Wolves, cougars, owls, sea lions and walruses are examples of carnivores, while koalas, pandas, gazelles, zebras and caterpillars are herbivores. Humans, ostriches, box turtles, black bears, red foxes and squirrels are omnivores. Carnivores feed on other animals, herbivores only feed on plant life and omnivores consume plants and animals.
Carnivores have physical traits specifically made for catching and consuming meat. Many carnivores have sharp teeth for tearing flesh, strong jaws or talons for trapping prey and keen vision for spotting prey. Herbivores usually have broad teeth for breaking down plants and seeds and stomachs adapted to digesting plant matter. Herbivores are further classified by the type of plants they eat, such as folivores, or animals that eat fruit. Omnivores are able to digest a variety of foods, allowing them to modify their diets when an ecosystem is threatened.
In an ecosystem, carnivores, herbivores and omnivores rely on each other for survival, and declining or increasing populations in one group can affect the sustainability of another. For example, carnivores typically feed on herbivores, regulating the number of plant-eating animals in one area. When human hunting practices reduce the number of carnivorous predators, the herbivore population may grow until it exceeds the local food supply. On the other hand, land development can deprive herbivores of plant life to eat, causing them to die off, drastically reducing the food supply for carnivores.