(Myocastor coypus), also nutria, a mammal of the order Rodentia. The coypu resembles a large rat. The body length is usually up to 60 cm (sometimes up to 85 cm), and the tail length is up to 45 cm. The animal may reach a weight of 12 kg. It has a blunt muzzle with long whiskers. The lips press tightly against the incisors, enabling the animal to chew underwater. The foot has four webbed toes, but the fifth toe is free. The mammary glands and nipples (four or five pairs) of the female are arranged high on the sides of the body to enable the young to nurse while in the water. The pelage consists of coarse guard hairs and a thick brownish underfur.
The natural area of the coypu is restricted to the southern half of South America. The animal has been acclimatized in France, Great Britain, Yugoslavia, the United States, and the USSR (Transcaucasia and southern Tadzhikistan). The coypu inhabits marshy riverbanks, reed and cattail lakes, and muddy alder and sedge marshes. It swims and dives well. The animal feeds on the young sprouts and roots of reeds, cattails, burweeds, water lilies, and water chestnuts, as well as on some mollusks. It leads a seminomadic life, remaining in one place when there is food and shelter. The coypu rests and bears its offspring in open nests built on swampy hillocks or in dense thickets; sometimes it nests in burrows dug in the riverbanks. It reproduces year-round. The gestation period lasts 127 to 133 days. A litter contains four to six young (rarely as few as one or as many as 12), which at birth have a coat of downy fur, can see, and have incisors that have broken through. The animals reach sexual maturity at the age of four or five months. The coypu has a life-span of eight to ten years.
Coypu fur, which is known as nutria, is highly valued. The coarse guard hairs are removed during processing. The animals are trapped alive to preserve young animals and pregnant females. They are also bred on fur farms, where they are usually kept in cages having a little house, a long run, and a pool of water. The animals are fed plant matter according to specific rations. Coypus are slaughtered for their skins and meat at the age of eight or nine months. On some farms the animals are kept in semiconfinement, in large fenced-in areas with shelter and bodies of water, and are given supplementary feeding. On other farms the animals are unconfined. There are coypu farms in Transcaucasia, Middle Asia, Moldavia, Byelorussia, the RSFSR, and the Ukraine. Fur farms in the USSR and in foreign countries (the United States, Canada, Finland, Argentina, Poland) raise both standard brown coypus and colored varieties (white, black, pink, beige, gold).
N. K. VERESHCHAGIN and N. P. KHRONOPULO