent existence if separated from the parent organism; see also \Jgenet\j \Jortet\j
\Bramicolous\b Living on twigs and branches; \Bramicole.\b
\Bramification\b A branch or dichotomy; branching.
\BRamphastidae\b Toucans; family of medium-sized to large Neotropical forest birds (Piciformes); bill variable, small to very large; habits gregarious, non-migratory, monogamous, feeding on fruit and small animals; nest in tree hole; contains about 30 species found from Mexico to Argentina.
\Bram's horn\b \JSepioidea\j
\Bramshorn snail\b \JBasommatophora\j
\Brange\b 1: The limits of the geographical distribution of a species or group. 2: Home \Jrange\j
\BRangoon creeper\b \JCombretaceae\j
\BRanidae\b Large family of riparian frogs (Anura); most species with aquatic eggs and larvae found in still waters, some in streams, others with terrestrial eggs and direct development; tadpoles with denticles, beak and single sinistral spiracle, barbels absent; contains about 590 species, including the edible frog; distribution largely cosmopolitan except for much of Australia and parts of South America.
\Branivorous\b Feeding on frogs; \Branivore\b, \Branivory.\b
\BRanunculaceae\b Buttercup, larkspur, hellebore, delphinium, anemone, clematis; diverse family of about 2000 species including many ornamental garden plants; mostly herbaceous perennials with typically bisexual flowers in which the carpels are usually distinct, forming simple pistils with several to many marginal ovules; widely distributed in temperate and boreal regions.
\BRanunculales\b Large order of dicotyledons (Magnoliidae) containing about 3200 species of herbs, shrubs or vines with variable flower morphology.
\Brapacious\b Feeding on prey.
\BRapateaceae\b Small family of Commelinales containing nearly 100 species of often coarse perennial herbs with basal, parallel-veined leaves; flowers with 3 petals, 3 sepals, 6 stamens and 3 united carpels; native to tropical South America.
\Brape\b \JBrassicaceae\j
\BRaphidae\b Dodos; family containing 3 species of large flightless pigeons (Columbiformes) from the Mascarene Islands in the Indian Ocean; extinct since the end of the 17th century as result of the activitites of man.
\BRaphidiidae\b Snakeflies; family containing about 100 species of mostly predatory neuropteran insects that feed on soft-bodied plant lice or on dead invertebrate remains; characterized by an elongate and highly mobile thorax.
\BRaphidioideae\b Order of pennate diatoms (Pennales) possessing a primitive type of raphe; also treated as a suborder, Raphidioidineae.
\BRaphidophyceae\b Class of predominantly freshwater chromophycote algae; characterized by biflagellate cells, with a hairy anterior flagellum and naked posterior flagellum; photosynthetic pigments include chlorophylls \Ia\i and \Ic\i and various xanthophylls, comprises a single order, Raphidomonadales, also treated as an order of the protozoan class Phytomastigophora, under the name Chloromonadida.
\Braptorial\b Adapted for seizing prey.
\Brasorial\b Adapted for scratching or scraping the ground.
\Braspberry\b \JRosaceae\j
\Brat\b 1: \JCricetidae\j (New World rats). 2: \JMuridae\j (Old World rats).
\Brat chinchilla\b \JAbrocomidae\j
\Brat opossum\b \JCaenolestidae\j
\Bratfish\b \JChimaeriformes\j
\Bratites\b A loose assemblage of flightless, running birds which lack a keel on the sternum.
\Brattail\b \JMacrouridae\j
\Brattlesnake\b \JViperidae\j
\BRaunkiaerian leaf size classes\b A system of classifying leaf sizes according to surface area; the 6 categories are leptophyll (up to 25 mm\U2\u), nanophyll (25-225 mm\U2\u), microphyll (225-2025 mm\U2\u), mesophyll (2025-18 225 mm\U2\u), macrophyll (18 225-164 025 mm\U2\u), megaphyll (over 164 025 mm\U2\u); the category notophyll has been added for a small mesophyll (2025-4500 mm\U2\u).
\BRaunkiaerian life forms\b A system of classification of the life forms of plants based on the type and position of the renewal buds with respect to ground level; categories include chamaephyte, cryptophyte, geophytc. helophyte, hemicryptophyte, hydrophyte, phanerophyte, therophyte.
\Braw data\b Data which have not been organized numerically or treated statistically.
\Bray\b \JRajiformes\j
\Brazor shell\b \JVeneroida\j
\Breaction\b Any change in the activity of an organism in response to a stimulus.
\Breaction time\b The time interval between a stimulus and the response to that stimulus.
\Brealized niche\b That part of the fundamental \Jniche\j actually occupied by a species.
\Brealm\b The largest of the biogeographical units, encompassing major climatic or physiographic zones.
\Brecapitulation\b The repetition of a sequence of ancestral adult stages in the embryonic or juvenile stages of descendants.
\BRecent\b \JHolocene\j
\Brecent\b Still existing; extant; See also \Jfossil\j
\Brecessive\b An allele that is not expressed in the phenotype except when homozygous; See also \Jdominant\j
\Brecessiveness\b The failure of one allele (recessive) to be expressed over another (dominant) in the phenotype of the heterozygote; See also \Jdominance\j
\Brecombination\b Any process that gives rise to a new combination of hereditary determinants, such as the reassortment of parental genes during meiosis through crossing over.
\Brecretion\b The elimination of mineral salts from plants in the same form in which they were taken up.
\Brecruitment\b The influx of new members into a population by reproduction or immigration.
\Brectilinear\b Used of growth or movement that proceeds in a straight line.
\BRecurvirostridae\b Avocets, stilts; family containing 11 species of medium-sized, long-legged, charadriiform shore birds, cosmopolitan in tropical and temperate coastal and marsh habitats; bill characteristically long and slender, upcurved or straight; habits gregarious, often migratory, monogamous, feeding on invertebrates and small vertebrates.
\Bred algae\b \JRhodophycota\j
\Bred bud\b \JCaesalpiniaceae\j
\Bred clay\b A pelagic sediment comprising an accumulation of volcanic and aeolian dust with less than 30% biogenic material.
\BRed Desert soil\b A zonal soil with a light reddish brown A-horizon overlying a heavy reddish alkaline B-horizon above calcareous material formed under warm temperate to dry tropical climates.
\Bred:far red ratio\b The proportion of red light to far red light in the radiation spectrum available to a plant.
\Bred light\b Solar radiation in the spectral range 620-680 nm.
\Bred mangrove\b \JRhizophorales\j
\Bred mud\b A well oxidized terrigenous marine sediment having a red coloration produced by ferric oxide.
\Bred mullet\b \JMullidae\j
\Bred panda\b \JProcyonidae\j
\Bred tide\b A reddish brown coloration of sea water caused by a bloom of dinoflagellates, usually belonging to the \JPeridiniales\j
\BReddish Brown lateritic soil\b A zonal soil, highly weathered, with a thin litter and duff layer, reddish brown slightly acidic A-horizon over a red or reddish brown clayey, strongly acidic, B-horizon, formed in forested warm temperate and tropical regions.
\BReddish Brown soil\b A zonal soil with a reddish brown surface layer over a darker red horizon and a light calcareous lower horizon, formed in warm, temperate to tropical, semi-arid climates beneath short grass and shrub vegetation.
\BReddish Chestnut soil\b A zonal soil with a thick red to dark brown A-horizon over a heavy reddish brown B-horizon and a calcareous lower horizon, formed in warm temperate, semi-arid climates beneath mixed grasses and shrub vegetation.
\BReddish Prairie soil\b A zonal soil with a dark reddish brown acidic A-horizon grading through a reddish brown soil to the parent material, formed in warm to temperate, humid to subhumid, climates under tall grasses.
\Bredfish\b \JScorpaenidae\j
\Bred-hot poker\b \JAloeaceae\j
\Bredia\b Sac-like larval stage of a digenean trematode parasite found within the molluscan intermediate hose, that asexually produces infective cercariae \Iq.v..\i
\Bredox potential (Eh)\b Oxidation-reduction potential; a measure of the tendency of a given system to act as an oxidizing (electron acceptor) or reducing (electron donor) agent.
\Breducer\b Any heterotrophic organism responsible for degrading or mineralizing organic matter.
\Breduction\b The process of producing or evolving simpler structures from more complex ones.
\Breduction division\b The first division of meiosis in which the chromosome complement is halved.
\BReduviidae\b Assassin bug, kissing bug; family containing over 4000 species of bugs (Heteroptera); most are predators of other arthropods which are seized with the front legs; some are blood suckers of mammals and birds and may act as vectors of diseases such as Chagas'.
\BRed-Yellow podzolic soil\b An acidic zonal soil with little or no litter, a light coloured leached A-horizon over a red to yellow clayey B-horizon, formed in humid warm temperate or tropical climates under coniferous or deciduous forest.
\Breedfish\b \JPolypteridae\j
\Breedmace\b \JTyphaceae\j
\Brefection\b The habit of an animal that eats its own faeces.
\Breflex\b A rapid innate stereotyped response to a stimulus involving the central nervous system.
\Breforestation\b The process of re-establishing a forest on previously cleared land; See also \Jafforestation\j
\Brefuge\b An area in which prey may escape from or avoid a predator.
\Brefugium\b An isolated habitat that retains the environmental conditions that were once widespread.
\Breg\b A stony desert.
\BRegalecidae\b Oarfishes; family containing 3 species of little-known mesopelagic lampridiform teleost fishes; body ribbon-like and naked, to 7 m in length; pelvic fins long and slender, dorsal fin elongate running entire length of body; teeth and anal fin absent; thought to feed mainly on euphausiid crustaceans.
\Bregeneration\b Renewal or restoration of structures or tissues, typically after loss or damage.
\Bregion\b 1: Any major world area supporting a characteristic biota; biogeographical region. 2: A major world area and climatic zone characterized by a 50-75% endemic flora or fauna.
\Bregolith\b All loose earth material above the underlying solid rock; more or less equivalent to the term \Jsoil\j
\BRegosol\b An azonal soil without pronounced horizons formed on unconsolidated soft mineral deposits such as loess or sand.
\Bregression\b A retreat of the sea from a land area; See also \Jtransgression\j
\BRegulidae\b Tit warblers; family of tiny passerine birds with pointed bills, found in scrub and heathland; commonly included in the family Sylviidae.
\Breindeer\b \JCervidae\j
\Brejecta\b That part of the total food or energy intake of an individual that is not utilized for production and respiration, and is lost as \Jegesta\j and \Jexcreta\j
\Brelative age\b The geological age of a fossil or rock expressed in relation to other fossils or events rather than as an actual number of years; See also \Jabsolute age\j
\Brelative dating\b A method of geological dating in which only the relative age of a rock is used, rather than the absolute \Jage\j; See also \Jabsolute dating\j
\Brelative humidity\b The ratio of the actual water vapour present to that of total saturation at the existing temperature, expressed as a percentage; see also \Jabsolute humidity\j \Jsaturation deficit\j
\Breleaser\b A stimulus that serves to initiate instinctive activity.
\Brelict species\b Persistent remnants of formerly widespread fauna or flora existing in certain isolated areas or habitats.
\Brem\b Abbreviation of röntgen equivalent man; defined as the equivalent dose of ionizing radiation having the same biological effect as a single röntgen unit of X-rays.
\BRemipedia\b Class of small cavernicolous crustaceans characterized by an elongate body bearing about 30 pairs of biramous trunk limbs; mostly predatory feeding on other crustaceans; about 6 species are known at present, all from inland marine caves.
\Bremora\b \JEcheneidae\j
\BRendzina soil\b An intrazonal soil with a dark friable upper A-horizon, a calcareous lower A-horizon over a light grey to yellow calcareous B-horizon, derived from calcium-rich parent material in humid and semi-arid climates under grasses or mixed grass and forest vegetation.
\BRensch's laws\b 1: That in cold climates races of mammals have larger litters and birds larger clutches of eggs than races of the same species in warmer climates. 2: That birds have shorter wings and mammals shorter fur in warmer climates than in colder ones; wing rule. 3: That races of land snails in colder climates have brown shells and those in warmer climates have white shells. 4: That the thickness of snail shell is positively associated with strong sunlight and arid conditions.
\Breplete\b Fully nourished; well fed.
\Breproduction\b The act or process of producing offspring.
\Breproductive effort\b That proportion of metabolic resources devoted to reproduction.
\Breproductive success\b The number of offspring of an individual surviving at a given time.
\BReptantia\b The lobster-like and crab-like decapod crustaceans; formerly used as a suborder of the Decapoda but now incorporated within the suborder \JPleocyemata\j
\BReptilia\b Class of primitively quadripedal, pentadactyl, tailed vertebrates comprising 3 extant subclasses, Anapsida (turtles, tortoises), Lepidosauria (lizards, snakes) and Archosauria (crocodiles); epidermal scales present; fertilization internal, eggs amniotic, development direct; most species oviparous, some ovoviviparous; abundant fossil record, including dinosaurs, pterosaurs, hadrosaurs and ichthyosaurs.
\Brepugnatorial\b Adapted for defence or offence.
\Brequiem shark\b \JCarcharhinidae\j
\BResedaceae\b Mignonette; small family of Capparales containing about 70 species of herbs restricted to the northern hemisphere; flowers usually arranged in racemes, with 2-8 sepals, 0-8 petals, 3 to many stamens and a superior ovary.
\Breservoir host\b A host that carries a pathogen without detriment to itself and which serves as a source of infection for other host organisms.
\Bresidence time\b That time a given substance remains within a system.
\Bresiniferous\b Producing resin (a mixture of compounds including polymerized acids, esters and terpenoids), which is commonly exuded by plants when tissues are damaged.
\Bresource\b Any component of the environment that can be utilized by an organism.
\Brespiration\b 1: The exchange of gases between an organism and its surrounding medium; breathing. 2: Intracellular oxidation of organic molecules to release energy and typically to produce carbon dioxide and water.
\Brespiratory quotient\b The ratio of the volume of oxygen consumed to the volume of carbon dioxide released.
\Bresponse\b Any change in an organism or a behaviour pattern as the result of a stimulus.
\Brestibilic\b Perennial.
\BRestionaceae\b Southern hemisphere grasses; family of about 400 species of perennial herbs often accumulating silica and with reduced leaf blades; widely distributed on nutrient-poor soils in the southern hemisphere.
\BRestionales\b Order of Commelinidae comprising 4 families of herbs with more or less grass-like or rush-like leaf blades and small inconspicuous flowers lacking nectar and wind-pollinated or self-pollinated; producing seeds with abundant mealy or starchy endosperm.
\BRetortamonadida\b Order of small parasitic zooflagellates with 2 or 4 flagella, one of which is deflected posteriorly across the cytostome; all species feed on bacteria in the guts of their hosts and are transmitted from host to host in an encysted form.
\Bretrogressive\b Pertaining to a process of dedifferentiation or reversal to a simpler state or form; \Bretrogression.\b
\BRetropinnidae\b Family containing 6 species of freshwater or anadromous salmoniform teleost fishes found in New Zealand and southeastern Australia; body slender and compressed, resembling the smelts; adipose fin small, dorsal fin positioned above anal.
\BRetziaceae\b Family of Gentianales containing a single species of erect, evergreen shrub confined to the Cape Province in South Africa.
\Breversion\b Return towards an ancestral condition, or from a cultivated to a wild state.
\Brevivescence\b Emergence from hibernation or some other quiescent state.
\BRhabditia\b Large subclass of secernentean nematodes containing free-living, microbivorous terrestrial forms and many parasites of both vertebrates and invertebrates; characterized by the complex valve consisting of 3 muscular, cuticle-lined lobes, in the hind part of the oesophagus; comprises 3 orders, Ascaridida, Rhabditida and Strongylida.
\BRhabditida\b Large order of rhabditian nematodes comprising free-living forms which typically feed on bacteria and other microorganisms, and parasitic forms found in insects, snails, other invertebrates and vertebrates.
\BRhabdocoela\b Group of mostly free-living turbellarians characterized by a straight gut and comprising the orders Catenulida, Macrostomida, Haplopharyngida and Neorhabdocoela; not used in modern classifications.
\BRhabdodendraceae\b Small family of Rosales containing 3 species of shrubs native to tropical South America.
\BRhadomonadales\b Order of colourless, non-phagotrophic euglenoid flagellates with a single emergent flagellum.
\BRhabdopleurida\b Order of colonial pterobranchs in which the individual zooids are attached to the stolon by a contractile stalk; single pair of arms on the mesosoma; gonads unpaired.
\BRhacophoridae\b Family of Old World tree-frogs (Anura) having adhesion disks on the digits; eggs and larvae typically aquatic; some deposit eggs on vegetation above still water, others have abbreviated development; contains about 95 species found from Africa and Madagascar through to Indo-Australian region.
\BRhamnaceae\b Buckthorn, deer brush, anchor plant; large family containing about 900 species of often thorny woody plants of widespread distribution especially in warm regions; characterized by a cymose inflorescence composed of small flowers usually with 4-5 sepals, small petals and stamens.
\BRhamnales\b Order of Rosidae consisting of 3 families of mucilage-producing and usually woody plants, Leeaceae, Rhamnaceae and Vitaceae.
\BRhamphichthyidae\b Small family of freshwater knifefishes (Siluriformes) from South America; body long, tapering posteriorly; anal fin well developed.
\BRhaphidophoridae\b Cave crickets; small family of wingless crickets (Ensifera) with very long, slender legs and antennae; found in moist environments, especially caves.
\Brhea\b \JRheidae\j
\BRheidae\b Rheas; family containing 2 species of large (to 1.5 m tall) South American ratites (Palaeognathae) found in open grassland and brush; legs long and powerful, bearing 3 digits; neck elongate, head feathered; habits cursorial, gregarious, polygamous, feeding on seeds, grasses and insects.
\BRheiformes\b Order of ratite birds comprising a single family, Rheidae.
\Brheocrene\b A flowing spring.
\Brheology\b The study of fluid movements; that aspect of limnology devoted to running waters.
\Brheophilous\b Thriving in or having an affinity for running water; \Brheophile\b, \Brheophily\b; See also \Jrheophobous\j
\Brheophobous\b Intolerant of running water; \Brheophobe, rheophoby\b; See also \Jrheophilous\j
\Brheophyte\b A plant inhabiting running water.
\Brheoplankton\b Planktonic organisms associated with running water.
\Brheopositive\b Sensitive to currents; used of organisms showing behavioural and other responses to air or water currents.
\Brheoreceptive\b Sensitive to water or air currents.
\Brheotaxis\b A directed response of a motile organism to a water or air current, either into the current (positive rheotaxis) or with the current (negative rheotaxis); \Brheotactic.\b
\Brheotrophic\b Pertaining to organisms that obtain nutrients largely from percolating or running water.
\Brheotropism\b An orientation response to a water or air current; \Brheotropic.\b
\Brheoxenous\b Used of organisms that occur only occasionally in running water; \Brheoxene.\b
\Brhexigenous\b Produced as a result of breakage or rupture.
\BRhinatrematidae\b Family containing 8 species of primitive terrestrial caecilians (Gymnophiona) found in tropical South America; body small (to about 300 mm) and covered with dermal scales, tail present; larvac aquatic bearing branched gills.
\BRhincodontidae\b Whale shark; monotypic family of very large (to 20 m) inoffensive orectolobiform elasmobranch fishes (carpet sharks), the largest of all fish species; body cylindrical with flattened head; gill openings large bearing internal filter screens; mouth terminal, teeth small and weakly differentiated; reproduction oviparous; circumtropical in pelagic waters, filter feeding on planktonic crustaceans, squid and small fishes.
\BRhinobatidae\b Family containing about 35 species of rhinobatiform fishes in which the body disk is elongate, and the tail moderately slender but not demarcated from disk; length to 1.5 m; caudal fin without distinct ventral lobe, axis upturned.
\BRhinobatiformes\b Guitarfishes; order of bottom-living, shallow water elasmobranch fishes (Batoidea); anterior body and pectoral fins discoidal, snout prolonged, tail slender, pelvic fins small; habits sluggish, feeding on fishes, crustaceans, molluscs and other benthic invertebrates; reproduction viviparous; comprises about 50 species in 3 families.
\BRhinocerotidae\b Rhinoceroses; family containing 5 species of massive terrestrial mammals (Perissodactyla) found in a variety of open savannah and forest habitats of the Oriental and Ethiopian regions; head elongate with 1 or 2 median horns composed of dense horny fibres, but lacking bone; skin very thick with sparse stiff hairs; habits typically nocturnal, solitary, herbivorous, grazing or browsing on vegetation.
\BRhinochimaeridae\b Family containing 8 species of small to medium-sized (to 1.5 m) deep-water (700-2000 m) holocephalan fishes; body compressed and naked, snout pointed, tail tapering; dorsal fins contiguous, caudal narrow with straight axis.
\BRhinocryptidae\b Tapaculos; family containing about 30 species of small to medium-sized terrestrial passerine birds that inhabit forests and grassland of the Neotropical region; body compact, bill short and pointed, wings short and rounded, flight poor; habits mostly solitary, cursorial, feeding on insects and seeds; nest in burrow, or in domed nest on ground or in tree or rock crevice.
\BRhinodermatidae\b Family containing 2 species of small (to 30 mm) terrestrial frogs (Anura) from temperate rainforests of Chile and Argentina; eggs terrestrial, tadpoles aquatic in one species, brooded in vocal sac of male in the other; sometimes included in the family Leptodactylidae.
\BRhinolophidae\b Horseshoe bats; family containing about 110 species of insectivorous microchiropteran Old World leaf-nosed bats, widespread in Ethiopian, Oriental and Australian regions; habits colonial or solitary, some species hibernate, others are migratory.
\BRhinophoridae\b Woodlouse flies; small family of flies (Diptera) the larvae of which are endoparasitic on terrestrial isopods (woodlice).
\BRhinophrynidae\b Monotypic family of fossorial toads (Anura) found in Central America; body length to 75 mm, head very small, limbs short and specialized for digging, ribs absent; larvae aquatic.
\BRhinopomatidae\b Mouse-tailed bats; family containing 3 species of small insectivorous microchiropteran bats found in arid habitats from North Africa to India.
\BRhinopteridae\b Cow-nosed rays; family containing about 10 species of tropical and subtropical, estuarine and coastal marine, myliobatiform elasmobranch fishes; body disk broader than long and demarkated from head, pectoral fins prolonged anteriorly as pair of lobes in front of snout; tail filamentous distally, caudal fin absent; mouth with series of grinding plates; feed on benthic molluscs and crustaceans dug up using pectoral fins.
\BRhipidistia\b Extinct group of tassel-finned fishes (Crossopterygia) with 2 dorsal fins, and stalked or lobate pectoral and pelvic fins; nares internal; known from the Devonian to the Permian.
\Brhithrous\b Pertaining to the upper reaches of a river; See also \Jpotamous\j
\Brhizanthous\b Used of plants producing flowers that appear to arise directly from the roots.
\Brhizobenthos\b Those organisms rooted in the substratum; \Brhizobenthic;\b See also \Jbenthos\j
\Brhizocarpous\b 1: Used of plants having perennial roots and annual stems and foliage. 2: Pertaining to perennial herbs that produce flowers and fruit below ground level as well as above ground.
\BRhizocephala\b Order of exclusively parasitic barnacles (Cirripedia) found only on crustacean hosts; body highly modified, consisting of a branching rootlet system penetrating the host and an external sac containing the reproductive organs; larval development typically includes nauplius and cyprid stages; contains about 250 species.
\BRhizochloridales\b Order of naked, amoeboid xanthophyceaen algae found in both freshwater and marine habitats; includes solitary and colonial forms, characterized by the lack of flagella.
\Brhizogenic\b Producing roots; stimulating root formation or growth; \Brhizogenesis.\b
\BRhizomastigida\b Order of mostly free-living zooflagellates which possess both flagella and pseudopodia; typically found in stagnant fresh waters.
\Brhizomenon\b All organisms rooted into the substratum; see also \Jephaptomenon\j \Jplanomenon\j
\BRhizomyidae\b Mole rats, bamboo rats; family containing 18 species of fossorial myomorph rodents from Ethiopian and eastern Oriental regions; body fusiform, limbs short, eyes reduced, tail present; typically burrow using incisor teeth or feet.
\Brhizophagous\b 1: Feeding on roots; \Brhizophage\b, \Brhizophagy.\b 2: Used of a plant that obtains nourishment through its own roots.
\Brhizophilous\b Growing on roots; \Brhizophile\b, \Brhizophily.\b
\BRhizophorales\b Red mangrove; order of Rosidae comprising the family Rhizophoraceae, which contains about 100 species of tanniferous trees and shrubs including several mangrove species; widely distributed in tropical regions; flowers hermaphrodite, with 3-16 sepals and petals, and 8 to many stamens.
\Brhizopleustohelophyte\b A plant rooted in the bank or bottom sediment of shallow water with a floating stem and emergent leaf-bearing shoots.
\BRhizopoda\b Cosmopolitan superclass of Sarcodina distinguished on the basis of their type of pseudopodia and by their lack of axopodia and internal skeletons; includes amoebae and foraminiferans; also treated as a distinct phylum of Protoctista.
\Brhizosphere\b The soil immediately surrounding plant roots that is influenced structurally or biologically by the presence of such roots; root zone; See also \Jphyllosphere\j
\BRhizostomeae\b Order of medusae (Scyphozoa) found primarily in shallow waters of the tropical Indo-Pacific Ocean; characterized by a domed or discoidal bell and by the fusion of the frilled edges of the oral arms over the mouth so that many suctorial mouths are formed.
\Brhizotaxis\b The spatial arrangement of roots; \Brhizotaxy.\b
\BRhodochaetales\b Order of marine red algae containing a single species with a branched filamentous body form.
\Brhododendron\b \JEricaceae\j
\BRhodophyceae\b The only class of the division \JRhodophycota\j; comprises 2 subclasses, Bangiophycideae and Florideophycideae.
\BRhodophycota\b Red algae; diverse assemblage of eukaryotic algae containing forms ranging from unicells to those with a true parenchymatous thallus, characterized by reddish plastids containing chlorophyll \Ia\i, phycobiliproteins and carotenoids; reproduction oogamous, the egg cell being produced inside an oogonium which is receptive to the non-motile male gamete; classified either as a division of eukaryotic algae or as a phylum of Protoctista, under the name Rhodophyta; comprises the Bangiophycideae and the Florideophycideac
\BRhodophyta\b Red algae; the \JRhodophycota\j treated as a phylum of Protoctista.
\BRhodymeniales\b Order of typically crustose or erect and frondose red algae found in marine habitats.
\BRhoipteleaceae\b Family of Juglandales comprising a single species of aromatic tree confined to Vietnam and southern China.
\BRhombifera\b Extinct class of echinoderms (Pelmatozoa) with biserial brachioles; known from the Lower Ordovician to the Upper Devonian.
\BRhombozoa\b Class of mesozoans found as endoparasites in the renal organs of cephalopod molluscs; characterized by a body organized into a superficial layer of somatic cells enclosing a medullary, axial cell; form 2 different kinds of embryos, nematogens and rhombogens, according to whether the host is juvenile or adult.
\Brhoophilous\b Thriving in creeks; \Brhoophile\b, \Brhoophily.\b
\Brhoophyte\b A creek plant.
\BRhopalosomatidae\b Cricket wasps; family of slender solitary wasps (Hymenoptera) which have parasitoidal larvae living and feeding in sacs attached to the abdomens of crickets; contains about 20 species.
\BR-horizon\b The bedrock underlying a soil profile; D-horizon; see soil horizons.
\Brhubarb\b \JPolygonales\j
\Brhyacophilous\b Thriving in, or having an affinity for, torrents; \Brhyacophile\b, \Brhyacophily.\b
\Brhyacophyte\b A plant living in a torrent.
\BRhynchobatidae\b Family containing 5 species of rhinobatiform fishes; length up to 2 m, body disk elongate, tail stout and not demarcated from disk; caudal fin with distinct ventral lobe.
\BRhynchobdellae\b Order of freshwater and marine leeches parasitic or predacious on a wide range of vertebrate and invertebrate hosts; pharynx forming protractile piercing proboscis, jaws absent; contains about 250 species in 3 families; one family, Piscicolidae (fish leeches), contains mostly marine forms.
\BRhynchocephalia\b Order of primitive lepidosaurian reptiles represented by a single extant family, the monotypic Sphenodontidae (tuatara).
\BRhynchocoela\b Alternative name for the \JNemertea\j
\BRhynchodida\b Order of hypostomatan ciliates found on the gills of freshwater and marine invertebrates; small rostrate forms with a single anterior sucking tube or tentacle which functions in ingestion; body nearly naked; reproduction generally by budding.
\BRhynchonellida\b Order of articulate brachiopods containing about 30 species; shell typically impunctate; spicules absent from soft parts: found in shallow water to 3000 m, attached to hard substrata.
\Brhythm\b Any cyclical variation in the intensity of a behavioural or physiological activity; \Brhythmicity.\b
\Bribbon worm\b \JNemertea\j
\Bribbonfish\b \JTrachipteridae\j
\Bribonucleic acid\b \JRNA\j
\Bribosomal RNA\b The structural RNA of the ribosomes; rRNA.
\Brice\b \JPoaceae\j
\Bricefish\b \JOryziatidae\j
\BRichter scale\b A logarithmic scale for measuring the magnitude of seismic disturbances; ranging from 1.5 for the smallest detectable tremor to 8.5 for a devastating earthquake.
\BRicinulei\b Monofamilial order of small (to 15 mm) ground-living predatory arthropods (Arachnida) containing about 30 species found in tropical West Africa and America; cephalothorax and abdomen joined by a broad waist; chelicerae forming scorpion-like pincers; respiration by means of tracheae.
\BRickettsias\b Group of mostly small, rod-like bacteria which possess typical bacterial cell walls and multiply by binary fission inside host cells.
\Bricochetal\b Type of jumping or bouncing locomotion involving the storage of energy in elastic tendons in one phase of the movement and its subsequent release during the power stroke.
\Bright whale\b \JBalaenidae\j
\Brill erosion\b The formation of many small channels due to erosion by surface water, especially on cultivated land.
\Bring species\b The graded series of populations along an extensive \Jcline\j that curves round on itself so that the populations at the extremes overlap but are unable to interbreed successfully.
\Bringed worm\b \JAnnelida\j
\Bringworm\b \JGymnascales\j
\Briparian\b Pertaining to, living or situated on, the banks of rivers and streams.
\Bripicolous\b Living on the banks of rivers and streams; \Bripicole.\b
\BRiss glaciation\b A glaciation of the Quaternary Ice \JAge\j in the Alpine area with an estimated duration of 100 000 years.
\BRiss-Würm interglacial\b The interglacial period preceding the Würm glaciation in the Alpine area; see Quaternary Ice Age.
\Brival\b Pertaining to a stream or rivulet.
\Briver dolphin\b \JPlatanistidae\j
\Briver ray\b \JPotamotrygonidae\j
\Briverine\b Pertaining to a river; formed by the action of a river.
\BRNA\b Ribonucleic acid; a polynucleotide that governs protein synthesis in a cell, existing in a variety of forms serving particular functions, such as messenger RNA, ribosomal RNA, transfer RNA.
\Broadrunner\b \JCuculidae\j
\Brobber fly\b \JAsilidae\j
\Brock crawler\b \JGrylloblattaria\j
\Brock jumper\b \JThysanura\j
\Brock oyster\b \JHippuritoida\j
\Brock rat\b \JEchimyidae\j
\Brockfish\b \JScorpaenidae\j
\BRodentia\b Diverse order of mostly small, herbivorous or omnivorous, terrestrial, arboreal or semiaquatic mammals (Glires); comprises about 1650 species in 33 families arranged in 3 suborders, Sciuromorpha (squirrels, beavers), Myomorpha (rats, mice, jerboas, hamsters, gerbils) and Hystricomorpha (porcupines, guinea-pigs); the largest order of Mammalia; incisor teeth chisel-like, continuously growing and separated from cheek teeth by broad gap (diastema).
\Brodenticide\b A chemical used to kill rodents.
\Brogue\b To remove undesirable weeds, diseased plants or genetic variants (rogues) from a population.
\Broller\b \JCoraciidae\j
\BRondeletiidae\b Whalefishes; cosmopolitan family containing 2 species of small (to 100 mm) bathypelagic beryciform teleost fishes; body devoid of scales but bearing vertical rows of small papillae; head large, jaws with many minute teeth.
\Bronquil\b \JBathymasteridae\j
\Brookery\b A breeding or nesting place for some mammals and birds.
\Broot parasitism\b A condition found in a semi-parasitic plant, the roots of which penetrate the roots of the host plant and remove elaborated food material.
\Brorqual\b \JBalaenopteridae\j
\BRosaceae\b Rose, hawthorn, bridal wreath, meadow sweet, strawberry, mountain ash, cherry, peach, apricot, plum, apple, pear, blackberry, raspberry; large family of herbs, shrubs or trees containing about 3000 species nearly cosmopolitan in distribution and including many species cultivated as edible fruits or as ornamentals; bisexual flowers arranged in racemes or cymes and with 5 sepals and petals, many stamens and, usually, a superior ovary.
\BRosales\b Large order of Rosidae containing 24 families of chemically and anatomically diverse, usually terrestrial plants which lack milky juice and internal phloem.
\Brose\b \JRosaceae\j
\Brosemary\b \JLamiaceae\j
\BRosidae\b Large subclass of dicotyledons producing various sorts of repellents, frequently alkaloids or triterpenoid compounds; flowers variable, usually with separate petals; contains nearly 60 000 species arranged in 114 families and 18 orders; majority of species belonging to Euphorbiales. Fabales, Myrtales, Rosales and Sapindales.
\BRostroconchia\b Extinct class of bilaterally symmetrical, bivalved, marine molluscs known from the Lower Cambrian to the Permian; shell with distinct anterior gape from which the foot probably emerged; shell without functional dorsal hinge.
\Brot\b Decay; decomposition.
\BRotatoria\b \JRotifera\j
\BRotifera\b Rotifers, wheel animalcules; phylum of microscopic pseudocoelomate animals found in aquatic habitats and occasionally in soil and damp moss; characterized by a typically unsegmented body covered by a cuticle which may be thickened into a lorica consisting of plates, and by the absence of a muscular body wall; pharynx (mastax) with internal jaws (trophi); excretory organs comprising pair of flame bulb protonephridia; many organs are syncytial but the nuclear number in adults is constant; sexes separate, although males may be rare and parthenogenesis is common; comprises 3 classes, Bdelloidea, Monogonata and Seisonidea; formerly known as Rotatoria.
\Broundhead\b \JPlesiopidae\j
\Broundworm\b \JNematoda\j
\Brove beetle\b \JStaphylinidae\j
\BRoveacrinida\b Extinct order of small, free-swimming, pelagic sea lilies (Crinoidea); known from the Triassic to the Cretaceous.
\Broyal poinciana\b \JCaesalpiniaceae\j
\BrRNA\b Ribosomal \JRNA\j
\I\Br\b\i\B-selected species\b A species characteristic of variable or unpredictable environments; typically with rapid development, high innate capacity for increase, early reproduction, small body size and semelparity; opportunistic species; \I\Br\b\i-strategist; See also \JK-selected species\j
\Brubber\b \JEuphorbiaceae\j
\BRubiaceae\b Madder, coffee, gardenia; large family containing about 6500 species of mostly tropical and subtropical, woody or herbaceous plants producing a wide range of repellent chemicals including iridoids and alkaloids; flowers usually bisexual and regular, commonly with 4 or 5 sepals, petals and stamens, and an inferior ovary.
\BRubiales\b Order of Asteridae containing 2 families of woody, or sometimes herbaceous, plants commonly producing iridoid compounds; leaves commonly opposite and flowers sympetalous but sometimes reduced; includes Rubiaceae and Theligonaceae.
