A beaver can fell a tree as thick as your leg. It uses its big front teeth, which are bright orange and never stop growing - the more they chew, the sharper they get. Once a tree falls, the beaver chops it into smaller logs and drags them to a river or stream.
With the logs, beavers build dams across streams. A dam blocks the flowing water and creates a calm pond. In the middle of the pond, they then build a 'lodge' - a wooden island house with an underwater front door. The whole family lives inside, safe from predators that don't swim.
A beaver's tail is one of nature's best tools. It is wide and flat, like a leather paddle. They use it for steering when swimming, balancing when standing up, and slapping it loudly on the water to warn the family that danger is near. The slap can be heard half a kilometre away.
Beavers help whole ecosystems. The ponds they create become homes for fish, frogs, ducks and dragonflies. Many birds nest in the dead trees that stand in the flooded water. Scientists call beavers a 'keystone species' - take them away, and the whole habitat changes.