Scientifically-speaking there are 11 mammal groups, and most Mammals are warm-blooded, have body hair, give live birth and nurse their young with milk from mammary glands. Check out these articles about all kinds of mammals.

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Why do warthogs have warts?

Storybook villains always seem to have warts. These unsightly growths may be indicators of wickedness in the fairy-tale world, but they're crucial features for some hogs living in the animal kingdom.

Why Do Raccoons Wash Their Food?

With their built-in masks and ability to snatch food, it seems raccoons were meant for a life of crime. But do these thieves wash away the evidence by rinsing food in water?

Mammal Pictures

Mammals are a ubiquitous and diverse class of animals. Learn all about mammals, including hippopotamuses, killer whales, sugar gliders and more, by viewing this mammal image gallery.

Why are otters playful?

If the animal world were school, otters would be those kids who never leave the playground. Always begging for five more minutes of recess, otters take playtime very seriously.

Can I catch plague from a prairie dog?

Prairie dogs may look cute and cuddly, but are these rodents harbingers of deathly plague? Since there aren't any underground pharmacies in prairie dog towns, will disease wipe out these animals?

Why do gorillas build new nests every night?

Besides our genetic similarities, gorillas also share our love of getting a good night's sleep -- except that their alarm clocks come in the form of dangerous predators and poachers.

Do moose really walk the streets of Alaskan cities?

If Bullwinkle had made the move up north, he would have felt right at home. Though moose in Alaska don't have squirrel sidekicks, they do take advantage of their urban surroundings.

Marsupial Pictures

Marsupials are mammals that commonly bear a pouch such as kangaroos and koalas. Did you know that two thirds of marsupial species are found in Australia? Find out more by viewing this marsupial image gallery.

Can manatees see underwater?

If you don't make it past that first "E" during your annual vision test, you might give bats a reprieve by calling yourself "blind as a manatee."

Are orangutans introverts?

Orangutans might be the most low-key of the world's apes, but that doesn't mean they don't like to socialize. So are these redheads miscast as loners, or are orangutans introverts?

Why do cougars scream?

If you come across a cougar, you might scream in fear. So if this predator could easily devour you, why might it harmonize your screech with its own tone-deaf shriek?

What happens to chimps used in medical research?

Their genetic similarity to humans makes chimps great subjects for medical research. But some countries are banning this research because these apelike similarities are a little too close for comfort.

Does panhandling kill black bears?

Although Yogi Bear thinks he's smarter than the average bear, he might not be using his brains when snatching picnic baskets. Does panhandling have more serious consequences than just extra calories?

How do leopards kill animals larger than they are?

With powerful jaws, massive paws and piercing claws, the leopard is built for hunting. But how can this cat possibly take down animals three times its size?

How do gazelles use body language?

Avoiding eye contact is a form of body language (and a sign you're probably lying). Gazelles might not use body language to lie, but they do rely on it to survive.

Why do tigers swim?

When cats go swimming, is it still considered doggy paddling? Tigers might not be invited to your next pool party, but they sure do love taking a dip.

Does a deer have exactly enough brains to tan its own hide?

It takes brains to tan leather is and we're not just talking keen intellect and skill. Sometimes that soft, supple feel of leather literally comes from using the old noggin.

What happens to whales when they die?

Vindictive whales like Moby Dick sometimes give these giants of the sea a bad rap. But whales do a lot for their ecosystem, especially after they go to Davy Jones' locker.

How Narwhals Work

What? You've never heard of a narwhal? Well, it's a cold-water-dwelling, deep-diving, vocalizing, halibut-munching wonder with its very own ivory crown. Did we mention its crazy tusk?

What is a lone wolf?

Loners might seem intriguing, but they lead dangerous lives -- a least those in the wolf world do. Lone wolves are outsiders, relying only on themselves to survive without a pack.

Could a fungus cause the extinction of bats?

Riddle me this: Why are bats showing up dead with a white powder streaked across their faces? Could a poorly understood fungus wipe them out? To the bat cave, readers!

Can chimpanzees learn human language?

So far, "Planet of the Apes" is pure fiction. But are chimps capable of learning human language (and eventually taking over the world)?

Why do kangaroos hop?

Million-dollar endorsement deals or a sneaker named the Air Roo aren't in the cards for kangaroos. Since these animals can't play in any Final Four championships, why do they hop?

How do reindeer find enough food in the tundra?

These reindeer won't find any candy canes or fruitcake buried in the frozen tundra. So how do these animals find enough food to sustain them through such extreme weather?

Do elephants never forget?

Elephants have amazing memories and are known to hold grudges for years against those who have wronged them. So, be careful who you're calling Dumbo.