American bullfrog, Rana catesbeiana often simply known as the bullfrog in Canada and the United States, is an aquatic frog, a member of the family Ranidae, or “true frogs”, native to much of North America. This is a frog of larger, permanent water bodies, swamps, ponds, and lakes, where it is usually found along the water's edge. The adult bullfrog skeleton is representative of tetrapod vertebrates, comprising an axial skeleton (skull and vertebrae) and an appendicular skeleton (pectoral girdle and forelimbs, pelvic girdle and hindlimbs). Ranids, however, lack ribs. The pronounced pair of dorsal humps in the back of ranid frogs are the ends of the pelvic ilia, homologues of the human hips. When in the air, as opposed to underwater, frogs continuously elevate and lower the floor of the mouth, which serves to ventilate the mouth, or buccal cavity, and exchange gases through the richly vascularized lining of the mouth. Periodically, the regular rhythmic pumping of the floor of the mouth is interrupted by a deeper lowering of the throat, at the extreme of which, the glottis opens and the throat muscles contract vigorously to force air from the mouth into the lungs—the nostrils are closed off. Fertilization is external in ranid frogs. In the mating grasp, or amplexus, the male rides on top of the female, grasping her with his forelimbs posterior to her forelimbs. The female bullfrog deposits her eggs in the water and the male simultaneously releases sperm.
Breeding begins in late spring or early summer. Males defend and call from territories, attracting females into a territory to mate. The call is reminiscent of the roar of a bull, hence the frog's common name. A female may produce up to 20,000 eggs in one clutch.
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Bullfrog
Bullfrog
Bullfrog
Bullfrog
Bullfrog
Bullfrog
Bullfrog pics
Bullfrog images
Bullfrog
Bullfrog
Bullfrog
Bullfrog
Bullfrog
Bullfrog