\Brubicolous\b Living on brambles; \Brubicole.\b
\Brubrification\b The appearance of a red coloration in a soil due to oxidative weathering and the formation of haematite.
\Bruderal\b 1: Pertaining to or living amongst rubbish or debris, or inhabiting disturbed sites. 2: A plant inhabiting such a habitat.
\BRudimicrosporea\b Subclass of minute microsporidian protozoans which are all hyperparasitic inside gregarines parasitizing mostly marine annelids; characterized by a rudimentary extrusion apparatus on the spores.
\Brugophilic\b Thriving on rough surfaces or in surface depressions; \Brugophile\b, \Brugophily.\b
\BRugosa\b Extinct order of solitary or compound corals (Zoantharia); large, diverse group known from the Cambrian to the Upper Permian; characterized by bilateral symmetry, with metasepta inserted between only 4 of the 6 primary septa.
\Brugotropism\b An orientation with respect to a surface depression or roughness; \Brugotropic.\b
\BRuminantia\b Suborder of cloven-hooved herbivorous ungulates (Artiodactyla) that possess a 4-chambered stomach and chew the cud (ruminate); feet with 2 or 4 digits and well developed hooves; horns or antlers typically present; comprises 5 families, Tragulidae (chevrotains), Antilocapridae (pronghorn), Giraffidae (giraffe), Cervidae (deer) and Bovidae (cattle, goats, sheep, antelopes).
\BRuncinoidea\b Order of small, marine opisthobranch molluscs, most of which are herbivores found in shallow water; characterized by an elongate, vermiform body which often lacks a shell and cephalic tentacles.
\Brunner\b An elongate creeping stem which arises from an axillary bud and gives rise to plantlets at the nodes, found commonly in rosette plants.
\Brunoff\b That part of precipitation that is not held in the soil but drains freely away.
\Brupestral\b Pertaining to or living on walls or rocks.
\Brupicolous\b Living on walls or rocks; \Brupicole.\b
\BRuppiaceae\b Ditch grass; cosmopolitan family of Najadales comprising a single variable species of glabrous herb submerged in alkaline or brackish water; flowers minute, borne in short, terminal racemes; pollen grain elongate, pollination occurring at water surface.
\Brush\b \JJuncaceae\j
\BRussian olive\b \JElaeagnaceae\j
\Brust fly\b \JPsilidae\j
\Brust fungus\b \JUredinales\j
\Brut\b A period of sexual excitement in a mammal.
\BRutaceae\b Citrus family; orange, lemon, lime, grapefruit, common rue; family of Sapindales containing about 1500 species of mostly woody, aromatic plants generally producing ethereal oils; widely distributed especially in warm regions; flowers typically with 4 or 5 sepals and petals, 8 or 10 stamens and a superior ovary.
\BRutoceratida\b Extinct order of cephalopods (Nautiloidea) in which the siphuncle is small and located near the centre of the chambers; known from the Lower Devonian to Middle Jurassic.
\Brye\b \JPoaceae\j
\BRynchopidae\b Skimmers; family containing 3 species of tropical charadriiform sea birds with long blade-like bill used to catch fish during skimming flight over water; habits gregarious, often crepuscular or nocturnal.
\Brypophagous\b Feeding on putrid matter or refuse; \Brypophage\b, \Brypophagy.\b
\BSaale glaciation\b A glaciation of the Quaternary Ice \JAge\j in northern Germany and Poland with an estimated duration (together with the Warthe glaciation) of 100 000 years.
\BSabellida\b Fanworms; order of sedentary and tubicolous polychaete worms comprising about 800 species in 4 families; prostomium and peristomium fused, supporting a crown of tentacles or branchiae around the mouth used for suspension feeding or respiration; tube construction carried out by anterior thoracic collar.
\BSabiaceae\b Small family of tanniferous trees, shrubs or woody vines found mainly in southeast Asia and tropical America.
\Bsable\b \JMustelidae\j
\Bsablefish\b \JAnoplopomatidae\j
\Bsabretooth\b \JEvermannellidae\j
\Bsabulicolous\b Living in sand; \Bsabulicole.\b
\Bsabuline\b Sandy; used especially of species growing on coarse sand.
\Bsac fungus\b \JAscomycotina\j
\BSaccifoliaceae\b Family of Gentianales containing a single species of subshrub native to southern Venezuela.
\BSaccopharyngidae\b Family of bizarre bathypelagic anguilliform teleost fishes (gulper-eels) possessing a huge mouth and many sharp curved teeth; body smooth, length to about 1.8 m, eyes set close to the snout; tail long and tapering.
\BSaccopharyngoidei\b Deep-sea gulper-eels; suborder of bizarre carnivorous bathypelagic anguilliform teleost fishes exhibiting loss of gas bladder, scales, ribs, and reduction of eyes, gill openings and caudal fin; tail long and tapering, mouth very large; comprises about 10 species in 3 families.
\BSacoglossa\b Order of generally small, often cryptically coloured, opisthobranch molluscs which typically feed on algae; characterized by the retention of older radula teeth in a ventral sac off the muscular, sucking pharynx.
\Bsac-winged bat\b \JEmballonuridae\j
\Bsaddle oyster\b \JOstreoida\j
\Bsage\b \JLamiaceae\j
\Bsagebrush\b \JAsterales\j
\BSagittariidae\b Secretary bird; monotypic family of large long-legged raptors (Falconiformes) found on open plains of southern and eastern Africa; wings broad; habits solitary, monogamous, mostly terrestrial, running to catch prey; feeds on vertebrates, especially snakes, and insects; nests in bush or tree.
\BSagittoidea\b The single class of the phylum \JChaetognatha\j
\Bsailfish\b \JIstiophoridae\j
\Bsalamander\b \JSalamandridae\j
\BSalamandridae\b Newts, salamanders; diverse family containing about 40 species of aquatic or amphibious Holarctic salamanders (Caudata); body length to 200 mm; metamorphosis complete; forelimbs, hindlimbs and lungs present; fertilization internal, males producing spermatophores; eggs typically aquatic, the larvae bearing large gills although some forms have terrestrial eggs and direct development.
\BSalangidae\b Icefishes; family containing 12 species of mostly small anadromous salmoniform teleost fishes from the Oriental region; body slender, transparent, subcylindrical, scales and pelvic axillary process absent; adipose fin present.
\BSalenioida\b Order of small (to 20 mm) echinoids (Echinacea) comprising about 13 extant species found mostly at continental slope depths; dentition stirodont, oral membrane with gill notches, anus displaced to one side by large apical plate; diverse fossil record in the Mesozoic.
\BSalicales\b Willow, poplar, cottonwood; order of Dilleniidae comprising the family Salicaceae which contains about 300 species of dioecious woody plants, best developed in northern temperate regions; flowers borne in unisexual catkins and primarily wind-pollinated.
\BSalientia\b Older name for the \JAnura\j
\Bsaline\b Salty; pertaining to soil or water rich in soluble salts.
\Bsalinity\b A measure of the total concentration of dissolved salts in sea water usually measured in parts per thousand (ppt); See also \Jchlorinity\j
\Bsalinization\b The process by which soluble salts accumulate in soil.
\Bsalmon\b \JSalmonidae\j
\Bsalmon shark\b \JLamnidae\j
\BSalmonidae\b Salmon, trout, chars, graylings, whitefishes; family containing 70 species of northern hemisphere, anadromous marine or freshwater, salmoniform teleost fishes; body compressed, to 1.5 m in length; adipose fin present, dorsal fin arising above or anterior to pelvics; pelvic axillary process present; commonly migrate upstream to spawn; salmonids are very important food-fishes widely exploited in pisciculture.
\BSalmoniformes\b Large order of soft-rayed marine and freshwater teleost fishes possessing many primitive or generalized features; swim bladder lacking connection to inner ear; adipose fin often present; comprises about 270 species in 4 suborders, Esocoidei (pikes, mudminnows), Salmonoidei (salmon, trout, chars), Argentinoidei (herring smelts, deep-sea smelts, barreleyes, slickheads, tubeshoulders) and Giganturoidei (giganturids).
\BSalmonoidei\b Suborder of marine, freshwater and anadromous teleost fishes comprising about 145 species in 7 families; including salmon, trout, chars, graylings, whitefishes, smelts, galaxiids and icefishes; adipose fin usually present; dorsal fin originating close to midpoint of body.
\Bsalp\b \JThaliacea\j
\BSalpida\b Order of pelagic tunicates (Thaliacea) that exhibit alternation of solitary, sexually reproducing (gonozooids) and compound, asexually produced forms, (ovozooids); zooids barrel-shaped with anterior inhalent and posterior exhalent openings producing locomotory water current; gonozooid hermaphrodite, larval stage absent, development viviparous.
\Bsalsuginous\b Pertaining to, or living in, habitats inundated by salt or brackish water; \Bsalsugine.\b.
\Bsalt lake\b An inland water body having a high salinity due to an excess of evaporation over precipitation.
\Bsalt marsh\b A flat poorly drained coastal swamp inundated by most high tides.
\Bsaltation\b 1: To move by leaping or bounding; saltatory. 2: A drastic and sudden mutational change; an abrupt evolutionary change.
\Bsaltatorial\b Pertaining to, or adapted for, leaping or bounding locomotion; saltatory.
\BSalticidae\b Jumping spiders; family containing about 4000 species of active predatory spiders (Araneae) with large eyes; prey jumped on from a distance, the jumping mechanism involving extension of legs by internal body pressure.
\Bsaltigrade\b Used of a leaping or hopping form of locomotion.
\BSalvadoraceae\b Mustard tree; family of Celastrales containing about 12 species of woody plants sometimes producing mustard oils; native from Africa through to southeast Asia.
\BSalviniales\b Water ferns; order of small ferns (Filicopsida) producing rhizomes which creep on the surface of the water, and hanging roots; typically heterosporous forming microsporangia and megasporangia in separate walled sporocarps.
\Bsamara\b A type of achene or nut in which the wall of the fruit (pericarp) is produced into a membranous wing to aid dispersal of the seed by wind.
\Bsamphire\b \JApiaceae\j
\Bsample\b Any subset of a population; a representative part of a larger unit used to study the properties of the whole.
\Bsand\b Cohesionless sediment particles of size range 2.0-0.0625 mm; subdivided into very coarse sand (2.0-1.0 mm), coarse sand (1.0-0.5 mm), medium sand (0.5-0.25 mm), fine sand (0.25-0.125 mm) and very fine sand (0.125-0.0625 mm);see sediment particle size.
\BSangamonian interglacial\b The interglacial period preceding the Iowan glaciation in North America; see Quaternary Ice Age.
\Bsanguicolous\b Living in blood; \Bsanguicole.\b
\Bsanguivorous\b Feeding on blood; \Bsanguivore\b, \Bsanguivory.\b
\BSantalaceae\b Sandalwood, false toadflax; cosmopolitan family containing about 400 species of hemiparasitic herbs and shrubs that attach to roots of other plants; flowers small, typically with 3-6 fused tepals and adnate stamens.
\BSantalales\b Order of Rosidae containing a diverse array of trees, or hemiparasitic (with chlorophyll) or fully parasitic (lacking chlorophyll) plants attached to trees, shrubs or herbs; leaves simple, often evergreen, sometimes reduced to scales; contains about 2000 species in 10 families, including the mistletoes (Viscaceae).
\BSapindaceae\b Goldenrain tree, soapberry, litchi; large family containing about 1500 species of mostly woody plants often with anomalous stem structure, widespread mainly in warm regions; flowers usually with 4 or 5 sepals and petals, 4,5,10 or many stamens and a superior ovary.
\BSapindales\b Order of Rosidae containing about 5400 species of chemically diverse, mostly woody, plants arranged in 15 families, the largest of which are the Sapindaceae and Rutaceae.
\Bsapodilla\b \JSapotaceae\j
\BSapotaceae\b Star apple, sapodilla; large family of Ebenales containing about 800 species of trees or shrubs with latex sacs; widespread chiefly in tropical regions; provides some edible fruits and produces gums, including chicle; ovary superior, fruit typically a berry.
\Bsaprobe\b 1: A saprophytic organism. 2: An organism thriving in water rich in organic matter.
\Bsaprobic\b 1: Pertaining to water rich in decaying organic matter. 2: \JSaprophytic\j
\Bsaprogenic\b Causing, or caused by, the decay of organic matter.
\BSaprolegniales\b Water moulds; order of oomycete fungi; mostly saprophytic in wet soil or aquatic habitats, occasionally parasitic.
\Bsapromyiophilous\b Pollinated by dung flies; \Bsapromyiophile\b, \Bsapromyiophily.\b
\Bsapropelic\b Used of organisms inhabiting mud rich in decaying organic matter; \Bsapropel.\b
\Bsaprophagous\b Feeding on dead or decaying organic matter; \Bsaprophage\b, \Bsaprophagy\b; See also \Jbiophagous\j
\Bsaprophilous\b 1: Thriving in humus-rich substrata. 2: Feeding on decaying organic matter; \Bsaprophile\b, \Bsaprophily.\b
\Bsaprophytic\b Used of a plant obtaining nutrients from dead or decaying organic matter; \Bsaprobic\b, \Bsaprophyte.\b
\Bsaprophytophagous\b Feeding on decomposing plant material; \Bsaprophytophage\b, \Bsaprophytophagy.\b
\Bsaproplankton\b Plankton organisms inhabiting water rich in decaying organic matter.
\Bsaprotrophic\b Obtaining nourishment from dead or decaying organic matter; \Bsaprotroph\b, \Bsaprotrophy\b.
\Bsaproxylobios\b Those organisms living in or on rotting wood.
\Bsaprozoic\b Used of an animal feeding upon decaying plant or animal matter in the form of dissolved organic compounds; \Bsaprozoite.\b
\BSarcodina\b Subphylum of Sarcomastigophora; protozoans possessing some kind of pseudopodia, most of which are free-living in soil and aquatic habitats; body typically naked but sometimes with external tests or internal skeletons; cysts are common and sexual reproduction when present usually involves flagellated gametes; comprises 2 superclasses, Actinopoda and Rhizopoda.
\BSarcolaenaceae\b Small family of usually evergreen woody plants, often with stellate hairs; confined to Madagascar.
\BSarcomastigophora\b Diverse phylum of protozoans comprising over 18 000 species which are widespread in aquatic habitats and soil, as well as in symbiotic or parasitic association with other animals and plants; possessing either flagella, pseudopodia or both and a single type of nucleus; asexual reproduction typically involves binary fission, and sexual reproduction, when present, involves fusion of gametes; typically heterotrophic, although some classifications include certain groups of autotrophic flagellated algae in this phylum; comprises 3 subphyla, Mastigophora, Opalinata and Sarcodina.
\BSarcophagidae\b Flesh flies; cosmopolitan family containing about 1400 species of medium-sized grey or black flies (Diptera); larvae maggot-like typically feeding mainly on decaying organic or faecal matter, although some are parasitic on other arthropods, earthworms or molluscs.
\Bsarcophagous\b Feeding on flesh; flesh-eating; \Bsarcophage\b, \Bsarcophagy.\b
\BSarcopterygii\b Lobe-finned fishes; group formerly used for the lungfishes (Dipnoi) and the crossopterygian fishes (coelacanths); sometimes also used to include the tetrapods.
\BSarcoptiformes\b Diverse suborder of free-living, predatory and parasitic mites (Acari) that includes cheese mites, scabies mites, and several families of oribatids (beetle or moss mites).
\Bsardine\b \JClupeidae\j
\BSargentodoxaceae\b Family of Ranunculales containing a single twining woody vine species native to China, Laos and Vietnam; characterized by numerous spirally arranged pistils.
\BSarraceniaceae\b New World pitcher plants, cobra plant; small family of Nepenthales containing 15 species of insectivorous herbs with leaves modified as pitchers containing a digestive liquid; found in North and South America.
\BSarsostraca\b Subclass of branchiopodan crustaceans comprising a single extant group, the fairly shrimps (\JAnostraca\j).
\Bsathrophilous\b Thriving on humus or decaying organic matter; \Bsathrophile\b, \Bsathrophily.\b
\Bsathrophyte\b A plant living on humus; \Bsathrophytic.\b
\Bsaturation deficit\b A measure of humidity, derived by subtracting the actual water vapour pressure from the maximum possible vapour pressure at a given temperature; See also \Jrelative humidity\j
\BSaturniidae\b Atlas moths, emperor moths; family containing about 1000 species of large moths (Lepidoptera) having conspicuous eye spots and banded markings on the wings; larvae of some species are economically important pests, causing damage to the foliage of various trees; pupal cocoons of some species are used for the production of silk.
\BSauria\b Lizards; large and diverse suborder of reptiles (Squamata) containing 3300 species in 17 families; body length to about 3 m; habits mostly terrestrial, diurnal or nocturnal, a few species fossorial or semiaquatic; limbs may be reduced in burrowing forms; feeding as herbivores, insectivores or as predators of small vertebrates; reproduction oviparous or ovoviviparous.
\BSaurischia\b Order of dinosaurs characterized by the lizard-type hip; includes large bipedal carnivores (Theropoda) and large quadripedal herbivores (Sauropoda).
\Bsaurochorous\b Dispersed or distributed by lizards or snakes; saurophilous; \Bsaurochore\b, \Bsaurochory.\b
\Bsaurophilous\b \JSaurochorous\j
\BSauropoda\b Group of saurischian dinosaurs containing many large, quadripedal herbivores; includes \IDiplodocus\i, the largest known terrestrial animal; known from the Jurassic and Cretaceous.
\BSauropterygia\b Extinct order of reptiles (Archosauria) comprising the plesiosaurs (Plesiosauroidea) and nothosaurs (Nothosauria).
\BSaururaceae\b Small family of aromatic rhizomatous herbs (Piperales) occurring in eastern Asia and North America.
\Bsaury\b \JScomberesocidae\j
\Bsavannah\b The tropical and subtropical grassland biome, transitional in character between grassland or desert and rain forest, typically having drought-resistant vegetation dominated by grasses with scattered tall trees; Tropical grassland biome; savanna.
\Bsaw shark\b \JPristiophoridae\j
\Bsawfish\b \JPristidae\j
\Bsawfly\b \JSymphyta\j
\Bsaxatile\b Living or growing among rocks.
\Bsaxicavous\b Rock-boring.
\Bsaxicolous\b Living or growing on or among rocks or stones; \Bsaxicole\b, \Bsaxicoline.\b
\BSaxifragaceae\b Saxifrage, astilbes, foam flower, bronze leaf; large family of Rosales containing herbs, often with red root tips and basal rosettes of leaves; best developed in the cold and temperate northern hemisphere; flowers usually bisexual with 5 sepals and petals, and 10 stamens.
\Bsaxifragous\b Living in rock crevices; \Bsaxifrage.\b
\Bscabious\b \JDipsacaceae\j
\Bscad\b \JCarangidae\j
\Bscale insect\b \JCoccoidea\j (Homoptera).
\Bscaled blenny\b \JClinidae\j
\Bscaleworm\b \JPhyllodocida\j
\Bscallop\b \JOstreoida\j
\Bscaly anteater\b \JManidae\j
\Bscaly-tailed squirrel\b \JAnomaluridae\j
\Bscansorial\b Climbing or adapted for climbing; scandent.
\BScaphopoda\b Tusk shells, tooth shells; class of exclusively marine, benthic molluscs found partly embedded in the sediment from the sublittoral to abyssal depths; characterized by a bilaterally symmetrical body with a curved, tubular calcareous shell open at both ends; head rudimentary with a proboscis used for capturing foraminiferans; foot protrusible and often modified for burrowing; possessing a radula, used for crushing shells of prey; comprises 2 orders, Dentaliida and Gadilida.
\BScarabaeidae\b Chafers, dung beetles; family containing about 25000 species of beetles (Coleoptera) the adults and larvae of which feed mainly on dung and carrion; larvae also found sometimes on roots and decaying vegetation; larvae typically C-shaped.
\BScaridae\b Parrotfishes; family containing 70 species of colourful tropical and warm temperate marine labroid teleost fishes (Perciformes) in which the jaws form a non-protractile parrot-like beak used to scrape algae and coral from hard surfaces; body length to 1.2 m.
\Bscarification\b Any chemical or physical treatment of a hard seed which renders it permeable.
\Bscat\b 1: \JScatophagidae\j 2: An animal faecal dropping.
\Bscatology\b The study of animal faeces; \Bscatological.\b
\BScatophagidae\b 1: Dung flies; family of small to large hirsute flies (Diptera) that feed mainly on dung; larvae phytophagous or scatophagous, often found in meadows. 2: Scats; small family of Indo-Pacific coastal marine and brackish-water teleost fishes (Perciformes) that feed mainly on bottom detritus and are often abundant around sewage outfalls; body deep, compressed, with high dorsal profile; 2 dorsal fins present; popular in the aquarium trade.
\Bscatophagous\b Feeding on faecal matter or dung; \Bscatophage\b, \Bscatophagy\b
\Bscavenger\b Any organism that feeds on carrion or organic refuse.
\BScenopinidae\b Window flies; cosmopolitan family containing about 250 species of small flies (Diptera) having a dark oblong body lacking bristles, commonly found on vegetation or on windows of houses.
\BScheuchzeriaceae\b Family of Najadales comprising a single species of cyanogenic rhizomatous herb found in bogs or other very wet habitats; typically possessing a bract beneath each flower; native to cooler parts of the northern hemisphere.
\BSchilbeidae\b Family containing 40 species of small (to 350 mm) Old World freshwater catfishes (Siluriformes) ranging from Africa to southeast Asia; body slender and compressed, dorsal fin short with single spine, or absent; anal fin very long; 2-4 pairs of barbels present.
\BSchindleriidae\b Family containing 2 species of small (to 25 mm) neotenic marine perciform teleost fishes found in the north north Pacific Ocean; adult body transparent retaining many larval characters.
\BSchisandraceae\b Small family of Illiciales containing about 50 species of glabrous, aromatic, evergreen or deciduous woody vines.
\BSchistostegales\b Order containing a single species of mosses (Bryidae) found in low-light habitats; protonema persistent, with light-refracting properties.
\Bschizocarp\b A dry fruit developed from 2 or more one-seeded carpels that divide into separate units at maturity.
\Bschizogenesis\b Reproduction by multiple fission; \Bschizogenetic.\b
\Bschizogony\b A type of multiple fission in which the parent organism (schizont) divides to form many new individuals (merozoites).
\BSchizomida\b Order of small (2-15 mm) predatory terrestrial arthropods (Arachnida); mesosoma bearing single pair of book lungs, metasoma with short terminal flagellum; chelicerae possessing fang, pedipalps spinose and raptorial; contains about 80 species, typically found in leaf litter of the tropics and subtropics; Schizopeltida.
\BSchizomycetes\b A group name formerly used for the bacteria when classified as fungi.
\BSchizopeltida\b \JSchizomida\j
\Bschizophyte\b A plant that reproduces by fission.
\BSchizopyrenida\b Order of naked lobose amoebae (Gymnamoeba) typically with a flagellate phase in the life cycle; widely distributed in aquatic habitats and soil.
\Bschool\b To aggregate and swim together in an organized manner; also the swimming group itself.
\BSciaenidae\b Drums, croakers; family containing about 200 species of coastal marine, brackish and freshwater, teleost fishes (Perciformes) widespread in tropical and temperate regions, that derive their common names from the ability to produce sounds by resonating the gas bladder; body elongate, weakly compressed, to 2 m in length; chin barbels may be present; 2 dorsal fins, the second elongate.
\BScincidae\b Skinks; very large cosmopolitan family of terrestrial lizards comprising more than 1000 species; body length to 650 mm, limbs usually small, reduced or absent in some fossorial forms; habits diurnal, insectivorous, some species herbivorous; reproduction oviparous or viviparous.
\BSciomyzidae\b Family containing about 500 species of small to large brown flies (Diptera) in which the larvae prey on aquatic or terrestrial molluscs.
\Bscion\b That part or structure transplanted from one plant to another during a graft.
\Bsciophilous\b Thriving in shaded situations, or in habitats of low light intensity; \Bsciophile\b, \Bsciophily.\b
\Bsciophyllous\b Having leaves that can tolerate shaded situations; skiophyllous; See also \Jheliophyllous\j
\Bsciophyte\b A plant growing in shady situations, or in habitats of low light intensity; See also \Jheliophyte\j
\Bscissiparous\b Used of multicellular organisms that reproduce by fission.
\BSciuridae\b Squirrels, marmots, prairie dogs; large cosmopolitan family containing about 250 species of diurnal, arboreal or terrestrial mammals (Rodentia); mostly herbivorous, feeding primarily on nuts, seeds and leaves, but some also taking invertebrates.
\BScleractinia\b Stony corals, true corals; large, diverse order of colonial zooantharians found mainly in shallow tropical seas between 30░N and 30░S; play central role in the formation of coral reefs by producing massive calcareous (aragonitic) exoskeletons into which the polyps can usually retract; colony growth takes place by asexual budding; formerly known as Madreporaria; over 2500 extant species species are known in addition to a large number of fossils.
\BSclerodermatales\b Puff balls; order of gasteromycete fungi producing subglobular fruiting bodies; typically found growing in mycorrhizal association.
\BSclerospongiae\b Class of sponges which secrete a basal skeleton of crystalline calcium carbonate; the living tissues are organized like those of demosponges and contain siliceous and spongin skeletal elements.
\BScolecomorphidae\b Small family of tropical eastern African terrestrial caecilians (Gymnophiona) comprising a single genus and 6 species; body length to 450 mm, scales and tail absent; reproduction viviparous.
\Bscolite\b A fossil worm-burrow.
\BScolopacidae\b Snipe, sandpipers, curlews, turnstones; family containing about 85 species of small to large charadriiform shore birds cosmopolitan in freshwater and marine marsh and shore habitats, also occasionally in dry grassland and woodland; bill usually long and slender, straight or curved; habits gregarious, often migratory, monogamous, feeding mainly on invertebrates.
\BScolopendrida\b Order containing about 500 species of small to large (to 300 mm) epimorphan chilopods found in soil, leaf litter or under bark and stones; ocelli present or absent; trunk composed of 25 or 27 segments bearing 21 or 23 pairs of legs; genital apparatus concealed; body often with conspicuous coloration.
\BScolopendromorpha\b \JScolopendrida\j
\BScolytidae\b Bark beetles; family of small, cylindrical beetles (Coleoptera) which excavate an egg chamber beneath tree bark; larvae fleshy and legless tunnelling away from chamber, through bark or wood.
\BScomberesocidae\b Sauries, skippers; family containing 4 species of small (to 35 mm) surface-living marine beloniform teleost fishes; body elongate, slender, compressed; jaws prolonged into narrow beak bearing many very small teeth, upper jaw shorter than lower; typically active zooplankton feeders that commonly skip and jump at the surface in large schools.
\BScombridae\b Tunas, mackerels; widespread tropical to temperate family of active, predatory, oceanic perciform teleost fishes; body spindle-shaped, to about 4 m in length; jaw teeth well developed, dorsal and anal fins with finlets; feed mainly on squid and other fishes, although smaller species are selective plankton feeders; contains 45 species many of which are important commercially and prized as sport fish.
\BScombroidei\b Suborder of medium-sized to large, active pelagic predatory perciform teleost fishes comprising about 100 species in 6 families and including mackerels, tunas, billfishes, swordfish and cutlassfishes.
\BScopelarchidae\b Pearleyes; family containing 17 species of pelagic predatory deep-sea myctophiform teleost fishes having telescopic eyes containing iridescent connective tissue; body compressed, mouth large; photophores present or absent; some forms hermaphroditic.
\BScopelosauridae\b Family containing 5 species of deep-sea myctophiform teleost fishes widespread in tropical and temperate oceans; body slender, subcylindrical becoming compressed posteriorly, head depressed; mouth and eyes large, teeth small and sharp; adipose fin present; photophores and swim bladder absent.
\BScophthalmidae\b Turbot, brill, topknot; family of North Atlantic and Mediterranean flatfishes (Pleuronectiformes) in which the eyes are located on the left side; both pelvic fins well developed.
\Bscopulous\b Pertaining to crags and steep overhanging cliffs.
\BScorpaenidae\b Scorpionfishes, rockfishes, redfishes, turkeyfishes; family of bottom-living tropical and temperate marine scorpaeniform teleost fishes widespread in nearshore and shelf waters; body robust, to 1 m in length, head large and spinose; dorsal and anal fins spinose, fin spines venomous; reproduction oviparous, one genus viviparous; contains about 330 species, some important as food-fish; the turkeyfishes (subfamily Pteroinae) are popular with aquarists.
\BScorpaeniformes\b Diverse order of marine, brackish and freshwater teleost fishes characterized by a large stout head, and body covered with spines or bony plates; comprises about 1000 species in 21 families, including scorpionfishes, rockfishes, stonefishes, sea robins, velvetfishes, sablefishes, greenlings, combfishes, flatheads, pigfishes, sculpins, poachers, lumpfishes and snailfishes.
\BScorpiones\b Scorpions; order of terrestrial arthropods (Arachnida) most of which are ground-dwelling nocturnal predators feeding on other arthropods; a few are arboreal or cavernicolous; length 10-180 mm, body divided into a carapace-bearing cephalothorax and slender segmented abdomen; pedipalps large and chelate; mesosoma bearing pectines and 4 pairs of book lungs; metasoma armed with conspicuous terminal sting; contains about 1200 species.
\BScrophulariaceae\b Foxglove, snapdragon, mullein, calceolaria, musk, toadflax, speedwell, lousewort, Indian paintbrush, antirrhinum; cosmopolitan family containing about 4000 species of mostly herbs, some of which are hemiparasitic or fully parasitic; fruit usually a 2-celled capsule with numerous seeds, rarely a berry.
\BScrophulariales\b Order of Asteridae containing 12 families characterized by a sympetalous irregular corolla bearing fewer functional stamens than corolla lobes.
\BSCUBA\b An acronym of self-contained underwater breathing apparatus; aqualung.
\Bscud\b \JAmphipoda\j
\Bsculpin\b Common name of various fishes of the families Cottidae, Icelidae, Cottocomephoridae, Cottunculidae and Psychrolutidae.
\BScuticociliatida\b Order of hymenostome ciliates abundant in marine and brackish habitats; either free-living or found in association with typically invertebrate hosts.
\BScutigerida\b Small order of mostly tropical anamorphan chilopods; eyes large and multifaceted, antennae very long with up to 400 minute articles; trunk composed of 15 pedigerous segments covered by 8 large tergal plates; legs elongate, for rapid cursorial locomotion.
\BScutigeromorpha\b \JScutigerida\j
\Bscuttle fly\b \JPhoridae\j
\BScyliorhinidae\b Cat sharks; widespread family containing 85 species of small to medium-sized (to 1.5 m), mostly benthic, carcharhiniform elasmobranch fishes; found from intertidal to 2000 m, feeding on fishes, crustaceans, molluscs and echinoderms; reproduction oviparous to fully viviparous.
\Bscyphistoma\b Sessile, polypoid larval stage of some jellyfishes (Scyphozoa) that may undergo asexual budding to produce further scyphistomae or transverse fission (strobilation) to form free-living medusae.
\BScyphostegiaceae\b Family of Violales comprising a single species of small glabrous tree found in Borneo; flowers borne in spikes, with 6 tepals, stamens forming a column and tiny carpels.
\BScyphozoa\b Jellyfish; class of exclusively marine cnidarians in which the medusoid stage is dominant; the attached polyp small, with single whorl of tentacles around the mouth; medusae produced by budding and subsequent transverse fission (strobilation); medusae typically flat or bell-shaped jellyfish, usually free-swimming but occasionally attached, with marginal tentacles and a median mouth; comprises 4 orders, Coronatae, Rhizostomeae, Semaeostomeae and Stauromedusae.
\BScytopetalaceae\b Small family of Theales containing about 20 species of glabrous woody plants, all native to Africa.
\BScytosiphonales\b Small order of brown algae exhibiting alternation of a large parenchymatous sporophyte and a small pseudoparenchymatous, encrusting, gametophyte generation.
\Bsea\b 1: A geographical division of an ocean. 2: An inland body of salt water.
\Bsea anemone\b \JActiniaria\j
\Bsea bass\b \JSerranidae\j
\Bsea bream\b \JSparidae\j
\Bsea breeze\b A light wind blowing off the sea on warm days when the land surface is warmer than the sea surface; See also \Jland breeze\j
\Bsea buckthorn\b \JElaeagnaceae\j
\Bsea cow\b \JSirenia\j
\Bsea cucumber\b \JHolothuroidea\j
\Bsea daisy\b \JConcentricycloidea\j
\Bsea devil\b \JCeratiidae\j
\Bsea fan\b \JGorgonacea\j
\Bsea gooseberry\b \JCtenophora\j
\Bsea grass\b \JZosteraceae\j
\Bsea hare\b \JAnaspidea\j
\Bsea holly\b \JApiaceae\j
\Bsea horse\b \JSyngnathidae\j
\Bsea lettuce\b \JUlvales\j
\Bsea lily\b \JCrinoidea\j
\Bsealion\b \JOtariidae\j
\Bsea moth\b \JPegasidae\j
\Bsea mouse\b \JPhyllodocida\j
\Bsea pansy\b \JPennatulacea\j
\Bsea pen\b \JPennatulacea\j
\Bsea perch\b \JEmbiotocidae\j
\Bsea robin\b \JTriglidae\j
\Bsea slug\b \JNudibranchia\j
\Bsea snake\b \JHydrophiidae\j
\Bsea snow\b The settlement of particulate organic detritus and living organisms down the water column.
\Bsea spider\b \JPycnogonida\j
\Bsea squirt\b \JAscidiacea\j
\Bsea star\b \JAsteroidea\j
\Bsea toad\b \JChaunacidae\j
\Bsea turtle\b \JCheloniidae\j
\Bsea urchin\b \JEchinoidea\j
\Bsea wasp\b \JCubozoa\j
\Bsea whip\b \JGorgonacea\j
\Bseafloor spreading\b The formation and lateral displacement of oceanic crust by upwelling of material from the Earth's mantle along mid-ocean ridges.
\Bseamount\b An elevated area of limited extent rising 1000 m or more from the surrounding ocean floor; guyot.
\Bsearch image\b A model for visual comparison, formed by individual predators which select certain prey types and ignore others.
\BSearsiidae\b Tubeshoulders; family containing 30 species of mostly small deep-sea salmoniform teleost fishes closely resembling the slickheads (Alepocephalidae); possessing sac of luminous fluid behind the gill cover, opening to outside via a tubular papilla.
\Bseason\b Any of the major climatic periods of the year; see also \Jaestival\j \Jhibernal\j, \Jhiemal\j, \Jserotinal, vernal\j
\Bseasonal\b Showing periodicity related to the seasons; used of vegetation exhibiting pronounced seasonal periodicity marked by conspicuous physiognomic changes.
\BSecernentea\b Class of nematodes almost all of which are terrestrial, although some occur in fresh water; most are parasitic, with over 3000 species found in animal hosts and over 2000 species found in plant hosts; characterized, in general, by a pore-like external opening of the cephalic chemosensory organs (amphids), 3 oesophageal glands, and sensory glands (phasmids) in the tail area; comprises 3 subclasses, Diplogasteria, Rhabditia and Spiruria.
\Bsecondary consumer\b Any heterotrophic organism that feeds directly on a primary \Jconsumer\j
\Bsecondary production\b The assimilation of organic matter by a primary consumer; see also \Jgross secondary production\j \Jnet secondary production\j
\Bsecondary sexual characters\b Those differences between the sexes that relate to structures other than the reproductive organs and gametes; See also \Jprimary sexual characters\j
\Bsecondary succession\b An ecological succession resulting from the agricultural or other activities of man, or that follows destruction of all or part of an earlier community.
