Castor canadensis | |
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A male North American beaver | |
Scientific classification | |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Rodentia |
Family: | Castoridae |
Genus: | Castor |
Species: | C. canadensis |
Binomial name | |
Castor canadensis Kuhl, 1820 |
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Subspecies | |
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Distribution of the North American beaver (dark green – native, light green – introduced) |
The North American beaver (Castor canadensis) is one of two extant beaver species. It is native to North America and introduced to Patagonia in South America and some European countries (e.g. Norway). In the United States and Canada, the species is often referred to simply as "beaver", though this causes some confusion because another distantly related rodent, Aplodontia rufa, is often called the "mountain beaver". Other vernacular names, including American beaver and Canadian beaver, distinguish this species from the other extant beaver species, Castor fiber, which is native to Eurasia. The North American beaver is an official animal symbol of Canada.
This beaver is the largest rodent in North America and competes with its Eurasian counterpart, the European beaver, for being the second-largest in the world, both following the South American capybara. Adults usually weigh from 11 to 32 kg (24 to 71 lb), with 20 kg (44 lb) being typical. The head-and-body length is 74–90 cm (29–35 in), with the tail adding a further 20–35 cm (7.9–13.8 in). Very old individuals can exceptionally exceed normal sizes, weighing more than 40 kg (88 lb) or even as much as 50 kg (110 lb).
Like the capybara, the beaver is semiaquatic. The beaver has many traits suited to this lifestyle. It has a large, flat, paddle-shaped tail and large, webbed hind feet. The unwebbed front paws are smaller, with claws. The eyes are covered by a nictitating membrane which allows the beaver to see under water. The nostrils and ears are sealed while submerged. A thick layer of fat under its skin insulates the beaver from its coldwater environment.