Hobbies And Interests
Senses
Of its five senses, the beaver's sense of smell reigns supreme. Since the beaver reserves its activity to the darker hours, it relies on a keen nose to determine whether a food source is edible, recognize others of its kind and detect suspicious characters and shady situations. The beaver's hearing, not quite comparable to its olfactory sense, identifies sounds, such as hissing and high-pitched utterances, made by other beavers. Beaver sight is negligible, corresponding to that of prey species that have eyes sitting on the sides of the face instead of at the front. This arrangement provides less acute vision over a wider visual field.
Teeth
Like most rodents, a beaver's teeth never stop growing. Beavers must keep their incisors sharp to be able to slice through tree bark; sharpening occurs while the beaver chews through tough substances and as the top and bottom teeth slide across one another. A wide gap exists between the incisors and the rest of the teeth to permit pieces of skin to curtain off the incisors from the mouth. This structural adaptation allows the beaver to chomp on wood comfortably without inhaling water or risk broken wood slivers injuring the mouth and throat.
Tail
A beaver does not use its tail to transport mud or slap it into place, a common misconception propagated by cartoons and human imagination. The tail provides a means of communication when slapped against the surface of the water, creating a sound that alerts other beavers of danger. Beavers use their tails to guide their movements under water and boost their swimming ability by acting as paddles. While sitting on its haunches gnawing at trees, the beaver uses the appendage to balance itself. The flattened, hairless tail disperses heat to keep the animal cool during energetic activities and prevents starvation because it contains reserve stores of fat to be used during food shortages.
Swimming Adaptations
Born into a life of swimming, a beaver can stay under water up to 15 minutes, equating to a travel distance of half a mile. As the beaver submerges, its heart rate slows to save oxygen for the brain. When it surfaces, the beaver can exchange 75 percent of the spent air in its expansive lungs for fresh air; in comparison, humans can only trade in 15 to 20 percent. Beavers possess membranes that stop up the openings to their ears and noses while a translucent layer slips over their eyes to prevent access to water. The beaver curls its front paws against its body, using its tail and massive hind legs -- equipped with webbing -- to propel itself through the water.
Beaver Constructions
Known for its building ability, the beaver constructs three types of structures. Dams measure between tens of feet to over a thousand feet in length, rising about 10 feet from their bases. Plant parts sit atop foundations composed of mud and rocks; a mixture of mud, rocks and vegetation binds the whole structure together. Beavers become very sensitive to the condition of their dams, racing to mend any crack or leak.
Lodges, which the beavers build about six feet high, provide housing for beaver families. Several entrances open into the lodge beneath the water, and the living area lies in a dry region at the very top. Sticks and mud compose the walls and keep out predators and the elements.
Beavers build castor mounds -- which feature lumps of mud, sticks and leaves sprinkled with beaver scent -- to announce their territories. The beaver produces the scent, called castor, in glands on its rump.