Otters are mostly nocturnal, and very powerful and graceful swimmers. They also appear to enjoy sliding down steep slopes, such as the banks of rivers or slopes covered by ice and snow. They tend to do this in groups. They also play with rocks and mussel shells in the water, tossing and diving for them. Unlike other weasels, otters are very social and tend to live in family groups.
Otters primarily feed on aquatic animals such as fish, crayfish, frogs, and other organisms.
Otter fur is one of the most beatiful and durable of furs, and thus are often used by humans. Although this and low water quality has led to their decline in some parts, they are now making a rebound through management efforts.