Beaver 4

A Beaver's tail:
It serves as a place to store fat.
It works as a rudder and also helps the hind feet push the animal forward when swimming.
It is a portable chair. They will either lean back against it when standing on their back legs or they will fold it around beneath them when sitting and grooming themselves.
When they sense danger, they will slap the surface of the water with it to warn other beavers.