Carnivores, omnivores and herbivores include cats and dogs, humans and birds, and deer and giraffes respectively. While herbivores eat plants, omnivores eat both plants and other animals and carnivores live almost exclusively on other animals.
Herbivores not only include large grazing animals such as sheep, cows and horses, but insects and aphids as well. There are many types of herbivores, such as ruminants, frugivore, detritivores and parasties. Ruminants or grazing animals, such as sheep, giraffes, cattle and camels, have multi-chambered stomachs. They regurgitate and chew partially digested food or cud to break down fibrous plant matter before passing the matter down into the stomach's second chamber. Frugivores such as oilbirds and koala bears eat only fruit.
Omnivores, which live on both plant and animal matter, include reptiles, fish, certain insects and mammals that are primarily carnivorous. These carnivorous omnivores include red foxes and coyotes, animals of opportunity that feed on what they can find. When fresh meat is scarce, they eat carrion or fruit. Box turtles eat berries and flowers as well and frogs and fish. Ants eat both seeds and other insects.
Carnivores such as wolves and seals live primarily on meat. Dog and cat species have sharp carnassial teeth that help them to rip through flesh. Sea lions, seals and walruses have fin feet that allow them to swim quickly after fish.