The American Bullfrog (Lithobates catesbeianus) also known as the North American bullfrog or simply bullfrog in Canada and the United States, is an aquatic frog, a member of the family Ranidae, or “true frogs”, native to much of North America. The word 'frog' is of uncertain origin. It was first attested in Old English as frogga, but the usual Old English word was frosc. However, by using the comparative method in linguistics resulted into the Proto-Germanic word for frog froskaz which stems from Proto-Indo-European preu meaning 'jump'. The 'bull' part of its name was combined with 'frog' into 'bullfrog', a portmanteau word referring to the aggresive behavior of the bullfrog during a territorial fight. This is a frog of larger, permanent water bodies, swamps, ponds, lakes, where it is usually found along the water's edge. On rainy nights, bullfrogs along with many other amphibians, go overland and may be seen in numbers on country roads. American bullfrogs live longer in warm weather. They have been widely introduced across North America. The original, naturally determined range did not include far western regions where it is found today. Bullfrogs grow on average to be about 3 and a half to 6 inches (9–15 cm) long in body length (although there are records of some as big as 8 inches), legs add another 7–10 inches (17–25 cm) to length. Females have an eardrum (tympanum) the same size as their eye. Males' eardrums are larger.
American bullfrogs are preyed upon by many animals such as foxes, herons, raccoons, otters, largemouth bass and even raptors. The bullfrog protects itself in two ways. First, its powerful legs allow them to move quickly and jump long distances to avoid predators. Second, it secrete a poison from the parotid glands behind its ears. This rarely kills a predator but can sicken it enough to never approach a bullfrog again.