The giant otter (Pteronura brasiliensis) is the largest mustelid in the world, although it is not as heavy as the sea otter. This semi-aquatic mammal inhabits the tropical river basins of South America. It lives in groups of about six, each communicating with chirping sounds. Generally, the group comprises an adult pair and their offspring of various liters. Each group controls its own stretch of stream, preferring those areas with plenty of cover.

The giant otter swims at high speed by waving its tail and body up and down, using its webbed feet to steer. On land it is far less agile, and is often seen sitting grooming itself. Giant otters are diurnal - only active during the day. The catch prey in their mouths and hold it in their forepaws to eat it on the shore. During the dry season, the otter groups are restricted to small areas of water, but when the rains come to flood the forest, the otters can roam over larger areas. Little is known about the mating habits of giant otters, other than that the young stay with their parents for a few years before reaching adulthood.

ARKive photos and videos of the giant otter