No matter what the activity, everything an animal does requires energy. Giraffes need energy to run; monkeys need energy to climb; children need energy to play. But where does all of this energy come from? All animals acquire energy from the food they eat. Depending on the type of animal, this food may consist of plants, animals, or a combination of both.
Animals that eat only plants are called herbivores. Most herbivores, including the giraffe, macaw, ground squirrel, and elephant in this video segment, eat a wide variety of plants and plant parts. Some herbivores, however, are very particular about the plant matter they eat. Wild pandas have evolved to eat nothing but bamboo plants -- a food that is plentiful where they live but not particularly nutritious for bears. Because of their inefficiency digesting plant material pandas need to eat a lot. Adult pandas spend 10 to 12 hours each day eating and consume about 40 pounds of food during that time.
Animals that eat only other animals are called carnivores. Polar bears, sharks, woodpeckers, and anteaters are all carnivores. Like herbivores, however, carnivores may generalize and eat a wide variety of animals, or specialize and eat only one type. Bald eagles, for example, are not very particular about the type of meat they eat. They eat road-killed animals or the occasional rabbit plucked from a field, fish they've caught fresh or rotting fish on the bank of a river. They are even known to scavenge for food in city dumps. In contrast, anteaters are highly specialized creatures. These animals eat little else besides ants and termites, and their sticky tongue and powerful front legs (for tearing into insect mounds) are perfectly adapted for doing just that.
Omnivores are the least choosy about what they eat. These animals, which include raccoons, opossums, and black and grizzly bears, eat both plants and animals, and often eat a wide variety of each. A typical grizzly bear, for example, will eat just about anything it can catch and get its mouth around. Grizzlies are known to kill their own food, including deer, but will also scavenge the carcasses of dead animals. They also eat fish, crustaceans, amphibians, small mammals, insects, berries, tree buds, and grass.