The beaver (Castor Canadensis) is North America’s largest rodent. Adult beavers typically weigh 45 to 60 pounds, but have been known to grow to 100 pounds. Native Americans greatly respected beavers, calling them “Little People”. Beavers and humans are alike in their ability to greatly alter their habitats to suit their own needs.
To obtain food and building materials, beavers are well known for their ability to topple large trees using nothing but their specially adapted incisor teeth and powerful lower jaw muscles. Beaver teeth never stop growing, so they do not become too worn despite years of chewing hardwoods. Their four front teeth (incisors) are self-sharpening due to hard orange enamel on the front of the tooth and a softer dentin on the back. Therefore as beavers chew wood the softer backside of the tooth wears faster, creating a chisel-like cutting surface.
The beaver’s most distinctive feature is their large flat tail, which serves as a rudder when swimming, a prop when sitting or standing upright, and a storehouse of fat for the winter. Beavers will also slap their tail on the surface of the water as a danger warning to other beavers or sometimes in play. They do not use it to carry mud.
Beavers are aquatic mammals with large webbed hind feet ideal for swimming, and hand-like front paws that allow them to manipulate objects with great dexterity. They have excellent senses of hearing and smell, and rely on these senses more than their less developed sense of eyesight. When swimming underwater a protective transparent membrane will cover their eyes, and flaps close to keep water out of their nostrils and ears. In addition, behind their incisors they have inner lips that allow them to carry sticks in their mouths while swimming without getting a mouthful of water.
Beaver fur consists of short fine hairs for warmth and longer hairs for waterproofing. They need to groom their fur daily to keep it waterproof, and frequently groom each other’s fur. They have castor glands on the under side of their abdomen from which they can excrete an oily substance (castor) that they use in the grooming process, and to mark their territory.