structural:reformatting
Feeding

Bullfrogs are voracious, opportunistic, ambush predators that prey on any small animal they can overpower and consume. Bullfrog stomachs have been found to contain rodents, small lizards and snakes, other frogs and toads, other amphibians, crayfish, other crustaceans, small birds, scorpions, tarantulas and bats, as well as the many types of invertebrates, such as snails, worms and insects, which are the usual food of ranid frogs. These studies revealed the bullfrog's diet to be unique among North American ranids in the inclusion of a large percentage of aquatic animals, such as fish, tadpoles, ram's horn snails, and dytiscid beetles, as well as the aquatic eggs of fish, frogs, insects, or salamanders. Cannibalism has been observed in bullfrog populations in resource-limited environments. Bullfrogs are able to capture large, strong prey because of the powerful grip of their jaws after the initial ranid tongue strike. However, there is a correlation found with size of prey relative to body size of the bullfrog. Juveniles and adults typically go after prey that is relative to their own body size. The bullfrog is able to make allowance for light refraction at the water-air interface by striking at a position posterior to the target's perceived location. The comparative ability of bullfrogs to capture submerged prey, compared to that of the green frog, leopard frog, and wood frog (L. clamitans, L. pipiens, and L. sylvaticus, respectively) was also demonstrated in laboratory experiments.

Prey motion elicits feeding behavior. First, if necessary, the frog performs a single, orienting bodily rotation ending with the frog aimed towards the prey, followed by approaching leaps, if necessary. Once within striking distance, the bullfrog begins its feeding strike, which consists of a ballistic lunge (eyes closed as during all leaps) that ends with the mouth opening. At this stage, the fleshy, mucus-coated tongue is extended towards the prey, often engulfing it, while the jaws continue their forward travel to close (bite) just as the tongue is retracted. Large prey that do not fit entirely into the mouth are stuffed in with the hands. In laboratory observations, bullfrogs taking mice usually swam underwater with prey in mouth, apparently with the advantageous result of altering the mouse's defense from counter-attack to struggling for air. Asphyxiation is the most likely cause of death of warm-blooded prey.