\Bsecretary bird\b \JSagittariidae\j
\Bsecretion\b 1: Any substance or product elaborated and released by a cell or gland to perform a specific function. 2: The process of elaboration and release; secretory; See also \Jexcretion\j
\Bsecular\b 1: Pertaining to periods of hundreds of years; see also \Jdecennial\j \Jmillennial. 2: Used of a process persisting for an indefinitely long period\j
\BSedentaria\b Taxon formerly used to group together all sedentary and tubicolous polychaete worms; See also \JErrantia\j
\Bsedentary\b Attached to the substratum; not freeliving.
\Bsedge\b \JCyperaceae\j
\Bsediment\b Particulate matter that has been transported by wind, water or ice and subsequently deposited, or that has been precipitated from water; sedimentation.
\Bsediment particle sizes\b See table for particle size classification and terminology.
\Bsedimentary rock\b Rock formed by deposition of particulate matter transported by wind, water or ice, or by precipitation from solution in water under normal surface temperatures and pressures, or by the aggregation of inorganic material from skeletal remains; see also \Jigneous rock\j \Jmetamorphic rock\j
\Bseed\b The dispersal and reproductive structure that develops from the fertilized ovule in higher plants, comprising an embryo with food supply either in the endosperm or in the cotyledons.
\Bseed bank\b The store of dormant seeds buried in soil.
\Bseed fern\b \JPteridospermales\j
\Bseedling stratum\b The lowest layer of a stratified forest community comprising germinating plants.
\Bseedsnipe\b \JThinocoridae\j
\Bsegmented spider\b Any of the trapdoor spiders in the suborder \JMesothelae\j
\Bsegregation, law of\b Mendel's first law; that in sexual organisms the two members of an allele pair or a pair of homologous chromosomes separate during gamete formation and that each gamete receives only one member of the pair.
\Bseiche\b A standing wave oscillation of an enclosed or partially enclosed water body that continues after the cessation of the original generating force, such as wind or heavy rain.
\Bseismonasty\b A growth movement of a plant in response to a non-directional shock or mechanical vibration stimulus; \Bseismonastic\b, \Bseismonic.\b
\Bseismotaxis\b A directed response of a motile organism to mechanical vibration or a shock stimulus; \Bseismotactic.\b
\Bseismotropism\b An orientation response to mechanical vibration or a shock stimulus; \Bseismotropic.\b
\BSeisonidea\b Class of exclusively marine rotifers found as epizoites on the gills of the crustacean \INebalia\i; characterized by a large body ending in a proximal adhesive disk and by the possession of fully developed males which produce spermatophores; comprises a single order, Seisonida.
\BSelachii\b Group of cartilaginous fishes containing all the sharks; Pleurotremata.
\BSelaginellales\b Spike mosses; small terrestrial plants usually with creeping stems bearing spirally arranged scale-like or needle-like leaves; roots dichotomously branching; sporangia borne in cones.
\Bselection\b 1: Non-random differential reproduction of different genotypes in a population. 2: Natural \Jselection\j
\Bselective breeding\b The selection by man of particular genotypes in a population because they exhibit desired characters; artificial selection.
\Bselenophyte\b A plant adapted to, or tolerating, high selenium levels in the soil, frequently used as an indicator of this particular soil type.
\Bselenotropism\b An orientation response to moonlight; \Bselenotropic.\b
\Bself-compatible\b Used of a plant that can be self-fertilized.
\Bself-fertilization\b The union of male and female gametes produced by the same individual; See also \Jcross fertilization\j
\Bselfing\b Self-fertilizing or self-pollinating.
\Bself-pollination\b Transfer of pollen from anther to stigma of the same flower or to another flower on the same plant; See also \Jcross pollination\j
\Bself-sterility\b The condition of hermaphroditic organisms that cannot produce viable offspring by self-fertilization.
\BSeligeriales\b Small order of mosses (Bryidae); small to medium-sized plants typically forming tufts or cushions on rocks.
\BSEM\b Scanning electron microscope.
\BSemaeostomeae\b Order of Scyphozoa found commonly in coastal waters of all seas and including the typical disk-shaped jellyfish of temperate regions; characterized by a simple mouth opening with 4 broad, lobed oral arms.
\Bsematic\b Pertaining to or serving as a signal or danger warning.
\Bsemelparous\b Pertaining to organisms that have only one brood during the lifetime; \Bsemelparity\b (big-bang reproduction); See also \Jiteroparous\j
\Bsemestrial\b Pertaining to periods of 6 months; half-yearly.
\Bsemidiurnal\b Having a period of about half a lunar day; equal to 12.42 h.
\BSemionotiformes\b Order of primitive bony fishes with a single extant family, Lepisosteidae (gars).
\Bsemiotics\b The study of communication.
\Bsemiparasitic\b Pertaining to an organism (partial parasite) that derives only part of its nourishment from its host, or that lives for only part of its life cycle as a parasite; \Bsemiparasite.\b
\Bsempervivum\b \JCrassulaceae\j
\Bsenescence\b The biological process of ageing; \Bsenescent.\b
\Bsenility\b The degenerative condition of old age; post-reproductive; \Bsenile.\b
\Bsenna\b \JCaesalpiniaceae\j
\Bsensibility\b The capacity to perceive a stimulus.
\Bsensitivity\b The capacity of an organism to respond to stimuli; irritability; \Bsensitive.\b
\Bsensory\b Pertaining to a sense organ or sensation.
\Bsepal\b Each element in the outermost whorl of a typical flower, probably representing a leaf modified as part of the protective outer layer (the calyx) of a flower.
\Bsepicolous\b Living in hedgerows; \Bsepicole.\b
\BSepioidea\b Cuttlefish, Ram's horn; order of benthic or near bottom cephalopod molluscs characterized by 8 arms and 2 tentacles which are used to capture prey; shell typically internal, forming the cuttlebone, but may be spirally coiled or absent.
\Bseptentrional\b Northern, northerly.
\Bseptic\b Heavily polluted; used of a habitat or zone of fresh water rich in decomposing organic matter, high in carbon dioxide and very low in dissolved oxygen.
\BSeptobasidiales\b Order of phragmobasidiomycete fungi containing about 200 species which grow on stems and leaves of woody plants; producing fruiting bodies usually adhering close to surface of host; many species are involved in complex associations with scale insects.
\Bsequoia\b \JTaxodiaceae\j
\Bseral stages\b The developmental stages of an ecological succession not including the climax community.
\Bsere\b A succession of plant communities in a given habitat leading to a particular climax association; a stage in a community succession; \Bseral.\b
\Bseriemas\b \JCariamidae\j
\Bserir\b A stony desert.
\Bserodeme\b A local interbreeding population characterized by immunological properties See also \Jdeme\j
\Bserology\b The study of antigens and antibodies; \Bserological.\b
\Bserotaxonomy\b Taxonomy based on serological characters.
\Bserotinal\b Pertaining to late summer.
\Bserotinous\b Coming late; used particularly with reference to late flowering plants, and for behaviour that occurs late in the day, or late in the season.
\BSerpentes\b Snakes; large cosmopolitan suborder of limbless reptiles comprising about 2250 species in 14 families; body length up to 10 m, forelimbs and girdle absent, hindlimbs and girdle vestigial or absent; tongue forked and extensible; left lung small or absent; habits terrestrial, arboreal or aquatic, carnivorous, many species venomous; reproduction oviparous or ovoviviparous; Ophidia.
\Bserpentinophilous\b Thriving in habitats rich in the mineral serpentine; \Bserpentinophile\b, \Bserpentinophily.\b
\Bserpulite\b A fossil polychaete tube.
\BSerranidae\b Sea basses, grouper; family containing about 370 species of primarily predatory demersal marine teleost fishes (Perciformes) widespread in inshore tropical and temperate waters, but also found in brackish and occasionally freshwater habitats; body robust to elongate, length to 3 m; 1 or 2 dorsal fins presnt; mouth large and protractile; many species hermaphroditic.
\BSerrasalmidae\b Piranhas, silver dollars; family containing 65 species of small to medium-sized South American freshwater characiform teleost fishes; dorsal fin situated at or behind mid-body, adipose fin present; dentition variable; piranhas are predators feeding on fishes and mammals, others herbivorous on fruits and seeds.
\BSerrivomeridae\b Family containing 10 species of pelagic deep-sea anguilliform teleost fishes resembling duckbill eels; body smooth, tapering posteriorly, jaws prolonged.
\Bsesame\b \JPedaliaceae\j
\Bsessile\b Non-motile; permanently attached at the base.
\Bseston\b The total particulate matter suspended in water.
\Bsewage\b Liquid or solid waste matter channelled through sewers.
\Bsex\b The sum of all structural, functional and behavioural characteristics distinguishing males, females and hermaphrodites; \Bsexual.\b
\Bsex chromosome\b A chromosome or group of chromosomes of eukaryotic organisms, represented differently in the sexes, responsible for the genetic determination of sex.
\Bsex linkage\b The location of a gene or character on a sex chromosome.
\Bsex mosaic\b A phenotype that manifests characters of both the male and the female.
\Bsex ratio\b The relative number of males and females in a population, expressed as the number of males per 100 females, or as a simple ratio.
\Bsexology\b The study of sex and sexual behaviour.
\Bsexual\b Pertaining to sex, sex-related characters or to the process of sexual reproduction.
\Bsexual dimorphism\b Marked phenotypic differences between males and females of the same species.
\Bsexual reproduction\b Reproduction involving the regular alternation of gamete formation by meiosis and gamete fusion (karyogamy) to form a zygote.
\Bsexual selection\b 1: Choosing a mate; the ability of individuals to differentiate and select a mate. 2: The differential abilities of individuals to acquire mates in competition with other individuals of the same sex.
\Bshad\b \JClupeidae\j
\BShantung soil\b Non-calcic Brown \Jsoil\j
\Bshark\b \JElasmobranchii\j
\Bshark-toothed whale\b \JSqualodontoidea\j
\Bshearwater\b \JProcellariidae\j
\Bsheep\b \JBovidae\j
\Bsheet erosion\b The removal of a more or less uniform layer of surface soil over a wide area by the action of runoff water.
\Bsheet-web spider\b \JAgelenidae\j
\Bshelf break\b The outer margin of the continental shelf marked by a pronounced increase in the slope of the sea bed.
\Bshe-oak\b \JCasuarinales\j
\Bshield bug\b \JPentatomidae\j
\Bshingle\b Rounded rock fragments larger than 16 mm in diameter.
\Bshipworm\b A member of the family Teredinidae of the order Myoida, containing about 65 species of usually marine bivalve molluscs which burrow into wood.
\Bshrimp\b \JDendrobranchiata\j and \JPleocyemata\j; prawn.
\Bshrimp plant\b \JAcanthaceae\j
\Bshrimpfish\b \JCentriscidae\j
\BSI Units (Système International d'Unités)\bAn internationally agreed system of metric units; comprising seven base units - metre, kilogram, second, ampere, Kelvin, candela and mole; other metric units may be derived units or supplementary units.
\BSialidae\b Alderflies; family containing about 50 species of primitive neuropteran insects which typically have slow, awkward flight; subaquatic, carnivorous larvae found in wellaerated fresh water.
\Bsib mating\b Mating of progeny derived from the same parents.
\Bsib pollination\b Pollination of one plant by another plant derived from the same parents.
\Bsiblings\b Organisms sharing close genetic relationship, especially those derived from the same parents; \Bsibs.\b
\Bsibling species\b Pairs or groups of closely related and frequently sympatric species which are morphologically indistinguishable but which are reproductively isolated.
\Bsiccocolus\b Living in dry arid habitats; \Bsiccocole.\b
\Bside-necked turtle\b \JPleurodira\j
\Bsidereal day\b The mean time taken for one revolution of the Earth; each year comprises 365.256 sidereal days; See also \Jsolar day\j
\Bsiderophilous\b Thriving in an iron-rich medium; \Bsiderophile\b, \Bsiderophily.\b
\Bsiderotrophic\b Used of water bodies rich in dissolved iron compounds.
\Bsidewinder\b \JCrotalidae\j
\BSierozem\b A zonal soil with pale grey A-horizon, a slightly darker alkaline B-horizon merging into a calcareous lower layer, formed in temperate to cool arid climates; cerozem.
\BSiganidae\b Rabbitfishes; family containing 10 species of herbivorous Indo-Pacific marine perciform teleost fishes; body oval, dorsal and anal fins elongate bearing venomous spines.
\Bsignal\b Any behaviour that conveys information from one individual to another.
\Bsiliceous ooze\b A fine-grained pelagic sediment containing more than 30% siliceous skeletal remains of pelagic organisms, primarily radiolarians and diatoms; See also \Jooze\j
\Bsilicoflagellate\b \JDictyochophycidae\j
\BSilicoflagellida\b \JDictyochophycidae\j treated as an order of the protozoan class Phytomastigophora.
\Bsilicolous\b 1: Living in soil rich in silica or silicates; \Bsilicole.\b 2: Growing on flints.
\Bsilicula\b A dry dehiscent fruit developed from 2 carpels fused to form a short, broad, flattened pod with 2 loculi separated by a false septum.
\Bsilification\b A process of fossilization in which the fossil is encrusted, partially replaced or impregnated with silica derived by the degradation of silicates, from biogenic organic silica solutions or from products of vulcanism.
\Bsiliqua\b A dry dehiscent fruit developed from 2 carpels fused to form a long, narrow pod with 2 loculi separated by a false septum; silique.
\Bsilkcotton tree\b \JBombacaceae\j
\Bsilkworm\b \JBombycidae\j
\Bsilky flycatcher\b \JBombycillidae\j
\Bsilky oak\b \JProteaceae\j
\BSilphidae\b Carrion beetles; family of beetles (Coleoptera) most of which are carrion feeders or scavengers although some are predators and plant feeders; contains about 175 species.
\Bsilt\b Cohesionless sediment particles between 0.004 and 0.0625 mm in diameter; coarse mud; see sediment particle sizes.
\Bsilt load\b The quantity of particulate matter carried in suspension by a stream or river; See also \Jbed load\j
\BSilurian\b A geological period within the Palaeozoic (\Ic\i. 441-413 million years B.P); see geological time scale.
\BSiluridae\b Family of small to large (70 mm - 3 m) Eurasian freshwater catfishes (Siluriformes); body elongate, naked, 2-3 pairs of barbels present; dorsal and pelvic fins small to absent, adipose fin absent, anal fin elongate, in some species continuous with caudal fin.
\BSiluriformes\b Catfishes; cosmopolitan order of small to very large, mostly freshwater, teleost fishes comprising over 2000 species in about 30 families; sexual dimorphism absent; median fins typically with strong spines, pelvics posterior to pectorals; gas bladder connected to inner ear.
\Bsilvics\b The study of forest trees; \Bsilvical.\b
\Bsilviculture\b The management and exploitation of forests.
\BSimaroubaceae\b Tree of heaven; family of Sapindales containing about 150 species of trees and shrubs mostly with very bitter bark and seeds; primarily tropical in distribution; flowers small with an intrastamenal disk; fruit often drupe-like.
\BSimenchelyidae\b Monotypic family of small (to 600 mm) deep-sea eels (Anguilliformes); snout short and blunt, mouth small; dorsal and anal fins long, continuous with caudal.
\BSimmondsiaceae\b Jojoba; family of Euphorbiales containing a single species of xeromorphic, evergreen dioecious shrub producing large, wax-containing seeds; native to southwestern United States and Mexico.
\BSimuliidae\b Black flies, buffalo flies; family containing about 1100 species of small biting flies (Diptera) that feed on the blood of warmblooded vertebrates and may be serious pests of cattle; one tropical species is a vector of river-blindness caused by a filarial parasite.
\Bsink\b A buffering reservoir; any large reservoir that is capable of absorbing or receiving energy or matter without undergoing significant change.
\Bsiotropism\b An orientation response to shaking; \Bsiotropic.\b
\BSiphonales\b \JBryopsidales\j; also treated as a distinct class of the protoctistan phylum Chlorophyta.
\BSiphonaptera\b Fleas; order containing about 1750 species of small wingless holometabolous insects that as adults are blood-feeding ectoparasites of warm-blooded animals, mainly mammals but including some birds; body compressed and hairy, mouthparts specialized for piercing and sucking; legs adapted for grasping and jumping; the larvae are blind and limbless, typically non-parasitic feeding on organic matter around domicile of host; fleas are of medical and veterinary importance as disease vectors and intermediate hosts of various parasitic worms.
\BSiphoniulida\b Order of minute (to 7 mm) helminthomorphan diplopods (millipedes) comprising only 2 species from Sumatra and Guatamala.
\BSiphonocladales\b Small order of tropical marine green algae in which the thallus is non-cellular (vesicular) and attached by rhizoids which are often septate.
\Bsiphonogamy\b Fertilization by means of a pollen tube; \Bsiphonogamous.\b
\BSiphonophora\b An exclusively marine order of colonial Hydrozoa found worldwide in surface waters; characterized by the lack of a medusa phase and by the polymorphism of the individual zooids; all zooids are in communication via their gastrovascular canals but zooids may be specialized as a gas float (pneumatophore), swimming bell (nectophore), for prey capture (dactylozooid), feeding (gastrozooid) or reproduction (gonozooid); several species, including the Portuguese man o'war, inflict painful stings.
\BSiphonophorida\b Order of mainly tropical helminthomorphan diplopods (millipedes) having a slender setose or glabrous body lacking a median dorsal suture; head prolonged anteriorly, bearing reduced suctorial mouthparts.
\BSiphonostomatoida\b Order containing about 1500 species of predominantly marine copepod crustaceans which have a tubular sucking mouth and are typically parasites of fishes and marine invertebrates.
\BSipuncula\b Peanut worms; small phylum of unsegmented sedentary coelomate marine worms that burrow into soft sediments, gravel, calcareous rock or coral, inhabit crevices or live beneath stones, and range from the intertidal to abyssal depths; body usually divided into stout trunk and elongate retractable anterior introvert carrying the mouth and often encircled by tentacles; gut U-shaped, opening on dorsal surface at base of introvert; larvae planktonic; contains about 320 species.
\Bsire\b In animal breeding, the male parent; See also \Jdam\j
\BSirenia\b Sea cows; order of large aquatic herbivorous mammals (Ferungulata) comprising 2 families, Trichechidae (manatee) and Dugongidae (dugong); head robust bearing large lips, teeth present or absent; body massive, forelimbs modified as flippers, hindlimbs absent, tail forming lateral flukes; eyes small, ear lobes absent.
\BSirenidae\b Sirens; family containing 3 species of eel-like aquatic salamanders (Caudata) from southeastern United States; hindlimbs and pelvic girdle absent; metamorphosis incomplete, external gills and gill slits present, eyelids absent; eggs laid singly or in groups on submergent vegetation, fertilization external.
\BSiricidae\b Horntails; family containing about 90 species of large wood wasps (Hymenoptera) typically having a long cylindrical body lacking a distinct waist and coloured black banded with red or yellow, or with metallic blue sheen; larvae bore into trees or wood, and may carry a fungus that causes damage to timber.
\BSisoridae\b Family containing about 40 species of freshwater catfishes (Siluriformes) found in fast-flowing montane streams of south and southeast Asia; body depressed, to 2 m length, some forms with ventral adhesive organ; dorsal fin bearing 2 spines; 4 pairs of barbels present.
\Bsitotropism\b An orientation response to a food stimulus; \Bsitotropic.\b
\BSittidae\b Nuthatches; family containing about 20 species of small passerine birds found primarily in forests and rocky habitats of the northern hemisphere; bill stout and compressed; legs short, toes and claws elongate, strong; habits solitary or weakly gregarious, arboreal, non-migratory, feeding mainly on insects and seeds; nest in tree or rock cavity.
\Bsivapithecines\b Extinct group of Miocene apes known from fossil fragments found in Europe, Turkey, India, Pakistan and China; closely resemble the ramapithecines and placed by some authorities in the same genus, \ISivapithecus\i; their hominid affinities are uncertain, having facial and other features that link them also to chimpanzees and gorillas as well as to orang-utans.
\Bskate\b \JRajiformes\j
\Bskatobios\b Those organisms inhabiting detritus or faecal matter; \Bskatobiont\b, \Bskatobiontic.\b
\Bskeletal soil\b \JLithosol\j
\Bskeleton shrimp\b \JCaprellidea\j
\Bskilfish\b \JAnoplopomatidae\j
\Bskimmer\b \JRynchopidae\j
\Bskin beetle\b \JDermestidae\j
\Bskink\b \JScincidae\j
\Bskiophilous\b Thriving in shaded situations, or in habitats of low light intensity; \Bskiophile\b, \Bskiophily.\b
\Bskiophyllous\b \JSciophyllous\j
\Bskiophyte\b A plant growing in shady situations or in habitats of low light intensity; See also \Jheliophyte\j
\Bskotophilic\b 1: Thriving in darkness or in darkened situations; scotophilic; \Bskotophile\b, \Bskotophily.\b 2: Pertaining to the dark phase of a light/dark cycle.
\Bskotoplankton\b Planktonic organisms living in darkness, below the photic zone; see also \Jknephoplankton\j \Jphaoplankton\j
\Bskototaxis\b The directed movement of a motile organism towards a dark area, as distinct from negative phototaxis; scototaxis; \Bskototactic.\b
\Bskototropism\b An orientation movement towards a dark area; scototropism; \Bskototropic.\b
\Bskua\b \JStercorariidae\j
\Bskunk\b \JMustelidae\j
\Bskunk cabbage\b \JAracaceae\j
\Bslack water\b An interval of low velocity tidal current, usually the period of reversal between ebb and flow.
\Bslater\b \JOniscoidea\j
\Bslick\b An aggregation of floating debris resulting in reduced wave activity and a shiny water surface.
\BSmilacaceae\b Nearly cosmopolitan family of Liliales comprising about 300 species of mostly climbing, herbaceous or woody vines with branched leafy stems frequently bearing recurved prickles; leaves petiolate and often with a pair of tendrils arising from the petiole, blades expanded and with curved convergent veins.
\Bsnow line\b The line marking the lower altitudinal limit of perpetual snow.
\Bsnowberry\b \JCaprifoliaceae\j
\Bsnowdrop tree\b \JStyracaceae\j
\Bsoap fish\b \JGrammistidae\j
\Bsoapberry\b \JSapindaceae\j
\Bsoari nut\b \JCaryocaraceae\j
\Bsocial\b Pertaining to a society, or to the interrelationships between organisms.
\Bsocial parasitism\b A symbiosis in which a parasite diverts to its own use the workers of the host-species society.
\Bsocialization\b The modification of the behaviour of an organism as an adaptation to social existence.
\Bsociety\b 1: A group of organisms of the same species which has a social structure and consists of repeated members or modular units. 2: A ranked category in the classification of vegetation; a small plant climax community.
\Bsociobiology\b Study of the biological basis of social behaviour.
\Bsociology\b The study of communities or of collectively organized groups of animals or plants.
\Bsociotomy\b The fission of a termite colony.
\Bsoft coral\b \JAlcyonacea\j
\Bsoft tick\b Any of the ixodid tick family Argasidae that have a leathery cuticle, a ventrally located head and no head plate.
\Bsoft-shelled clam\b \JMyoida\j
\Bsoft-shelled turtle\b \JTrionychidae\j
\Bsoil\b The superficial weathered layers of the Earth's crust and any intermixed organic material.
\Bsoil evolution\b The sequence of changes in a soil profile during development towards maturity.
\Bsoil granulation scale\b A scale of soil particle sizes: coarse gravel/rubble (greater than 20 mm diameter), gravel (20-2 mm diameter), coarse sand (2-0.2 mm diameter), fine sand (0.2-0.02 mm diameter), silt/dust (0.02-0.002 mm diameter), fine silt/clay (less than 0.002 mm diameter).
\Bsoil horizons\b The horizontal subdivisions of a soil profile; often given the notation O-, A-, E-, B-, C- and R-horizons. See below.
\Bsoil moisture deficit\b The amount of water required to restore soil to its field \Jcapacity\j
\Bsoil profile\b A vertical section of a soil through the system of horizontal layers (soil horizons) more or less within the depth zone penetrated by plant roots.
\Bsoil reaction\b The measure of acidity or alkalinity of a soil, categorized according to pH value; extremely acid (less than 4.5), very strongly acid (4.5-5.0), strongly acid (5.1-5.5), moderately acid (5.6-6.0), slightly acid (6.1-6.5), neutral (6.6-7.3), slightly alkaline (7.4-7.8), moderately alkaline (7.9-8.4), strongly alkaline (8.5-9.0), very strongly alkaline (greater than 9.1).
\Bsoil skeleton\b The chemically inert quartz fraction of a soil.
\Bsoil structure\b The macrostructure of a soil; the aggregation of soil particles into compound units (or peds), described according to shape of units - crumb (rounded), prismatic (vertically elongated), and platy (flattened).
\BSolanaceae\b Potato, tomato, capsicum (peppers), belladonna, Chinese lantern, aubergine, egg plant, thorn apple, tobacco, petunia, deadly nightshade, henbane, jimsonweed; large family containing about 2300 species of herbs, shrubs, vines or trees; often prickly, commonly producing alkaloids especially of the tropane and nicotine groups; cosmopolitan in distribution but best developed in South America; flowers usually regular and bisexual, commonly with 5 sepals and petals, 5 or fewer stamens and a superior ovary that develops into a berry or capsule.
\BSolanales\b Order of Asteridae containing 8 families of plants often producing alkaloids but never cardiotonic glycosides; the majority of species are in the families Convolvulaceae and Solanaceae.
\Bsolar day\b The mean time interval between consecutive sunrises, or any other given position of the sun; 24 h; see also \Jlunar day\j \Jsidereal day\j
\Bsolar radiation\b The radiant energy emitted by the sun; the ecosphere receives solar radiation at wavelengths ranging from 290 nm to about 3000 nm.
\Bsolarization\b The inhibitory effect of extremely high light intensities on photosynthesis, resulting largely from photo-oxidation.
\Bsoldier beetle\b \JCantharidae\j
\Bsoldier fly\b \JStratiomyidae\j
\Bsoldierfish\b \JHolocentridae\j
\Bsole\b \JSoleidae\j
\BSoleidae\b Soles; family containing about 120 species of primarily shallow marine soleiform flatfishes (Pleuronectiformes) in which the eyes are on the right side of the head; body length to 500 mm; some species commercially important as food-fishes.
\BSolemyoida\b Order of burrowing, marine protobranch bivalve molluscs characterized by the anterior shell-closing muscle being much larger than the posterior and by a papillate sole on the foot.
\BSolenochilida\b Extinct order of globose cephalopod molluscs (Nautiloidea) in which the siphuncle is ventral and the sutures simple; known from Lower Carboniferous to end of Permian.
\BSolenodontidae\b Family of primitive, rat-like, terrestrial, nocturnal mammals (Insectivora) found in forests of Cuba and Hispaniola; contains 2 Recent monotypic genera, both rare, one possibly extinct.
\BSolenogastres\b Class of marine, free-living or epizoic molluscs which feed almost exclusively on cnidarians; characterized by a vermiform, laterally compressed body which is primitively shell-less although the mantle enclosing most of the body comprises one or more layers of embedded calcareous scales or spicules and a covering cuticle; foot represented by a long midventral groove; comprises about 180 species in 4 orders, Cavibelonia, Neomeniamorpha, Pholidoskepia and Sterrofustia; formerly known as the Aplacophora.
\BSolenostomidae\b Family containing 4 species of small (to 170 mm) tropical Indo-Pacific, shallow marine gasterosteiform pipefishes; body stout, with armour of bony plates, snout elongate; female pelvic fins attached to body distally to form a brood pouch for eggs.
\BSoleoidei\b Soles; suborder of primarily marine flatfishes (Pleuronectiformes) comprising 2 families, Soleidae and Cynoglossidae; median fins lacking spine rays, pectorals small or absent; jaws asymmetrical, vomerine and palatine teeth absent; use undulations of body for locomotion.
\Bsolifluction\b The gradual downhill flow of fragmented surface material, typically over a frozen substratum.
\BSolifugae\b \JSolpugida\j
\BSolifugida\b \JSolpugida\j
\Bsolitary wasp\b \JEumenidae\j
\BSolod soil\b Soloth \Jsoil\j
\BSolonchak\b An intrazonal soil with grey shallow salty surface layer over a fine mulch and a greyish salty lower horizon, formed in subhumid to arid climates under conditions of poor drainage and halophytic vegetation.
\BSolonetz\b An intrazonal soil with a thin friable surface layer over a dark alkaline horizon, formed in subhumid to arid climates under conditions of moderate drainage and sparse halophytic vegetation; soil formed by leaching of salts from a \JSolonchak\j soil.
\BSoloth\b An intrazonal soil with a light brown friable leached surface layer over a dark lower horizon, formed as a desalinated, decalcified, degraded \JSolonetz\j soil, in subhumid to arid climates under conditions of moderate drainage; Solod soil.
\BSolpugida\b Wind scorpions, sun scorpions; order of long-legged predatory arthropods (Arachnida) comprising about 900 species confined mostly to deserts and arid habitats; chelicerae massive, pedipalps elongate and leg-like; first pair of legs small and slender, used as feelers; abdomen 11-segmented, bearing 3 pairs of tracheae.
\Bsolstitial tide\b The tide occurring near the times of the solstices when the sun reaches its greatest northerly or southerly declination; See also \Jtropic tide\j
\Bsolubility\b The extent to which a substance (solute) mixes with a liquid (solvent) to produce a homogeneous mixture (solution).
\BSomali Current\b A warm surface ocean current that flows northwards off the coast of Somalia, produced by the southwesterly winds of the summer monsoon; South West Monsoon Drift; see ocean currents.
\BSomasteroidea\b Subclass of primitive asterozoan echinoderms comprising a single living species in the order, Goniactinida.
\Bsomatic\b Pertaining to the body or any nongerminal cell, tissue, structure or process.
\Bsomatogamy\b A form of \Jplasmogamy\j in which somatic cells or hyphae fuse.
\Bsomatogenesis\b The development of somatic structure; \Bsomatogenetic.\b
\Bsomatropism\b An orientation response to the substratum; \Bsomatotropic\b, \Bsomatropic.\b
\Bsonagram\b A graphic representation of animal vocalizations.
\Bsong\b An elaborate vocal signal.
\Bsoniferous\b Capable of producing sounds; \Bsonic.\b
\BSonneratiaceae\b Small family of Myrtales containing 8 species of tanniferous trees with internal phloem; all native to the Old World tropics; flowers often nocturnal, sour-smelling and pollinated by bats.
\BSooglossidae\b Small family containing 3 species of terrestrial frogs (Anura) confined to the Seychelle Islands.
\Bsooty mould\b \JChaetothyriales\j
\BSordariales\b Order of pyrenomycete fungi which are widely distributed on plant debris, seeds and dung; characterized by a dark, membranous ascocarp wall and mostly cylindrical asci which are deliquescent at maturity.
\Bsorghum\b \JPoaceae\j
\BSoricidae\b Shrews; family containing about 250 species of small, active, mouse-like mammals (Insectivora) which may be terrestrial, semiaquatic or burrowing.
\BSoricoidea\b Superfamily of insectivores (Lipotyphla) comprising the families Soricidae (shrews) and Talpidae (moles), also sometimes including the Solenodontidae (solenodon), Tenrecidae (tenrecs) and Chrysochloridae (golden moles).
\Bsorosis\b A multiple fruit derived from the ovaries of several flowers.
\Bsorrel\b \JPolygonales\j
\Bsorus\b A reproductive structure comprising several spore-producing sporangia; found on the underside of fern fronds and in some algae and fungi; \Bsori.\b
\Bsouari nut\b \JCaryocaraceae\j
\Bsour gum\b \JNyssaceae\j
\Bsourwood\b \JEricaceae\j
\BSouth Atlantic Gyre\b The major anticlockwise circulation of surface ocean water in the South Atlantic; see ocean currents.
\BSouth Equatorial Countercurrent\b A warm surface ocean current that flows eastwards in the equatorial Pacific; see ocean currents.
\BSouth Equatorial Current\b A warm surface ocean current that flows westwards in the equatorial Pacific and forms the northern limb of the South Pacific Gyre; see ocean currents.
\BSouth Indian Gyre\b The major anticlockwise circulation of surface ocean water in the southern Indian Ocean; see ocean currents.
\BSouth Pacific Gyre\b The major anticlockwise circulation of surface ocean water in the South Pacific; see ocean currents.
\BSouth West Monsoon Drift\b Somali \JCurrent\j
\Bsow bug\b \JOniscoidea\j
\Bsoybean\b \JFabaceae\j
\Bspadefish\b \JEphippidae\j
\Bspadefoot toad\b \JPelobatidae\j
\Bspadix\b A \Jspike\j of usually unisexual flowers on a fleshy central axis, typically protected by a large petal-like bract, the spathe.
\Bspaghetti eel\b \JMoringuidae\j
\BSpalacidae\b Mole rats; family containing 3 species of fossorial myomorph rodents found in southern Europe and around the eastern Mediterranean; body fusiform, length to 300 mm, eyes and tail absent; limbs short; incisor teeth used for digging; feed mainly on tubers and roots.
\BSpanish moss\b \JBromeliales\j
\BSparganiaceae\b Bur reeds; family of Typhales containing 13 species of perennial herbs emergent from shallow water or with floating leaves; native chiefly to north temperate regions.
\BSparidae\b Porgies, sea breams; family containing about 100 species of primarily bottom-feeding teleost fishes (Perciformes) widespread in tropical and temperate seas; body deep and compressed, to 1.2 m length; head large, mouth weakly protractile; single dorsal fin present; many species hermaphroditic.
\BSpatangoida\b Heart urchins, bottle urchins; cosmopolitan order of littoral to abyssal echinoids (Atelostomata) comprising about 275 species; exhibiting pronounced bilateral symmetry and variously specialized spines and tube-feet; mouth displaced to anterior position; burrow into soft sediment maintaining respiratory passages to surface by means of long spines or tube-feet; fossil record extends from the Cretaceous.
\BSpathebothriidea\b Order of tapeworms parasitic in freshwater and marine fishes and utilizing crustaceans as intermediate hosts; characterized by a weakly developed scolex and by the absence of external segmentation but possessing several, serially arranged, sets of reproductive organs.
\Bspawn\b The eggs of certain aquatic organisms; also the act of producing such eggs or egg masses.
\Bspay\b The removal of, or interference with the activity of, the ovaries of a female; See also \Jgeld\j
\Bspecialization\b Evolutionary adaptation to a particular mode of life or habitat.
\Bspecialized\b Adapted to perform a particular function; highly modified from the ancestral condition and no longer able to carry out the function performed when in the ancestral state.
\Bspeciation\b The formation of new species; the acquisition of reproductive isolating mechanisms producing discontinuities between populations.
\Bspecies\b 1: A group of organisms, minerals or other entities formally recognized as distinct from other groups. 2: A taxon of the rank of species; in the hierarchy of biological classification the category below genus; the basic unit of biological classification; the lowest principal category of botanical and zoological classification.
\Bspecies odour\b The particular odour found on the bodies of social insects that is peculiar to a given species.
\Bspecies richness\b The absolute number of species in an assemblage or community.
\Bspecies-flock\b A group of several ecologically diverse and closely related species that have evolved within a single macrohabitat, such as a particular lake basin.
\Bspecific\b Pertaining to a particular individual, trait, or species.
\Bspectre\b \JPhasmoptera\j
\Bspeedwell\b \JScrophulariaceae\j
\BSpelaeogriphacea\b Primitive order of small, blind, shrimp-like peracaridan crustaceans comprising a single freshwater, cavernicolous species found in southern Africa; eggs incubated in ventral brood pouch.
\Bspeleology\b The study of caves; \Bspeleological.\b
\Bspeleotherm\b A structure within a cave formed by the deposition of secondary minerals, such as a stalactite or stalagmite.
