Carnivores include those animals that obtain their nutrition by consuming other animals. It comes from a combination of Latin words literally meaning "flesh devourers." Carnivores are at the top levels of every food chain - primary carnivores feed on herbivores, secondary carnivores feed on primary carnivores, and so on. Due to the Second Law of Thermodynamics, the number of trophic levels is typically limited to a maximum of four or five. There is a general correlation that the higher up on the food chain you go, the number of organisms decreases but their individual size increases. Herbivores typically have large or complex stomachs and long intestines to allow for enough time to adequately digest their high-cellulose diet. Because their food is similar in chemical composition to their own body chemistry, carnivores don't have to go through an extensive digestion process and thus have simple stomachs and short intestines. Another interesting contrast is that herbivores tend to be continuous feeders and carnivores tend to eat periodic meals. Carnivores thus have more leisure time in which to relax. During times of food gathering, however, carnivores are generally more active and more aggressive than their herbivore counterparts.

Animals within the Order Carnivora include the flesh-eating mammals such as dogs, cats, wolves, bears, and weasels. These animals have carnassial teeth which are adapted for cutting and shearing their food. They are distributed worldwide except for Australia and Antarctica. Other carnivores which are not within this specific Order include a wide-range of animals such as blue-gill sunfish, large-mouth bass, sharks, and other fish; owls, hawks, and other birds; seals, sea otters, killer whales, and other marine mammals; and alligators, humans and other terrestrial vertebrates. Animals that ingest both plant and animal matter are called omnivores.