Adult male bullfrog
Least Concern (IUCN 3.1)
Species: R. catesbeiana
Natural range - red;
Introduced range - dark green
The American bullfrog, 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, but there is some dispute as to whether Lithobates catesbeianus is a more correct name. This frog 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.
The hind legs of the bullfrog are used as food and it is harvested from the wild in North America and several countries into which it has been introduced. It is also cultured in controlled environments, though this is a difficult undertaking, and there is some international trade in frog legs.
4 Breeding behavior
4.2 Aggressive behavior
5 Growth and development
8 Human use
10 External links
Although some authorities accept the specific name Rana catesbeiana, others consider this frog should be included in the genus Lithobates as Lithobates catesbeianus.
Mitochondrial DNA studies of New World species put Rana catesbeiana in the Aquarana group of ranids and suggest this clade is a sister group to Rana sylvatica, the wood frog. The data strongly supported the monophyly of the Aquarana grouping, which includes the green frog (Rana clamitans) and the Florida bog frog (Rana okaloosae), which appear to have recently diverged, and the closely related American bullfrog (R. catesbeiana) and river frog (R. heckscheri). This placement was disputed by Darrel Frost and the American Museum of Natural History, who placed most of the North American ranids in the genus Lithobates. His view is rejected by Stuart (2008) and Pauly et al. (2009) and it is not accepted by Amphibiaweb.
The dorsal surface of the bullfrog has an olive-green basal color, either plain or with a mottling and banding of grayish-brown. The ventral surface is off-white blotched with yellow or gray. There is often a marked contrast in color between the green upper lip and the pale lower lip. The eyes are prominent with brown irises and horizontal almond-shaped pupils. The tympani (eardrums) are easily seen and the dorsolateral folds of skin end close to them. The limbs are blotched or banded with gray. The forelegs are short and sturdy and the hind legs long. The hands are not webbed, but the feet have webbing between the digits with the exception of the fourth toe.
Bullfrogs are dimorphic, with males being smaller than females, and having yellow throats tympani larger than their eyes, whereas the tympani in females are about the same size as the eyes. Bullfrogs measure about 3.6 to 6 in (9 to 15 cm) from snout to vent. They grow fast in the first eight months of life, typically increasing in weight from 5 to 175 g (0.18 to 6.2 oz), and large mature individuals can weigh up to 500 g (1.1 lb). Exceptional bullfrogs can possibly attain 800 g (1.8 lb) and measure up to 8 in (20 cm) in length.