\Bsperm\b Male gamete; spermatozoon.
\Bsperm whale\b \JPhyseteridae\j
\Bspermatize\b Fertilize; impregnate.
\Bspermatocyte\b The cell that produces male gametes by meiotic division: See also \Joocyte\j
\Bspermatogamete\b A male gamete; sperm.
\Bspermatogenesis\b The process of sperm formation; spermogenesis; \Bspermatogenic.\b
\BSpermatophyta\b The seed-bearing plants; a division of plants comprising the gymnosperms (Pinophyta) and angiosperms (Magnoliophyta); probably arose from pteridophyte ancestors during the Devonian.
\Bspermatozoon\b A male gamete; sperm; spermatozoan.
\Bspermiogenesis\b The transformation of a spermatid into a spermatozoon.
\Bspermology\b The study of seeds.
\Bspermophilic\b Feeding on seeds; \Bspermophile\b, \Bspermophily.\b
\BSphacelariales\b Order of widely distributed brown algae with a tufted filamentous body form; growth usually occurring from a large, dense, apical meristematic cell.
\BSphaerocarpales\b Small order of liverworts (Hepaticopsida); plants organized as a small lobate thallus or a stem-like axis with lateral leaves or a dorsal lamina: possessing smooth rhizoids; female sex organs not involving apical cell; produce a sporophyte capsule on a short to obsolescent stalk which liberates spores as its walls decay.
\BSphaeropleales\b Small order of freshwater green algae in which the thallus is an unbranched filament composed of very elongate, banded, multinucleate cells.
\BSphaeropsidales\b Large order of coelomycete fungi containing over 6000 species which are mostly parasitic or saprobic on plant material; produce fruiting bodies containing a conidia-producing layer within enclosing walls of sterile tissues.
\BSphaerosepalaceae\b Small family of Theales comprising 14 species of woody plants with simple unicellular hairs, confined to Madagascar.
\BSphaerotheriida\b Order of oniscomorphan diplopods (millipedes) comprising about 160 species widespread in the southern hemisphere, except South America.
\Bsphagnicolous\b Living in peat-moss; \Bsphagnicole.\b
\Bsphagnophilous\b Thriving on \ISphagnum\i moss, or in \ISphagnum\i-rich habitats; \Bsphagnophile\b, \Bsphagnophily.\b
\BSphagnopsida\b Peat mosses; class of bryophytes comprising a single genus, \ISphagnum\i; typically found in acidic mire habitats and may dominate lowland boreal areas of northern hemisphere; stems mostly erect and sparsely, dichotomously branching with differentiated stem, branch and leaves; stem consisting of central core surrounded by cortical cells and a hyalodermis; sporophytes produced terminally and borne on a stalk (pseudopodia) of gametophytic tissue.
\BSphecidae\b Digger wasps; family of minute to large, winged wasps (Hymenoptera) which dig nests in soil, wood or other plant cavities; adults feeding on nectar, honeydew or occasionally on blood fluids oozing from captured prey; eggs laid one per cell on prey placed in cell by female; sometimes additional prey are brought during larval development; contains nearly 8000 species, distributed worldwide except for extremely cold regions.
\Bsphecology\b The study of wasps.
\BSpheniscidae\b Penguins; family containing 18 species of flightless marine neornithine birds widespread in the cold Southern Ocean extending north to Galapagos Islands; very efficient swimmers using wings modified as flippers; feet positioned posteriorly providing upright stance; move on land by hopping, walking or tobogganing; coloration typically black and white; feed on fishes, crustaceans and squid.
\BSphenisciformes\b Order of birds comprising a single family, Spheniscidae (penguins).
\BSphenocleaceae\b Family of Campanulales containing only 2 species of annual herbs with large air passages in the cortex; pantropical in distribution.
\BSphenodontidae\b Tuatara; monotypic family of primitive lizard-like reptiles (Rhyncocephalia) confined to a few small islands off New Zealand; body length to about 0.5 m; inhabit petrel burrows, feeding nocturnally on invertebrates and small vertebrates; estimated to take 20 years to attain sexual maturity.
\BSphenomonadales\b Order of colourless euglenoid flagellates which may be osmotrophic or phagotrophic.
\BSphenopsida\b Horsetails; the \JEquisetophyta\j classified as a subdivision of the Pteridophyta.
\BSphinctozoa\b Subclass of calcareous sponges containing a single species found in shaded submarine caves and crevices between 5 and 40 m in the Indo-West Pacific; characterized by the production of a solid aragonite skeleton consisting of a series of chambers.
\BSphingidae\b Hawk moths; family of medium-sized to large moths (Lepidoptera) typically having long triangular wings and an elongate body, adapted for hovering flight; several are mimics of hummingbirds or bumblebees; contains about 850 species, most abundant in tropical regions; larvae of some species are pests of agricultural crops such as tomato, tobacco and sweet potato.
\Bsphingophilous\b Pollinated by hawk moths or nocturnal Lepidoptera; \Bsphingophile\b, \Bsphingophily.\b
\BSphyraenidae\b Barracudas; family containing 18 species of large (to 1.8 m) tropical and subtropical, predatory marine teleost fishes (Perciformes) found mainly in inshore waters and estuaries; body slender with pointed snout, mouth large bearing strong sharp teeth; 2 dorsal fins present; popular as sport and food-fishes.
\BSphyraenoidei\b Suborder of predatory marine teleost fishes (Perciformes) comprising a single family, Sphyraenidae (barracudas).
\Bsphyric\b Pertaining to rock slides.
\BSphyrnidae\b Hammerhead sharks; family containing 8 species of small to large (to 6 m) marine carcharhiniform elasmobranch fishes in which the sides of the head are expanded into flattened blades bearing the eyes; found in shallow waters, to 300 m depth in tropical and warm temperate regions, feeding mainly on other fishes; reproduction viviparous, with yolk sac placenta; the expanded head lobes are thought to enhance manoeuvrability.
\Bspider\b \JAraneae\j
\Bspider beetle\b \JPtinidae\j
\Bspider monkey\b \JCebidae\j
\Bspider plant\b \JLiliaceae\j
\Bspider wasp\b \JPompilidae\j
\Bspiderwort\b \JCommelinaceae\j
\Bspike\b A racemose inflorescence comprising stalkless flowers on an elongated central axis.
\Bspike moss\b \JSelaginellales\j
\Bspikefish\b \JTriacanthidae\j
\Bspiladophilous\b Thriving on clay or in clay-rich habitats; \Bspiladophile\b, \Bspiladophily.\b
\Bspiladophyte\b A plant living on clay soils.
\Bspinach\b \JChenopodiaceae\j
\Bspindle tree\b \JCelastraceae\j
\BSpinosauridae\b Extinct family of carnivorous dinosaurs (Saurischia) in which the neural spines were elongated, presumably forming a sail-like dorsal fin; known from the Cretaceous.
\BSpintherida\b Order of polychaete worms comprising a single family and about 9 species ectoparasitic on marine sponges; body flattened ventrally, anterior parapodia fused, pharynx large and eversible; parapodia biramous; cirri and branchiae absent.
\BSpinulosida\b Large order of intertidal to deep-sea asteroidean echinoderms that includes the notorious crown-of-thorns sea star, \IAcanthaster\i, which can cause extensive damage to coral reefs when abundant.
\BSpionida\b Order of burrowing or tubicolous, marine and occasionally freshwater, polychaete worms comprising about 700 species in 8 families, found from intertidal to abyssal depths; body divided into distinct regions; prostomium bearing pair of tentacular palps; pharynx eversible, ciliated, unarmed; parapodia biramous with simple setae.
\BSpiraculata\b Extinct order of echinoderms (Blastoidea) with hidden hydrospire slits; known from the Silurian to the Permian.
\Bspirea\b \JVerbenaceae\j
\BSpiriferida\b Extinct order of articulate brachiopods with spiral brachidia; known from the Ordovician to the Jurassic.
\BSpirobolida\b Order of helminthomorphan diplopods (millipedes) comprising about 450 species, having a largely tropical distribution but extending into temperate North America body cylindrical, polished, to 180 mm length; some large species can eject an allomone spray over distances of up to 1 m.
\BSpirochaetes\b Group of helical, non-flagellated motile bacteria which are chemoheterotrophic and occur as free-living saprobic forms in aquatic habitats, or as pathogens.
\BSpirophorida\b Small order of tetractinomorph sponges usually found on soft bottom sediments to which they are attached by a base mat of tangled spicules.
\BSpirostreptida\b Diverse order containing about 1500 species of helminthomorphan diplopods (millipedes) that includes the largest known species with a body length of 300 mm; body may have up to 90 segments.
\BSpirotricha\b Sole subclass of polyhymenophoran ciliates.
\BSpiruria\b Subclass of secernentean nematodes that are obligate parasites of vertebrates typically with arthropod intermediate hosts; characterized by 6 apical lobes surrounding the mouth or by 2 lateral lips; males have 2 spicules often unequal in length; comprises 2 orders, Spirurida and Camallanida.
\BSpirurida\b Order of spirurian nematodes found as parasites of terrestrial and aquatic vertebrates, and in annelids; involving various invertebrate intermediate hosts in the life cycle; characterized by a cephalic hook and a pore-like phasmid on the tail of the newly hatched larva.
\Bspittlebug\b \JCercopidae\j
\BSplachnales\b Small order of mosses (Bryidae); plants forming mats and tufts on soil or decaying organic matter; stems erect and simple or forked, bearing terminal sporophytes; sometimes classified in the Funariales.
\Bsplash erosion\b The displacement of soil particles by impacting rain droplets.
\Bsplash zone\b The region of the shore immediately above the highest water level that is subject to wetting by splash from breaking waves; see marine depth zones.
\Bsponge\b \JPorifera\j
\Bspongicolous\b Living on or in sponges; \Bspongicole.\b
\Bspongilla fly\b \JNeuroptera\j
\BSpongiomorphida\b Extinct order of cnidarians (Hydroida) exhibiting a structure of stellate, vertical tubules; found in warm shallow seas during the Triassic and Jurassic.
\Bspoonbill\b \JThreskiornithidae\j
\Bspoonworm\b \JEchiura\j
\Bspore\b A plant reproductive cell capable of developing into a new individual, directly or after fusion with another spore; produced either by meiosis (meiospores) or by mitosis (gonidia).
\Bsporiferous\b Bearing or producing spores.
\BSporochnales\b Order of brown algae found in warm waters; characterized by a branched body form with the branches terminating in distinctive tufts of filaments.
\Bsporogamy\b Production of spores by an organism developed from a zygote; \Bsporogamic. \b
\Bsporogenesis\b The formation of spores; reproduction by means of spores; \Bsporogenic.\b
\Bsporogenous\b Spore-producing.
\Bsporogony\b Multiple fission of a cell (sporont) to produce many dormant spores (sporozoites); \Bsporogonous\b.
\Bsporophyte\b The diploid, spore-producing, asexual generation in the life cycle of a plant; typically formed by fusion of haploid gametes.
\BSporozoa\b Class of apicomplexan protozoans which generally reproduce by alternation of asexual and sexual phases, the latter resulting in the formation of resistant cysts containing infective stages (sporozoites) which commence the asexual phase; contains about 3900 species in 3 subclasses, Gregarinia, Coccidia and Piroplasmia; Telosporidea.
\BSporozoasida\b A group of unicellular organisms comprising the \JGregarinia\j and the \JCoccidia\j; treated as a class of the protoctistan phylum Apicomplexa.
\Bsport\b Any freak, or somatic mutation, that deviates from the basic type; rogue.
\Bsporulation\b The production or liberation of spores.
\Bspory\b The formation of spores; reproduction by means of spores.
\Bspray zone\b The region of the shore immediately above the splash zone that is subject to wetting by the spray from breaking waves; see marine depth zones.
\Bspring tide\b A tide of maximum range occurring at the time of new and full moon, when the gravitational attraction of the sun and the moon act together during \Jsyzygy\j; See also \Jneap tide\j
\Bspringhaas\b \JPedetidae\j
\Bspringtail\b \JCollembola\j
\BSpumellarida\b Order of radiolarians (Polycystina) in which the central capsule is uniformly perforated and which produce swarmers containing a crystal of strontium.
\Bspurge laurel\b \JThymelaeaceae\j
\BSqualidae\b Large cosmopolitan family containing about 70 species of small to medium-sized (to 7 m) squaliform sharks; body slender or stout, dorsal fins small, with or without spines, mouth short; mostly benthic, active or sluggish, some species mesoor bathypelagic; reproduction viviparous, without placenta.
\BSqualiformes\b Order of small to medium-sized (0.1-7 m) squalomorph sharks, mostly benthic in deep water to 3000 m; body subcylindrical with 2 dorsal fins, anal fin absent, caudal fin with small lower lobe, rostrum trough-shaped; notochord usually constricted with well calcified vertebral centra.
\BSqualodontoidea\b Shark-toothed whales; extinct superfamily of toothed whales (Odontoceta) resembling porpoises, often with an elongate beak carrying triangular teeth proximally; widely distributed during the Miocene.
\BSqualomorphii\b Superorder of primarily deepwater elasmobranch fishes comprising about 80 species in 3 orders, Hexanchiformes, Squaliformes and Pristiophoriformes.
\BSquamata\b Large and very diverse order of lepidosaurian reptiles comprising 3 suborders, Sauria (lizards), Serpentes (snakes) and Amphisbaenia (worm lizards); habits including terrestrial, aquatic, arboreal and fossorial; reproductive strategies vary from oviparous to viviparous; contains the great majority of living reptiles.
\Bsquash\b \JCucurbitaceae\j
\Bsquat lobster\b \JAnomura\j
\BSquatinidae\b Angel sharks, monkfish; family containing 10 species of tropical to warm temperate elasmobranch fishes; body strongly depressed, pectoral fins large and demarcated from head, pelvic and caudal fins also well developed; mouth bearing numerous small sharp teeth; feed on fishes, molluscs and crustaceans; reproduction viviparous, without placenta.
\BSquatiniformes\b Monofamilial order of benthic marine elasmobranch fishes.
\BSquatinimorphii\b Superorder of neoselachian elasmobranch fishes comprising a single order, Squatiniformes.
\Bsquid\b \JTeuthoidea\j
\Bsquirrel\b \JSciuridae\j
\Bsquirrel monkey\b \JCebidae\j
\Bsquirrelfish\b \JHolocentridae\j
\BSSSI\b Site of special scientific interest.
\Bstable fly\b \JMuscidae\j
\BStachyuraceae\b Small family of Violales containing about 6 species of tanniferous shrubs or small trees native from the Himalayan region to Japan; typically with waxy yellow flowers in leaf axils, arranged in groups of 12-20 in stiff, catkin-like raceme.
\BStackhousiaceae\b Family of Celastrales containing about 25 species of xerophytic, rhizomatous herbs; native principally to Australia and New Zealand; flowers typically with 5 fused sepals, 5 free or partly fused petals, 5 stamens and a superior ovary; seeds large with fleshy endosperm.
\Bstade\b A climatic episode within a glacial stage during which a secondary glacial advance occurs; \Bstadial\b; See also \Jinterstade\j
\Bstag beetle\b \JLucanidae\j
\Bstagnicolous\b Living in stagnant water; \Bstagnicole.\b
\Bstagnoplankton\b Planktonic organisms and floating vegetation of stagnant water bodies \Bstagnoplanktonic.\b
\Bstalked puffball\b \JTulostomatales\j
\Bstamen\b Each of the male reproductive organs a flower; typically differentiated into a filament bearing a distal anther where the pollen is produced; the whorl of stamens as known as the androecium.
\Bstaminode\b A sterile stamen.
\Bstand\b A unit of vegetation comprising a single species, homogeneous in composition and age.
\Bstanding crop\b Biomass; the total mass of organisms comprising all or part of a population or other specified group, or within a given area, measured as volume, mass (live, dead, dry, ash-free) or energy (calories); standing stock.
\BStannomida\b Order of Xenophyophores distinguished by the general flexibility of the body and by the presence of organic threads in the test; known only from the Indo-Pacific Ocean.
\BStaphyleaceae\b Bladdernut; family of Sapindales containing about 50 species of mucilage-producing shrubs and trees of widespread distribution; flowers arranged in showy panicles, each flower usually with 5 sepals, petals and stamens, and a superior ovary.
\BStaphylinidae\b Rove beetles; widely distributed family of often small beetles (Coleoptera) with usually short, truncate elytra; containing about 30 000 species found in a variety of habitats, especially leaf litter; mostly predators but some feed on fungal spores.
\Bstar anise\b \JIlliciaceae\j
\Bstar apple\b \JSapotaceae\j
\Bstar thistle\b \JAsterales\j
\Bstarch\b Complex carbohydrate composed of D-glucose molecules, occurring in 2 forms, amylase (straight-chained) and amylopectin (branch-chained).
\Bstar-eater\b \JAstronesthidae\j
\Bstarfish\b \JAsteroidea\j
\Bstargazer\b \JUranoscopidae\j
\Bstarling\b \JSturnidae\j
\Bstasis\b Cessation or retardation of growth or movement; \Bstatic.\b
\Bstasophilous\b Thriving in stagnant water; \Bstasophile\b, \Bstasophily.\b
\Bstasophyte\b A stagnant-water plant.
\Bstatary\b Pertaining to a relatively quiescent phase in the activity of a colony of social insects.
\Bstatice\b \JPlumbaginales\j
\Bstatistics\b Any kind of numerical data collection, organization and analysis; the branch of mathematics dealing with generalization, estimation and prediction in situations where uncertainty exists.
\Bstaurogamy\b Cross \Jfertilization\j
\BStauromedusae\b Small order of medusae (Scyphozoa) found primarily in shallow cold temperate and polar seas; characterized by a sessile medusa stage, typically attached to the substratum by an aboral stalk; Lucernariidae.
\Bsteady state\b An apparently unchanging condition of a system maintained at equilibrium by antagonistic processes.
\BStegosauridae\b Stegosaurs; extinct family of quadripedal, ornithischian dinosaurs; typically armoured with a double row of plates and spines along the back and tail; known mainly from the Jurassic.
\BStegostomatidae\b Zebra shark; monotypic family of inoffensive bottom-dwelling orectolobiform elasmobranch fishes (carpet sharks) found in coastal marine and estuarine waters of the Indian Ocean and western Pacific; body length to 4 m, pectoral fins much larger than pelvics, caudal without ventral lobe; reproduction oviparous; young with light markings on dark background, becoming dark spots on light surface in adult.
\BSteindachneriidae\b Monotypic family of tropical western Atlantic deep-water gadiform teleost fishes sometimes classified as part of the Macrouridae or Merlucciidae; tail elongate and tapering, single dorsal and anal fins; photophores present.
\BStellatosporea\b Class of \JAscetospora\j parasitic on invertebrates, characterized by the speckled appearance of the cytoplasm due to the presence of minute, electron-dense particles (haplosporosomes).
\BStelleroidea\b Sole extant class of \JAsterozoa\j
\Bstem wasp\b \JSymphyta\j
\Bstem-flow\b Rainwater flowing down a tree trunk or plant stem.
\BStemmiulida\b Order of helminthomorphan diplopods (millipedes) comprising about 70 species found in damp forest litter of the New World tropics; body compressed with marked dorsal suture; these millipedes may be very active and are able to jump clear of the substratum; the young hatch with numerous body segments and many pairs of legs.
\BStemonaceae\b Family of Liliales comprising about 30 species of erect herbs, herbaceous vines or low shrubs; commonly producing lactone alkaloids of a unique type; leaves consisting of a long petiole and broad blade with curved convergent primary veins; fruit is a bivalved capsule; native to eastern Asia, Malesia and northern Australia.
\BStemonitida\b The slime mould subclass \JStemonitomycetidae\j, treated as an order of the protozoan group Myxogastria.
\BStemonitomycetidae\b Subclass of plasmodial slime \Jmoulds\j (Myxomycetes) comprising a single order, Stemonitales, characterized by a plasmodium formed from a flattened network of strands which mass into a fan with trailing veins prior to formation of fruiting body which grows upwards from the underside of the plasmodial thallus; spores carried in dark masses within the fruiting body.
\BStenidae\b Small family of dolphins comprising 4 species which are commonly included in the family \JDelphinidae\j
\Bstenobaric\b Tolerant of a narrow range of atmospheric pressure or hydrostatic pressure; See also \Jeurybaric\j
\Bstenobathic\b Tolerant of a narrow range of depth; See also \Jeurybathic\j
\Bstenobenthic\b Living on the sea or lake bed within a narrow range of depth; See also \Jeurybenthic\j
\Bstenobiontic\b Used of an organism requiring a stable uniform habitat; See also \Jeurybiontic\j
\Bstenochoric\b Having a narrow range of distribution; See also \Jeurychoric\j
\Bstenoecious\b Restricted to a narrow range of habitats and environmental conditions; see also \Jamphioecious\j \Jeuryoecious\j
\Bstenohaline\b Used of organisms that are tolerant of only a narrow range of salinities; see also \Jeuryhaline\j \Jholeuryhaline\j, \Joligohaline\j, \Jpolystenohaline\j
\Bstenohydric\b Tolerant of a narrow range of moisture levels or humidity; \Icf\i euryhydric.
\Bstenohygric\b Tolerant of a narrow range of atmospheric humidity; See also \Jeuryhygric\j
\Bstenoionic\b Having or tolerating a narrow range of pH; See also \Jeuryionic\j
\BStenolaemata\b Class of marine bryozoans comprising a single order, Cyclostomata, in which the zooids are typically cylindrical and calcified; polymorphism limited to autozooids (feeding), gynozooids (female, reproductive) and kenozooids (structural); lophophore circular, epistome absent; reproduction involves polyembryony in which embryo repeatedly subdivides.
\BStenolpelmatidae\b Sand crickets, stone crickets; family of large, wingless, orthopterodean insects (Ensifera); commonly found in rotting logs, under stones or burrowing in sand; antennae typically longer than body.
\Bstenolumic\b Tolerant of a narrow range of light intensity; See also \Jeurylumic\j
\Bstenomorphic\b Pertaining to organisms that are of small size owing to cramped habitat conditions.
\Bstenophagous\b Utilizing only a limited variety of foods or food species; \Bstenophage\b, \Bstenophagy\b; See also \Jeuryphagous\j
\Bstenophotic\b Tolerant of a narrow range of light intensity; See also \Jeuryphotic\j
\BStenopodidea\b Shrimps; infraorder of pleocyematan decapod crustaceans; pleura of second abdominal segment not overlapping those of first segment; third thoracic leg chelate.
\Bstenothermic\b Tolerant of a narrow range of environmental temperatures; \Bstenotherm\b; See also \Jeurythermic\j
\Bstenothermophilic\b Tolerant of only a narrow range of high temperatures; \Bstenothermophile\b, \Bstenothermophily\b; See also \Jeurythermophilic\j
\Bstenotopic\b 1: Tolerant of a narrow range of habitats; \Bstenotopy\b. 2: Having a narrow geographical distribution; see also \Jamphitopic\j \Jeurytopic\j
\Bstenotropic\b Used of organisms exhibiting a limited response or adaptation to changing environmental conditions; \Bstenotropism\b; See also \Jeurytropic\j
\Bstenoxenous\b Tolerating only a narrow range of host species; See also \Jeuryxenous\j
\BStephanoberycidae\b Pricklefishes; family containing 3 species of small (to 120 mm) tropical abyssobenthic or bathypelagic beryciform teleost fishes; head very large, teeth minute and villiform; caudal fin bearing about 10 procurrent spines.
\Bsteppe\b Semi-arid areas of treeless grassland found in the mid-latitudes of Europe and Asia.
\Bstercoraceous\b Living on or in dung.
\BStercorariidae\b Skuas; family containing 5 species of large gull-like charadriiform sea birds; bill stout and strongly hooked, wings long and pointed, legs short; habits predacious, gregarious, aggressive, migratory, monogamous, feeding on variety of animals and carrion; cosmopolitan in distribution, breeding in high polar latitudes.
\BSterculiaceae\b Cacao, flame tree, bottletrees; family of Malvales containing about 1000 species of mostly woody tanniferous plants with stellate hairs or peltate scales; commonly producing complex cymes of regular flowers with 3-5 sepals, 5 or no petals, 2 whorls of stamens and superior ovaries.
\Bstereokinesis\b A change in linear or angular velocity in response to a contact stimulus; \Bstereokinetic.\b
\BStereomyxida\b Order of Acarpomyxa containing 4 species of marine amoebae with branched pseudopodia serving as organs of locomotion or flotation.
\Bstereotaxis\b A directed response of a motile organism to continuous contact with a solid surface; \Bstereotactic.\b
\Bstereotropism\b An orientation response to a contact stimulus; \Bstereotropic\b
\Bsterile\b 1: Unable to produce viable propagules or to reproduce sexually; \Bsterility.\b 2: Free from contamination by microorganisms.
\BSternaspida\b Order of polychaete worms comprising a single family of 6 species that burrow in littoral to abyssal soft sediments; body short and papillose; prostomium and peristomium naked, pharynx eversible, unarmed.
\BSternoptychidae\b Hatchetfishes; cosmopolitan family containing 35 species of tiny (to 70 mm) luminescent pelagic marine stomiiform teleost fishes found from surface to depths over 3500 m; body very deep and compressed, silvery; mouth almost vertical, eyes occasionally telescopic; photophores present on ventral surface.
\Bsterrhophilous\b Thriving on moorland; \Bsterrhophile\b, \Bsterrhophily.\b
\Bsterrhophyte\b A moorland plant.
\Bsterric\b Pertaining to a heath community or heathland habitat.
\BSterrofustia\b Order of solenogastres characterized by a mantle integument with several layers of solid, mainly needle-like, calcareous bodies, and by the presence of stalked epidermal papillae.
\BStichaeidae\b Pricklebacks; family containing about 55 species of mainly northern Pacific, intertidal and shallow marine, blennioid teleost fishes (Perciformes); body slender, to 500 mm length, naked or with small scales; dorsal fin long and spinose.
\Bstick insect\b \JPhasmoptera\j
\Bstickleback\b \JGasterosteidae\j
\Bstigma\b The receptive apex of a carpel in flowering plants upon which the pollen grain germinates.
\BStigonematales\b Order of complex blue-green algae found in freshwater and marine habitats; contains uniseriate or multiseriate filamentous forms that exhibit true branching.
\BStilbellales\b Cosmopolitan order of hyphomycete fungi comprising about 500 species in a single family; includes many saprophytes as well as parasites of flowering plants and insects.
\Bstock\b 1: The stem of a plant that receives a graft. 2: \JBrassicaceae\j
\BStolidobranchia\b Order of littoral to abyssal, solitary or colonial, tunicates (Ascidiacea) having the gonads in the body wall, and the branchial sac with internal longitudinal bars and folding; fertilization often external with free-living larva, but development may be more or less direct and may include asexual budding from atrial wall.
\Bstolon\b A branch which comes into contact with the ground and may produce a new plant from an axillary bud at a node touching the soil.
\BStolonifera\b Order of primitive colonial octocorals found mainly in shallow tropical seas; characterized by the production of simple cylindrical polyps from a ribbon-like stolon creeping over the substratum.
\BStolonoidea\b Extinct order of encrusting or sessile graptolites known from the Lower Ordovician.
\BStomatopoda\b Mantis shrimps; only extant order of the crustacean subclass Hoplocarida, containing about 350 species, most abundant in shallow tropical seas; all are raptorial predators, typically inhabiting burrows and crevices from where they emerge to spear or smash prey using powerful claws.
\BStomiatidae\b \JStomiidae\j
\BStomiidae\b Scaly dragonfishes; family containing 9 species of luminescent deep-sea stomiiform teleost fishes; body elongate, to 400 mm in length, photophores present laterally and ventrally; long barbel below mouth bearing light organ acting as lure; teeth fang-like.
\BStomiiformes\b Order of mainly deep-sea luminescent teleost fishes comprising about 230 species in 8 families and including bristlemouths, lightfishes, hatchetfishes, viperfishes, dragonfishes, snaggletooths, and loosejaws.
\BStomochordata\b \JHemichordata\j
\Bstone\b A sediment particle larger than 20 mm in diameter; a component of gravel; see sediment particle size.
\BStone Age\b An archaeological period dating from about 10 000 years B.P.; the earliest technological period of human history characterised by the use of stone tools; three periods are recognised, Palaeolithic, Mesolithic and \JNeolithic\j
\Bstone cricket\b \JStenolpelmatidae\j
\Bstone curlew\b \JBurhinidae\j
\Bstone plant\b \JAizoaceae\j
\Bstonefish\b \JSynanceiidae\j
\Bstonefly\b \JPlecoptera\j
\Bstonewort\b \JCharophyceae\j
\Bstony coral\b \JScleractinia\j
\Bstorey\b A horizontal layer of a given height within a stratified plant community.
\Bstork\b \JCiconiidae\j
\Bstorm petrel\b \JHydrobatidae\j
\Bstrandline\b A line on the shore comprising debris deposited by a receding tide; commonly used to denote the line of debris at the level of extreme high water.
\Bstratification\b Organization into horizontal layers; the structuring of a community or a habitat into superimposed horizontal layers.
\Bstratigraphic range\b The distribution of a taxon through geological time, determined by its distribution in strata of known geological age.
\Bstratigraphic unit\b A geological stratum or group of adjacent strata treated as a unit for the purposes of classification with reference to one or more characters.
\Bstratigraphy\b Study of the origin, composition, distribution and succession of rock strata.
\BStratiomyidae\b Soldier flies; cosmopolitan family of small to medium-sized flies (Diptera) in which the body commonly has a metallic sheen; contains about 1400 species several of which are wasp mimics.
\Bstratosphere\b 1: The nearly uniform cold ocean water masses in high latitudes and near-bottom waters of middle and low latitudes; ocean water below the thermocline. 2: The layer of the atmosphere above the troposphere, 15-50 km above the Earth's surface, in which temperature ceases to fall with increasing height, typically without strong convection currents; See also \Jtroposphere\j
\Bstratum (strata)\b 1: A layer, as of rock, possessing characters that serve to distinguish it from adjacent layers. 2: A horizontal layer of vegetation within a stratified plant community.
\Bstrawberry\b \JRosaceae\j
\BStreblidae\b Batfly; family of small flies (Diptera) that are blood-feeding ectoparasites of bats.
\BStrelitziaceae\b Bird-of-paradise, traveller's tree; small family of Zingiberales containing only 7 species of large perennial herbs or banana-like trees native to South Africa; flowers adapted to pollination by birds or insects; each flower usually with 6 perianth segments, 5 or 6 stamens and an inferior ovary, but always grouped into striking inflorescences.
\BStrepsiptera\b Small order of holometabolous insects that are endoparasites of other insects (Hymenoptera, Hemiptera, Orthopterodea, Thysanura); sexual dimorphism pronounced, male with broad head, reduced forewings and fan-like hindwings; female typically larviform and limbless; about 400 species in 2 suborders, Mengenillidia and Stylopidia.
\BStrepsirhini\b Prosimians; suborder of primates comprising 6 families, Lemuridae and Cheirogaleidae (lemurs), Indriidae (indriid lemurs), Daubentoniidae (aye aye), Galagidae (galagos) and Lorisidae (lorises); nostril with lateral slit; rhinarium moist and glandular; mandible not fully fused medially; distributed through the Ethiopian and Oriental Regions.
\Bstress\b Any environmental factor that restricts growth and reproduction of an organism or population; any factor acting to disturb the equilibrium of a system.
\Bstridulation\b Production of sound by rubbing together of specially modified structures or surfaces; \Bstridulate.\b
\BStrigeidida\b Order of digenetic \Jtrematodes\j characterised by 2 pairs of flame cells (excretory organs) in the miracidia larva; includes the blood fluke, \ISchistosoma\i, that causes bilharzia (schistosomiasis).
\BStrigidae\b Owls; family containing about 135 species of small to large nocturnal raptors found in grassland and woodland habitats worldwide; head large with round facial disk; habits typically solitary, monogamous, non-migratory, nocturnal or crepuscular, mostly arboreal, feeding on a variety of small vertebrates and insects; nest in tree hole or ground burrow.
\BStrigiformes\b Owls; order of nocturnal raptors comprising about 150 species in 2 families, Tytonidae and Strigidae; head large and mobile, eyes and ears well developed, bill strong and hooked, wings broad, feet short and strong; crop absent; prey on variety of small vertebrates and insects.
\Bstrobilation\b Reproduction by successive budding.
\Bstrobilus\b Cone; a reproductive structure consisting of closely packed sporophylls (leaves specialised to bear sporangia) in lower vascular plants, or ovuliferous scales (leaves specialised to bear ovules basally) in gymnosperms.
\BStromateidae\b Butterfishes; family containing 13 species of coastal marine perciform teleost fishes; body deep and compressed, to 500 mm length, pelvic fins absent, caudal deeply forked; young live in association with jellyfish.
\BStromateoidei\b Suborder of marine perciform teleost fishes comprising about 60 species in 6 families, including medusa fishes, driftfishes and butterfishes; young typically found in association with medusae and siphonophores.
\Bstromatolite\b Rock-like sedimentary structure found in warm, shallow marine habitats; built up from mats of blue-green algae and trapped sediment particles; also found as fossils.
\BStromatoporoida\b Order of sclerosponges containing many fossil forms and two extant genera with reticulate skeletons composed of the aragonite form of calcium carbonate.
\BStrongylida\b Order of parasitic rhabditian nematodes in which the adults are found in vertebrate hosts and the larval stages are either parasites of annelids or molluscs, or feed on bacteria; characterised by the muscles in the copulatory bursa of the male.
\BStrophomenida\b Large order of extinct brachiopods (Articulata) with one valve flat or concave and the other convex; hinge line straight; known from the Lower Ordovician to the Lower Jurassic.
\Bstrophotaxis\b A twisting movement in response to an external stimulus; \Bstrophotactic. \b
\BStruthionidae\b Ostrich; monotypic family of large ratite birds (Palaeognathae) found in open arid parts of Africa and Arabia; legs long and powerful, bearing 2 digits; neck elongate, head naked, eyes large; feathers plumose; female smaller than male; habits gregarious, cursorial, polygamous, feeding largely on plant material; the ostrich is the largest living bird, up to 2.5 m tall.
\BStruthioniformes\b Order of ratite birds comprising the monotypic family, Struthionidae (ostrich).
\Bsturgeon\b \JAcipenseridae\j
\BSturnidae\b Starlings; family containing about 110 species of Old World passerine birds found in variety of forest, grassland and open habitats from Africa to Australia; plumage often dark with metallic sheen; bill slender to robust, straight or curved; habits gregarious, arboreal to terrestrial, mostly non-migratory, feeding on invertebrates, seeds and fruit; nest solitary or colonial, made of twigs or grass, on or off the ground.
\Bstygon\b The groundwater biotope; see also \Jcrenon\j \Jthalasson\j, \Jtroglon\j
\Bstygophilic\b Thriving in caves or subterranean passages; \Bstygophile\b, \Bstygophily.\b
\Bstygoxenous\b Found only occasionally in caves or subterranean passages; \Bstygoxene. \b
\BStylasterina\b Hydrocorals; order of marine Hydrozoa known from most seas and a range of depths, characterized by a colonial polyp generation which secretes a calcareous skeleton; free medusae not produced but sessile medusoid gonophores are retained in cavities in the colony.
\Bstyle\b The sterile, often elongate, portion of a carpel between the ovary and the terminal stigma.
\BStylidiaceae\b Trigger plants; family of Campanulales containing about 150 species of mostly herbs with a basal rosette of grass-like leaves which possess an irritable style column which participates in pollination; widely distributed in southern hemisphere; fruit typically a capsule.
\BStylommatophora\b Amber snails, door snails, edible snail, garden snails, slugs; large cosmopolitan order containing about 15 000 species of terrestrial pulmonate snails; characterized by eyes situated on the tips of the upper pair of retractile tentacles, and with a lower pair of usually tactile tentacles; typically possessing an external shell.
