Origins of Frog-on-Frog Violence

This lady explains the bullfrog cannibalism thing:

"Cannibalism may seem purely destructive, but it can, in fact, be quite beneficial. Clearly, a voracious cannibalistic species would rapidly eat itself out of existence. When cannibalism occurs in response to overcrowding, for example, it can increase the species’ chances for survival. A population rising too rapidly without restraints can eliminate its own food supply. During a harsh winter or drought, when food is scarce it is clearly to a species’ advantage for at least some of the population to remain well fed and healthy even at the expense of others. Among species that produce many offspring, such as frogs, cannibalism of siblings helps ensure that some young develop into adults, thus continuing the species. Cannibalism appears to be an inherited trait in some species."

The wikipedia article is excellent. Citizens for Responsible Human Food Consumption might want to study this for talking points.