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Giant River Otter: That's One Big Otter! printer.gif

Giant River Otters are huge aquatic mammals that live in the Amazon watershed, as well as many other rivers in the South American rainforest. They are dark brown in color, with sleek, velvety fur and large, webbed feet. Giant River Otters can grow to 6 and a half feet in length and weigh 75 pounds.

Giant River Otters spend most of their lives in the water, hunting during the day and sleeping at night. Their diet consists almost exclusively of fish, which they hunt using their incredibly sensitive whiskers, called "vibrissae." These whiskers can sense changes in water pressure and movement, which helps the otter to locate its prey. Otters can hold their breath for several minutes as they search for their lunch beneath the water. One adult otter can eat 9 pounds of fish a day!

Giant River Otters live in family groups called "holts" of up to 10 otters that hunt, sleep, and play together. They are the only species of otter that live in communal groups. Each group has its own range, or territory, which does not overlap with any other otter groups. A range consists of at least one lake and several creeks or parts of a large river. Otters mark their territories by spraying a musky smell at the boundaries, so that other otter groups will not invade.

Grooming is very important to river otters. They must keep their coats clean so that they stay water-resistant. When an otter leaves the water it will roll around to dry itself. Sometimes the otter ends up with soil caked on its fur. Then, it will scratch with its hind legs and claws. The otter then scratches its head and around its eyes, muzzle and ears. Its webbed feet are used to remove food from between the teeth (no easy "feet"). Social bonding occurs when Giant Otters groom each other. Mated pairs do this often. When done, they will lay side-by-side with a paw over each other nose-to-tail and their heads resting on each other's backs.

Giant River Otters are at the top of the rainforest food chain, and are not threatened by any natural predators. They used to be quite common throughout South America, but are now one of the most endangered species in the rainforest. Otters are primarily endangered because of habitat destruction and water pollution. Many efforts are underway to protect Giant River Otters. The are now a protected species, and it is illegal to hunt them, though some illegal hunting still occurs.

For more information, check out these websites.
Wilderness Classroom's Rainforest Library

Otter Net, a site created by 4th grade students working to protect the Giant River Otter

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