Physical Adaptations

Beaver by pond in Grand Teton National Park, photo public domain (owned by National Park Service)
Image credit: Grand Teton National Park (National Park Service)
  • Beavers are the second largest extant rodent in the world (behind the capybara), standing 60-90cm tall and weighing about 11-31 kg.
  • Beavers are semiaquatic, and are accordingly equipped with features that enable them to spend long stretches of time in the water, such as:
    • webbed feet,
    • large lungs,
    • clear eyelids,
    • and closable orifices (ears and nostrils).
  • Beavers have powerful teeth; their dental formula is 1-0-1-3/1-0-1-3 (indicating large incisors and an herbivorous diet). These incisors are coated in a strong enamel and never stop growing; continuous gnawing ensures they never become excessive or cumbersome to the animal, but sharpness is nevertheless sustained due to the techniques employed in felling these trees.
  • Beavers’ thermoregulating features include:
    • thick, dense fur
    • production of a natural, water repellent oil called castoreum (which also functions as a territory marking feature via the pungent odor it produces)
    • ample fat storage, even in the tail.
  • The beaver’s tail:
    • assists in swimming and functions as a balancing agent when the beaver is gnawing down and modulating trees;
    • produces a loud, slapping noise when struck against the water, functioning doubly as a warning signal, and a way to startle and intimidate predators;
    • and stores fat to maintain a comfortable body temperature.
  • Beavers’ ability to digest bark and wood stems from the existence of a bacteria in the digestive tracts of beavers that breaks down the cellulose in these tree parts that is indigestible to the majority of creatures. Its diet is largely comprised of birch, tubers, and deciduous tree bark.