The coypu or nutria (Myocastor coypus) is a large, crepuscular, semi aquatic rodent native to South America. It is also present in Europe, Asia, and North America. In most regions, the coypu is considered a pest. In Eastern Europe and Central Asia, it is still valued for its fur. It is the only species in the genus Myocastor. It is an herbivore that has been introduced from South America to every continent except Australia and Antarctica. Africa is the only continent where the introduced nutria never became fully established. The animal is adapted to subtropical to mild temperate climates.
The coypu somewhat resembles a very large rat in appearance. Adults are typically 10-20 lbs (5 to 9 kg) in weight, and 15 to 24 inches (40 to 60 cm) long. It has a 12 to 18 inch (30 to 45 cm) tail. Their bright orange-yellow incisor teeth can identify them. The nipples of female nutria are on her back. This allows their young to feed while the female is in the water.
Nutria can also be mistaken for another widely dispersed semi-aquatic rodent that occupies the same wetland habitats, the muskrat. However, the muskrat is smaller, more tolerant of cold climates.
There are several subspecies of coypu in their native range that includes parts of Argentina, Bolivia, Brazil, Chile, Paraguay and Uruguay. While as many as six different subspecies have been named.