A mammal is a warm-blooded animal. They can live in the water or on the land, and in a variety of environments. They can exist in warm weather or cold because their warm blood and fur let them survive both hot and cold temperatures.
One type of water-dwelling mammal is a dolphin. Many people think dolphins are fish, but they are not. They are mammals because they breathe air, give birth to live young instead of laying eggs, have warm blood, and have hair. You can’t see the hair on a dolphin normally since it only appears for a short while after the dolphin is born, but they, like all mammals, do have hair for at least a portion of their life.
Another mammal that you might be more familiar with is a house cat. This is a better fit to our usual conception of a mammal. We can see how cats are covered in soft fur, and you may have even witnessed a cat give birth to live baby kittens. Cats are also warm-blooded, which means that their blood stays at approximately the same temperature regardless of the environment.
There are many other kinds of mammals in the world too. One kind of mammal that lives in very hot weather is a desert jackrabbit. This animal keeps its temperature regulated by running its warm blood up through its big ears, which act like a radiator to keep the blood at body temperature. Rabbits have live babies, lots of them, and are covered with a light layer of fur that keeps the sun off their skin.
Conversely, there are mammals that live in very cold weather, like walruses. Rather than using fur to regulate their temperature, walruses use a thick layer of fat, called blubber, to keep warm. Even the babies are born with this thick layer of fat on them. They have hair in the form of whiskers on their faces which almost look like mustaches!
Humans are mammals too! It’s obvious if you think about it. We have live babies – everyone has seen a baby. We have hair on our heads, and some people have hair other places on their bodies too. We are warm-blooded and we obviously breathe air, not water. We fit all the requirements to be a mammal.
There are as many different kinds of mammals in the world as there are environments for them to live in. Evolution means that animals change to fit their environment, so there are many different kinds of animals designed to suit different environments. There are mammals that live in the oceans, mammals that live in the Arctic and Antarctic, mammals that live in the desert, and mammals that live in every type of climate in between.
The five mammals named in this article are just a sampling of the many thousands of different mammal species that exist in the world. If you want to know more about mammals, try your local natural sciences museum or local library. They should have lots of interesting facts about mammals.