10 Interesting Facts About Carnivores

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Carnivores—by which we mean, for the purposes of this article, meat-eating mammals—are some of the most feared animals on earth. These predators come in all shapes and sizes, ranging from two-ounce weasels to half-ton bears, and they eat everything from birds, fish, and reptiles to each other. 

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Carnivores Can Be Divided Into Two Basic Groups

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It may not be much help when you're trying to make sense of bears and hyenas, but there are two major "superfamilies" of carnivores, the Canidae and the Feloidea. As you may already have guessed, Canidae includes dogs, foxes, and wolves, but it's also home to animals as diverse as skunks, seals, and raccoons. Feloidea includes lions, tigers, and house cats, but also animals you might not think are all that closely related to felines, such as hyenas and mongooses. (There used to be a third carnivore superfamily, Pinnipedia, but these marine mammals have since been subsumed under the Canidae.)

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There Are 15 Basic Carnivore Families

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The two superfamilies of canid and felid carnivores are divided into 15 families. The canids include Canidae (wolves, dogs, and foxes), Mustelidae (weasels, badgers, and otters), Ursidae (bears), Mephitidae (skunks), Procyonidae (raccoons), Otariidae (eared seals), Phocidae (eared seals), Aeluridae (red pandas), and Odobenidae (walruses). The felids include Felidae (lions, tigers, and cats), Hyaenidae (hyenas), Herpestidae (mongooses), Viverridae (civets), Prionodontidae (linsangs), and Eupleridae (small mammals of Madagascar).

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Not All Carnivores Are Devoted Meat Eaters

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It may seem strange, considering that their name literally means "meat eater," but carnivores have a wide range of diets. On one end of the scale are the cats of family Felidae, which are "hypercarnivorous," obtaining nearly all of their calories from fresh meat (or, in the case of house cats, tin cans). On the other end of the scale are outliers like red pandas and raccoons, which eat small amounts of meat (in the form of bugs and lizards) but spend the rest of their time foraging for tasty vegetation. There is even one exclusively vegetarian "carnivore," the palm civet of family Viverridae!

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Carnivores Can Only Move Their Jaws up and Down

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When you watch a dog or cat eat, you may be intrigued (or vaguely repulsed) by the sloppy, chomping, up-and-down motion of its jaws. You can attribute this to the characteristic shape of the carnivoran skull: the jaws are positioned, and the muscles are attached, in such a way as to disallow side-by-side movement. One positive thing about the arrangement of the carnivoran skull is that it allows for a larger brain than other mammals, which is why cats, dogs, and bears, as a whole, tend to be much smarter than goats, horses, and hippos.

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All Carnivores Descend From a Common Ancestor

Depiction of a Miacis skull

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As far as paleontologists can tell, all carnivores alive today—ranging from cats and dogs to bears and hyenas—are ultimately descended from Miacis, a tiny, one-pound mammal that lived in western Europe about 55 million years ago, only 10 million years after the dinosaurs had gone extinct. There were mammals before Miacis—these animals evolved from therapsid reptiles during the late Triassic period—but the tree-dwelling Miacis was the first to be equipped with the characteristic teeth and jaws of carnivorans, and served as a blueprint for later carnivoran evolution.

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Carnivores Have Relatively Simple Digestive Systems

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As a general rule, plants are much more difficult to break down and digest than fresh meat—which is why the guts of horses, hippos, and elks are packed with yards upon yards of intestines, and often more than one stomach (as in ruminant animals like cows). By contrast, carnivores have relatively simple digestive systems, with shorter, more compact intestines and a higher stomach-volume to intestine-volume ratio. (This explains why your house cat throws up after eating grass; its digestive system simply isn't equipped to process the fibrous proteins of plants). 

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Carnivores Are the World's Most Efficient Predators

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You can make a case for sharks and eagles, of course, but pound-for-pound, carnivores may be the most dangerous predators on earth. The crushing jaws of dogs and wolves, the blazing speed and retractable claws of tigers and cheetahs, and the muscular arms of black bears are the culmination of millions of years of evolution, during which a single missed meal could spell the difference between survival and death. In addition to their bigger brains, carnivores are also equipped with exceptionally sharp senses of sight, sound, and smell, which makes them all the more dangerous when pursuing prey.

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Some Carnivores Are More Social Than Others

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Carnivores exhibit a wide range of social behavior, and nowhere are the differences more pronounced than between the two most familiar carnivore families, felids, and canids. Dogs and wolves are intensely social animals, usually hunting and living in packs, while most big cats tend to be solitary, forming small family units only when necessary (as in the pride of lions). In case you're wondering why it's so easy to train your dog, while your cat won't even show the courtesy to respond to its name, that's because canines are hard-wired by evolution to follow the lead of the pack alpha, while tabbies simply couldn't care less.

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Carnivores Communicate in a Wide Variety of Ways

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Compared to herbivorous mammals like deer and horses, carnivores are some of the loudest animals on earth. The barks of dogs and wolves, the roars of big cats, the grumbles of bears, and the eerily laugh-like hooting of hyenas are all different means of asserting dominance, initiating courtship, or warning others of danger. Carnivores can also communicate non-verbally: via scent (urinating on trees, emitting foul scents from anal glands) or via body language (entire treatises have been written about the aggressive and submissive postures adopted by dogs, wolves, and hyenas in different social situations).

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Today's Carnivores Aren't Much Smaller Than They Used to Be

Southern elephant seal

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Back in the Pleistocene epoch, about a million years ago, practically every mammal on earth had a comically huge ancestor in its family tree: witness the two-ton prehistoric armadillo Glyptodon. But this rule doesn't apply to carnivores, many of which (like the Saber-Toothed Tiger and the Dire Wolf) was fairly bulky, but not significantly bigger than their modern descendants. Today, the largest carnivore on earth is the southern elephant seal, the males of which can attain weights of over five tons; the smallest is the appropriately named least weasel, which tips the scales at less than half a pound.