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Stoppers for ears and nose?
The beavers have valves in their ears which close to keep the water out when they are swimming. They also have valves in their nostrils which form a watertight seal, so that they do not get water up their noses when they dive or swim under water. And beavers have one more—they have a flap of skin behind their front teeth so that they can cut with their front teeth and keep their throat closed. Useful? Surely is when they need to cut down a tree underwater. Or carry a stick in their front teeth while swimming underwater. (How did Mr. Beaver figure out how to accomplish this?)
Goggles to protect their eyes?
The beavers have something better than goggles. Their Designer has equipped them with a transparent eyelid that closes when they enter the water. This special eyelid protects their eyes from nasty debris floating in the water, so that even with their eyes “closed” they can keep swimming and see where they are headed.
Ability to steer themselves through the water?
Beavers are clearly built to travel through water. Their broad, flat tails function as rudders, helping the beaver to maneuver large logs and to swim in the direction they intend.
Designed to build
What does one need to be able to build in a woody, wet environment? Our marvelous Designer has equipped Mr. and Mrs. Beaver with a set of tools that go with them wherever they go.
Sharp cutting tools
A beaver is said to be able to cut down a willow tree 5 inches in diameter in a minute. (Have you heard the phrase, “working like a beaver”?) How do they do it? Our great Designer has provided the tools: two self-sharpening, chisel-like incisor teeth on each jaw at the very front of the beaver's mouth. It just happens that the upper teeth overlap the lower incisors(!), creating friction that keeps the teeth at chisel sharpness.
Don't teeth wear down from continually gnawing, chopping, and chewing tree trunks, branches and bark? Beaver teeth come with a lifetime warranty—their front incisors never stop growing as long as the beaver lives. (Did the beaver plan or design this feat? Wouldn't we like to grow ourselves a new set of teeth as we age?!)
Superstrong cutting tools
The beaver's front teeth are also superstrong. While our teeth are covered with calcium, the exterior surface of the beaver's teeth is covered with iron. The beaver's teeth are built for durability.
Engineering skills
Often the first evidence of beavers is the sudden appearance of a dam across a river or creek. Quickly the area behind the dam becomes a muddy pond—just what the beavers want. The main reason: their chief predators don't like to walk through muddy, wet areas.
The beaver's engineering skills are amazing. If the water is slow moving, the beaver will build a dam straight across the water. If the water in the stream is fast flowing, they will build the dam on a curve, so that it can withstand the force of water more effectively. Beavers have even been known to slow down the speed of the river upstream by piling in branches to reduce the water's speed so that it won't wash away their home.
In the shallow water above the dam, Mr. and Mrs. Beaver construct their lodge, or sometimes in the bank adjacent to the river or pond. Using small intertangled twigs, sticks, branches, and other debris, they create a large mounded structure. This lodge has one central above-water chamber, usually eight to twelve feet high and three feet wide. All the entrances are submerged—an ingenious design to keep unwelcome predators (like eagles and wolves) out of the beaver lodge.
In the fall of the year, the beavers plaster the outside of their lodge mound with mud, making a concrete-like layer that no predator can easily break through. This also makes the lodge waterproof—except for the peak, which is left open to allow air and light to enter.
In addition to building very cozy lodges, the beavers also dredge out underwater channels—grooves in the bottom of the lake, likely connecting their favorite eating places.
Who taught the beaver these highly specialized techniques of construction?
The beavers' dam, lodge, and pile of stored food are shown here in a cutaway view.
Credit: ABC's of Nature, ed. Richard L. Sheffel
Dinner and snacks
Beavers are vegetarians, feeding primarily on the inner bark, leaves, and shoots of woody plants. They eat the bark, buds, stems, and twigs of trees such as aspen, maple, willow, birch, black elder, and black cherry. They really like soft plants, too, and grasses, mushrooms, ferns, and the roots of water plants are favorite snacks.
When fall comes, the beavers start stockpiling winter food supplies. They sink large amounts of branches into the mud close to the entrances of their homes, so that even during a severe winter they have plenty of food just outside the door.
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