9/21/2023 0 Comments Beaver tail![]() ![]() They originated in North America in the late Eocene and colonized Eurasia via the Bering Land Bridge in the early Oligocene, coinciding with the Grande Coupure, a time of significant changes in animal species around 33 million years ago ( myr). Modern beavers are the only extant members of the family Castoridae. īeavers belong to the rodent suborder Castorimorpha, along with Heteromyidae ( kangaroo rats and kangaroo mice), and the gophers. Phylogeny of extant and extinct relatives of modern beavers based on genetics and morphology. EvolutionĮurasian beaver ( Castor fiber) Castorimorpha ![]() canadensis, and nine have been classified for C. Twenty-five subspecies have been classified for C. The difference in chromosome numbers prevents them from interbreeding. (The Eurasian has 48 chromosomes, while the North American has 40.) Prior to that, many considered them the same species. However, they were not confirmed to be separate species until the 1970s, when chromosomal evidence became available. Ĭarl Linnaeus coined the genus Castor in 1758 he also coined the specific (species) epithet fiber. The Eurasian beaver is slightly longer and has a more lengthened skull, triangular nasal cavities (as opposed to the square ones of the North American species), a lighter fur color, and a narrower tail. There are two extant species: the North American beaver ( Castor canadensis) and the Eurasian beaver ( C. The name beaver is the source for several names of places in Europe including Beverley, Bièvres, Biberbach, Biebrich, Bibra, Bibern, Bibrka, Bobr, Bjurbäcker, Bjurfors, Bober, Bóbrka and Bjurlund. The genus name Castor has its origin in the Greek kastor and translates as ' beaver '. The ultimate origin of the word is an Indo-European root for ' brown '. The English word beaver comes from the Old English word beofor or befor and is connected to the German word biber and the Dutch word bever. In human culture, the beaver symbolizes industriousness, especially in connection with construction it is the national animal of Canada. ![]() Their populations have since rebounded, and they are listed as species of least concern by the IUCN Red List of mammals. Before protections began in the 19th and early 20th centuries, overhunting had nearly exterminated both species. Castoreum has been used in medicine, perfume, and food flavoring beaver pelts have been a major driver of the fur trade. Historically, beavers have been hunted for their fur, meat, and castoreum. Beavers can also recognize their kin by their anal gland secretions and are more likely to tolerate them as neighbors. Beavers hold territories and mark them using scent mounds made of mud, debris, and castoreum-a liquid substance excreted through the beaver's urethra-based castor sacs. After their first year, the young help their parents repair dams and lodges older siblings may also help raise newly-born offspring. Adult males and females live in monogamous pairs with their offspring. Their infrastructure creates wetlands used by many other species, and because of their effect on other organisms in the ecosystem, beavers are considered a keystone species. Dams restrict water flow, and lodges serve as shelters. They are herbivorous, consuming tree bark, aquatic plants, grasses and sedges.īeavers build dams and lodges using tree branches, vegetation, rocks and mud they chew down trees for building material. Beavers can be found in a number of freshwater habitats, such as rivers, streams, lakes and ponds. The two species differ in skull and tail shape and fur color. They have stout bodies with large heads, long chisel-like incisors, brown or gray fur, hand-like front feet, webbed back feet, and tails that are flat and scaly. Beavers are the second-largest living rodents, after capybaras, weighing up to 50 kg (110 lb). There are two existing species: the North American beaver ( Castor canadensis) and the Eurasian beaver ( C. fiber populations in Mongolia and northwestern China, as well as reintroduced populations in the United Kingdom) īeavers (genus Castor) are large, semiaquatic rodents of the Northern Hemisphere. canadensis populations in Europe and Patagonia, but missing C. Range of the living beavers as of 2016 (including introduced C. ![]()
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