River otters are well suited to life in the water. They have streamlined bodies, webbed feet and long, tapered tails. Their ears and nose close when they go underwater. Dense, oily fur and heavy layers of body fat insulate them in the water. The have an acute sense of smell, and prominent facial whiskers, which are extremely sensitive to touch. Otters are dark brown with pale brown or gray bellies. The muzzle and throat are silvery. Males and females look alike, although males are larger
They are graceful, powerful swimmers and can remain submerged 3–4 minutes. On land, they travel with a
loping gait. On snow or ice, they alternate loping with sliding.
Similar species: The American mink is smaller (total length up to 27 inches), almost entirely brown (with a white chin
and irregular white spots on the throat, chest, and belly), with a tail that is not obviously thick at the base, not flat on
the bottom, and not obviously tapering from the body toward the tip). The only other otter in North America is the endangered sea
otter, which occurs in seawater only along the Pacific Coast and not in Missouri.
Size: Total length: 35½ to 53 inches; weight: 10–30 pounds.