Although both mammals and desired for their fur, there are unique differences between a river otter and sea otter. Each is playful, curious and depends on water for it's food source.

The sea otter is a mammal of the weasel family well adapted for sea life. It can be found off the central Californian coast, western Alaska and the Bering Sea. It is known for its highly desirable fur.

Its hind feet are broad and webbed and function as oars. Its teeth are flat and broad enabling it to crack the shells of shellfish. It will float on its back with food on its stomach using a flat stone to crack open the food.

It measures 5 feet in length with a 12 inch tail and weighs 30 to 100 pounds. Its feet are short, square and hairy with a hairy tail. It whiskers are long and sensitive enabling it to find food in dark waters. Usually feeding in the morning and before sunset, it hunts in short dives. It can hold its breath for up to five minutes. It feeds on sea urchins, abalone, mussels, clams and large snails. Its fur is dark brown with a silver tint. It protects itself from cold water by air trapped between its long hair fibers. If the hair is soiled, the insulating feature is lost.

It is an independent, curious and playful animal. It will coo or grunt when content and whistle or scream when threatened. Its predators are orcas, sea lions and bald eagles. It also will be attacked by sharks, but the sharks rarely eat it. It has been hunted for over 170 years for its fur and has recently been threatened by extinction. Now protected by an international treaty, its population is on the rise but it is still classified as endangered. It does well in captivity and is featured in many zoos and aquariums.

There are several types of river otters: North American, Southern River, Neotropical, Eurasian and Japanese. It is a mammal that is adapted to aquatic life and known for its playfulness and prized fur.

It can be found in inland streams, estuaries and sea coves in most parts of the word. It measures 5 feet including a tail of 2 feet. It is brown with the lips, chin and throat red-gray. It has a long cylindrical body, flattened head, broad snout, small eyes and ears, thick lips and long whiskers. The front legs are short and the hind legs and feet are large with webbed toes and hairy pads.

It feeds on fish, birds, frogs, crayfish and water rats. It will catch its food in the water and bring it on land. Closing its nostrils and ears while swimming, it can remain underwater for long periods of time.

It digs it own den on river banks but will retreat to the water when frightened. It is not affected by frigid water and will float for periods of time in the freezing water. It is a playful animal and likes to slide down snowy river banks.

Its predators are alligators, crocodiles, killer whales, bobcats, mountain lions, coyotes, gray wolves, red foxes, black bears and domestic dogs. Humans also are predators since they hunt it for its fur. It is also susceptible to pollution, parasites and diseases such as distemper, rabies and urinary infection.