What Is a Mammal?

Answer:

Adaptability is surely the hallmark of the mammals, a group so successful that its members range from pole to pole and can be found in the air and in the water as well as on land and in the trees.

Mammals range in size from the 100-foot blue whale, the largest animal ever to grace the earth, to the pygmy shrew, which measures less than 4 inches long.

All mammals are warm-blooded, breathe air, and have hair and a backbone, and their females produce milk. Their brains are bigger and more complex than any other animal’s.