Archeological remains have been uncovered from 200 BC to the mid-1400s. Otters are expert swimmers and divers, swimming at an average speed of seven miles per hour and staying underwater for up to 2 minutes. Unlike muskrats or beavers, the otter barely makes a ripple when swimming or splash when diving. Their specially built ears and nose have a valve-like skin that closes and keeps the otter watertight underwater. The otters nose is diamond shaped, with two nostrils at the bottom of the nose.
Otters communicate with their noses, mainly by smelling marked territories.
When they do talk, it is with chirps, chuckles, grunts, whistles and screams. River otters are most active from early evening through early morning. They are active all year, even in the cold Alaskan winters. Otters' webbed and clawed feet are good for running and swimming. River otters can run up to 15-l8 mph.