Mammals are a very diverse class of animals, ranging in size from the pygmy shrew, which weighs about 1/8 of an ounce, to the great blue whale, which can weigh up to 160 tons (that’s 320,000 pounds).
Most of us learned, at some time in our school days, that mammals have four features that distinguish them from other types of animals:
They have hair (or fur, if you prefer)
Babies are born live
Mothers suckle the young
There are a few minor exceptions to these rules. For example, the platypus and the echidna are classified as mammals, but they lay eggs rather than give birth to live babies. And some mammals, notably several species of whales, are hairless. However, all mammals have hair or fur at some point in their development, though they may lose it, or most of it, by the time they become adults.
There are nearly 5,000 known species of mammals. Some of them are found only in small geographical areas, but many species cover a very broad range. And, although quite a few mammals are small, such as the pygmy shrew mentioned above, the largest animals on earth are all mammals. Elephants, hippopotami, rhinoceroses, moose, bison, and several species of whales are all larger than any animals in any of the other classes.
To find out more about some of the zoo’s mammals, select a species in the navigation bar at the right of this page.