\BStylophoridae\b Tube-eye; monotypic family of mesopelagic lampridiform teleost fishes widespread in tropical seas; body ribbon-like, to 280 mm in length; head large with tubular eyes, mouth markedly protractile; dorsal fin extending entire length of body, anal fin short, pelvics comprising solitary fin ray, caudal fin bearing 2 long filaments.
\BStyracaceae\b Silver-bell tree, snowdrop tree; family of Ebenales containing about 150 species of trees or shrubs often cultivated as ornamentals or as sources of gums; typically with 4 or 5 sepals and petals, and the same number or twice as many stamens.
\Bsubaerial\b Occurring immediately above the surface of the ground, or at the ground/air interface.
\BSubatlantic period\b A period of Blytt-Sernander \Jclassification\j (\Ic.\i 2500 years B.P. to present), characterized by beech and linden vegetation and by mild and wet conditions.
\Bsubboreal\b Pertaining to a climate or biogeographic zone approaching frigid or boreal conditions.
\BSubboreal period\b A period of the Blytt-Sernander \Jclassification\j (\Ic.\i 4500-2500 years B.P.), characterized by oak, ash and linden vegetation and by cooler and drier conditions than in the Subatlantic period.
\Bsubduction zone\b A zone in which the edge of one tectonic plate descends below an adjacent plate.
\Bsubfossil\b A post-Pleistocene fossil; used of plant and animal remains not strictly Recent but which are not old enough to be regarded as fossil.
\Bsubgeocolous\b Living underground; \Bsubgeocole.\b
\Bsubhydrophilous\b Thriving in habitats experiencing periodic inundation by fresh water; \Bsubhydrophile\b, \Bsubhydrophily.\b
\Bsublethal\b Not causing death by direct action, but possibly modifying behaviour, physiology, reproduction, or life cycle, and showing cumulative effects.
\Bsubliminal\b Below \Jthreshold\j level; insufficient to elicit a response.
\Bsublittoral\b 1: The deeper zone of a lake below the limit of rooted vegetation. 2: The marine zone extending from the lower margin of the intertidal (littoral) to the outer edge of the continental shelf at a depth of about 200 m; sometimes used for the zone between low tide and the greatest depth to which photosynthetic plants can grow; see marine depth zones.
\Bsubmergent\b Pertaining to a plant or plant structure growing entirely under water; See also \Jemergent\j
\Bsubmersed\b Pertaining to a plant or plant structure growing entirely under water; See also \Jemersed\j
\Bsubmission\b The behaviour exhibited by an animal, defeated in an aggressive contact, to prevent further attack.
\Bsubsidence theory\b That the upward growth of coral atolls and barrier reefs matched the slow subsidence of a volcanic island over a prolonged period of time; postulated to explain the formation of coral atolls.
\Bsubsoil\b The layer of soil beneath the topsoil and overlying the bed rock; the C-horizon of a soil profile.
\Bsubspecies\b A group of interbreeding natural populations differing morphologically and genetically, and often isolated geographically from other such groups within a biological species but interbreeding successfully with them where their ranges overlap.
\Bsubstrate\b 1: The substance acted upon by an enzyme, or that utilized by a microorganism as a food source. 2: \JSubstratum\j
\Bsubstratohygrophilous\b Thriving on moist substrata; \Bsubstratohygrophile\b,\Bsubstratohygrophily. \b
\Bsubstratum\b The sediment, surface, or medium to which an organism is attached or upon which it grows; substrate.
\Bsubterranean\b Living or occurring beneath the surface of the Earth.
\Bsubxerophilous\b Thriving in moderately dry situations; \Bsubxerophile\b, \Bsubxerophily. \b
\Bsuccession\b Ecological succession \Iq.v.;\i the chronological distribution of organisms within an area; the geological sequence of species within a habitat.
\Bsucculency\b The condition of having specialized fleshy tissue in a plant root or stem for the conservation of water; \Bsucculent.\b
\Bsucker\b 1: \JCatostomidae\j 2: An underground shoot arising adventitiously from the base of the stem or from the roots, and emerging to form a new plant.
\Bsucker-footed bat\b \JThyropteridae\j
\Bsucking louse\b \JAnoplura\j
\BSuctoria\b Suctorians, Tentaculifera; subclass of kinetofragminophoran ciliates characterized by suctorial tentacles used for prey capture and feeding, commonly on other ciliates; widely distributed in marine and freshwater habitats, often attached to other organisms and sometimes endosymbiontic in invertebrates and vertebrates.
\Bsudd\b A floating mass of plant material.
\Bsuffructicose chamaephyte\b A \Jchamaephyte\j subtype in which the upper vegetative and flowering shoots die back leaving only the lower parts to survive unfavourable seasons.
\Bsugarcane\b \JPoaceae\j
\BSuidae\b Swine, pigs; family containing 8 species of omnivorous terrestrial ungulates (Artiodactyla) native to the Ethiopian, Oriental and Palaearctic regions but now cosmopolitan through domestication; canine teeth forming tusks, hooves well developed; stomach comprising 2 chambers; typically gregarious, in forest habitats.
\BSuiformes\b Suborder of mostly omnivorous cloven-hooved ungulates (Artiodactyla) comprising 3 families, Suidae(pigs), Tayassuidae (peccaries) and Hippopotamyidae (hippopotamuses); feet with 4 digits, each of which may be in contact with the ground; hooves well developed or not.
\BSulidae\b Gannets, boobies; cosmopolitan family containing 9 species of medium-sized to large coastal marine birds (Pelecaniformes) that feed on fishes caught by plunging from flight, breed in colonies, nesting in trees or on the ground.
\Bsulphur plant\b \JPolygonales\j
\Bsulphuretta\b The prokaryotic and protistan inhabitants of anaerobic sulphur-rich deposits.
\Bsumach\b \JAnacardiaceae\j
\Bsun scorpion\b \JSolpugida\j
\Bsunbeam snake\b \JXenopeltidae\j
\Bsunbird\b \JNectariniidae\j
\Bsunbittern\b \JEurypygidae\j
\Bsundew\b \JDroseraceae\j
\Bsundrop\b \JOnagraceae\j
\Bsunfish\b 1: \JMolidae\j 2: \JCentrarchidae\j
\Bsunflower\b \JAsterales\j
\Bsungrebe\b \JHeliornithidae\j
\Bsunset shell\b \JVeneroida\j
\Bsuperfoetation\b The fertilization of a plant ovary by two or more kinds of pollen.
\Bsuperior ovary\b \JHypogyny\j
\Bsupernatant\b Floating at the surface.
\Bsupernumerary chromosome\b Any chromosome or chromosome fragment differing from the normal A-chromosomes in structure, genetic effectiveness and pairing behaviour; a B-chromosome.
\Bsuperorganism\b Any colony possessing features of social organization analogous to the physiological properties of a single organism; any group of organisms acting as a single functional unit.
\Bsuperparasitism\b 1: Parasitism of a host that is itself a parasite; \Bsuperparasite\b. 2: The multiple infection of a host by several parasites, usually of a similar kind.
\Bsuperterranean\b Occurring at or above ground level.
\Bsuprafolious\b Growing on leaves.
\Bsupralithion\b Those aquatic organisms swimming above rock, but dependent upon it as a food source.
\Bsupralittoral\b The region of the shore immediately above the highest water level and subject to wetting by spray or wave splash; splash zone; spray zone; see marine depth zones.
\Bsuprapelos\b Those aquatic organisms swimming above soft mud that are dependent upon it as a food source.
\Bsuprapsammon\b Those aquatic organisms swimming above sand that are dependent upon it as a food source.
\Bsupratidal\b The zone on the shore above mean high tide level.
\Bsurf\b The waves breaking on the shore.
\Bsurf clam\b \JVeneroida\j
\Bsurf fly\b \JCanaceidae\j
\Bsurfperch\b \JEmbiotocidae\j
\Bsurgeonfish\b \JAcanthuridae\j
\BSurianaceae\b Small family of Rosales containing 6 species of shrubs or trees; widespread in tropics, especially along coasts.
\Bsurvival of the fittest\b The differential and greater success of the best adapted genotypes.
\Bsurvivorship\b The proportion of individuals from a given \Jcohort\j surviving at a given time.
\Bsusceptible\b Prone to influence by a stimulus, or to infection by parasites or pathogens; \Bsusceptibility.\b
\Bsuspended animation\b The temporary suspension of life processes.
\Bsuspension\b A dispersion of fine insoluble particulate matter in a fluid.
\Bsuspension feeder\b Any organism that feeds on particulate organic matter suspended in water.
\Bswallow\b \JHirundinidae\j
\Bswallower\b \JChiasmodontidae\j
\Bswallowtail\b \JPapilionidae\j
\Bswamp\b Wet spongy ground, saturated or intermittently inundated by standing water, typically dominated by woody plants but without an accumulation of surface peat.
\Bswamp eel\b \JSynbranchidae\j
\Bswan\b \JAnatidae\j
\Bswarm cell\b An amoeboid cell produced by a germinating spore in the Myxomycota \Iq.v.,\i and characterized by the absence of a cell wall and possession of 2 anterior flagella.
\Bswarm-spore\b Motile spore in certain algae, fungi and protozoans; zoospore; swarmer.
\Bsweat bee\b \JHalictidae\j
\Bswede\b \JBrassicaceae\j
\Bsweet fern\b \JMyricales\j
\Bsweet gum\b \JHamamelidaceae\j
\Bsweet pea\b \JFabaceae\j
\Bsweet potato\b \JConvolvulaceae\j
\Bsweet William\b \JCaryophyllaceae\j
\Bswell\b 1: A deep-water, wind-generated, wave system of long periodicity. 2: An area that has subsided less than the surrounding area and is covered by a thinner sequence of sedimentary deposits.
\Bswift\b \JApodidae\j
\Bswine\b \JSuidae\j
\BSwiss cheese plant\b \JAracaceae\j
\Bswordfish\b \JXiphiidae\j
\Bsycamore\b \JPlatanaceae\j
\BSycettida\b Order of calcaronian sponges of variable size and shape; canal system consisting of either radially arranged tubes, or scattered spherical chambers; widely distributed in all oceans, from intertidal to depths of about 4000 m.
\Bsyconium\b A type of false fruit (pseudocarp) in which achenes are carried on the inside of a hollow receptacle.
\Bsycophagous\b Feeding on figs; \Bsycophage\b, \Bsycophagy.\b
\Bsylvestral\b Pertaining to, or inhabiting, woods and shady hedgerows; \Bsylvestrine. \b
\BSylviidae\b Warblers; family containing about 350 species of primarily Old World passerine birds found in forest, grassland and open habitats; habits gregarious to solitary, arboreal or terrestrial, some species migratory; feed on insects and arachnids by gleaning or hawking; nest in trees or reeds.
\Bsymbiology\b The study of symbioses.
\Bsymbiont\b A participant in a symbiosis; a symbiotic organism.
\Bsymbiosis\b The living together of two organisms; the relationship between two interacting organisms or populations, commonly used to describe all relationships between members of two different species, and also to include intraspecific associations; sometimes restricted to those associations that are mutually beneficial; symbioses; \Bsymbiont\b, \Bsymbiotic.\b
\Bsymbiotrophic\b Used of an organism obtaining nourishment through an symbiotic relationship; \Bsymbiotrophy.\b
\BSymmetrodonta\b Extinct order of primitive mammals (Pantotheria) that were probably small predators; molar teeth 3-cusped; known mainly from the late Jurassic and Cretaceous.
\Bsympatric\b Used of populations, species or taxa occurring together in the same geographical area; the populations may occupy the same habitat (biotic sympatry) or different habitats (neighbouring sympatry) within the same geographical area; \Bsympatry;\b see also \Jallopatric\j \Jdichopatric\j, \Jparapatric\j
\Bsymphily\b An amicable relationship between one organism (the symphile) and its host colony of social insects; \Bsymphilic.\b
\BSymphyacanthida\b Small order of acantharians in which the bases of 20 radial spines are intimately fused into a solid central body.
\BSymphyla\b Class of small blind mandibulate arthropods that inhabit soil and woodland litter; trunk 14-segmented, bearing 12 pairs of legs in the adult, and a pair of posterior cerci with spinning glands; legs may be elongate in active forms; sexes separate with little dimorphism, eggs laid in soil; most are phytophagous, rarely saprophagous; contains about 160 species.
\BSymphyta\b Sawflies, horntails, woodwasps, stem wasps; suborder of hymenopteran insects comprising about 4700 species, in which the adults are winged and wasp-like with a broad waist between first and second abdominal segments; female ovipositor rod-like or saw-like; larvae caterpillar-like feeding on, or boring into, leaves, stems or wood; Chalastogastra.
\BSymplocaceae\b Family of Ebenales containing about 250 species of usually evergreen, glabrous trees or shrubs; found mostly in tropical and warm temperate regions.
\BSynanceiidae\b Stonefishes; family containing 30 species of bizarre tropical Indo-Pacific coastal marine scorpaeniform teleost fishes having powerfully venomous dorsal fin spines; body extremely robust, often warty, scales absent; body length to 600 mm.
\BSynaphobranchidae\b Cutthroat eels; family containing about 10 species of predatory deep-sea anguilliform teleost fishes; dorsal and anal fins continuous with caudal; mouth large; gill openings close together or forming single ventral aperture.
\Bsynaposematic coloration\b Protective coloration in which the warning signal is shared with other species, as in Müllerian mimicry; See also \Japosematic coloration\j
\BSynapsida\b Subclass of mammal-like reptiles characterized by a single temporal opening in the skull above which the postorbital and squamosal bones meet; includes the therapsids, which are ancestral to the mammals, and the pelycosaurs.
\Bsynaptospermy\b The clumping of seeds by means of cohering or interlocking surface structures.
\Bsynaptospory\b The clumping of spores by means of cohering or interlocking surface structures.
\BSynbranchidae\b Swamp eels; family containing 15 species of circumtropical freshwater teleost fishes (Synbranchiformes) with slender eel-like body lacking paired fins; dorsal and anal fins greatly reduced; body length to 1.5 m; atmospheric oxygen is utilized by gulping air into vascularized gill pouch or hind gut; during drought some species burrow into the mud.
\BSynbranchiformes\b Order of eel-like, tropical freshwater teleost fishes comprising a single family, Synbranchidae (swamp eels).
\BSyncarida\b Superorder of freshwater eumalacostracan crustaceans comprising 2 extant orders, Anaspidacea and Bathynellacea; representing relicts of a diverse and formerly widespread marine group.
\Bsynchronic\b Existing or occurring at the same time; contemporaneous; See also \Jallochronic\j
\Bsynchronous hermaphrodite\b Any organism producing mature sperm and ova at the same time; simultaneous hermaphrodite; See also \Jconsecutive hermaphrodite\j
\Bsynclerobiosis\b Symbiosis between two species of social insects that usually inhabit separate colonies.
\Bsynchorology\b Study of the occurrence, distribution and classification of plant communities.
\Bsyncytium\b A multinucleate protoplasmic mass not differentiated into cells.
\Bsyndiacony\b A mutually beneficial relationship between ants and plants; \Bsyndiaconic. \b
\BSyndiniophycidae\b Subclass of marine dinoflagellates which are parasitic on various protistan and invertebrate hosts; typically endoparasitic, sometimes intracellular parasites.
\Bsynecology\b Study of the ecology of organisms, populations, communities, or systems; See also \Jautecology\j
\Bsynecthry\b Commensalism in which the participants (synecthrans) display mutual dislike.
\Bsynergism\b 1: Cooperative action of two or more agencies such that the total is greater than the sum of the component actions; \Bsynergetic\b, \Bsynergistic.\b 2: \JMutualism\j
\Bsyngamete\b A diploid cell formed by the fusion of two haploid gametes; zygote.
\Bsyngamy\b Sexual reproduction; fusion of male and female gametes; \Bsyngametic.\b
\Bsyngenesis\b Sexual reproduction; \Bsyngenetic.\b
\Bsyngenic\b Having the same set of genes; See also \Jallogenic\j
\BSyngnathidae\b Pipefishes, sea horses; family containing 175 species of tropical and warm temperate, shallow marine or freshwater gasterosteiform teleosts; body elongate with armour of bony rings, length to 500 mm, but usually much smaller; mouth terminal on long snout used as suction pipette to catch small invertebrates; tail prehensile in sea horses; swim using dorsal and pectoral fins.
\Bsyngonic\b Producing male and female gametes in the same gonad; \Bsyngony;\b See also \Jdigonic\j
\Bsynhesma\b A swarming society, or a swarm.
\BSynhymeniida\b Order of hypostomatan ciliates that have a cylindrical shape with bipolar ciliary rows over the general body surface: all free-living and mostly freshwater forms.
\Bsynmorphology\b The study of floristic composition, minimal area, and distribution of a plant community.
\BSynodidae\b \JMochokidae\j
\BSynodontidae\b Lizard fishes; family containing 35 species of bottom-living, carnivorous, myctophiform teleost fishes found in tropical and warm temperate shallow waters to 550 m depth; body slender, subcylindrical, bearing heavy shiny scales, pelvic fins abdominal; head depressed, mouth large with long sharp teeth; photophores and gas bladder absent.
\Bsynoecy\b 1: A symbiosis between a colony of social insects and a tolerated guest organism (a synoekete). 2: The production by an organism of both male and female gametes; \Bsynoecious.\b
\Bsynpiontology\b The study of ancient patterns of distribution and migration of plant communities.
\Bsyntopic\b Pertaining to populations or species that occupy the same macrohabitat, are observable in close proximity and could thus interbreed; \Bsyntopy;\b See also \Jallotopic\j
\Bsyntrophy\b The condition exhibited by two organisms mutually dependent for food.
\Bsynusia\b A community of species with similar forms and ecological requirements; a habitat of characteristic and uniform conditions; \Bsynusial.\b
\Bsynxenic\b Used of a culture comprising two or more organisms under controlled conditions.
\Bsynzoochorous\b Dispersed by the agency of animals; \Bsynzoochore.\b
\Bsyringa\b \JOleaceae\j
\BSyringocnemida\b Extinct order of solitary Archaeocyatha having a conical shape and an outer wall with simple pores; known from the Lower Cambrian.
\Bsyringograde\b A form of locomotion in which the organism propels itself with a jet of water; jet propulsion.
\BSyrphidae\b Hover flies; cosmopolitan family containing over 5000 species of small to large, colourful flies (Diptera) often found hovering over flowers; adults feed on pollen and nectar, and mimic bees and wasps; larvae are diverse and feed as phytophages, saprophages, scavengers, or as predators of aphids and caterpillars.
\Bsyrtidophilous\b Living on dry sand-bars; \Bsyrtidophile\b, \Bsyrtidophily.\b
\Bsyrtidophyte\b A dry sand-bar plant.
\BSystellommatophora\b Slugs; small order of slug-like pulmonate molluscs which lack a shell but possess 2 pairs of tentacles, the upper bearing the eyes; typically with the pulmonary cavity located posteriorly.
\Bsystematics\b The classification of living organisms into hierarchical series of groups emphasizing their phylogenetic interrelationships; often used as equivalent to taxonomy.
\Bsystemic\b Used of a chemical absorbed and transported throughout the tissues of a plant to make them toxic to fungi (systemic fungicide) or insects (systemic insecticide).
\Bsyzygy\b 1: A close association between protozoans prior to gamete formation, but during which nuclear fusion does not occur. 2: The time at which the sun and moon are in line, either in conjunction or in opposition, with respect to the Earth; See also \Jquadrature\j
\B2,4,5-T\b 2,4,5-Trichlorophenoxyacetic acid; a translocated hormone weedkiller used to control scrub and woody vegetation.
\BTabanidae\b Horseflies, clegs, deerflies; cosmopolitan family of robust biting flies (Diptera) especially abundant in marshy habitats, that feed on blood and are of medical and veterinary importance as pests of livestock, as well as vectors of diseases such as loiasis and tularaemia.
\BTabulata\b Extinct order of colonial corals (Zoantharia) possessing well developed tabulae; important as reef-building organisms in the Palaeozoic.
\BTabulospongida\b Order of sclerosponges represented by a single living species; characterized by a basal skeleton of the calcite form of calcium carbonate with a lamellar microstructure.
\BTaccaceae\b Arrowroot; pantropical family of Liliales comprising about 10 species of perennial herbs with large, long-petiolate, basal leaves having parallel or palmate veins; flowers trimerous, grouped in umbels, and with 6 perianth segments, 6 stamens and inferior ovaries; fruit usually a berry; seeds with copious endosperm containing reserves of protein and oil.
\Btacheion\b Actively moving aquatic organisms comprising both crawling (herpon) and free-swimming forms.
\Btachyauxesis\b Allometric growth in which a given structure is relatively larger in large individuals than in small ones.
\BTachyglossidae\b Echidnas (spiny anteater); family containing 2 or 3 species of small terrestrial, semifossorial, egg-laying mammals (Monotremata) found in Australia and New Guinea; body covered with coarse hair and spines, tail vestigial; tongue long and sticky, teeth absent; feet with strong claws used to dig out termites and other invertebrates on which they feed, and to escape from predators; eggs incubated in a transitory abdominal pouch.
\Btachysporous\b Used of a plant that disperses its seeds quickly.
\BTachysuridae\b \JAriidae\j
\Btactile\b Pertaining to the sense of touch.
\Btadpole\b The long-tailed larval form of frogs and toads (Anura).
\Btadpole shrimp\b \JNotostraca\j
\Btagmosis\b The functional specialization occurring within metamerically segmented animals, producing a subdivision of the body into distinct regions (tagmata).
\Btaiga\b Northern coniferous forest \Jbiome\j; the ecosystem adjacent to the Arctic tundra, but used with varying scope to include only the Arctic timberline ecotone through to the entire sub-Arctic subalpine north temperate forest.
\Btailless whip scorpion\b \JAmblypygi\j
\BTalpidae\b Moles, desmans; family containing about 20 species of small fossorial or semiaquatic mammals (Insectivora) in which the eyes are reduced or absent; feet webbed in aquatic species (desmans), or broad with stout claws in burrowing forms (moles); distributed through the Holarctic and Oriental regions.
\BTamaricaceae\b Tamarisk; family of Violales containing about 100 species of often evergreen shrubs or small trees found in halophytic or xerophytic habitats in Eurasia and Africa; flowers typically bisexual, with 4 or 5 sepals and petals, and 4-5, 8-10 or many stamens, and a superior ovary.
\Btamarin\b \JCallitrichidae\j
\Btamarisk\b \JTamaricaceae\j
\Btanager\b \JThraupidae\j
\BTanaidacea\b Order containing about 550 species of small marine peracaridan crustaceans found in benthic habitats from the littoral zone to abyssal depths; often tube-dwelling; body elongate, carapace reduced, eggs retained in brood pouch.
\Btang line\b The highest continuous line on the shore along which a particular seaweed grows; has variously been applied to wracks, laminarians and other algal forms; See also \Jalgal line\j
\BTantulocarida\b Class of microscopic copepod-like crustaceans found as ectoparasites on other marine crustaceans; larval stages and females attached to host by minute adhesive disk, adult males free-swimming, with copulatory stylet on seventh trunk segment; contains about 10 species, mainly from deep oceanic waters.
\Btapaculos\b \JRhinocryptidae\j
\Btapestry\b A more or less continuous cover of trees on a steep slope.
\Btapetail\b \JEutaeniophoridae\j
\Btapeworm\b \JEucestoda\j (Cestoda)
\Btaphocoenosis\b An assemblage of dead organisms brought together at or after the time of death, or of fossils that were buried together; \Btaphocoenose\b; See also \Jbiocoenosis\j
\Btaphoglyph\b An imprint in a sediment of a dead or dying organism.
\Btaphonomy\b Study of the environmental phenomena and processes that affect organic remains after death, including the processes of fossilization.
\BTaphrinales\b Order of hemiascomycete fungi comprising a single worldwide genus of about 100 species, all of which parasitize ferns and higher plants, producing galls or other lesions on leaves, stems and fruits.
\Btaphrophilous\b Thriving in ditches; \Btaphrophile\b, \Btaphrophily.\b
\Btaphrophyte\b A ditch plant.
\BTapiridae\b Tapirs; family containing 4 species of forest-dwelling nocturnal mammals (Perissodactyla) in which the nose is developed into a short, mobile trunk; feed mainly on aquatic plants and fruit; one species is Oriental in distribution, the others Neotropical.
\Btarantula\b 1: Any of the large hairy spiders in the family Theraphosidae that often appear rather sluggish but have a strong bite. 2: A species of wolf spider (Lycosidae) found in Italy and southern France.
\BTardigrada\b Water bears; phylum of microscopic (50-1200 \Fm\nm) coelomates found in the surface water films on mosses, lichens, liverworts, algae and plant litter, or in the interstices of soil; body cylindrical to flattened with 4 pairs of stumpy legs bearing claws or other armature; mouthparts typically styliform for piercing, with muscular sucking pharyx; sexes separate, monomorphic, some species parthenogenetic; comprises about 380 species in 3 orders, Heterotardigrada, Mesotardigrada and Eutardigrada.
\BTarphyceratida\b Extinct order of nautiloids (Cephalopoda) having simple septa; known from the Ordovician and Silurian.
\Btarpon\b \JMegalopidae\j
\BTarsii\b Monofamilial infraorder of primates (suborder Haplorhini).
\BTarsiidae\b Tarsiers; family of small nocturnal, arboreal primates containing 3 species found in the Oriental and Australian regions; lower jaw not fused medially; eyes and ears very large; limbs slender, hindlimbs longer than forelimbs and used for jumping, toes bearing disk-shaped pads; feed on insects and other small animals.
\BTarsipedidae\b Honey possum; monotypic family of small (to 180 mm) arboreal diprotodont marsupials found in southwestern Australia; marsupium opens anteriorly, tail prehensile; tongue long and protrusible for feeding on nectar and pollen.
\BTasmanian devil\b \JDasyuridae\j
\BTasmanian wolf\b \JThylacinidae\j
\Btassel-finned fish\b \JCoelacanthiformes\j
\BTaxaceae\b Yew; family of evergreen conifers (Pinatae); shrubs to trees with needle-like or linear leaves spirally arranged; male (staminate) cones solitary or on spikes, with 2-8 pollen sacs per scale; female (pistillate) cones with a coloured fleshy aril surrounding the hard seed.
\Btaxis\b A directed reaction or orientation response of a motile organism towards (positive) or away from (negative) the source of the stimulus; \Btactism\b; \Btactic\b; see also \Jklinotaxis\j \Jtelotaxis\j, \Jtropotaxis\j
\BTaxodiaceae\b Sequoia: family of tall resiniferous coniferous trees (Pinatae); leaves spirally arranged on small branchlets; male (staminate) cones with 2-9 pollen sacs per scale; female (pistillate) cones solitary with 2-9 ovules per scale; when mature, the cone is leathery to woody.
\Btaxon\b A taxonomic group of any rank, including all the subordinate groups; any group of organisms, populations, or taxa considered to be sufficiently distinct from other such groups to be treated as a separate unit; \Btaxa.\b
\Btaxonomic hierarchy\b A hierarchical system of taxonomic categories arranged in an ascending series of ranks; in botany the following 12 main ranks are recognized - Kingdom, Division, Class, Order, Family, Tribe, Genus, Section, Series, Species, Variety, Form; in zoology 7 main ranks are recognized - Kingdom, Phylum, Class, Order, Family, Genus, Species; additional categories can be introduced by the use of super-and sub-prefixes.
\Btaxonomy\b The theory and practice of describing, naming and classifying organisms.
\BTaxopodida\b Order of Heliozoa comprising a single species with a skeleton of 14 rosettes of strong hollow spines and many additional rods; abundant at depths of 300 m in the Mediterranean.
\BTayassuidae\b Peccaries; family containing 3 species of omnivorous terrestrial ungulates (Artiodactyla) found in the Neotropical and southern Nearctic regions; 3 digits on the hindlimbs, 4 on the forelimbs, hooves well developed; stomach comprising 3 chambers.
\Btea\b \JTheaceae\j
\Bteak\b \JVerbenaceae\j
\Bteasel\b \JDipsacaceae\j
\Btecnophagous\b Used of an individual that feeds on its own eggs; \Btecnophage\b, \Btecnophagy.\b
\Btectology\b The study of organisms as groups of morphological units or individuals.
\Btectonic\b Pertaining to the movement of the rigid plates that comprise the Earth's crust, and to deformation of the crustal plates.
\Btegulicolous\b Living on tiles, as of lichens; \Btegulicole.\b
\BTeiidae\b Whiptail; family containing about 200 species of tropical New World lizards (Sauria) that possess a long tail; head plates separated from skull bones; mainly terrestrial, but some semiaquatic or arboreal; habits chiefly diurnal, insectivorous, a few species predatory on vertebrates; reproduction oviparous.
\Btelegamic\b Pertaining to the process or behaviour of attracting a mate from a distance.
\Btelegenesis\b Artificial insemination.
\Bteleology\b The doctrine that natural phenomena result from, or are shaped by, design or purpose; \Bteleological.\b
\BTeleostei\b Teleosts; loose assemblage of bony fishes (Osteichthyes) that excludes the primitive orders, Acipenseriformes, Amiiformes and Semionotiformes; sometimes used as an infraclass.
\BTeleostomi\b The true bony fish (Osteichthyes) with a terminal mouth.
\Bteleplanic\b Used of pelagic larvae that have a protracted planktonic existence, with the capacity for widespread dispersal.
\BTelestacea\b Order of colonial octocorals found in shallow and deep water in which polyps arise from a creeping stolon and by budding from existing polyps.
\BTeliomycetes\b Class of basidiomycotine fungi, all of which parasitize vascular plants; resting spores (teliospores) are produced which germinate with a promycelium or a basidium; the septate mycelium invades the host intercellularly, penetrating cells to obtain nutrients by means of specialized haustoria; contains 2 orders, Uredinales and Ustilaginales.
\Btelmatology\b The study of wetlands, swamps and marshy areas.
\Btelmatophilous\b Thriving in wet meadows; \Btelmatophile\b, \Btelmatophily.\b
\Btelmatophyte\b A wet-meadow plant.
\Btelmatoplankton\b Planktonic organisms of freshwater bogs and marshes.
\Btelmicolous\b Living in freshwater marshes; \Btelmicole.\b
\Btelmophagous\b Used of an organism, usually an insect, that feeds from a blood pool produced by tissue laceration; \Btelmophage.\b
\BTelosporidea\b \JSporozoa\j
\Btelotaxis\b An orientation response of a motile organism to a single stimulus without reference to other sources of stimulation; see also \Jklinotaxis\j \Jtropotaxis\j
\BTEM\b Transmission electron microscope.
\BTemnocephala\b Order of flatworms (Turbellaria) found on the outer surface of various freshwater animals, usually crustaceans; possess a pharynx and bag-shaped intestine; often treated as a suborder of the Neorhabdocoela.
\BTemnopleuroida\b Order of mainly sublittoral Indo-West Pacific sea urchins (Echinacea) comprising about 120 extant species; test depressed or spherical, to 150 mm in diameter, with or without sculpturing, dentition camarodont; includes the venomous \IToxopneutes\i that has large pedicellariae able to pierce human skin.
\Btemperate\b 1: Moderate; not excessive or extreme; used of climates with alternating long warm summers and short mild winters. 2: Pertaining to latitudes between the tropics and the polar circles in each hemisphere; see also \Jpolar\j \Jtropical\j
\BTemperate grassland biome\b Continental grassland regions such as pampas, prairies, steppes and veld, characterized by a rainfall intermediate between forest and desert, a long dry season, seasonal extremes of temperature; dominated by grasses and large grazing mammals, with burrowing animals frequent.
\BTemperate forest biome\b Mixed forest of conifers and broad-leaf deciduous trees, or mixed conifer and broad-leaf evergreen trees, or entirely broad-leaf deciduous, or entirely broad-leaf evergreen trees, found in temperate regions across the world; characterized by high rainfall (temperate rainforests), warm summers, cold winters occasionally subzero, and seasonality; typically with dense canopies, understorey saplings and tall shrubs, large animals, carnivores dominant, and very rich in bird species.
\Btemporary parasite\b A parasite that makes contact with its host only for feeding.
\BTenebrionidae\b Darkling ground beetles; family containing about 18 000 species of small to medium-sized beetles (Coleoptera) that feed on a wide variety of materials, mostly of plant origin and including stored products such as flour.
\Btenpounder\b \JElopidae\j
\BTenrecidae\b Tenrecs, otter shrews; diverse family of small (75-600 mm) terrestrial mammals (Insectivora) containing about 35 species found in central and west Africa and Madagascar.
\BTentaculata\b Class of ctenophores possessing tentacles.
\BTentaculifera\b \JSuctoria\j
\BTentaculitida\b Extinct order of molluscs (Cricoconarida) known from Lower Ordovician to Upper Devonian.
\Btenuis\b Benthic larval stage of teleost fishes in the family, Carapidae (pearlfishes).
\Btepal\b Each element in the perianth of a flower which does not have differentiated sepals and petals.
\Btephra\b Clastic volcanic materials ejected from a volcano during an eruption and transported through the air.
\BTephritidae\b Fruit flies; cosmopolitan family of small colourful flies (Diptera) that feed on sap and fruit; larvae are phytophagous and are economically important pests of apples, olives, cucumbers, celery and other crops; comprises about 4000 species, most widespread in tropical regions.
\Btephrochronology\b Geological dating based on the layering of volcanic ash.
\Btera- (T) Prefix used to denote unit x 10\B\U12\u; see metric prefixes.\b\b
\Bteratogenic\b Causing developmental malformations or monstrosities; \Bteratogenesis.\b
\Bteratology\b The study of malformations and monstrosities; \Bteratologic.\b
\BTerebellida\b Order of tubicolous polychaete worms comprising about 1000 species in which body regions are strongly differentiated; prostomium and peristomium fused, branchiae typically present anteriorly; oral tentacles used for deposit feeding and tube construction.
\BTerebrantia\b \JParasitica\j
\BTerebratulida\b Order of articulate brachiopods comprising about 250 species in which the shell is punctate, often with light coloration; pedicle variable, functional or absent; spicules present or absent in soft parts; epifaunal, typically sessile and attached, intertidal to depth of 5000 m.
\Btermitophilic\b Having an affinity for termites; inhabiting termite nests; \Btermitophile\b, \Btermitophily.\b
\Btern\b \JLaridae\j
\Bterraneous\b Pertaining to, or living on, the land or ground surface; terrestrial.
\Bterrapin\b \JEmydidae\j
\Bterraqueous\b Comprising both land and water.
\Bterrestrial\b Pertaining to, or living habitually on, the land or ground surface.
\Bterrestrial biomes\b The major biogeographical regions of the world's land surface; see map on page 48.
\Bterricolous\b Living on or in soil; used of an organism that spends most of its active life on the ground; \Bterricole.\b
\Bterrigenous\b Derived from the land.
\Bterrigenous mud\b A marine sediment comrising at least 30% silt and sand derived from the land; see also \Jblack mud\j \Jblue mud\j, \Jgreen mud\j, \Jred mud, white mud\j
\Bterritoriality\b Behaviour related to the defence of a territory.
\Bterritory\b An area within the home \Jrange\j occupied more or less exclusively by an animal or group of animals of the same species, and held through overt defence, display or advertisement; \Bterritorial.\b
\BTertiary\b A geological period of the Cenozoic era (\Ic.\i 65-1.6 million years B.P.), comprising the Palaeocene, Eocene, Oligocene, Miocene and Pliocene; see geological time scale.
\BTestaceafilosida\b Order of Filosa; testate amoebae with filose pseudopodia (filopodia), the test usually with one opening, sometimes 2; reproduction typically by binary fission; mostly found in fresh water, soil and forest litter, occasionally marine.
