#Threat Display# ^w^ Observation by Dr. Don Nelson and Richard Johnson raises the question of whether some sharks attack in response to threat. ^w^ The Grey Reef Shark is an unusually aggressive shark for its size, and can be provoked to exhibit a special posture prior to attack. ^w^ In normal swimming patterns the shark holds its body in a fairly level position and the pectoral fins stay relatively straight out from the sides of the body. When the shark is startled or cornered, it may begin a pattern of exaggerated swimming. The head and tail swing back and forth in broad sweeps. The shark arches its back, and lowers its pectoral fins.