Otters are playful animals that belong to the Mustelidae family, which includes weasels, badgers, and wolverines. They are semi-aquatic mammals that live in rivers, lakes, and coastal areas. They have long, slim bodies with short legs and webbed feet, which help them swim quickly. They also have thick fur to keep them warm in cold water. Otters are known for their playful behavior, such as sliding down muddy banks, playing with rocks, and chasing each other.