\BTestacealobosa\b Subclass of amoebae with lobose pseudopodia and tests, comprising 2 orders, Arcellinida and Trichosida.
\Btestate amoeba\b \JArcellinida\j
\BTestudines\b Turtles, terrapins, tortoises; order of aquatic and terrestrial reptiles (Chelonia) characterized by a rigid body shell comprising a dorsal carapace and a ventral plastron; jaws beaked, without teeth; girdles within the rib cage; reproduction oviparous; contains about 220 extant species in 11 families; distribution cosmopolitan, except for high latitudes and high montane regions.
\BTestudinidae\b Tortoises; family containing about 40 species of herbivorous, terrestrial reptiles (Testudines: Cryptodira) widespread in grassland and arid habitats; carapace typically domed, limbs stout with reduced digits.
\BTethys\b The epicontinental sea separating Laurasia from Gondwana following the break up of \JPangaea\j in the Mesozoic.
\Btetra\b \JAlestidae\j
\BTetracentraceae\b Family containing a single species of deciduous trees (Trochodendrales) known from Nepal, China and Burma.
\BTetractinomorpha\b Subclass of demosponges ranging in form from encrusting to massive and branching, found from the intertidal to the abyssal zone; characterized by a skeleton of tetraxonid and monaxonid megascleres; reproduction oviparous.
\BTetragonidiales\b Small order of freshwater flagellate algae (Cryptophyceae).
\BTetrameristaceae\b Small family of Theales containing 2 species of trees or shrubs from Malaysia and the Guayana highlands.
\BTetramerocerata\b Suborder of pauropods widespread in tropical to cold temperate regions; body with 9-10 pedigerous segments, antennae weakly telescopic, mandibles specialized for piercing, tracheae absent; feed on liquid foods; contains about 500 species in 4 families, the vast majority in one family, Pauropodidae.
\BTetraodontidae\b Puffers; family containing about 120 species of tropical and subtropical, marine, brackish and freshwater teleost fishes found on reefs and sea-grass beds; body robust, to 0.9 m length, naked or minutely spinose; jaws forming parrot-like beak; when threatened pufferfishes inflate the body with water; flesh may be highly toxic.
\BTetraodontiformes\b Order of tropical and temperate marine teleost fishes comprising about 300 species in 8 families, including spikefishes, triggerfishes, filefishes, boxfishes, pufferfishes, porcupinefishes and sunfishes; body usually armoured with plates, shields or spines; many species are venomous.
\BTetraonidae\b Grouse; family containing 16 species of medium-sized gallinaceous birds (Galliformes) widespread in cool temperate forests and grasslands of the northern hemisphere; habits solitary or gregarious, polygamous or monogamous, feeding on berries, buds and insects; nest in a scrape on the ground.
\BTetraphidae\b Subclass of mosses (Bryopsida); small, light-green plants forming loose mats on acidic rock surfaces, rotting wood, or epiphytically on tree ferns; capsule has a peristome with only 4 teeth.
\BTetraphyllidea\b Order of tapeworms (Eucestoda) parasitic in elasmobranchs, utilizing molluscs and crustaceans as first intermediate hosts, and molluscs or fishes as second intermediate hosts; characterized by a scolex of typically 4 stalked or sessile bothridia, commonly divided into loculi, and by a segmented body.
\Btetraploid\b A polyploid having 4 sets of homologous chromosomes; \Btetraploidy\b See also \Jploidy\j
\BTetrapoda\b Subgroup of vertebrates with 4 limbs; includes all terrestrial vertebrate taxa - amphibians, reptiles, birds and mammals; See also \JPisces\j
\BTetrasporales\b Order of mostly freshwater or terrestrial green algae in which the cells are usually massed into gelatinous colonies.
\BTettigoniidae\b Grasshoppers, katydids; large family of orthopterodean insects (Ensifera) in which auditory communication is well developed; ovipositor sword-shaped; most of the 5000 species are phytophagous.
\BTeuthoidea\b Squid; order of marine carnivorous cephalopod molluscs which are typically streamlined, active swimmers found in shallow coastal and open oceanic waters; characterized by the reduction of the shell to an internal, cartilaginous rod, by 8 arms and 2 tentacles, and by posteriorly developed fins.
\Bthalassic\b Pertaining to the sea or deep oceanic waters.
\BThalassinidea\b Mud lobsters; infraorder of pleocyematan decapod crustaceans; sometimes classified as a section of the \JAnomura\j
\BThalassocalycida\b Small order of pelagic ctenophores found in tropical and subtropical waters; characterized by an expanded body which forms a medusa-like bell around the mouth and by the lack of tentacular sheaths.
\BThalassocyathida\b Extinct order of Archaeocyatha; cup-shaped animals with single walls, known from the Lower Cambrian.
\Bthalasson\b The marine biotope; see also \Jcrenon\j \Jstygon\j, \Jtroglon\j
\BThalassomycetales\b The single order of elliobiophycid dinoflagellates.
\Bthalassophilous\b Thriving in the sea; \Bthalassophile\b, \Bthalassophily.\b
\Bthalassophyte\b A marine plant.
\Bthalassoplankton\b Marine planktonic organisms.
\BThaliacea\b Salps; class of solitary or colonial, pelagic tunicates that have the branchial (anterior, inhalent) and atrial (posterior, exhalent) siphons at opposite ends of body; the water current may be used for propulsion; a ventral stolon is present posterior to the endostyle from which asexual budding occurs; 3 orders recognized, Pyrosomida, Doliolida and Salpida.
\BThallobionta\b Subkingdom of plants comprising eukaryotic algae and fungi; See also \JEmbryobionta\j
\BThallophyta\b A group name formerly used for all plant-like organisms lacking differentiation into roots, stems and leaves.
\Bthallus\b A primitive plant body lacking differentiated true leaves, stems and roots.
\Bthamnobiontic\b Living in bushes and shrubs; \Bthamnobiont.\b
\Bthamnocolous\b Living on or in bushes and shrubs; \Bthamnocole.\b
\Bthamnophilic\b Thriving on, or living in, bushes or shrubs; \Bthamnophile\b, \Bthamnophily.\b
\Bthanatocoenosis\b An assemblage of organisms brought together after death; \Bthanatocenosis\b; See also \Jbiocoenosis\j
\Bthanatogeography\b Study of the distributions of dead organisms.
\Bthanatology\b Study of death and dead organisms.
\Bthanatosis\b Death-feigning behaviour; death feint.
\BTheaceae\b Camellia, tea; family containing about 600 species of woody, tanniferous plants with large showy flowers comprising 4-7 sepals and petals, many stamens and usually a superior ovary; widespread in tropical and subtropical regions; the leaves of \ICamellia sinensis\i are used to make tea.
\BTheales\b Order of Dilleniidae containing 18 families of mostly trees and shrubs, sometimes evergreen, very often tanniferous and with mucilage or resin in special cells or ducts.
\BThecanephria\b Order of pogonophoran marine worms possessing a horseshoe-shaped anterior body cavity in the tentacular region with medial ciliated ducts opening to the exterior; spermatophores typically foliate.
\BThecina\b Suborder of \JAmoebida\j; also treated as a class of the protoctistan phylum Rhizopoda.
\BThecodontia\b Primitive order of archosaurian reptiles with teeth set in sockets; probably ancestral to dinosaurs, pterosaurs and crocodiles; known from the Upper Permian to the Upper Triassic.
\BThecostomata\b Pteropods; cosmopolitan order of pelagic marine, opisthobranch molluscs which feed on planktonic organisms carried to the mouth by ciliary tracts; typically with a calcareous shell, and a foot greatly modified for swimming by enlargement into lateral fins.
\Bthegosis\b The process of tooth sharpening; tooth-grinding behaviour.
\BTheligonaceae\b Family of Rubiales containing only 3 species of herbs with wind-pollinated unisexual flowers; found in eastern Asia, the Mediterranean and the Canary Islands.
\Bthelygenic\b Producing offspring that are entirely, or predominantly, female; \Bthelygeny\b; see also \Jallelogenic\j \Jamphogenic\j, \Jarrhenogenic\j, \Jmonogenic\j
\BThelyphonida\b \JUropygi\j
\Bthelytoky\b Obligatory parthenogenesis in which a female gives rise only to female offspring; \Bthelytokous\b; See also \Jarrhenotoky\j
\BTheophrastaceae\b Small family of Primulales containing about 100 species of woody, often palm-like, plants native to the tropical New World.
\BTheraphosidae\b Tarantulas; family of large, hairy spiders characterized by a group of 8 eyes, and by claw tufts; feed on large insects and small vertebrates which are typically chewed.
\BTheraponidae\b Tiger perches, tigerfish; family containing 35 species of predatory Indo-Pacific marine brackish and freshwater teleost fishes (Perciformes); body oblong and compressed, to 500 mm length; dorsal fin deeply notched with 11-14 fin spines; may produce sounds by action of muscles on the swim bladder.
\BTherapsida\b Order of synapsid reptiles which were ancestral to the mammals; known from the Permian to the early Jurassic.
\BTheria\b The viviparous mammals; a subclass of mammals comprising 2 extant infraclasses. Metatheria (marsupials) and Eutheria (placentals), and a fossil infraclass, Pantotheria.
\Bthermobiology\b Study of the effect of heat on living organisms and biological processes.
\Bthermocleistogamy\b Self-pollination within flowers that fail to open because of unfavourable temperature conditions; \Bthermocleistogamic.\b
\Bthermocline\b A horizonal temperature discontinuity layer in a lake in which the temperature falls by at least 1░C per metre depth; a boundary layer in the sea in which temperature changes sharply with depth.
\Bthermogenesis\b The production of heat; \Bthermogenic.\b
\Bthermohaline\b Pertaining to both temperature and salinity.
\Bthermolabile\b Unstable or destroyed when exposed to high temperatures; See also \Jthermostable\j
\Bthermonasty\b A reponse to a non-directional temperature stimulus; \Bthermonastic.\b
\Bthermopegic\b Pertaining to hot-water springs.
\Bthermoperiodic\b Pertaining to the response of an organism to periodic changes in temperature; \Bthermoperiodicity.\b
\Bthermophilic\b Thriving in warm environmental conditions; used of microorganisms having an optimum for growth above 45░C; \Bthermophile\b, \Bthermophily.\b
\Bthermophobic\b Intolerant of high temperatures.
\Bthermophylactic\b Heat-resistant; tolerant of high temperatures.
\Bthermophyte\b 1: A plant tolerant of, or thriving at, high temperatures. 2: A hot-spring plant.
\BThermosbaenacea\b Small order of primitive pancaridan crustaceans containing 10 species found in hot springs, freshwater hypogean and marine habitats; carapace reduced but forming a dorsal brood chamber; eyes absent.
\Bthermostable\b Relatively stable or resistant to heat; See also \Jthermolabile\j
\Bthermotaxis\b The directed response of a motile organism towards (positive) or away from (negative) a temperature stimulus; \Bthermotactic.\b
\Bthermotoxy\b Death or injury caused by heat; \Bthermotoxic.\b
\Bthermotropism\b An orientation response to a temperature stimulus: \Bthermotropic.\b
\Btherophyllous\b Deciduous; used of plants that have leaves only during the warm season.
\Btherophyte\b An annual plant; a plant that completes its life cycle in a single season, passing unfavourable seasons as a seed; See also \JRaunkiaerian life forms\j
\BTheropoda\b Suborder of bipedal, carnivorous dinosaurs (Saurischia) known from the Triassic to the Cretaceous; includes the coelosaurs and carnosaurs.
\Bthigmokinesis\b A change in the velocity of linear or angular movement of an organism in response to a contact stimulus; \Bthigmokinetic.\b
\Bthigmomorphosis\b A change in form due to contact; \Bthigmomorphic.\b
\Bthigmotaxis\b A directed response of a motile organism to a continuous contact with a solid surface; \Bthigmotactic.\b
\Bthigmothermic\b Used of an animal that draws heat into its body from contact with a warmed object in the environment; \Bthigmotherm.\b
\Bthigmotropism\b An orientation response to touch or a contact stimulus; \Bthigmotropic.\b
\Bthinicolous\b Living on sand dunes; \Bthinicole.\b
\BThinocoridae\b Seedsnipe; family containing 4 species of small quail-like charadriiform birds having a short finch-like bill, found in dry open habitats of South America; feed mainly on seeds and other plant material.
\Bthinophilous\b Thriving on sand dunes; \Bthinophile\b, \Bthinophily.\b
\Bthinophyte\b A sand-dune plant.
\Bthiobios\b Those organisms inhabiting anaerobic sulphur-rich deposits; \Bthiobiotic.\b
\Bthiogenic\b Sulphur-producing.
\Bthiophilic\b Thriving in sulphur-rich habitats; \Bthiophile\b, \Bthinophily.\b
\Bthinophyte\b A sand-dune plant.
\Bthiobios\b Those organisms inhabiting anaerobic sulphur-rich deposits; \Bthiobiotic.\b
\Bthiogenic\b Sulphur-producing.
\Bthiophilic\b Thriving in sulphur-rich habitats; \Bthiophile\b, \Bthiophily.\b
\Bthistle\b \JAsterales\j
\Bthixotropic\b Used of a colloidal sediment that becomes liquid as a result of agitation or pressure; \Bthixotropy\b; See also \Jdilatent\j
\Btholichthys\b Larval stage of fishes in the family Chaetodontidae.
\BThoracica\b Acorn barnacles, goose barnacles; largest order of barnacles (Cirripedia) containing about 700 living species; mostly sessile filter feeders with the body enclosed within protective calcareous plates; thoracic legs modified as food-gathering cirri; found attached to hard substrata at all depths from the intertidal to the abyss, also found on whales and other marine animals.
\Bthorn apple\b \JSolanaceae\j
\Bthornbill\b \JMaluridae\j
\Bthorny coral\b \JAntipatharia\j
\Bthorny-headed worm\b \JAcanthocephala\j
\BThraupidae\b Tanagers; family containing about 240 species of New World passerine birds found mostly in tropical forests and woodland; plumage often colourful; bill robust and conical, frequently hooked; habits solitary to gregarious, arboreal, non-migratory, feeding on insects, fruit and flowers; nest in tree or bank.
\Bthreadfin\b \JPolynemidae\j
\Bthreefin blenny\b \JTripterygidae\j
\Bthremmatology\b Study of animal and plant breeding in domestic situations.
\Bthresher shark\b \JAlopiidae\j
\Bthreshold\b The minimum level or value of a stimulus necessary to elicit a response; See also \Jsubliminal\j
\BThreskiornithidae\b Ibises, spoonbills; family containing 33 species of medium-sized wading birds (Ciconiiformes) having long legs, long bills and large broad wings; bill decurved (ibises) or straight and spatulate (spoonbills); feed on fishes and other aquatic organisms; breed in colonies, nesting in trees or on the ground; widespread in tropical and warm temperate freshwater and coastal marine habitats.
\Bthrips\b \JThysanoptera\j
\BThripidae\b Family of thysanopteran insects comprising about 1500 species, including most of the economically important thrips.
\Bthroatwort\b \JCampanulaceae\j
\Bthrush\b \JTurdidae\j
\BThurniaceae\b Small family of Juncales comprising only 3 species of coarse perennial herbs with spheroidal silica bodies in shoots and stems; small flowers borne in large, dense terminal heads; native to tropical South America.
\Bthumbless bat\b \JFuripteridae\j
\BThylacinidae\b Tasmanian wolf; monotypic family of dog-like carnivorous marsupials recorded in modern times only from Tasmania but thought to be extinct since 1936; body length to 2 m; habits nocturnal, typically living in a den amongst rocks or logs and feeding on other marsupials and birds.
\BThylacomyidae\b Family of long-eared rabbit-like burrowing bandicoots found in southern Australia; habits nocturnal, feeding on insects and small vertebrates.
\Bthyme\b \JLamiaceae\j
\BThymelaeaceae\b Spurge laurel, mezereon; cosmopolitan family of Myrtales containing about 500 species of mostly poisonous shrubs; individual flowers bisexual, and regular with 4-5 petaloid sepals, usually 4-5 or 8-10 stamens and a superior ovary; flowers arranged in racemose inflorescences.
\BThyropteridae\b Sucker-footed bats; family containing 2 species of bat (Microchiroptera) having stalked suckers on the wrists and ankles; found in the Neotropical region and West Indies.
\BThysanoptera\b Thrips; order of small (0.5-15 mm) hemipterodean insects comprising about 5000 species that feed on plant juices, fungi, spores, pollen or body fluids of other arthropods such as mites and scale insects; mouthparts specialized for piercing and sucking; mouth cone asymmetrical, right mandible reduced, left mandible modified as stylet; wings slender, frequently reduced or absent.
\BThysanura\b Silverfish, firebrats, bristletails, rock jumpers; order of primitive wingless insects (Apterygota) commonly found amongst decaying wood, in leaf litter, caves and human habitations, or in association with ants and termites; feed on fungi, lichens, algae, pollen, or decaying vegetable matter; body length 5-25 mm, abdomen terminating in pair of long cerci and long median filament; sexes similar or weakly dimorphic; development ametabolous; contains about 600 species.
\Btick\b \JIxodida\j
\Btickseed\b \JAsterales\j
\Btidal current\b The alternating horizontal movement of water associated with the rise and fall of the tide.
\Btidal day\b The period between two consecutive high waters at a given place, averaging 24 h 51 min (24.84 h).
\Btidal flat\b An extensive flat tract of land alternately covered and uncovered by the tide, and comprising mostly unconsolidated mud and sand.
\Btidal marsh\b A low-elevation marshy coastal area formed of mud and the root mat of salt-loving plants, regularly inundated during high tides.
\Btide\b The periodic rise and fall of the ocean water masses and atmosphere, produced by gravitational effects of the moon and sun on the Earth.
\Btide cycle\b The duration of a given tidal sequence, as for example a lunar month or a tidal day.
\Btide range\b The difference in height between consecutive high and low waters.
\BTiliaceae\b Linden, lime, bass wood; family of mostly tropical and subtropical trees often with stellate hairs or peltate scales; flowers usually with 5 sepals and petals, many free stamens and superior ovaries; phloem fibres from species of the herbaceous genus, \ICorchorus\i are used as jute.
\Btill\b Material deposited directly by ice.
\BTillodontia\b Extinct order of mammals known from the northern hemisphere during the Palacocene and Eocene; some were bear-sized but with rodent-like incisors.
\BTilopteridales\b Small order of sublittoral brown algae with a loosely branched filamentous body form; found in cold waters of the northern hemisphere.
\Btilth\b The physical condition of a soil in relation to its fitness for plant growth.
\BTimaliidae\b Babblers; diverse family containing about 275 species of Old World passerine birds found in variety of forest and grassland habitats from Africa to Australia; habits gregarious or solitary, mostly arboreal and non-migratory, feeding on insects and fruit; nest composed of sticks and mud, on or off the ground.
\Btimber beetle\b \JCerambycidae\j
\Btimber line\b The line marking the latitudinal or upper altitudinal limit of normal dense tree growth.
\BTinamidae\b Tinamous; family containing 47 species of small New World ground-living palaeognathous birds found in variety of forest, brush and grassland habitats; still capable of flight; body compact, neck and wings short, tail inconspicuous, legs strong; bill weak, moderately long and weakly decurved; sexes similar although female larger than male; habits mostly crepuscular, secretive, often polygamous, feeding on seeds and fruit; range extends from Mexico to Argentina.
\BTinamiformes\b Order of small New World ratites containing a single family, Tinamidae (tinamous).
\Btinamou\b \JTinamidae\j
\BTineidae\b Clothes moths; family of small or minute moths containing about 3000 species some of which are pests of stored products and cause damage to woollen materials.
\Btintinnid\b \JOligotrichida\j
\Btiphicolous\b Living in ponds; \Btiphicole.\b
\Btiphophilous\b Thriving in ponds; \Btiphophile, tiphophily.\b
\Btiphophyte\b A pond or pool plant.
\BTipulidae\b Craneflies, daddy longlegs, leatherjackets; largest family of dipteran insects containing more than 13 000 species; adult body slender with narrow wings and long fragile legs, antennae 6-segmented; commonly feed on plant juices and nectar.
\Btoadstool\b Informal name for any typical umbrella-shaped fungal fruiting body.
\Btobacco\b \JSolanaceae\j
\Btolerance\b 1: The ability of an organism to endure extreme conditions. 2: The range of an environmental factor within which an organism or population can survive.
\Btomato\b \JSolanaceae\j
\Btombolo\b A sand-bar connecting an island or group of islands with the mainland.
\Btomiparous\b Reproducing by fission; \Btomiparity.\b
\Btongue sole\b \JCynoglossidae\j
\Btonotaxis\b The directed response of a motile organism to a change in osmotic pressure or to an osmotic stimulus; \Btonotactic.\b
\Btonotropism\b An orientation response to an osmotic stimulus; \Btonotropic.\b
\Btooth shell\b \JScaphopoda\j
\Btoothcarp\b \JCyprinodontidae\j
\Btop minnow\b \JCyprinodontidae\j
\Btop shell\b \JArchaeogastropoda\j
\Btopknot\b \JScophthalmidae\j
\Btopochemotaxis\b A directed response of a motile organism towards the source of a chemical stimulus; \Btopochemotactic.\b
\Btopodeme\b A local interbreeding population occurring in a particular geographical area; See also \Jdeme\j
\Btopogalvanotaxis\b The directed response of a motile organism towards the source of an electrical stimulus; \Btopogalvanotactic.\b
\Btopographic desert\b A low-rainfall desert region located in the middle of a continental landmass.
\Btopography\b All natural and man-made surface features of a geographical area; \Btopographical.\b
\Btopophototaxis\b The directed response of a motile organism towards the source of a light stimulus; \Btopophototactic.\b
\Btopotaxis\b The directed response of a motile organism to spatial differences in the intensity of a stimulus, especially with reference to the source of the stimulus; \Btopotactic.\b
\Btopotropism\b An orientation response towards the source of a stimulus; \Btopotropic.\b
\Btopsoil\b The upper soil layer or layers containing some organic matter.
\Btornaria\b Ciliated planktotrophic larva of enteropneust and planctosphaeroidean hemichordates.
\BTorpedinidae\b Torpedo rays, electric rays; family containing 15 species of marine torpediniform fishes; body length to 2 m, disk broader than long, 2 dorsal fins present; mouth large, teeth small and formed of single cusps; depth range from littoral to 500 m.
\BTorpediniformes\b Electric rays, torpedo rays; order comprising about 40 species of mostly small (to 2 m) elasmobranch fishes (Batoidea) in which the body disk is strongly flattened, subcircular, and contains large electric organs; body devoid of denticles; caudal fin large with axis straight; habits benthic, sluggish, using electric organ to stun prey; reproduction viviparous, without placenta; found mainly in the tropics and subtropics, ranging from the littoral to depths over 1000 m.
\Btorpedo ray\b \JTorpedinidae\j
\Btorpid\b Dormant; lacking vigour.
\Btorpor\b A dormant state.
\Btorrentfish\b \JCheimarrichthyidae\j
\Btorrenticolous\b Living in river torrents.
\Btortoise\b \JTestudinidae\j
\Btortoiseshell butterfly\b \JNymphalidae\j
\BTortricidae\b Large cosmopolitan family of small moths (Lepidoptera) the larvae of which have diverse leaf rolling, mining, boring and gallforming habits; comprises about 4000 species and includes many serious agricultural pests such as the codling moth, numerous fruit moths, and the spruce and pine budworms.
\Btoucan\b \JRamphastidae\j
\Btouch-me-not\b \JBalsaminaceae\j
\Btouraco\b \JMusophagidae\j
\BTovariaceae\b Small family of Capparales containing 2 species of coarse herbs or soft shrubs, native to tropical America.
\Btoxic\b Poisonous.
\Btoxicity\b The virulence of a poisonous substance (the toxicant).
\Btoxicology\b The study of poisonous substances and their effects.
\Btoxigenic\b Producing toxin.
\Btoxin\b A biogenic poison, usually proteinaceous.
\BToxotidae\b Archerfishes; family containing 6 species of small (to 250 mm) Indo-Pacific, coastal marine to freshwater, perciform teleost fishes frequently found in mangrove habitats; body deep and compressed, dorsal profile somewhat flattened; eyes large, mouth strongly protractile; feed on insects dislodged from vegetation by spitting drops of water over distances up to 3 m; archerfishes are popular amongst aquarists.
\Btrace\b Any distinct biogenic structure either fossil or recent, such as a track, trail, burrow, boring or faecal cast.
\Btrace element\b An element essential for normal growth and development of an organism, but required only in minute quantities.
\Btrace fossil\b A sedimentary structure resulting from the activity of a living animal, such as a track, burrow or tube.
\BTracheophyta\b Vascular plants; division of plants possessing vascular tissues (xylem and phloem) for internal transport of nutrients and water; includes the pteridophytes (Filicophyta), gymnosperms (Pinophyta) and angiosperms (Magnoliophyta).
\BTrachichthyidae\b Slimeheads; family containing about 15 species of beryciform teleost fishes widespread in shallow inshore as well as deep oceanic waters; body deep and compressed, to 500 mm in length; head with large mucous cavities.
\BTrachinidae\b Weeverfishes; family of venomous, bottom-dwelling, coastal marine teleost fishes (Perciformes) containing 4 species widespread in the eastern Atlantic; body to 400 mm in length, head depressed, eyes dorsal, mouth oblique; first dorsal fin spines and opercular spines with poison glands; live partly buried in sand during the day emerging to feed at night.
\BTrachipteridae\b Ribbonfishes; family containing 8 species of mesopelagic lampridiform teleost fishes; body elongate, to 1.7 m in length, compressed, silvery, scales deciduous; caudal and dorsal fins elongate, caudal with upper lobe only, anal fin absent; feed mainly on fishes, squid and crustaceans.
\BTrachylina\b Primitive order of Hydrozoa occurring mostly in open water in the warmer oceans, characterized by the reduction or loss of the polyp generation; the medusoid stage is a transformed actinula larva and is not homologous with the medusae of other hydrozoans.
\BTrachypsammiaceae\b Extinct order of octocorals possessing a central medullar canal system; known only from the Permian.
\Btrade wind\b Uniform tropical oceanic wind system blowing towards the equator from the northeast in the northern hemisphere and from the southeast in the southern hemisphere.
\Btradescantia\b \JCommelinaceae\j
\BTragulidae\b Chevrotains; family containing 4 species of small (up to about 1 m length) forestdwelling ungulates (Artiodactyla: Ruminantia) found in tropical Ethiopian and Oriental regions; upper canines elongate; horns absent; feet with 4 digits; habits nocturnal or crepuscular, solitary, feeding mainly on fruit and fleshy plant material; these ungulates do not ruminate.
\Btrahiras\b \JErythrinidae\j
\Btrail pheromone\b A chemical substance laid down as a trail by one individual and followed by another member of the same species.
\Btrait\b Any character or property of an organism.
\Btramp\b A species having a wide geographical range and an efficient means of dispersal.
\Btranscription\b Synthesis of messenger RNA from a DNA molecule acting as a template; See also \Jtranslation\j
\Btransduction\b The transfer of genetic material from donor to recipient microorganism, as from one bacterial cell to another by a bacteriophage.
\Btransect\b A line or narrow belt used to survey the distributions of organisms across a given area.
\Btransfer RNA\b A relatively small RNA molecule that transfers a given amino acid to a polypeptide chain during \Jtranslation\j of messenger RNA at the site of protein synthesis in a ribosome; tRNA.
\Btransgression\b The spread of the sea over a land area; See also \Jregression\j
\Btransient\b Of short duration; transitory.
\Btranslation\b The sequential reading of the base sequence of messenger RNA and its translation into a specific amino acid chain during protein synthesis in ribosomes; See also \Jtranscription\j
\Btranslocated herbicide\b A herbicide that is dispersed throughout the plant tissue following absorption through the leaves or roots.
\Btranslocation\b 1: The transport of material within a plant. 2: Movement of a segment of a chromosome to another part of the same chromosome or to a different chromosome.
\Btranspiration\b Loss of water vapour from an organism through a membrane or through pores.
\Btranspiration efficiency\b The ratio of dry organic matter produced by a plant to water loss by transpiration.
\Btransplant\b Transfer of tissue from one part of an organism to another, or to another organism.
\BTrapaceae\b Water chestnut; small family of Myrtales containing about 15 species of aquatic annual herbs; native to tropical and subtropical Africa and Eurasia.
\Btraplining\b A feeding strategy during which an animal visits a sequence of widely dispersed food sources, obtaining a small part of its daily food requirement at each feeding station.
\Btrauma\b Injury or stress caused by an extrinsic agent; \Btraumatic, traumatism.\b
\Btraumatonasty\b A growth response to a traumatic stimulus; \Btraumatonastic.\b
\Btraumatotaxis\b Movement of organisms, cells or organelles in response to injury; \Btraumatotactic.\b
\Btraumatotropism\b An orientation response to injury or stress; \Btraumatotropic.\b
\Btraveller's tree\b \JStrelitziaceae\j
\Btree creeper\b \JCerthiidae\j
\Btree line\b The line which marks the northerly, southerly or upper altitudinal limit of tree cover.
\Btree of heaven\b \JSimaroubaceae\j
\Btree shrew\b \JTupaiidae\j
\Btree sloth\b \JBradypodidae\j
\Btree swift\b \JHemiprocnidae\j
\Btreehopper\b \JMembracidae\j (Homoptera).
\Btree-ring chronology\b Study of annual growth rings of trees for the purposes of dating.
\BTremandraceae\b Family of Polygalales containing 28 species of heather-like shrubs, native to Australia and Tasmania; flowers often brightly coloured, with 3-5 sepals and petals, twice as many stamens, and a superior ovary.
\BTrematoda\b Class of exclusively parasitic flatworms characterized by a dorsoventrally flattened body covered with a cuticle, one or more attachment organs (holdfasts), a well developed gut consisting of mouth, pharynx, oesophagus and 1 or 2 intestinal caeca, usually with no anus; reproductive system well developed, usually hermaphroditic and producing numerous encapsulated eggs; comprises over 8000 species grouped into 3 subclasses, Monogenea, chiefly parasitizing fish, Aspidogastrea, endoparasites of molluscs, fishes and turtles, and Digenea, parasitizing all groups of vertebrates.
\BTrentepohliales\b Small order of green algae in which the thallus forms an erect tuft or prostrate disk of loosely packed, branched, uniseriate filaments; found subaerially and occasionally as parasites, in the tropics and subtropics.
\BTrepostomata\b Extinct order of bryozoans known from the Ordovician to the Permian; colonies solidly built of calcite, the individuals forming long tubes.
\BTriacanthidae\b Spikefishes, triplespines; family containing 20 species of small (to 70 mm) bottom-living tetraodontiform teleost fishes found in shallow coastal waters and in the deep sea; pelvic fins typically reduced to pair of strong spines.
\Btriacylglycerol\b An ester of glycerol and carboxylic or fatty acids; often important as energy storage molecules in plants.
\BTriakidae\b Hound sharks; widespread family containing about 40 species of small to medium-sized (to 2 m) inoffensive carcharhiniform elasmobranch fishes that are benthic or pelagic in continental seas from the intertidal to 500 m; may be locally common; feed on fishes and a variety of invertebrates, especially crustaceans; reproduction ovoviviparous to viviparous; sometimes treated as part of the Carcharhinidae.
\BTriassic\b A geological period of the Mesozoic era (\Ic.\i 245-210 million years B.P.); Trias; see geological time scale.
\BTribonematales\b Order of freshwater and marine algae (Xanthophyceae) characterized by their filamentous organization; cells within filaments mostly uninucleate.
\BTrichechidae\b Manatees; family containing 3 species of large nocturnal, herbivorous aquatic mammals (Sirenia) found in tropical freshwater and coastal habitats of the western and eastern Atlantic; incisor and canine teeth absent; tail fluke without median notch.
\BTrichiales\b Order of Myxogastromycetidae characterized by fruiting bodies that lack lime but bear brightly coloured spores internally; contains about 80 species typically found on litter and decaying wood.
\BTrichiida\b The slime mould order \JTrichiales\j, treated as an order of the protozoan group Myxogastria.
\BTrichiuridae\b Cutlassfishes; family containing 17 species of scombroid teleost fishes (Perciformes) found mostly in midwater to about 1000 m depth; body elongate and compressed, to 1.5 m in length, jaw teeth fanglike; pelvic and caudal fins small or absent; feed on squid, crustaceans and other fishes.
\BTrichocephalida\b Small order of enoplian nematodes found only as parasites of vertebrates; characterized by arrangement of the oesophageal glands in a single row, and by the protrusible axial spear present in early larval stages but lost in the adult.
\BTrichodontidae\b Sandfishes; family containing 2 species of northern Pacific, shallow marine perciform teleost fishes, typically found partly buried in sandy sediment; body compressed, deeply convex ventrally, to 300 mm in length, mouth subvertical opening on top of head; anal fin elongate, pectorals broad; exploited as food-fish in Japan.
\BTrichomonadida\b Order of mostly parasitic zooflagellates with 4 to 6 flagella, one of which is recurrent and either free or adhered to the body surface forming an undulating membrane.
\BTrichomycetes\b Class of zygomycotine fungi comprising obligate gut symbionts of various arthropods that obtain nutrients from material in host's digestive tract; usually attached to chitinous lining of hind gut; 4 orders recognized, Amoebidiales, Asellariales, Eccrinales and Harpellales.
\BTrichomycteridae\b Family of small (to 150 mm) Central and South American freshwater catfishes (Siluriformes); body often vermiform, naked, dorsal fin lacking spine; 2-3 pairs of barbels present; contains about 180 species, some parasitic on other fishes, others free-living and nocturnal or crepuscular, burrowing in substratum during the day.
\BTrichoptera\b Caddisflies; order of holometabolous insects containing about 7000 species in which the adults are terrestrial and the larvae and pupae are almost exclusively aquatic in fresh water; adults are moth-like with hairy forewings held at an oblique vertical angle at rest, and are liquid feeders; larvae are caterpillar-like and construct a variety of protective cases, silken nets or other domiciles in fresh water, feeding on algae, fungi, or decomposing plant material.
\BTrichosida\b Order of multinucleate amoeboid protozoans (Testacealobosa) which produce flexible fibrous sheaths with multiple apertures; common in shallow coastal and estuarine waters.
\BTrichostomatida\b Primitive order of vestibuliferan ciliates in which the ciliature of the vestibule is derived during fission from the terminal portions of the ciliary rows over the general body surface; occasionally free-living but mostly found as endocommensals in the digestive tracts of ruminants.
\BTricladida\b Large order of typically free-living turbellarians found commonly in marine, freshwater and terrestrial habitats; characterized by a single pair of ovaries, a posteriorly directed plicate pharynx and an intestine divided into an anterior median and 2 posterior branches, all highly diverticulated; often attaining large size, most are predatory; some are resistant to desiccation.
\BTriconodonta\b Extinct order of carnivorous, early mammals (Prototheria) known from the late Triassic to the early Cretaceous; molar teeth with row of 3 sharp cusps.
\Btrigenetic\b Pertaining to a symbiont requiring three different hosts during the life cycle; see also \Jdigenetic\j \Jmonogenetic\j
\Btrigger plant\b \JStylidiaceae\j
\Btriggerfish\b \JBalistidae\j
\BTriglidae\b Sea robins, gurnards; family containing 85 species of bottom-living, tropical and temperate, marine scorpaeniform teleost fishes found on soft sediments of inshore and shelf waters; body often armoured with bony plates, head large and ornate; pectoral fins large with a number of isolated fin rays; use muscles acting on swim bladder for sound production.
