Nutria, or Coypu, a large South American rodent. It has been introduced into the United States, where it inhabits marshy areas in Louisiana, Oregon, Washington, and along the Atlantic coast. With its small eyes and ears, short legs, and long, scaly tail, the nutria resembles a rat. It has webbed hind feet and is a strong swimmer. The nutria is yellowish-brown or reddish-brown above and pale yellow below. It has a whitish muzzle. The fur is composed of two layers—a layer of coarse guard hairs and an inner layer of soft hair. The nutria is about 38 inches (97 cm) long, including a 15-inch (38-cm) tail and weighs 20 pounds (9 kg). It lives in a burrow during the day and feeds at night on plants. After a gestation period of 130 days, the female gives birth to a litter of four to six young. In Louisiana, nutrias are trapped for their pelts, which are used for coats and hats.

The nutria is Myocastor coypus of the family Myocastoridae.