Trading companies shipped beaver fur throughout the world to be made into coats or hats. Hunters killed so many beavers that hardly any were left in North America by the late 1800's. The U.S. and Canadian governments passed laws to protect the animals. Today, beavers, like many other wild animals, can be trapped only at certain times of the year. Unlike most other kinds of mammals, beavers keep growing throughout their lives.
Most beavers look larger than they really are because of their humped backs and thick fur.
No one knows why these huge beavers disappeared. The beaver has a broad head, with large and powerful jaws. Its rounded ears and small nostrils can close tightly to keep water out. A beaver has three eyelids on each eye. Two outer eyelids, one upper and one lower, fit around the eye.