Otters are aquatic mammals that live in rivers, streams, and other bodies of water. They are members of the Mustelidae family, which includes weasels, badgers, and wolverines. Otters have long, slim bodies with short legs and webbed feet, and they are well adapted for swimming. They have thick fur to keep them warm in cold water, and their long tails help them steer and propel themselves through the water. Otters are playful and social animals, and they often hunt and play together in groups.