[How It Works] Dense underfur acts as insulation and keeps the skin dry with the help of castor oil. They produce an oil called castor oil that they rub through their fur with a split toenail called a grooming claw, making their fur water proof. (It has to be regularly reapplied by the beaver.) [Advantage] The waterproof fur keeps the skin dry and warm while the beaver is immersed in cold water. [Ability/feature] 
Waterproof coat
E a t i n g u n d e r w a t e r
O x y g e n c o n s e r v a t i o n
C u t t i n g d o w n t r e e s
W a t e r p r o o f c o a t
U n d e r w a t e r v i s i o n
F l a t , w i d e t a i l
V a l v e s i n e a r s a n d n o s e
W e b b e d h i n d f e e t