A carnivore is an organism that mostly eats meat, or the flesh of animals. Sometimes carnivores are called predators. Organisms that carnivores hunt are called prey.
Carnivores are a major part of the food web, a description of which organisms eat which other organisms in the wild. Organisms in the food web are grouped into trophic, or nutritional, levels. There are three trophic levels. Autotrophs, organisms that produce their own food, are the first trophic level. These include plants and algae. Herbivores, organisms that eat plants and other autotrophs, are the second trophic level. Carnivores are the third trophic level. Omnivores, creatures that consume a wide variety of organisms from plants to animals to fungi, are also the third trophic level.
Autotrophs are called producers, because they produce their own food. Herbivores, carnivores, and omnivores are consumers. Herbivores are primary consumers. Carnivores and omnivores are secondary consumers.
Many carnivores eat herbivores. Some eat omnivores, and some eat other carnivores. Carnivores that consume other carnivores are called tertiary consumers. Killer whales, or orcas, are a classic example of tertiary consumers. Killer whales hunt seals and sea lions. Seals and sea lions are carnivores that consume fish, squid, and octopuses.
Some carnivores, called obligate carnivores, depend only on meat for survival. Their bodies cannot digest plants properly. Plants do not provide enough nutrients for obligate carnivores. All cats, from small house cats to huge tigers, are obligate carnivores.
Most carnivores are not obligate carnivores. A hypercarnivore is an organism that depends on animals for at least 70 percent of its diet. Plants, fungi, and other nutrients make up the rest of their food. All obligate carnivores, including cats, are hypercarnivores. Sea stars, which prey mostly on clams and oysters, are also hypercarnivores.
Mesocarnivores depend on animal meat for at least 50 percent of their diet. Foxes are mesocarnivores. They also eat fruits, vegetables, and fungi.
Hypocarnivores depend on animal meat for less than 30 percent of their diet. Most species of bears are hypocarnivores. They eat meat, fish, berries, nuts, and even the roots and bulbs of plants. Hypocarnivores such as bears are also considered omnivores.
The planet’s largest animal is a carnivore. The blue whale can reach 30 meters (100 feet) long and weigh as much as 180 metric tons (200 tons). It feeds by taking huge gulps of water and then filtering out tiny shrimp-like creatures called krill. The blue whale can eat about 3.6 metric tons (4 tons) of krill every day—that’s about 40 million of the little creatures. The largest land carnivore is the polar bear, which feeds mainly on seals.
Carnivores have biological adaptations that help them hunt. Carnivorous mammals such as wolves have strong jaws and long, sharp teeth that help them grab and rip apart their prey. Plant-eaters, on the other hand, usually have big molars that help them grind up leaves and grasses.
Lions, cougars, and other cats have sharp claws that they use to hunt. Birds such as hawks and owls also hunt with their claws, called talons. Many carnivorous birds, called raptors, have curved beaks that they use to tear apart their prey.
Many carnivores grab their prey in their mouths. Great blue herons wade slowly through shallow water and then suddenly snatch a fish, crab, or other creature from the water. Toads grab mice in their mouths. Sperm whales dive deep into the ocean where they bite hold of squid.
Spiders capture their prey—usually insects—by trapping them in a sticky web. Other carnivores attack their prey with a bite or a sting that injects toxic venom into the victim. The venom either paralyzes or kills the prey. Snakes such as king cobras have hollow fangs that act like needles to inject venom. Cobras mostly prey on other snakes. Jellyfish have stingers on their tentacles, which paralyze fish swimming nearby.
Most carnivores are animals, but plants and fungi can be carnivores also. The Venus flytrap is a plant that catches insects in its leaves. When an insect brushes against the sensitive hairs on the leaf, the leaf folds in two and snaps shut. The insect is trapped inside. Other carnivorous plants, such as the sundew, produce a sticky material that catches insects.
Fungi are a group of organisms that include mushrooms, molds, and mildew. Some fungi trap and consume tiny organisms. Most carnivorous fungi prey on microscopic worms called nematodes, which they trap with suffocating rings.
Certain types of carnivores have specific diets. Some, such as sea lions, eat mainly fish. They are called piscivores (piscis is the Latin word for fish).
Others, such as lizards, eat mainly insects. They are called insectivores. Many bats are also insectivores. One little brown bat can eat a thousand mosquitoes in an hour. Some insects are themselves insectivores. These include ladybugs, dragonflies, and praying mantises.
Carnivores that have been known to attack and eat human beings are known as man-eaters. Some species of sharks, alligators, and bears are called man-eaters. However, no carnivore specifically hunts human beings or relies on them as a regular food source.
Cannibals are carnivores that eat the meat of members of their own species. Many animals practice cannibalism. For some species, cannibalism is a way of eliminating competitors for food, mates, or other resources. Chimpanzees and bears, for example, will hunt and consume the young of family members, sometimes their own offspring. Praying mantis females will kill and eat the bodies of their mates.
Many carnivores are scavengers, creatures that eat the meat of dead animals, or carrion. Unlike other types of carnivores, scavengers usually do not hunt the animals they eat. Some, such as vultures, consume animals that have died from natural causes. Others, such as hyenas, will snatch meat hunted by other carnivores. Many insects, such as flies and beetles, are scavengers.
Some carnivores, including sea lions, feed often. Others, such as king cobras, can go months between meals.
Carnivores in the Food Chain
For a healthy ecosystem, it is important that the populations of autotrophs, herbivores, and carnivores be in balance. Energy from nutrients is lost at each trophic level. It takes many autotrophs to support a fewer number of herbivores. In turn, a single carnivore may have a home range of dozens or even hundreds of miles. A Siberian tiger, for instance, may patrol a range of 1,000 square kilometers (386 square miles).
In some places, the disappearance of large carnivores has led to an overpopulation of herbivores, disrupting the ecosystem. Wolves and cougars are traditional predators of white-tailed deer, for instance. But hunting and development have eliminated these predators from the northeastern United States. Without natural predators, the population of white-tailed deer has skyrocketed. In some areas, there are so many deer that they cannot find enough food. They frequently stray into towns and suburbs in search of food.
Carnivores depend on herbivores and other animals to survive. Zebras and gazelles once traveled in great herds over the plains of Africa. But these herds have shrunk and are now mostly confined to parks and wildlife reserves. As the numbers of these herbivores decline, carnivores such as African wild dogs, which prey on them, also decline. Scientists estimate that only 3,000 to 5,500 African wild dogs remain in the wild.