描述
The true frogs, family Ranidae, have the widest distribution of any frog family. They are abundant throughout most of the world, occurring on most continents except Antarctica. The true frogs are present in North America, northern South America, Europe, Asia, Madagascar, Africa, and from the East Indies to New Guinea; the species native to Australia—the Australian wood frog (Hylarana daemelii)—is restricted to the far north. Typically, true frogs are smooth and moist-skinned, with large, powerful legs and extensively webbed feet. The true frogs vary greatly in size, ranging from small—such as the wood frog (Rana sylvatica)—to the largest frog in the world, the goliath frog (Conraua goliath). Many of the true frogs are aquatic or live close to water. Most species lay their eggs in the water and go through a tadpole stage. However, as with most families of frogs, there is large variation of habitat within the family. Those of the genus Tomopterna are burrowing frogs native to Africa and exhibit most of the characteristics common to burrowing frogs around the world. There are also arboreal species of true frogs, and the family includes some of the very few amphibians that can live in brackish water.