breed. The green frog and the pickerel frog mature in about three years. In captivity, a bullfrog may live more than 15 years. But few species of frogs live longer than 6 to 8 years in the wild. Many are eaten by such enemies as bats, herons, raccoons, snakes, turtles, and fish. Adult frogs eat mainly insects and other small animals, including earthworms, minnows, and spiders. Most frogs use their sticky tongue to capture prey. The tongue is flipped out of the mouth in response to movement by the prey. Most frogs have teeth only on their upper jaw. Toads lack teeth altogether. As a result, frogs and toads swallow their prey in one piece. To aid in the swallowing process, the frog's eyes sink through openings in the skull and force the food down the throat. More than 20 kinds of true frogs live in the United States. Many of these frogs also live in Canada. A group of related species known as leopard frogs are the most widespread. Leopard frogs range from the Atlantic coast to eastern California and from northern Canada to the Mexican border. The bullfrog, which may grow up to 8 inches (20 centimeters) long, ranks as the largest American and Canadian frog. Other common true frogs of the United States and Canada include the green frog, the pickerel frog, and the wood frog. Unlike most other true frogs, the wood frog spends much of its time away from water. It lives in damp wooded areas of Alaska, Canada, and the Midwestern and Eastern United States. Tree frogs, like true frogs, live on all continents except Antarctica. Most tree frogs measure less than 2 inches (5 centimeters) long and dwell in trees. About 25 species of tree frogs live in the United States. Some of these species are also found in Canada. Common species in the Eastern United States include the green tree frog, the gray tree frog, and the spring peeper. Western tree frogs include the California tree frog, the canyon tree frog, and the Pacific tree frog. Some North American ...
