Adults have a conspicuous round eardrum, called the tympanum, located on either side of the head. The tympanum is up to twice as large as the eye. A ridge of skin starts behind the eye, runs over the eardrum, and ends at the base of the front legs. There are no lateral ridges on the back. The hind legs are large and powerful and may be banded or blotched with brown.
Males have a singular throat pouch that is pale to bright yellow.
Females have a white throat. Tadpoles are drab olive green with many tiny black pinhead-sized specks scattered throughout the tail fin and on the back. They may grow up to five inches in length. Distribution Bullfrogs are perhaps the most widely distributed amphibian in North America. Today, bullfrogs are found across most of the lower 48 states as well as in Mexico, Cuba and Jamaica.