American Bullfrog

Description
Bullfrogs grow on average to be about 3.5 to 6.0 inches (9–15 cm) in body length (although there are records of some up to 8.0 inches), legs add another 7–10 inches (17–25 cm) to length. 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.

Growth and development
Eggs hatch in three to five days. Time to metamorphosis ranges from a few months in the southern to three years in the northern parts of the geographic range.Maximum lifespan in the wild is estimated at eight to 10 years, but one captive lived almost 16 years.

Feeding
A juvenile with a small, grey, oval-shaped area on top of the head, the parietal eye
Native habitat

Stomach content studies going back to 1913 suggest the bullfrog preys on any animal it can overpower and stuff down its throat. Bullfrog stomachs have been found to contain rodents, small turtles, snakes, frogs (including bullfrogs), birds, and a bat, as well as the many invertebrates which are the usual food of ranid frogs. These studies furthermore reveal the bullfrog's diet to be unique among North American Rana in the inclusion of large percentages of aquatic animals, e.g., fish, tadpoles, planorbid snails, and dytiscid beetles. The specialized ability of bullfrogs to capture submerged and large, strong prey comprises a pronounced biting motor pattern that follows up on the initial and typical ranid tongue strike.Adaptation to target image displacement due to light refraction at the water-air interface consists of the bullfrog's application of tongue surface comparatively posterior to the perceived location of the prey target. The comparative ability of bullfrogs to capture submerged prey, compared to that of the green frog, leopard frog, and wood frog (R. clamitans, R. pipiens, R. sylvatica, respectively) was also demonstrated in laboratory experiments.