Solitary aquatic frog (Rana catesbeiana) named for its loud call. The largest U.S. frog, native to the eastern states, the bullfrog has been introduced into the western states and into other countries. The bullfrog is green or brown with a white to yellowish belly and dark-barred legs. Its body is about 8 in. (20 cm) long, and its hindlegs may be 10 in. (25 cm) long. Large adults weigh 1 lb (0.5 kg) or more. Bullfrogs usually live in or near a body of still water. They are used for food and as laboratory animals. The name is sometimes applied to other large frogs.