We've all seen those toys that, with a few tweaks, transform from cars into robots and vice versa. The American Beaver is a bit like one of those toys when it dives underwater, changing instantly from a lumbering rodent to a sleek aquatic creature.
Aside from its webbed hind feet and rudderlike tail, which make swimming easier, the beaver has special valves that keep water out of its ears and nose. These valves close as soon as the beaver enters the water. A flap of skin seals its mouth, too, though the flap leaves the front teeth exposed so the beaver can carry branches. And then there are the beaver's built-in goggles -- clear membranes that slide over its eyes and protect them from floating debris.
Click here to learn more about the American Beaver.