The Serengeti-Mara ecosystem supports one the largest and most diverse mammal populations in the world. Since the [P 017 / dung beetle] depends on mammals for its habitat and food source, they are found by the millions in areas where mammals are most abundant such as the plains. The dung beetle not only reduces the amount of dung in the area but also facilitates fertilization of the soil by burying it.
There are thousands of species of dung beetle, but they can be categorized into three types, depending on their relationship with the dung. The "rollers" make balls of dung to roll away from the heap for burial. The "[L3 401 / tunnelers]" transfer dung to tunnels they burrow below the heap. The least evolved, the "dwellers," do not relocate food but rather live, eat and lay eggs directly on the droppings. All three types can be found on the same dung heap.
The roller is the most evolved type of dung beetle. The two front legs are curved and equipped with four strong teeth that act as scoops and rakes. Once dung is collected, the dung beetle forms a ball by patting and pressing the dung with its front legs. The short front legs are specially adapted for this purpose and are different from the middle and hind legs which have five-jointed feet. The front legs are missing the feet.
Once the ball is formed, it is rolled away from the heap. The ball is held between the curved back legs as the dung beetle moves backwards in search of a place to bury it. A chamber, a little larger than the ball is dug a few inches deep. Once the ball is in the chamber, the beetle feeds on it for several days. Once the ball has been consumed, the dung beetle emerges from the chamber and flies away in search of a fresh supply of dung.
When the female prepares to lay its egg, it uses the softer part of the dung heap. It forms a ball in the same way, but digs a larger chamber below the surface allowing enough space for her to move completely around the ball. She pats the surface of the ball smooth with her front legs. Once the ball is round and smooth, she forms a hollow on one side and deposits an oval-shaped, white egg. She then smooths the edge of the hollow up to cover the egg leaving a bump on the ball, similar in shape to a pear. She then leaves the chamber and closes it behind her by pushing dirt over the top.
The exterior of the pear-shaped ball hardens forming a crust which keeps the interior moist. When the egg hatches after a couple of weeks, the white larva devours the soft dung. After two to three weeks, the larva has eaten all of the interior and lies snugly within the crust where it changes to a chrysalis. A month later, it breaks out of its "dung cocoon" and emerges from the chamber as an adult.
