Bullfrog Ballet

The bullfrog is the largest of the North American ranids. Reaching a body length of 20 centimetres (7.9 in), bullfrogs weigh up to 750 grams (1.7 lb). Females are typically larger than males. Males have a tympanum twice the diameter of the eye, and a yellow throat. Female tympanum diameter is the same as that of the eye. Bullfrogs are generally varying shades of green or brown. The head is usually mostly green. The body varies from olive to brown, and may be darkly blotched or spotted. The hindlimbs may be darkly banded.

Similar species include the green frog (Rana clamitans) and pig frog (Rana grylio). The bullfrog may be distinguished from the green frog by the bullfrog's lack of dorsolateral folds, prominent, seam-like skin folds that course down the sides of the back of the green frog. The pig frog has a more pointed snout and its fourth toe (counting medially to laterally) is webbed whereas that of the bullfrog extends un-webbed beyond the other toes.

The adult bullfrog skeleton is representative of tetrapod vertebrates, comprised of 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.

The bullfrog skull is highly fenestrated. The orbits open ventrally through the roof of the mouth to accommodate eye retraction during locomotion and swallowing. The skull bears a continuous row of tiny teeth on the maxilla and premaxilla and a pair of small vomerine teeth on the palate. The mandible is toothless.

The bullfrog nervous system consists of a brain, spinal cord, and peripheral nerves including cranial nerves, spinal nerves, and sympathetic nerves serving organs such as the heart, gastrointestinal tract, kidneys, gonads.