\Btrigoneutic\b Producing three broods in a single season; \Btrigoneutism\b; see also \Jmonogoneutic\j \Jdigoneutic\j, \Jpolygoneutic\j
\BTrigoniaceae\b Family of Polygalales containing 24 species of woody plants, widespread in moist forests of tropical America; flowers irregular, with 5 sepals, 3-5 petals, 3-12 stamens on one side, and a superior ovary; fruit usually a capsule.
\BTrigonioida\b Small order of marine paleoheterodont bivalves found burrowing in shallow waters of the Indo-Pacific.
\BTrilobita\b Trilobites; subphylum of primitive aquatic arthropods known from the Cambrian to the Permian; body divided into anterior cephalon, thorax and posterior pygidium; trilobed appearance due to pair of longitudinal furrows running length of body; compound eyes often present; limbs typically with ambulatory inner branch and foliaceous, respiratory outer branch.
\BTrimeniaceae\b Small family of trees or climbing shrubs (Laurales) restricted to New Guinea, New Caledonia, Fiji and eastern Australia.
\Btrimonoecious\b Used of an individual plant bearing male, female and hermaphrodite flowers.
\Btrimorphic\b Used of organisms having three distinct forms in the life cycle, or in a population; \Btrimorphism.\b
\Btrioecious\b Used of a plant species having male, female and hermaphrodite flowers on different individuals; see also \Jdioecious\j \Jmonoecious\j
\BTrionychidae\b Soft-shelled turtles; family containing about 20 species of large (to 1 m) predatory freshwater turtles (Testudines: Cryptodira) found in North America, North Africa and the Indo-Pacific region; carapace without horny scutes; snout forming a proboscis bearing fleshy lips; feet webbed.
\Btriplespine\b \JTriacanthidae\j
\Btripletail\b \JLobotidae\j
\Btriploid\b A polyploid having three sets of homologous chromosomes; \Btriploidy\b See also \Jploidy\j
\Btripod fish\b \JBathypteroidae\j
\BTripterygiidae\b Threefin blennies; family containing about 100 species of small (to 90 mm) tropical marine perciform teleost fishes found mainly in coral and rocky habitats; 3 dorsal fins present, the first 2 spinose, the third soft-rayed; sexual dimorphism pronounced.
\Btripton\b Non-living particulate matter suspended in water; a component of \Jseston\j
\Btriton shell\b \JMesogastropoda\j
\Btritonymph\b Immature stage, between protonymph and adult, found in some mites (Acari).
\BTriuridaceae\b Family of about 70 species of small mycotrophic herbs (Triuridales) without chlorophyll, with a single ring of vascular bundles in the stem and leaves reduced to scales; widespread in tropical and subtropical regions; flowers regular, borne in racemes.
\BTriuridales\b Order of Alismatidae comprising 2 small families of mycotrophic herbs lacking chlorophyll, with endospermous seeds and distinct or nearly distinct carpels, Petrosaviaceae and Triuridaceae.
\Btrivoltine\b Having three generations or broods per year; See also \Jvoltine\j
\Btrixenous\b Used of a parasite utilizing three host species during its life cycle; \Btrixeny\b; see also \Jdixenous\j \Jheteroxenous\j, \Jmonoxenous\j, \Joligoxenous\j
\BtRNA\b Transfer \JRNA\j
\BTrochilidae\b Hummingbirds; family containing about 340 species of small colourful New World birds (Apodiformes) noted for their acrobactic hovering flight; bill slender, tongue extensible, adapted for feeding on nectar, pollen and insects from flowers; sexes dimorphic; habits solitary, mostly monogamous, often migratory.
\BTrochodendraceae\b Primitive family of Trochodendrales containing a single tree species with tiny green flowers lacking a perianth; fruit is a follicle.
\BTrochodendrales\b The most archaic surviving order of the Hamamelidae comprising two monotypic families of trees, the Tetracentraceae and the Trochodendraceae, both native to eastern Asia.
\Btrochophore\b Free-swimming, unsegmented ciliated larval stage of polychaetes, sipunculans, echiurans, entoprocts, bryozoans, brachiopods, phoronids and molluscs.
\Btrochosphere\b \JTrochophore\j
\Btroglobiont\b An obligate cavernicole; an organism found only in caves or subterranean passages; see also \Jtroglophile\j \Jtrogloxene\j
\BTroglodytidae\b Wrens; family containing about 60 species of small active passerine birds found in variety of forest, woodland and open arid habitats of the Old World; body compact, wings short and rounded, tail erect; habits typically solitary, arboreal, some species migratory, monogamous to polygamous; nest in trees, bushes, grass, or banks.
\Btroglon\b The biotope comprising subterranean water bodies in caves and subterranean passages; see also \Jcrenon\j \Jstygon\j, \Jthalasson\j
\Btroglophile\b An animal frequently found in underground caves or passages but not confined to them; see also \Jtroglobiont\j \Jtrogloxene\j
\Btroglophilic\b Thriving in caves and subterranean passages; \Btroglophile\b, \Btroglophily.\b
\Btrogloxene\b An organism found only occasionally in caves or subterranean passages; \Btrogloxenous\b; see also \Jtroglobiont\j \Jtroglophile\j
\BTrogoniformes\b Order of colourful, sedentary, arboreal birds found worldwide in tropical forests; feed on fruit, insects and other small animals; contains about 35 species in a single family, Trogonidae.
\BTrogonophiidae\b Family containing 6 species of worm lizards (Amphisbaenia) found in North Africa and southwestern Asia.
\BTrombidiformes\b Trombidiid mites; diverse suborder of mites (Acari) that contains many predatory and parasitic species; includes spider mites, harvest mites, velvet mites and water mites.
\Btroop\b A group of primates; a flock or assemblage of birds or mammals.
\BTropaeolaceae\b Nasturtium; family of Geraniales containing about 90 species of mustard oil-producing herbs, often climbing with twining petioles; confined to the New World; flowers bisexual, irregular and often showy, with 5 sepals forming a spur below the flower, 5 irregular petals, 8 stamens and a superior ovary.
\Btrophallaxis\b Mutual or unilateral exchange of food between colony members.
\Btrophic\b Pertaining to nutrition; \Btrophism.\b
\Btrophic level\b 1: Each step of a food chain or food \Jpyramid\j, from producer to primary, secondary or tertiary consumer. 2: The nutrient status of a body of fresh water.
\Btrophic unit\b A group of individuals of one or more species occupying the same relative position in a food chain.
\Btrophobiosis\b Symbiosis in insects in which food is obtained from one species (the trophobiont) by another in return for protection.
\Btrophodynamics\b Study of the energy relationships of feeding strategies and food webs.
\Btrophogenic\b 1: Produced by, or resulting from, food or feeding behaviour. 2: Used of the illuminated surface layer of a lake in which photosynthesis occurs; See also \Jtropholytic\j
\Btropholytic\b Pertaining to the deeper part of a lake below the \Jtrophogenic\j zone, in which organic matter is utilized as the energy source.
\Btrophotaxis\b The directed response of a mobile organism towards (positive) or away from (negative) a food stimulus; \Btrophotactic.\b
\Btrophotropism\b An orientation response to food; \Btrophotropic.\b
\Btropic bird\b \JPhaethontidae\j
\Btropic tide\b The tide occurring twice monthly when the moon reaches its greatest northerly or southerly declination; See also \Jsolstitial tide\j
\Btropical\b 1: Pertaining to the zone between the Tropic of Cancer (23░27' N) and the Tropic of Capricorn (23░27' S); see also \Jpolar\j \Jtemperate. 2: Used of a climate characterized by high temperature\j, \Jhumidity and rainfall\j, \Jand having rare light frosts at night\j
\Btropical desert\b Hot dry desert situated close to the Tropics of Cancer and Capricorn, where subtropical high pressure meteorological conditions result in very low sporadic rainfall.
\BTropical grassland biome\b The circumtropical savannah belt transitional between equatorial forest and grassland, characterized by constant high temperature, a long dry season, low-fertility soil, frequent fires, dominated by grasses and scattered trees and large grazing mammals; Tropical savannah biome.
\Btropical lake\b A lake having a surface temperature that never falls below 4░C at any time of year.
\BTropical rainforest biome\b A circumtropical forest region characterized by constant high humidity and temperature, no frost, little seasonal fluctuation of climate except precipitation, typically with a rich variety of trees, a dense canopy, lianas and epiphytes, little undergrowth, an abundance of birds and arboreal vertebrates and the greatest diversity of animal life in any terrestrial biome.
\Btropical zone\b The latitudinal zone between 15.0░and 23.5░in either hemisphere.
\Btropicopolitan\b Cosmopolitan within the tropics.
\BTropidophiidae\b Family containing 20 species of small (to 500 mm) terrestrial, ovoviviparous booid snakes (Serpentes) from West Indies and Mexico through to northern South America.
\Btropism\b An orientation or growth response of a non-motile organism or one of its parts towards (positive) or away from (negative) a stimulus; \Btropic.\b
\Btropoparasite\b An organism that lives as an obligate parasite for only part of its life cycle.
\Btropophilous\b Thriving in an environment that undergoes marked periodic fluctuations of light, temperature and moisture; \Btropophile\b, \Btropophily. \b
\Btropophyte\b A plant that thrives under mesic conditions for part of the year and xeric conditions at other times.
\Btroposphere\b 1: The warm upper layer of oceanic water at middle and low latitudes, typically having strong currents; ocean waters above the \Jthermocline\j 2: The layer of the atmosphere below the stratosphere extending from ground level to 10-15 km above the Earth's surface\j, \Jin which temperature falls rapidly with increasing altitude, typically with active convection currents; See also \Jstratosphere\j
\Btropotaxis\b An orientation response of a motile organism in which the stimulus is compared simultaneously on each side of the midline by bilateral sense organs, such that no deviations from the line of movement are required to compare the intensities of the stimuli; see also \Jklinotaxis\j \Jtelotaxis\j
\Btrout\b \JSalmonidae\j
\Btrout-perch\b \JPercopsidae\j
\Btrue fungi\b \JEumycota\j
\Btruffle\b The underground fruiting body of some species of \JTuberales\j; often edible.
\Btrumpet creeper\b \JBignoniaceae\j
\Btrumpeter\b 1: \JPsophiidae\j 2: \JLatridae\j
\Btrumpetfish\b \JAulostomidae\j
\Btrunkfish\b \JMolidae\j
\BTryblidioidea\b The only order comprising the class \JMonoplacophora\j; contains Recent forms and fossils from Cambrian onwards.
\BTrypanorhyncha\b Order of tapeworms parasitic in cartilaginous fishes (elasmobranchs); characterized by a scolex consisting of 2-4 bothridia and 4 eversible, apical tentacles used for attachment to the host; utilize molluscs and crustaceans as intermediate hosts.
\Btryphobiontic\b Inhabiting bogs.
\Btsetse fly\b \JGlossinidae\j
\Btsunami\b A large ocean wave caused by submarine volcanic or earthquake activity.
\Btuatara\b \JSphenodontidae\j
\Btube anemone\b \JCeriantharia\j
\Btube-eye\b \JStylophoridae\j
\Btubenose\b \JAulorhynchidae\j
\Btuber\b A swollen part of a root or stem, typically modified for storage and lasting for a single year only.
\BTuberales\b Order of discomycete fungi that produce underground fleshy or waxy, fruiting bodies (truffles) which are highly prized as food; characterized by underground ascocarps that remain closed and by asci that have lost their active spore-discharge mechanism.
\BTuberculariales\b Order of hyphomycete fungi in which the fertile hyphae are compacted into false fruiting bodies called sporodochia, which are highly variable in shape, texture and colour; most species are saprophytes and parasites of flowering plants.
\Btubeshoulder\b \JSearsiidae\j
\Btubesnout\b \JAulorhynchidae\j
\Btubicolous\b Tube-dwelling; \Btubicole.\b
\BTubificina\b Sludge worms; large suborder of oligochaete worms (Haplotaxida) found in fresh water; chaetae diverse, gills sometimes present; blood may contain haemoglobin pigment.
\BTuboidea\b Extinct order of sessile, dendroid graptolites known from the Lower Ordovician to Upper Silurian.
\BTubulidentata\b The smallest extant order of mammals comprising a single species, the aardvark (Orycteropodidae); characterized by the absence of tooth enamel, each tooth having tubular pulp cavities surrounded by hexagonal dentine prisms.
\BTubulina\b Suborder of \JAmoebida\j; also treated as a class of the protoctistan phylum Rhizopoda.
\Btulip\b \JLiliaceae\j
\Btulip shell\b \JNeogastropoda\j
\Btulip tree\b \JMagnoliaceae\j
\BTulostomatales\b Stalked puffballs; small order of gastromycete fungi that produce more or less globose fruiting bodies supported on a stalk (stipe).
\Btumulus\b Pertaining to dunes.
\Btun\b A resistant cryptobiotic stage in tardigrades.
\Btun shell\b \JMesogastropoda\j
\Btuna\b \JScombridae\j
\BTundra biome\b A barren treeless region north of the Arctic Circle (Arctic tundra), also found above the tree line of high mountains (alpine tundra) and on some sub-Antarctic islands; characterized by very low winter temperatures, short cool summers, permafrost below a surface layer subject to summer melt; dominated by lichens, mosses, sedges and low shrubs, vast seasonal swarms of insects, and migratory animals.
\BTundra soil\b A zonal soil with abundant litter and duff, a dark brown peaty A-horizon rich in organic material over a greyish B-horizon; formed under conditions of extreme cold, high humidity and poor drainage.
\BTungidae\b Jiggers, sand fleas; family containing 10 species of siphonapteran insects (fleas) in which the females bury themselves beneath the skin of the host and then swell up by engorging blood.
\BTunicata\b Tunicates; subphylum of solitary or colonial, sessile or free-living, marine invertebrate chordates in which the adult body lacks segmentation and body cavity, and is enclosed in a soft, sometimes gelatinous test; water passes through a large branchial sac by ciliary action via inhalent and exhalent siphons, food particles being trapped by mucus secreted by the endostyle; the gut is U-shaped; typically hermaphroditic, oviparous, the larval stage possessing the chordate features of a notochord, dorsal nerve chord and elongate post-anal tail; colonies formed by asexual budding; about 1250 species are recognized in 3 classes, Ascidiacea, Thaliacea and Appendicularia; Urochordata.
\BTupaiidae\b Tree shrews; family containing 15 species of small arboreal and terrestrial mammals (Insectivora) found in the Oriental Region; habits diurnal, active, omnivorous, locomotion scansorial.
\BTurbellaria\b Class of mostly free-living, predatory flatworms, but including some commensal and parasitic forms, found commonly in freshwater and marine habitats, and in some damp terrestrial situations; characterized by the possession of a sperm with 2 flagella, a blind gut with no anus, an unsegmented body and a cellular ciliated epidermis; most forms have a muscular pharynx and some possess statocysts; comprises 12 orders.
\Bturbid\b Cloudy; opaque with suspended matter.
\Bturbidite\b A marine sediment deposited at the base of a submarine slope by a turbidity current.
\Bturbidity current\b A gravity flow resulting from a mass of unstable sediment sliding down a submarine slope.
\Bturbot\b \JScophthalmidae\j
\Bturbulence\b Irregular motion or agitation of liquids or gases; See also \Jlaminar flow\j
\BTurdidae\b Thrushes; diverse family of small passerine birds found in a variety of forest, grassland and open habitats, worldwide; habits solitary to gregarious, arboreal or terrestrial, migratory or non-migratory, feeding mainly on insects, worms, molluscs and fruit; nest typically cup-shaped, on or off the ground; contains about 300 species, including wheatears, chats, bluebirds, nightingale and blackbirds.
\Bturfaceous\b Pertaining to bogs.
\Bturfophilous\b Thriving in bogs; \Bturfophile, turfophily.\b
\Bturkey\b \JMeleagridae\j
\Bturkeyfish\b \JScorpaenidae\j
\BTurneraceae\b Small family of Violales containing about 120 species of often cyanogenic herbs or shrubs; native mainly to tropical or warm temperate regions of America and Africa.
\BTurnicidae\b Hemipodes; family containing 14 species of small quail-like gruiform birds found in tropical and warm temperate open woodland and grassland of the Old World from Europe to Australia; habits solitary, terrestrial, flight usually short and explosive, female polyandrous; feed on seeds and insects, nest on the ground.
\Bturnip\b \JBrassicaceae\j
\Bturnover\b 1: The ratio of productive energy flow to standing crop biomass in a community or ecosystem. 2: That fraction of a population which is exchanged (lost by mortality and emigration, replaced by recruitment). 3: Water circulation occurring in deep temperate lakes in spring and autumn, tending to equalize temperature throughout the water column.
\Bturnstone\b \JScolopacidae\j
\Bturtle\b \JTestudines\j
\Bturtle grass\b \JHydrocharitales\j
\Btusk shell\b \JScaphopoda\j
\Btussock moth\b \JLymantriidae\j
\Btychopelagic\b Used of organisms that are normally benthic, but which have been carried up into the water column by chance factors.
\Btychoplankton\b Organisms occasionally carried into the plankton by chance factors such as turbulence; \Btychoplanktont, tychoplanktonic.\b
\Btychopotamic\b Pertaining to aquatic organisms thriving in the still backwaters of rivers and streams; see also \Jautopotamic\j \Jeupotamic\j
\BTylenchida\b Order of diplogasterian nematodes containing fungal feeders, and parasites of insects and higher plants; characterized by the presence of an axial spear in the oesophagus.
\BTylopoda\b Suborder of cloven-hooved ungulates (Artiodactyla) comprising a single extant family, Camelidae (camels, llamas), and many fossil families of ruminant-like artiodactyls known from the Eocene to the Pliocene.
\BTyphaceae\b Cattails, reedmace; cosmopolitan family of often dense, colonial, perennial herbs growing in marshes or in shallow water; with numerous wind-pollinated flowers borne in dense, cylindrical spikes, female flowers typically lower down spike, male flowers in upper part.
\BTyphales\b Order of Commelinidae comprising 2 small families of aquatic or semiaquatic perennial herbs, the bur reeds (Sparganiaceae) and the cattails (Typhaceae).
\BTyphlonectidae\b Family containing about 20 species of aquatic South American caecilians (Gymnophiona); body length to about 700 mm, scales and tail absent; reproduction oviparous or viviparous, larvae without gill slits; distribution confined to Orinoco, Amazon and Paraná Basins in South America.
\BTyphlopidae\b Family of worm-like, insectivorous, burrowing snakes (Serpentes) widespread in tropical and subtropical regions; length up to 1 m; teeth present on upper jaw only; eyes concealed beneath scales; contains about 150 species.
\BTyphogena\b Superorder of blind helminthomorphan diplopods (millipedes) comprising 2 orders, Siphonophorida and Platydesmida; mouthparts reduced, sternal and pleural sclerites loosely articulated; 8 pairs of legs present anterior to gonopods.
\BTyrannidae\b Tyrant flycatchers; diverse family containing about 375 species of Neotropical passerine birds found in wide variety of habitats from wet forest to arid open areas; habits arboreal to terrestrial, solitary, monogamous, feeding on insects and small vertebrates; nest on or above the ground.
\BTytonidae\b Barn owls; cosmopolitan family containing 11 species of medium-sized nocturnal raptors (Strigiformes); head large with heart-shaped facial disk; habits solitary, monogamous, non-migratory, feeding on variety of small mammals, birds and insects.
\Bubiquitous\b Having a worldwide distribution, effect or influence; widespread; cosmopolitan.
\BUdden grade scale\b A scale of sediment particle \Jsize\j, categories based on a doubling or halving, above or below, respectively, the fixed reference point of 1 mm.
\Buliginous\b Inhabiting swampy soil or wet muddy habitats.
\Bulluco\b \JBasellaceae\j
\BUlmaceae\b Elm, hackberry; family of Urticales containing about 150 species of woody plants widely distributed in the northern hemisphere; often with mineralization of cell walls, especially in the epidermis; flowers borne in small clusters on twigs, each flower with a 4-8 lobed perianth, the same number of stamens and an ovary of 2 fused carpels.
\Bulmification\b The process of peat formation.
\BUlotrichales\b Small order of unbranched filamentous green algae; filaments composed of uninucleate cells each containing a parietal, laminate or cylindrical chloroplast; also treated as a class of the proctoctistan phylum Chlorophyta.
\Bultrananoplankton\b Planktonic organisms less than 2 \Fm\nm in diameter.
\Bultraplankton\b Planktonic organisms less than 5 \Fm\nm in length or diameter.
\Bultrastructure\b Cellular structure studied with the aid of a transmission electron microscope; fine structure.
\Bultraviolet radiation (UV)\b That part of the solar radiation spectrum below a wavelength of 380 nm.
\BUlvales\b Sea lettuce; order of essentially marine or brackish-water green algae in which the body is a multicellular thallus typically in the form of a monostromatic blade, tube or sac; including \IUlva\i and \IEnteromorpha\i.
\Bumbel\b 1: A typically umbrella-shaped inflorescence in which all pedicels arise at the apex of an axis; commonly compound. 2: Any member of the family \JApiaceae\j
\BUmbellales\b \JApiales\j
\BUmbelliferae\b \JApiaceae\j
\Bumbraticolous\b Living in shaded habitats; \Bumbraticole\b; See also \Jlucicolous\j
\Bumbrella shell\b \JNotaspidea\j
\BUmbridae\b Mudminnows; family containing 5 species of small (to 200 mm) freshwater salmoniform teleost fishes found in streams and rivers of northern temperate and Arctic regions; body elongate and weakly compressed; swim bladder may serve accessory respiratory function.
\Bumbrophilic\b Thriving in shaded habitats; \Bumbrophile\b, \Bumbrophily.\b
\Bunderstorey\b The vegetation layer between the overstorey or canopy and the ground-storey of a forest community, formed by shade tolerant trees of moderate height.
\Bundulipodia\b All flagella and cilia sharing a 9+2 microtubular structure.
\Bungulate\b Any large hoof-bearing, grazing mammal; extant species typically belonging to the orders Perissodactyla and Artiodactyla.
\Bunguligrade\b Walking or running on hooves or the modified tips of one or more digits.
\Bunicorn plant\b \JMartyniaceae\j
\Buniformitarianism\b The doctrine that natural geological processes affecting the Earth are still operating at essentially the same rate and intensity as they have throughout geological time; actualism; See also \Jcatastrophism\j
\BUnionoida\b Naiads, pearly freshwater mussels; order of freshwater paleoheterodont bivalve molluscs which release a parasitic larval stage (the glochidium) after incubation in a marsupium formed from the gills in the female.
\Buniparous\b 1: Producing a single offspring in each brood; see also \Jbiparous\j \Jmultiparous. 2: Having only one brood during the life cycle\j
\BUniramia\b Phylum or subphylum of arthropods comprising 2 (or 3) classes, Myriapoda (pauropods, diplopods, chilopods, symphylans), Insecta (insects) and, by some authorities, Onychophora; characterized by a single pair of antennae, 1 or 2 pairs of maxillae, uniramous limbs, and mandibles that bite transversely at the tip.
\Bunisexual\b 1: Used of a population or generation composed of individuals of one sex only. 2: Used of an individual having either male or female reproductive organs and producing only male or female gametes. 3: Used of a flower possessing only male or female reproductive organs; imperfect flower; See also \Jbisexual\j
\Bunistratal\b Pertaining to vegetation lacking distinguishable horizontal layering; See also \Jmultistratal\j
\Bunivoltine\b Having one brood or generation per year; See also \Jvoltine\j
\Bunivorous\b Feeding on only one type of food; \Bunivore\b, \Bunivory.\b
\BUpupidae\b Hoopoes; small group of colourful woodland birds (Coraciiformes) found in Africa and in temperate parts of Eurasia; habits monogamous, mostly non-migratory, feeding largely on insects and other invertebrates; nest in hole in tree or bank, nest commonly foul smelling.
\Bupwelling\b An upward movement of cold nutrient-rich water from ocean depths.
\BUranoscopidae\b Stargazers; family containing 25 species of bottom-living, tropical and warm temperate, marine teleost fishes (Perciformes) typically found partly buried in sand or sandy mud; body robust and deep, to 600 mm in length, head large, mouth vertical; some species have electric organ derived from modified eye muscles.
\BUredinales\b Rust fungi; large cosmopolitan order of parasitic teliomycete fungi occurring as an intercellular mycelium within the host plant; producing emergent reproductive units or spores which are wind-disseminated; most cause infections of host organs, often in economically important crops; includes the genus \IPuccinia\i which has over 4000 species parasitizing cereal crops and many other host plants.
\BUrkaryota\b One of the three primary kingdoms (\Jurkingdoms\j) of living organisms\j, \Jcomprising all eukaryote organisms; see also \JEubacteria\j \JArchaebacteria\j
\Burkingdoms\b The three primary kingdoms proposed recently as a basic tripartite scheme for grouping all living organisms, as an alternative to the widely used five-\Jkingdom\j scheme of Whittaker; see also \JEubacteria\j \JArchaebacteria\j, \JUrkaryote\j
\BUrochordata\b \JTunicata\j (sea squirts).
\BUrodela\b \JCaudata\j; modern order of tailed amphibians.
\BUrolophidae\b Stingrays; family containing about 30 species of mostly small, shallow marine, myliobatiform elasmobranch fishes having a largely tropical and subtropical distribution; body disk oval to subcircular, tail bearing one or more serrated spines, caudal fin well developed; feed on crustaceans and polychaetes; reproduction viviparous.
\BUropeltidae\b Family of small fossorial booid snakes (Serpentes) containing about 50 species from India through southeast Asia to New Guinea; typically possessing an enlarged scale near the tip of the tail.
\Burophilic\b Thriving in habitats rich in ammonia; \Burophile, urophily.\b
\BUropodina\b Large and diverse suborder of free-living mites that derive their name from the curious anal secretion which forms a stalk by which the phoretic deutonymphs of many species attach to insects or other arthropods.
\BUropygi\b Whip scorpions, vinegaroons; order of nocturnal predatory terrestrial arthropods (Arachnida); body length 15-75 mm, chelicerae with proximal fang, pedipalps powerful and spinose; first pair of legs long and slender; abdomen divided into broad mesosoma bearing book lungs and short metasoma sporting an apical whip-like flagellum; contains about 85 species.
\BUrsidae\b Bears; family containing 7 species of large terrestrial to arboreal mammals (Carnivora) found in Holarctic, Oriental and northwestern Neotropical regions; most are omnivorous with diets including terrestrial and aquatic vertebrates, insects and other invertebrates, carrion, fruit and diverse plant material.
\BUrticaceae\b Nettles; family of mostly herbaceous plant species having a widespread distribution; often with stinging hairs, and a tendency towards mineralization of cell walls; flowers unisexual, with a 4 or 5-segmented perianth; 4-5 stamens in male flowers; ovary one-celled.
\BUrticales\b Large and ecologically diverse order Hamamelidae; woody or herbaceous plants all with reduced flowers which may be windor insect-pollinated; often with cystoliths or milky latex; contains 6 families, Barbeyaceae, Ulmaceae, Cannabaceae, Moraceae, Cecropiaceae and Urticaceae.
\BUstilaginales\b Smut fungi; large cosmopolitan order of parasitic teliomycete fungi parasitizing vascular plants, including cereals and sugar cane; mycelia grow within host tissues; sporulation produces soot-like masses of teliospores on the surface of the host plant.
\Bvadal\b Floating close to the shore.
\Bvagile\b Wandering; freely motile; mobile.
\Bvagility\b The tendency of an organism or population to change its location or distribution with time; mobility; \Bvagile.\b
\Bvaginicolous\b Living in secreted sheaths or cases; \Bvaginicole.\b
\Bvagrant\b Unattached; wandering; used of unattached wind-blown organisms, and of organisms that move about by their own activity.
\BValdian glaciation\b The most recent glaciation of the Quaternary Ice \JAge\j in Russia, with an estimated duration of about 70 000 years.
\BValerianaceae\b Cosmopolitan family of Dipsacales containing about 300 species of mostly herbs with a characteristic rank odour caused by ethereal oils; flowers occur in compound cymose or capitate inflorescences; each flower typically with 1-3 minute sepals, 3-5 petals, 1-4 stamens and an inferior ovary.
\Bvalvate dehiscence\b Spontaneous release of the contents of a ripe fruit through a valve, flap or other large aperture.
\BValvatida\b Large order of often colourful, intertidal to deep-sea, asteroidean echinoderms typically with rigid body, large disk, short to long arms and suckered tube feet; anal pore present.
\BValvifera\b Suborder of marine and brackishwater isopod crustaceans in which the uropods are enlarged and fold towards the midline, covering and protecting the respiratory pleopods.
\Bvampire bat\b \JPhyllostomatidae\j
\Bvampire squid\b \JVampyromorpha\j
\BVampyromorpha\b Vampire squid; order of cephalopod molluscs comprising a single cosmopolitan, deep-water species resembling both octopuses and squid; characterized by a pair of tendril-like filaments and 8 long arms connected by an extensive web.
\BVarangian glaciation\b A widespread glaciation during the Precambrian era, about 670 million years B.P.
\BVaranidae\b Monitor lizards, Komodo dragon; small family of medium-sized to very large (200 mm to 3 m) terrestrial lizards (Sauria); habits diurnal, preying on variety of invertebrates and vertebrates; reproduction oviparous; contains 21 species ranging from Africa to Australia, and also on some Pacific islands.
\Bvariant\b Any individual or group showing marked deviation from type, in form, quality or behaviour.
\Bvariegation\b The occurrence within an individual of a mosaic phenotype, typically with respect to coloration; partial albinism in plants.
\Bvarve\b A banded layer of sediment deposited in a lake during the course of a single year; comprising a paler coarse layer deposited in spring and summer and a darker fine layer deposited in autumn and winter.
\Bvascular plant\b Any plant containing specialized conducting tissues, \Ii.e.\i xylem and phloem, and typically differentiated into roots, stems and leaves; Tracheophyta.
\BVaucheriales\b Order of algae (Xanthophyceae) commonly found forming mats over moist soil and mud; characterized by the lack of cell walls in the vegetative filaments (siphoneous organization).
\Bvector\b 1: An organism that carries or transmits a pathogenic agent; See also \Jcarrier. 2: Any agency responsible for the introduction or dispersal of an animal or plant species\j
\Bvegetable sponge\b \JCucurbitaceae\j
\Bvegetation\b The total plant life or cover in an area; also used as a general term for plant life; See also \Jfaunation\j
\Bvegetative\b Pertaining to assimilative, somatic and trophic growth processes rather than to reproduction.
\Bvegetative reproduction\b Reproduction by asexual processes such as budding or fragmentation; vegetative propagation.
\Bveil fish\b \JVeliferidae\j
\Bveld\b The open temperate grassland areas of southern Africa, typically with scattered shrubs or trees; veldt.
\BVeliferidae\b Veil fish; family containing 3 species of moderately deep-water, Indo-Pacific lampridiform teleost fishes; body deep and compressed, to 300 mm length; dorsal and anal fins very large with scaly basal sheaths.
\Bveliger\b Free-swimming larval stage of some molluscs possessing a large ciliated apical lobe used in swimming and feeding, a foot, shell and other adult features.
\BVelloziaceae\b Widespread family of Liliales comprising about 250 species of resinous or gum-producing xerophytic shrubs; slender stem appearing stout because of persistent leaf bases on upper part and adventitious roots on lower parts; producing solitary, trimerous flowers.
\Bvenation\b The pattern of veins in a leaf of vascular plants, or in an insect's wing.
\BVeneroida\b Large order of mainly marine heterodont bivalve molluscs which are generally active burrowers or nestlers, rarely sedentary forms; characterized by more or less equal shell valves, two shell-closing muscles and by the structure of the hinge; includes the heart shells, cockles, giant, surf and fingernail clams, razor shells, sunset shells, Venus shells and wedge shells.
\Bvenomous\b Poisonous; noxious; venomproducing.
\BVenus shell\b \JVeneroida\j
\BVenus's fly trap\b \JDroseraceae\j
\BVenus' flower basket\b \JHexasterophora\j
\BVerbenaceae\b Teak, spiraea, pagoda flower; family of Lamiales containing about 2600 species of sometimes roughly hairy herbs and woody plants, mostly from tropical regions; flowers bisexual and arranged in cymose or racemose heads frequently set off by an involucre of coloured bracts; individual flowers bisexual and commonly with 5 sepals, 5 petals forming a narrow tube basally, and 4 stamens.
\Bvernal\b Pertaining to the spring; see also \Jaestival\j \Jhibernal\j, \Jhiemal\j, \Jserotinal\j
\Bvernal pool\b A temporary pool formed during spring from meltwater or flood water.
\Bvernalization\b A process of thermal induction in plants, in which growth and flowering are promoted by exposure to low temperatures.
\Bvernation\b The pattern of folding and rolling of leaves in a bud.
\BVerongiida\b Order of ceractinomorph sponges found most commonly in tropical and warm temperate waters from the intertidal zone down to 400 m; characterized by a branching or reticulate skeleton of spongin fibres which are not differentiated into size categories.
\BVerrucariales\b Order of loculoanoteromycetid fungi which are lichenized or parasitic in lichen thalli; widespread in temperate and cold regions.
\Bversicoloured\b Exhibiting colour change, or different colours; variegated.
\BVertebrata\b Subphylum of chordates characterized by the presence of a braincase, vertebral column, medial fins, skeleton of bone and/or cartilage, skin comprising dermal and epidermal layers, heart and blood cells, kidney, liver, pancreas and neural crest; higher vertebrates also possess jaws, teeth, paired fins/or limbs having an internal skeleton articulating with girdles, bony scales, feathers or hair, lungs, and in tetrapods a neck formed by specialization of the vertebral column; 8 classes are traditionally recognized. Placodermi (extinct), Agnatha (jawless fishes), Chondrichthyes (cartilaginous fishes). Osteichthyes (bony fishes), Amphibia (amphibians), Reptilia (reptiles), Aves (birds) and Mammalia (mammals).
\BVespertilionidae\b Cosmopolitan family of mainly insectivorous microchiropteran bats containing about 280 species; habits solitary to gregarious, often migratory; some species hibernate.
\Bvespertine\b Pertaining to the evening.
\BVespidae\b Social wasps; family of truly social or socially parasitic wasps (Hymenoptera) which construct nests of regularly arranged cells made of masticated plant fibres; colonies consist mostly of sterile females; larvae are fed on a masticated paste of arthropod prey; contains about 800 species distributed worldwide.
\BVestibulifera\b Subclass of kinetofragminophoran ciliates characterized by the presence of a usually apical invagination (vestibular cavity) at the base of which lies the cell mouth and pharyngeal apparatus; includes free-living aquatic and soil forms as well as endocommensals in the stomachs of mammals.
\Bvestigial\b Degenerate or imperfectly developed; used of structures or functions that have become diminished or reduced during the course of evolution or ontogeny; \Bvestige.\b
\BVestimentifera\b Order of pogonophoran worms lacking a mesosomal bridle; body devoid of setae; can attain considerable size (2 m) when living in association with deep-sea hydrothermal vents.
\Bvetch\b \JFabaceae\j
\Bvexillifer\b Pelagic larval stage of teleost fishes in the family Carapidae (pearlfishes).
\Bviable\b Having the capacity to live, grow, germinate or develop; \Bviability.\b
\Bviatical\b Growing on the roadside or beside paths.
\Bviburnum\b \JCaprifoliaceae\j
\Bvicariance\b The existence of closely related forms (vicariants) in different geographical areas, which have been separated by the formation of a natural barrier (a vicariance event).
\Bvice-counties\b Biogeographical subdivisions of former administrative counties in Britain, used as unit areas in distributional studies.
\Bvicine\b Used of organisms invading or entering from adjacent areas or communities.
\Bvinegar fly\b \JDrosophilidae\j
\Bvinegaroon\b \JUropygi\j; vinegarone.
\BViolaceae\b Viola, violet, pansy; large family of herbaceous or woody plants widespread from northern temperate regions to tropical rainforests; typically with bisexual flowers each comprising 5 sepals, petals and stamens and a superior ovary.
