Carnivores: Facts About Meat Eaters
Carnivores such as lions are at the top of the food chain.
Credit: Gudkov Andrey / Shutterstock.com

A carnivore is an animal or plant that eats the flesh of animals. Most, but not all, carnivorous animals are members of the Carnivora order; also, not all members of the Carnivora order are carnivorous. 

"A 'carnivore' is simply any species that eats meat, and this can range from carnivorous plants and insects to what we typically think of when we hear the word carnivore, like tigers or wolves," Kyle McCarthy, an assistant professor of wildlife ecology in the University of Delaware's College of Agriculture and Natural Resources, told Live Science. 

Carnivora is an order of mammals that includes canids such as wolves, dogs; felids (cats); ursids (bears); mustelids (weasels); procyonids (raccoons); pinnipeds (seals); and others, according to Encyclopedia Britannica, making up 12 families and 270 species in all. While some carnivores do eat only meat, some carnivores also supplement their diets with vegetation on occasion. For example, bears are omnivores — they eat plants and meat — and pandas are herbivores, which primarily eat plants, further explained McCarthy.

Venus flytraps have hinged leaves that snap shut when prey triggers sensitive hairs.
Venus flytraps have hinged leaves that snap shut when prey triggers sensitive hairs.
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There are more than 600 species of carnivorous plants, according to the Botanical Society of America. They get some of their nutrients by trapping and digesting insects and sometimes, small frogs and mammals. Because the most common prey for most carnivorous plants are insects, they are also called insectivorous plants. 

While most plants absorb nitrogen from the soil through their roots, carnivorous plants get nitrogen from animals prey that get trapped in their modified leaves. Traps work in various ways. A Venus flytrap, for example, has hinged leaves that snap shut when trigger hairs are touched. A pitcher plant has a pitfall trap; its leaves fold into deep pits filled with digestive enzymes. Sundews and butterworts have sticky mucus on their stalks.

There are three different types of carnivores, and each type has diets that consist of varying levels of meat consumption. 

Carnivores that eat mostly meat are called obligate carnivores; they cannot properly digest vegetation. The cat family, including lions, tigers and small cats, for example, are obligate carnivores. Obligate carnivores are also called hypercarnivores, which are animals whose diet consists of at least 70 percent meat, according to National Geographic.

Many hypercarnivores, such as some members of the Carnivora order, have heavy skulls with strong facial musculature to aid in holding prey, cutting flesh or grinding bones. Many also have a special fourth upper molar and first lower molar. "They close together in a shearing action, like scissors, which allows animals to slice meat from their prey," said McCarthy. These two teeth together are called the "carnassial teeth." A rare example of a hypercarnivore that does not have carnassial teeth is the crabeater seal. It has teeth that strains tiny zooplankton such as krill from the water, according to the University of Michigan's Animal Diversity Web (ADW).

Bears are members of the Carnivora order, but they are omnivores — they eat meat and plants.
Bears are members of the Carnivora order, but they are omnivores — they eat meat and plants.
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Animals that depend on meat for at least 50 percent of their diet are called mesocarnivores. To supplement their diet, these animals will eat fruits, vegetables, and fungi. Mesocarnivores are typically small to mid-size species and often live close to human populations. Raccoons, foxes and coyotes are example of mesocarnivores.

Hypocarnivores are carnivores that eat the least amount of meat. They consume meat for less than 30 percent of their diet. These animals eat meat, fish, berries, nuts and roots. These animals can also be considered omnivores. Hypocarnivores have smaller carnassial teeth and larger molars to accommodate their varied diets.

The world's largest animal is also the world's largest carnivore. The blue whale grows up to 100 feet (30 meters) long and weighs up to 200 tons (180 metric tons). The largest carnivore on land is the polar bear, which can weigh 880 to 1,320 lbs. (400 to 600 kilograms), and can grow to 8.6 feet long (2.6 m) from nose to tail, according to the Guinness Book of World Records. The smallest carnivore is the least weasel. It can grow up to 16 inches long (40.6 centimeters) and weigh up to 7 ounces (198 grams). 

Though carnivores come in many shapes in sizes, but they often have some common similarities. Most carnivores have relatively large brains and high levels of intelligence. They also have less complicated digestive systems than herbivores. For example, many herbivores have multiple stomachs, while carnivores only have one, according to Encyclopedia Britannica. 

Though all carnivores eat meat at some level, the frequency of their feeding can vary. Warm-blooded carnivores tend to burn a lot of calories. Because of this, they have to hunt and eat often to keep to keep up their energy levels. Cold-blooded carnivores, use less calories and can rest days or even months between meals, for example. 

Carnivores are third trophic level of the food web, along with omnivores. Carnivores eat other carnivores, as well as herbivores and omnivores, depending on their species, according to National Geographic. 

As the top of the food web, carnivores keep the populations of other animals in check. If a carnivore population is wiped out by plague, drought, human intervention or other factors, an area can experience an overpopulation of other creatures lower in the food chain.

Sometimes, carnivores will be introduced into an area to help with overpopulation. For example, wolves were reintroduced to Yellowstone National Park to help with the elk population. In turn, this reintroduction has allowed woody plants to recover from the consumption of too many elk, according to the University of Michigan

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