Beth Scott, age 9, of Hurdland, Mo., for her question:
Does a beaver wear out his teeth?
Animals do not have the tooth trouble we have. They do not feast on the sweets and the soft drinks that cause our cavities. Instead, they bite, chew, chomp and gnaw tough foods to keep their teeth healthy. If mr. Beaver gave up gnawing, he soon would have very serious tooth troubles.
The beaver is a busy woodsman. He works with another beaver to cut down trees. In l5 minutes this pair of beavers can cut through a woody trunk that is 4 inches thick. Then the lumber is cut into logs and used to make clever dams and canals that keep the streams and ponds from draining dry. Twigs and branches are cut to build a wonderful beaver house under the water. More twigs are cut and saved for winter food.
When all this work is done it is time to start repairs. A busy beaver's chores are never done. A human woodsman uses axes and saws to chop down trees and cut his lumber. But the beaver has no ax or saw. A chisel is a sturdy tool with sloping sides and a straight, sharp cutting edge. Mr. Beaver does his woodwork with chisels, and he has four splendid chisels of his very own.
They are his long front teeth two in his top jaw and two in his bottom jaw. He uses them to gnaw all through the day and sometimes through part of the night. Once in a while he stops his woodworking chores to gnaw a meal of bark from a willow or aspen tree. And all this gnawing wears away the tips of his teeth. But strange to say, his special gnawing teeth grow no shorter. Chances are, they will last him all his life, which may be almost 20 years.
Your teeth grow to the proper size and then stop growing. But the beaver's gnawing teeth never stop growing. They grow longer from the roots as the tips wear down at the other end. The enamel coating is harder on the front of each tooth. As he gnaws, the back of the tooth wears down faster than the front. This makes a sloping edges and each gnawing tooth is shaped like a sturdy chisel. And mr. Beaver must keep on gnawing or those chisel teeth will grow too long for comfort.
The beaver is called a rodents which means a gnawing animal. Squirrels and woodchucks are also rodents and so are muskrats and gophers. Hamsters and porcupines are rodents and so are rats and mice,. There are about 2,000 different rodents in the world. All of them have gnawing teeth. These rodent teeth wear down at the tips but they never get any shorter because they never stop growing.