\BViolales\b Large order of Dilleniidae containing about 5000 species in 24 families; diverse assemblage of herbs to trees but with the great majority of species contained in the families Begoniaceae, Cucurbitaceae, Flacourtiaceae, Passifloraceae and Violaceae.
\Bviolet\b \JViolaceae\j
\Bviolet snail\b \JMesogastropoda\j
\Bviperfish\b \JChauliodontidae\j
\BViperidae\b Vipers, rattlesnakes, moccasins; cosmopolitan family containing about 180 species of medium-sized highly venomous snakes (Serpentes); typically terrestrial, nocturnal, feeding on small mammals, a few species arboreal or fossorial; reproduction oviparous or ovoviviparous.
\BVireonidae\b Vireos; family containing about 40 species of small passerine birds found in forest habitats of the New World; plumage usually greenish, bill robust and weakly hooked, feet strong; habits solitary, arboreal, sometimes migratory, feeding on insects and fruit; cupshaped nest placed in tree.
\Bvirgin\b 1: Pertaining to a native habitat, fauna or flora that is essentially unaffected by the activities of man. 2: An animal that has not copulated.
\BVirginia creeper\b \JVitaceae\j
\BVirginian waterleaf\b \JHydrophyllaceae\j
\Bvirginiparous\b Used of organisms reproducing only by parthenogenesis.
\Bvirology\b The study of viruses.
\Bvirulence\b The capacity of a pathogen to invade host tissue and reproduce; the degree of pathogenicity.
\Bviruliferous\b Virus-carrying; used of organisms harbouring viruses.
\BVirus\b Kingdom of prokaryotes comprising the viruses.
\Bviruses\b A group of microorganisms traditionally regarded as a kingdom of prokaryotes; consist of a proteinaceous shell (capsid) containing the viral nucleic acid; growth and replication takes place only within a host cell, with the viral nucleic acid causing the host cell to synthesize the materials necessary for making more viral particles; recently regarded by some authorities as being rogue sections of the host nucleic acid which have become self-replicating by diverting the resources of the host cell.
\BViscaceae\b Mistletoes; cosmopolitan family of Santalales containing about 350 species of brittle evergreen shrublets hemiparasitic on tree branches and producing haustoria that penetrate and ramify within the host.
\Bviscacha\b \JChinchillidae\j
\Bvisible light\b That part of the solar radiation spectrum between the wavelengths 380 and 780 nm.
\BVitaceae\b Grape vine, Virginia creeper, Boston ivy; Vitidaceae; family of Rhamnales containing about 700 species of mostly woody vines, commonly with leaf-opposed tendrils; mainly found in warm regions; flowers small and arranged in cymose inflorescences, each with 4-5 sepals, petals and stamens, and a superior ovary.
\Bvitellogenous\b Yolk-producing.
\Bviticolous\b Growing on vines; \Bviticole.\b
\BVitidaceae\b \JVitaceae\j
\BViverridae\b Civets, mongooses, genet; diverse family of terrestrial and arboreal mammals (Carnivora) containing about 70 species widespread in Ethiopian, Oriental and southern Palaearctic regions; body typically long and slender, limbs short, tail elongate; mostly carnivorous, feeding on small vertebrates and invertebrates, some forms omnivorous.
\Bviviparous\b 1: Producing live offspring from within the body of the parent; \Bviviparity\b, \Bvivipary\b; see also \Jlarvipary\j \Joviparous\j, \Jovoviviparous. 2: Germinating while still attached to the parent plant\j
\Bvixigregarious\b Sparsely distributed; occurring in small, poorly defined groups.
\Bvocalization\b Production of songs, calls and other vocal sounds by animals.
\BVochysiaceae\b Family of Polygalales containing about 200 species of mostly woody plants with a resinous juice; native mainly to tropical America.
\Bvolant\b Adapted for flying or gliding.
\Bvolcanism\b Volcanic activity.
\Bvolcanogenic\b Used of a sediment produced as a result of volcanic activity.
\Bvole\b \JCricetidae\j
\Bvoltine\b Pertaining to the number of broods or generations per year or per season; usually quantified with a prefix as in univoltine, bivoltine, trivoltine, quadrivoltine, multivoltine.
\Bvoltinism\b A behavioural polymorphism in insects in which some members of a population enter diapause and others do not.
\Bvolute\b \JNeogastropoda\j
\Bvolvation\b Enrolment of the body to form a ball.
\BVolvocales\b Order of typically flagellate, motile green algae distributed ubiquitously in freshwater, brackish and marine habitats; typically with uninucleate cells which may be solitary or united into colonies of definite structure (coenobia); cells usually containing a single cup-shaped chloroplast; also treated as a class of the protoctistan phylum Chlorophyta, and as an order of the protozoan class Phytomastigophora, under the name Volvocida.
\BVolvocida\b \JVolvocales\j treated as an order of the protozoan class Phytomastigophora.
\BVombatidae\b Wombats; family containing 2 species of burrowing diprotodont marsupials from Australia and Tasmania; body length to about 1 m, incisor teeth long, limbs subequal, tail vestigial; marsupium opening posteriorly; habits typically nocturnal, herbivorous.
\Bvoucher specimen\b Any specimen identified by a recognized authority for the purposes of forming a reference collection.
\Bvulcanism\b Volcanic activity.
\Bvulture\b 1: \JCathartidae\j (New World vultures). 2: \JAccipitridae\j (Old World vultures).
\Bwagtail\b \JMotacillidae\j
\Bwalkingstick\b \JPhasmoptera\j
\Bwallaby\b \JMacropodidae\j
\BWallace's line\b The boundary separating the Oriental and Australian zoogeographical regions drawn to the west of Weber's \Jline\j and passing between the Philippines and Maluku (Moluccas) in the north, then southwest between Sulawesi and Borneo, and continuing south between Lombok and Bali.
\BWallace's realms\b The major zoogeographical regions - Neotropical, Nearctic, Palaearctic, Oriental, Australian and Ethiopian.
\BWallacea\b The transition zone between the Oriental and Australian zoogeographical regions, bounded to the east by Weber's \Jline\j and to the west by Wallace's \Jline\j, and comprising Sulawesi, Lombok, Flores and Timor.
\Bwallflower\b \JBrassicaceae\j
\Bwalnut\b \JJuglandaceae\j
\Bwalrus\b \JOtariidae\j
\Bwandering jew\b \JCommelinaceae\j
\Bwarble fly\b \JOestridae\j
\Bwarbler\b \JSylviidae\j
\Bwarm monomictic lake\b A lake with a winter overturn in which the water temperature never falls below 4░C; See also \Jcold monomictic lake\j
\Bwarm temperate zone\b The latitudinal zone between 34.0░and 45.0░in either hemisphere.
\Bwarm-blooded\b \JHomoiothermic\j
\Bwarning coloration\b Conspicuous coloration used to advertize the noxious, unpalatable, or otherwise harmful properties of an organism to a potential predator.
\Bwart snake\b \JAcrochordidae\j
\BWarthe glaciation\b A glaciation of the Quaternary Ice \JAge\j in northern Germany and Poland with an estimated duration (together with the Saale glaciation) of 100 000 years.
\Bwasp\b \JVespidae\j (Apocrita, Aculeata).
\Bwater bear\b \JTardigrada\j
\Bwater boatman\b \JNotonectidae\j
\Bwater capacity\b The amount of water that a soil can retain against gravity.
\Bwater chestnut\b \JTrapaceae\j
\Bwater cycle\b The global biogeochemical cycle of water involving exchange between the hydrosphere, atmosphere, lithosphere and living organisms; hydrologic cycle.
\Bwater table\b The horizontal plane defining the upper limit of the ground layer fully saturated with water.
\Bwater willow\b \JLythraceae\j
\Bwatercress\b \JBrassicaceae\j
\Bwatermelon\b \JCucurbitaceae\j
\Bwatershed\b An elevated boundary area separating tributaries draining into different river systems.
\Bwax flower\b \JAsclepiadaceae\j
\Bwax myrtle\b \JMyricales\j
\Bwaxbill\b \JEstrildidae\j
\Bwaxwing\b \JBombycillidae\j
\BW-chromosome\b The sex chromosome which in cases of female heterogamety is present in the female only; see also \JX-chromosome\j \JY-chromosome\j, \JZ-chromosome\j
\Bweasel\b \JMustelidae\j
\Bweasel shark\b \JHemigaleidae\j
\Bweather\b Local, short-term atmospheric conditions; See also \Jclimate\j
\Bweathering\b Physical, chemical and biological changes resulting from exposure to the atmosphere, that accompany soil formation from parent rock.
\Bweaver finch\b \JPloceidae\j; weavers.
\Bweb spinner\b \JEmbiidina\j
\BWeber's line\b The boundary separating the Oriental and Australian zoogeographical regions drawn to the east of Wallace's \Jline\j and passing between Maluku (the Moluccas) and Sulawesi to the north, and between Timor and the Kei Islands to the south.
\Bwedge shell\b \JVeneroida\j
\Bweed\b Any plant growing where it is not wanted.
\Bweeverfish\b \JTrachinidae\j
\Bweevil\b \JCurculionidae\j
\BWeichselian glaciation\b The most recent glaciation of the Quaternary Ice \JAge\j in northern Germany and Poland with an estimated duration of about 70 000 years; subdivided into Pomeranian, Frankfurt and Brandenburg glaciations.
\BWelwitschiidae\b Subclass of gymnosperms (Pinophyta) containing a single species occurring in the arid deserts of Angola and southwestern Africa; stem is an inverted woody cone and bears 2 leaves only, which are very long, strap-like, and grow throughout the life of the plant.
\Bwentletrap\b \JMesogastropoda\j
\BWentworth grade scale\b An extension of the Udden grade \Jscale\j with descriptive class terms for sediment particles.
\BWest Australia Current\b A cold surface ocean current that flows northwards off the west coast of Australia, fed from the Antarctic circumpolar Current and forming the eastern limb of the South Indian Gyre; see ocean currents.
\BWest Greenland Current\b A cold surface ocean current that flows northwards off the west coast of Greenland, giving rise to the cold Labrador Current; see ocean currents.
\BWest Wind Drift\b A major cold surface ocean current that flows eastwards through the Southern Ocean producing a circumglobal Antarctic circulation; Antarctic Circumpolar Current; see ocean currents.
\Bwetland\b An area of low-lying land, submerged or inundated periodically by fresh or saline water.
\Bwhale\b \JCetacea\j
\Bwhale louse\b \JCyamidae\j
\Bwhale shark\b \JRhincodontidae\j
\Bwhalefish\b Small bathypelagic beryciform teleost fishes having flabby body with distensible stomach; fin spines and gas bladder absent; luminous organs often present; used for members of the families Barbourisiidae, Cetomimidae and Rondeletiidae.
\Bwheat\b \JPoaceae\j
\Bwheatear\b \JTurdidae\j
\Bwheel animalcule\b \JRotifera\j
\Bwhelk\b \JNeogastropoda\j
\Bwhip scorpion\b \JUropygi\j
\Bwhipspider\b \JAmblypygi\j
\Bwhiptail\b \JTeiidae\j
\Bwhirligig beetle\b \JGyrinidae\j
\Bwhisk fern\b \JPsilotophyta\j
\Bwhistler\b \JPachycephalidae\j
\Bwhite ant\b \JIsoptera\j
\Bwhite butterfly\b \JPieridae\j; white.
\Bwhite mangrove\b \JCombretaceae\j
\Bwhite mud\b A terrigenous marine sediment derived from coral reef debris.
\Bwhite rust\b \JPeronosporales\j
\Bwhite whale\b \JMonodontidae\j; beluga.
\Bwhite-eye\b \JZosteropidae\j
\Bwhitefish\b \JSalmonidae\j
\Bwhitefly\b \JAleyrodidae\j (Homoptera).
\Bwild bottlebrush\b \JGreyiaceae\j
\Bwild cinnamon\b \JCanellaceae\j
\Bwild type\b The natural or typical form of an organism, strain or gene, arbitrarily designated as standard or normal for comparison with mutant or aberrant individuals or alleles.
\Bwillow\b \JSalicales\j
\Bwillow herb\b \JOnagraceae\j
\Bwilting\b Loss of turgidity in plants caused by an excess of water loss by transpiration over water uptake by absorption from the soil.
\Bwind scorpion\b \JSolpugida\j
\Bwindchill\b The effect of the wind in causing excessive cold penetration into plants.
\Bwindkill\b Plant death resulting from the effects of wind.
\Bwindow fly\b \JScenopinidae\j
\Bwindow-pane shell\b \JOstreoida\j
\Bwinkle\b \JMesogastropoda\j
\Bwinnowing\b Grading and separation of the fine fractions of particulate matter by wind or water currents.
\BWinteraceae\b One of the most archaic families of flowering plants (Magnoliales), containing about 100 species of trees and shrubs widely distributed in the southern hemisphere; characterised by regular and bisexual flowers with 2-6 sepals, 2 to many petals, 15 to many stamens and a superior ovary.
\Bwireworm\b \JElateridae\j
\BWisconsin glaciation\b The most recent glaciation of the Quaternary Ice \JAge\j in North America, with an estimated duration (together with the Iowan glaciation) of about 70 000 years.
\Bwisteria\b \JFabaceae\j
\Bwitch hazel\b \JHamamelidaceae\j
\Bwobbegong\b \JOrectolobidae\j
\Bwolf\b \JCanidae\j
\Bwolf herring\b \JChirocentridae\j
\Bwolf spider\b \JLycosidae\j
\Bwolffish\b \JAnarhichatidae\j
\BWolstonian glaciation\b A glaciation of the Quaternary Ice \JAge\j in the British Isles with an estimated duration of 100 thousand years; Gipping glaciation.
\Bwolverine\b \JMustelidae\j
\Bwombat\b \JVombatidae\j
\Bwood sorrel\b \JOxalidaceae\j
\Bwood swallow\b \JArtamidae\j
\Bwood warbler\b \JParulidae\j
\Bwoodcreeper\b \JDendrocolaptidae\j
\Bwoodland\b An area of vegetation dominated by a more or less closed stand of short trees.
\Bwoodlouse\b \JOniscoidea\j
\Bwoodlouse fly\b \JRhinophoridae\j
\Bwoodpecker\b \JPicidae\j
\Bwoodwasp\b \JXiphydriidae\j (Symphyta).
\Bwoodworm\b \JAnobiidae\j
\Bwoody plant\b A perennial plant having a secondarily thickened lignified stem.
\Bwoolly bear\b The hairy, caterpillar-like larval stage of beetles of the family Dermestidae and of moths of the family Arctiidae.
\Bwoolly monkey\b \JCebidae\j
\Bwork\b Any structure or impression resulting from the activity of an animal, including tubes, burrows, nests and tracks.
\BWürm glaciation\b The most recent glaciation of the Quaternary Ice \JAge\j in the Alpine area with an estimated duration of about 70 000 years; subdivided into Würm 3, Würm 2 and Würm 1 glaciations.
\BXanthophyceae\b Class of chromophycote algae found in freshwater and marine habitats and varying in organization from unicellular to filamentous or siphoneous; characterized by the possession of chlorophylls \Ia\i and \Ic\i, and various carotenoids, and by the production of motile zoospores which are typically pearshaped with a hairy, anteriorly directed flagellum and a shorter, naked, posteriorly directed flagellum; also classified as a separate phylum of Protoctista under the name Xanthophyta.
\Bxanthophyll\b A type of photosynthetic pigment; including the primary light-absorbing pigments of brown algae, fucoxanthin and peridinin.
\BXanthophyllaceae\b Family of Polygalales containing about 40 species of small trees native to the Indo-Malaysian region; flowers pentamerous, one petal usually hood-like; fruit indehiscent, woody or somewhat fleshy.
\BXanthophyta\b The \JXanthophyceae\j treated as a phylum of Protoctista; comprises 4 classes, Heterochloridales, Heterococcales, Heterosiphonales and Heterococcales,
\BXanthorrhoeaceae\b Grass trees; small family of Liliales comprising about 55 species of stout, often arborescent shrubs or coarse short-stemmed herbs; often with persistent old leaf bases and with perennial, parallel-veined and often pungent leaves; restricted to Australia, New Caledonia and New Guinea.
\BXantusiidae\b Night lizards; family containing 14 species of viviparous terrestrial lizards (Sauria) found in Central and North America; habits mostly crepuscular, insectivorous.
\BX-chromosome\b The sex chromosome which in cases of male heterogamety is present in both sexes; see also \JW-chromosome\j \JY-chromosome\j, \JZ-chromosome\j
\BXenarthra\b Suborder of mammals (Edentata) characterized by additional articulations in the lumbar vertebrae; comprises the South American edentates known since the Eocene including the anteaters and sloths (Pilosa) and the armadillos (Cingulata).
\Bxenautogamous\b Used of organisms in which cross fertilization normally occurs, but in which self-fertilization is possible; \Bxenautogamy.\b
\BXenicidae\b New Zealand wrens; family containing 4 species of small insectivorous passerine birds with short rounded wings and short tail; habits solitary or gregarious, arboreal or terrestrial, flight weak; nest domeshaped, in tree or rock crevice.
\Bxenobiosis\b Symbiosis in which one species lives freely within the colony of another species whilst maintaining broods separately.
\Bxenobiotic\b A foreign (allochthonous) organic chemical; used of environmental pollutants such as pesticides in runoff water.
\BXenocongridae\b False moray eels; family containing 15 species of little-known tropical and warm-temperate anguilliform teleost fishes; body smooth, dorsal and anal fins elongate and continuous with caudal, pectorals present or absent.
\Bxenodeme\b A local interbreeding population of a parasite that differs from other demes in its host specificity.
\Bxenoecic\b Inhabiting the empty domicile or shell of another organism; \Bxenoecy.\b
\Bxenogamy\b Cross fertilization; fertilization between flowers on different plants; See also \Jgeitonogamy\j
\Bxenogenous\b Originating from outside the organism or system.
\Bxenology\b The study of host-parasite relationships.
\Bxenoparasite\b A parasite infesting an organism that is not its normal host; \Bxenoparasitism.\b
\BXenopeltidae\b Sunbeam snake; family containing a single species of burrowing snakes (Serpentes) found in southeastern Asia; scales iridescent; feeds mainly on small vertebrates, including other snakes.
\BXenophyophorea\b Class of giant marine rhizopod protozoans found primarily in the deep-sea benthos; body consists of a multinucleate plasmodium enclosed within a branching organic tube and a massive test composed of organic and inorganic foreign matter (xenophyae); comprises 2 orders, Psamminida and Stannomida.
\BXenopneusta\b Small order of echiuran marine worms in which the longitudinal muscles of the trunk body wall are between the outer circular and inner oblique layers, the blood system is open, there are 2 or 3 pairs of nephridia and the hind gut is modified as a respiratory chamber; feed on suspended particles and bacteria using mucus net placed across opening of burrow.
\BXenosauridae\b Small family of robust, diurnal lizards (Sauria), comprising 3 terrestrial, insectivorous species from Central America, and a single semiaquatic piscivorous species from China.
\BXenungulata\b Extinct order of mammals known from the Cenozoic of South America; separated from the Pyrotheria by differences in premolars and canine teeth.
\Bxerantic\b Becoming parched or dried up; withering.
\Bxerarch succession\b An ecological succession beginning in a dry habitat; see also \Jhydrarch succession\j \Jmesarch succession\j
\Bxeric\b Having very little moisture; tolerating or adapted to dry conditions.
\Bxerochastic\b Used of a fruit in which dehiscence is induced by desiccation; \Bxerochasy\b; See also \Jhygrochastic\j
\Bxerochore\b That region of the Earth's surface covered by dry desert.
\Bxerocleistogamy\b Self-pollination within flowers that remain unopened because of inadequate moisture; \Bxerocleistogamic.\b
\Bxerocolous\b Living under dry conditions; \Bxerocole.\b
\Bxerogeophyte\b A plant which enters a resting stage during periods of drought.
\Bxerohylophilous\b Thriving in dry forests; \Bxerohylophile\b, \Bxerohylophily.\b
\Bxerohylophyte\b A dry-forest plant.
\Bxeromorphic\b Pertaining to plants having structural or functional adaptations to prevent water loss by evaporation; \Bxeromorphism\b, \Bxeromorphy. \b
\Bxerophilous\b Thriving in dry habitats; \Bxerophile\b, \Bxerophily.\b
\Bxerophobous\b Intolerant of dry conditions; \Bxerophobe\b, \Bxerophoby.\b
\Bxerophyte\b A plant living in a dry habitat, typically showing xeromorphic or succulent adaptations and able to tolerate long periods of drought; \Bxerophytic\b; see also \Jhydrophyte\j \Jhygrophyte\j, \Jmesophyte\j
\Bxeropoophilous\b Thriving in heathland; \Bxeropoophile\b, \Bxeropoophily.\b
\Bxeropoophyte\b A heath plant.
\Bxerosere\b An ecological succession commencing on a dry rock surface.
\BXerothermal period\b A postglacial interval of warmer and drier climate; approximately equivalent to the Altithermal \Jperiod\j or the Subboreal \Jperiod\j; Long Drought; See also \JHypsithermal period\j
\Bxerothermic\b Used of organisms tolerating or thriving in hot and dry environments; \Bxerotherm.\b
\Bxerotherous\b Used of organisms adapted to dry summer conditions.
\Bxerotropism\b An orientation response of plants to desiccation; \Bxerotropic.\b
\BXiphiidae\b Swordfish; monotypic family of large (to 4.5 m) predatory scombroid teleost fishes (Perciformes) characterized by a long pointed rostrum; jaw teeth and pelvic fins absent; feeds on squid and other fishes.
\BXiphodontidae\b Extinct family of primitive artiodactyls known from the Eocene and Oligocene of Europe.
\BXiphosura\b King crabs, horseshoe crabs; order of large benthic marine arthropods (Chelicerata) comprising a single extant family with 4 species; carapace expansive covering all appendages; prosomal appendages consisting of chelicerae, pedipalps and 4 pairs of legs, 3 of which have pincers; opisthosoma with 6 pairs of limbs and 5 pairs of gills.
\BXiphydriidae\b Woodwasps; cosmopolitan family containing about 90 species of wasps (Hymenoptera) typically having a slender cylindrical body lacking a distinct waist, and an awl-like ovipositor in the female; coloration black, banded with red, yellow or white; larvae commonly bore into dead branches of trees and shrubs.
\BXylariales\b Large order of pyrenomycete fungi containing thousands of species, mostly saprobic on wood, soil, plant debris and dung but occasionally parasitic.
\Bxylophagous\b Feeding on wood; \Bxylophage\b, \Bxylophagy.\b
\Bxylophilous\b Thriving on or in wood; \Bxylophile\b, \Bxylophily.\b
\Bxylophyte\b 1: A woody plant. 2: A plant living in or on wood.
\Bxylotomous\b Used of organisms able to cut or bore into wood.
\BXyridaceae\b Yellow-eyed grass; family of Commelinales containing more than 200 species of herbs, usually having basal leaves and flowers with 3 sepals, petals, stamens and carpels; petals united into corolla tube, usually yellow in colour; widespread in tropical and subtropical regions.
\Byam\b \JDioscoreaceae\j
\BYarmouthian interglacial\b An interglacial period in the middle of the Quaternary Ice \JAge\j in North America.
\BY-chromosome\b The sex chromosome which in cases of male heterogamety is present in the male only; see also \JW-chromosome\j \JX-chromosome\j, \JZ-chromosome\j
\Byeast\b \JEndomycetales\j; a fungus found in the form of single cells and reproducing by budding or by fission.
\Byellow-eyed grass\b \JXyridaceae\j
\Byew\b \JTaxaceae\j; an evergreen coniferous shrub or tree with needle-like or linear leaves, spirally arranged.
\Byield\b That part of production utilized by a consumer species or by a group belonging to a higher trophic level.
\Byucca\b \JAgavaceae\j
\BZamiaceae\b Cycads; family of gymnosperms (Pinophyta) containing about 80 species of cycads; pinnules with straight venation; widely distributed in tropical and temperate America, Australia and Africa.
\BZaniolepididae\b Combfishes; family containing 2 species of small (to 300 mm) marine scorpaeniform teleost fishes found in shallow waters along the North American west coast; body elongate, anteriorly compressed, body scales ctenoid.
\BZannichelliaceae\b Horned pondweed; family of Najadales comprising a few species of rhizomatous herbs with thread-like stems; growing submerged in fresh, alkaline or brackish water; flowers unisexual, usually lacking perianth or with 3 reduced scales; ffemale flowers with up to 9 free carpels each terminating in a long horn bearing the stigma; fruits are achenes.
\BZapodidae\b Jumping mice; family containing 10 species of small myomorph rodents found in Palaearctic and Nearctic regions; hindlimbs longer than forelimbs; typically nocturnal, feeding on fruit, seeds and insects; most species hibernate during winter.
\BZ-chromosome\b The sex chromosome which in cases of female heterogamety is present in both sexes; see also \JW-chromosome\j \JX-chromosome\j, \JY-chromosome\j
\Bzebra\b \JEquidae\j
\Bzebra plant\b \JAcanthaceae\j
\Bzebra shark\b \JStegostomatidae\j
\BZeidae\b Dories; family of mostly shallow marine zeiform teleost fishes, cosmopolitan in temperate waters; body deep and strongly compressed, often silvery, to 600 mm length, naked or with tiny scales; typically having large mouth and protrusible eyes; dorsal, anal, and pelvic fins spinose.
\BZeiformes\b Small order of deep-bodied marine teleost fishes found in tropical or temperate waters to about 600 m depth; body strongly compressed, mouth protractile, pelvic fins thoracic or jugular; comprises 6 families, including dories, boarfishes and oreos.
\Bzeitgeber\b Any external stimulus that acts to trigger or phase a biological rhythm.
\BZeledoniidae\b Wren-thrush; family containing a single species of passerine birds found in Central America; usually included in the Turdidae.
\BZeugloptera\b Suborder of primitive lepidopteran insects comprising about 100 species in which the adults have toothed functional mandibles, unspecialized maxillae, and feed on pollen; larvae found in soil feeding on liverworts and detritus.
\Bzincophyte\b A plant adapted to, or tolerating, high zinc levels in the soil.
\BZingiberaceae\b Ginger; family of about 1000 species of leafy-stemmed herbs with silica cells and scattered ethereal oil-secreting cells; native to tropical regions, especially in southern Asia; flowers trimerous, with 3 sepals and petals, 6 stamens and an inferior ovary, bilaterally symmetrical; fruit usually a capsule.
\BZingiberales\b Order of the subclass Zingiberidae consisting of 8 families of almost exclusively tropical herbs or small trees with an unbranched trunk; broad, fragile leaf blade having a prominent midrib and numerous lateral veins in a pinnate-parallel arrangement; flowers basically trimerous, but often bilaterally symmetrical.
\BZingiberidae\b Subclass of monocotyledons (Liliopsida) consisting of 2 orders of terrestrial or epiphytic herbs that lack secondary growth; leaves are alternate with a sheathing base and a narrow, parallel-veined blade; flowers showy and adapted for pollination by nectar-gathering insects and other animals; fruit usually a capsule or berry, seeds with copious endosperm storing food as starch.
\BZiphiidae\b Beaked whales; family containing 18 species of little-known marine mammals (Odontoceta) widespread in deeper waters of cool temperate to tropical oceans and seas; teeth typically absent in upper jaw, sparse or absent in lower jaw; thought to feed mainly on squid.
\BZoantharia\b Subclass of Anthozoa containing solitary and colonial representatives which may be naked or enclosed within a calcareous exoskeleton; characterized by paired mesenteries in the gastrovascular cavity of the polyp, typically arranged in multiples of 6; Hexacorallia; comprises 5 extant orders, Actiniaria, Corallimorpharia, Scleractinia, Ptychodactiaria and Zoanthinaria.
\BZoanthinaria\b Order of zoantharians found in abundance in warm shallow seas but also known from deeper and colder waters; typically resembling sea anemones but usually colonial or social with polyps arising from a common basal stolon or mat; lacking an intrinsic skeleton; Zoanthidea.
\BZoarcidae\b Eelpouts; family containing 65 species of mainly shallow marine gadiform teleost fishes widespread in cold waters; body length to 1 m, tail tapering, caudal fin continuous with dorsal or anal, pelvics reduced or absent; sexual dimorphism marked in some species.
\Bzoea\b A larval stage found in higher crustaceans; at least one pair of biramous locomotory thoracic limbs is present; usually with compound eyes.
\Bzoidiogamy\b Fertilization by a motile male gamete; \Bzoidiogamic.\b
\Bzoidiophilous\b Pollinated by animals; \Bzoidiophily.\b
\Bzonal soil\b A deep soil having moderate internal and surface drainage with a well defined profile comprising several distinct horizons; used of mature soils with well developed characteristics that reflect the influence of vegetation and climate as soil-forming factors; see also \Jazonal soil\j \Jintrazonal soil\j
\Bzonation\b The distribution of organisms in distinctive areas, layers or zones.
\Bzone\b 1: An area, or subdivision of a biogeographical region that has a characteristic biota. 2: A stratum or series of strata distinguished by characteristic fossils; \Bzonal.\b
\Bzoobenthos\b Those animals living in or on the sea bed or lake floor.
\Bzoochorous\b Dispersed by the agency of animals; \Bzoochore\b, \Bzoochory.\b
\Bzoocoenosis\b An animal community.
\Bzoodomatia\b Plant structures acting as shelters for animals.
\Bzooecology\b The study of relationships between animals and their environment; animal ecology.
\Bzooflagellate\b \JZoomastigophora\j
\Bzoogamete\b A motile gamete.
\Bzoogamous\b 1: Used of animals that reproduce sexually; \Bzoogamy.\b 2: Used of plants having motile gametes.
\Bzoogenic\b Produced by or associated with the activity of animals.
\Bzoogeographical regions\b The major geographical divisions of the Earth's land surface characterized by a particular faunal composition; the 6 original regions were Australian, Ethiopian, Nearctic, Neotropical, Oriental and Palaearctic; see map on page 412.
\Bzoogeography\b Study of the geographical distribution of animals and animal communities.
\Bzoolith\b An animal fossil.
\Bzoology\b The study of animals; \Bzoological.\b
\BZoomastigina\b Zooflagellates; phylum of Protoctista comprising unicellular heterotrophic organisms possessing at least one flagellum, often more; may be free-living or parasitic.
\BZoomastigophora\b Zooflagellates; class of Mastigophora comprising mostly parasitic but sometimes free-living protozoans, with one to several hundred flagella, all of which are obligate heterotrophs lacking plastids; pseudopodia as well as flagella are present in some forms; reproduction by binary or multiple fission although sexual processes have been confirmed in some species; equivalent in part to the protoctistan phylum Zoomastigina.
\Bzoometry\b The application of statistical methods to the study of animals; \Bzoometrics.\b
\Bzoomorphic\b 1: Pertaining to or produced by the activity of animals; \Bzoomorphosis.\b 2: Having the form of an animal.
\Bzooneuston\b The animals of the neuston; \Bzooneustonic.\b
\Bzoonosis\b A disease transmitted from animals to man under natural conditions; also used more loosely for any disease of animals; \Bzoonoses.\b
\BZoopagales\b Order of zygomycete fungi which are haustorial ectoparasites or endoparasites of other fungi, protistans and animals; also treated as a class of the phylum Zygomycota.
\Bzooparasitic\b Used of a parasite having an animal host.
\Bzoophagous\b Feeding on animals or animal matter; \Bzoophage\b, \Bzoophagy.\b
\Bzoophilous\b Pollinated by animals; having an affinity for animals; \Bzoophile\b, \Bzoophily.\b
\Bzoophyte\b Any animal that resembles a plant in morphology or mode of life; \Bzoophytic.\b
\Bzooplankton\b The animals of the plankton; \Bzooplanktont\b; See also \Jphytoplankton\j
\Bzoosaprophagous\b Feeding on decaying animal matter; \Bzoosaprophage\b, \Bzoosaprophagy. \b
\Bzoosemiotics\b The study of animal communication.
\Bzoosis\b Any disease caused by an animal.
\Bzoospore\b An independently motile spore in protistans, some fungi and algae.
\Bzoosuccivorous\b Used of organisms that feed on liquid secretions of animals, or on decaying animal matter; \Bzoosuccivore\b, \Bzoosuccivory.\b
\Bzootoxin\b A poison produced by an animal.
\BZooxanthellales\b Order of photosynthetic marine dinoflagellates that are intracellular symbionts in foraminiferans, radiolarians, acantharians, cnidarians and molluscs; their presence in corals greatly enhances the calcification of reef-building corals.
\BZoraptera\b Order of tiny (2-3 mm) orthopterodean insects somewhat resembling slender termites, comprising about 20 species, most widespread under bark and logs in wet tropical habitats; there are 2 adult forms, one white, blind and wingless, the other pigmented, with eyes, and bearing 2 pairs of slender membranous deciduous wings.
\BZosteraceae\b Sea grass, eelgrass; family of Najadales comprising about 12 species of rhizomatous marine herbs growing intertidally or submerged at depths down to 50 m; with slender parallel-veined leaves and small unisexual, water-pollinated flowers.
\BZosteropidae\b White-eyes; family containing about 80 species of small Old World passerine birds widespread in forest habitats from Africa to Japan and New Zealand; bill short and slender, tongue grooved and frilled distally; habits gregarious, arboreal, active, feeding on insects, nectar and fruit; nest in trees.
\BZygnematales\b Large order of essentially freshwater or subaerial green algae (Chlorophyceae) containing two body forms, either uniseriate filaments, like \ISpirogyra\i, or unicellular as in the desmids; characterized by sexual reproduction involving conjugation and the formation of a thick-walled, resistant zygote; equivalent in composition to the protoctistan phylum Gamophyta.
\Bzygogenesis\b Reproduction during which male and female nuclei fuse; \Bzygogenetic.\b
\Bzygogenic\b Resulting from fertilization.
\Bzygomorphic\b Irregular; used of bilaterally symmetrical flowers.
\BZygomycetes\b Class of zygomycotine fungi characterized by a type of asexual reproduction involving the endogenous production of non-motile sporangiospores; comprises 6 orders, Dimargaritales, Endogonales, Entomophthorales, Kickxellales, Mucorales and Zoopagales.
\BZygomycota\b \JZygomycetes\j; treated as a distinct phylum of the kingdom Fungi.
\BZygomycotina\b Cosmopolitan subdivision of true fungi (Eumycota) containing many free-living, saprophytic and parasitic forms, characterized by sexual reproduction involving the fusion of 2 gametangia to form a zygospore; also reproducing asexually by sporangia or conidia formation; hyphae typically lacking septa; comprises 2 classes, Zygomycetes and Trichomycetes.
\Bzygophase\b The diploid phase of a life cycle; See also \Jgamophase\j
\BZygophyllaceae\b Lignum vitae, creosote bush; family of Sapindales containing about 250 species of shrubs, trees and herbs; mostly from warm arid regions; flowers regular, usually with 4 or 5 overlapping sepals and petals; stamens arranged in whorls of 5, ovary superior and often winged; fruit variable.
\Bzygophyte\b A plant produced by sexual reproduction.
\BZygoptera\b Damselflies; suborder containing about 3000 species of paleopterous insects (Odonata) in which the forewings and hindwings are of similar shape, typically held together above the abdomen at rest; larvae aquatic, body slender with caudal gills.
\Bzygosis\b Union of gametes; conjugation; \Bzygotic.\b
\Bzygospore\b A thick-walled, usually dark-pigmented resting spore formed by zygomycotine fungi.
\Bzygotaxis\b The mutual attraction between male and female gametes; \Bzygotactic.\b
\Bzygote\b A fertilized gamete; a diploid cell formed by the fusion of two haploid gametes.
