Otters are playful aquatic creatures that belong to the Mustelidae family, which also 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, webbed feet, and a thick fur coat that helps them stay warm in the water. They are known for their playful behavior, such as sliding down muddy banks and playing with rocks and sticks.