They prey on anything from dragonflies and bats to sharks, antelopes and even buffalo. Although attacks on humans have occurred, most species of crocodilian don't include humans as a food source. In fact, it has been suggested that a person bending down over a water source may resemble an antelope in the eyes of a crocodile and this is why the attacks occur. The species that habitually hunt humans are the Nile and Indo-Pacific crocodiles. The American crocodile, black caiman and the Indian mugger will on occasion kill humans for food or to defend their nests or territories.
Crocodilians are extremely energy efficient.
Because of this, they do not have to heat themselves using energy fueled by food as humans and other mammals do. Usually crocodilians need only eat once a week or less to maintain their energy levels. This behaviour is called gaping and it is done when the crocodile or alligator is basking in the sun. It is thought that this may act in cooling the crocodile, however, since they also do this during rain and at night it could suggest that gaping has a social function as well. Crocodilians are well adapted to water, as well as land.