Carnivores are predators that eat mostly meat. Included in the list of carnivores are dogs, cats, sea lions and wolves. Many carnivores eat herbivores, so they are known as secondary consumers. Those who eat other carnivores are known as tertiary consumers. Obligate carnivores depend on meat in order to survive, and cannot depend on plants for survival, since they are unable to properly digest the plants or receive enough nutrients from them. Although most carnivores are animals, the Venus flytrap is an example of a plant that is a carnivore. Its leaves are able to sense the presence of and trap insects in its leaves.
Carnivores have bodies that have adapted to support them with hunting and eating other animals. Most have very sharp teeth, so that they can more easily snatch and rip apart their prey, and have bodies that help them move very quickly. Others, like wolves, have very strong and powerful jaws that they use to overpower larger animals. Some birds have spectacular eyesight that enables them to spot their prey more easily.
A key role of carnivores is to serve as population control, maintaining the balance in the ecosystem. The vulnerable animals, such as those who are very old or very sick are usually the first to serve as prey for carnivores. Without this natural occurrence, some populations would grow too large or others might spread disease.
Sources:
http://www.nhptv.org/natureworks/nwep10a.htm
http://education.nationalgeographic.com/education/encyclopedia/carnivore/?ar_a=1