American Bullfrog

The American bullfrog (Lithobates catesbeianus or Rana catesbeiana), often simply known as the bullfrog in Canada and the United States, is an aquatic frog, a member of the family Ranidae, or “true frogs”. This species has traditionally been classified as Rana catesbeiana, however the classification has been changed to Lithobates due to paraphyly in Ranidae. This frog has an olive green back and sides blotched with brownish markings and a whitish belly spotted with yellow or grey. The upper lip is often bright green and males have yellow throats. It inhabits large, permanent water bodies, such as swamps, ponds, and lakes, where it is usually found along the water's edge. The male bullfrog defends a territory during the breeding season. His call is reminiscent of the roar of a bull, which gives the frog its common name. This frog is native to southern and eastern parts of the United States and Canada, but has been widely introduced across other parts of North, Central and South America, Western Europe, and parts of Asia, and in some areas is regarded as an invasive species.

http://en.wikipedia.org/wiki/American_bullfrog