Beavers are part of the Castor genus under the Castoridae family (which contains only one extant genus, the aforementioned one).
Five species can be found under this genus, two of which are extant – C. canadensis and C. fiber, the North American and the Eurasian beaver, respectively. C. californicus, C. praefiber, and C. neglectus are now extinct.
This animal is known for its dam-building abilities, making the best out of the rocks, vegetation, and branches it can find around its habitat.
As semi-aquatic rodents, beavers are essential for the ecosystem; the dams they build generate wetlands ecosystems home to many species.
The Castor genus is widely spread worldwide (in its native areas).
Estimates suggest that Europe shelters as many as one million beavers, whereas the North American beaver population consists of about 10-15 million specimens.
Now that we’ve gotten the basics out of the way, let’s talk more about the different beaver types that still exist today.
2. North American Beaver
The North American beaver is native to North America but has been introduced to Europe and South America.
Due to its popularity and population density, this species is known and commonly referred to as a beaver.
The cute little animal is so popular that New York and Oregon named it their official state mammal.
Even though they are widely spread throughout North America, beavers were not initially inhabiting this region.
The oldest fossil records have been found in Germany and date back 10 to 12 million years. Scientists believe the semi-aquatic rodents used the Bering Strait to migrate to North America.
Castor canadensis is one of the largest rodents in the world, but the largest in North America.
This species is the world’s third-largest rodent; the Eurasian beaver is the second, and the South American capybara is the largest.
They usually weigh about 44 lbs and are roughly 29-35 inches long (head and body).
The tail of the North American beaver is about 7.9-13.8 inches long.
While beavers are known to build dams, their expertise also extends to lodges.
These resemble islands, as they’re located within bodies of water.
The lodges have two parts – the underwater section as an entry point and the living space above the water’s surface.
Beavers access their lodge via several underwater access points.
1. Eurasian beaver
The Eurasian beaver was on the brink of extinction but was eventually saved sometime after the 20th century.
Today, the species can be found in Mongolia, China, Scandinavia, the United Kingdom, Spain, and Central Europe.
It is not, however, as widespread as it used to be.
For example, countries that used to shelter Castor fiber, such as Moldova, Portugal, and Turkey, no longer have specimens in the wild.
Castor fiber was hunted intensively for its fur and castoreum.
The latter is a yellowish exudate extractor for mature beavers, specifically from their castor sacs.
This substance was once used as a food additive, but today it is common in the industries of perfume and tincture making.
There are several differences between the Eurasian and the North American beaver in terms of body, head, and fur.
The most important one, however, is that Castor fiber has 48 chromosomes, whereas Castor canadensis has 40.
This fact alone makes the two species incompatible for breeding.
Despite their incredible building skills, beavers are equipped with rather poor eyesight.
Luckily, a couple of other characteristics provide them with the tenacity needed to build dams and lodges.
First, beavers can see underwater thanks to their transparent eyelids.
On top of that, studies show that their senses of touch, smell, and hearing are also enhanced.
Sources
- https://en.wikipedia.org/wiki/North_American_beaver
- https://en.wikipedia.org/wiki/Beaver
- https://en.wikipedia.org/wiki/Eurasian_beaver
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