Muskrat, semi-aquatic rodent found in North America, eastern Scandinavia, and north, central, and western Europe. Its body, about 30 cm (12 in) long, is covered with brown to blackish outer hairs and a dense underfur. The tail, almost as long as the body and nearly hairless, is scaly and flattened laterally; it is used as a rudder in swimming. The hind feet are partly webbed. Musk (hence the animal’s name) is secreted by glands near the genitals. A muskrat’s house is a pile of vegetation set in a slow-moving river or a freshwater or salt-water marsh, lake, or pond, or the animal may construct a burrow in a river bank. Its diet is mostly water plants, but it also eats freshwater mussels, other invertebrates, and even fish. One female can bear several litters, of 1 to 11 young, in one year, especially in warmer regions; the gestation period is about one month. Muskrat fur is commercially important; the animal was introduced into Europe for this purpose but has also become a pest there. It was introduced into the British Isles around 1930 but was exterminated by 1939.

Scientific classification: The muskrat belongs to the family Muridae, order Rodentia. It is classified as Ondatra zibethicus.