The river otter is a large, semi-aquatic member of the weasel (or mustelid) family. They are long-bodied, short-haired furbearers with a powerful, thick tail used for swimming. They bound, jump, slide and play-fight to keep in shape for hunting. Their fur is a dark brown with lighter colored throats and bellies. Males can be up to 25 pounds, whereas females tend to be 19 pounds or less. Otters have webbed toes and valves in their nose and ears that they can close when underwater, both adaptations to help them swim. They have one litter per year with an average of two to three young per litter. They eat primarily fish, though they also may eat crayfish, frogs, muskrats and reptiles.