Beavers can be very hospitable hosts and sometimes open their lodges to families of muskrats. It may be that when cohabiting, they help one another keep an eye out for predators.

Giardiasis, popularly known as beaver fever, is a parasitic disease caused by Giardia duodenalis. Humans may contract Giardiasis from beavers when they drink water inhabited by them. Symptoms may include diarrhea, abdominal pain, and weight loss.

There are only two species of beavers--the North American beaver (Castor canadensis) and the Eurasian beaver (Castor fiber).

Nictitating membranes or transparent "third eyelids" act as goggles, allowing them to see underwater with their eyes closed.

Beavers don't just build homes from trees, they also eat them. North American beavers prefer aspen trees while Eurasian beavers prefer willow. Both tree species grow quickly and have soft wood for chewing and peeling.

The Catholic Church traditionally considered the beaver to be part beast and part fish. The Church allowed the scaly, fish-like tail to be eaten on meatless Fridays during Lent. Beaver tails were a delicacy in medieval Europe and were described as having the flavor of a nicely dressed eel.

Beavers have a lifespan of 10-15 years in the wild, and can live up to 20 years in captivity.