Muskrat

Article By:

Whitaker, John O., Jr. Department of Biology, Center for North American Bat Research and Conservation, Indiana State University, Terre Haute, Indiana.

Last reviewed:January 2020

DOI:https://doi.org/10.1036/1097-8542.440900

A large aquatic rodent, Ondatra zibethicus, in the family Cricetidae and in the vole subfamily (Arvicolinae). It is known as the common muskrat (see illustration). It is dark reddish-brown, with a long, essentially naked, scaly, laterally compressed tail. The pelage is dense and shiny, and consists of a thick coat of underfur over which lies a covering of long, glossy guard hairs. The ears and eyes are relatively small for an animal of this size. The hindfeet bear webbed toes and are much larger than the front feet. The anterior faces of the upper incisors are yellowish-orange. The body length ranges about 14–16 in. (400–640 mm), with the tail about 7–12 in. (180–300 mm). The average weights of muskrats from Indiana are 1215 grams (2.67 lb) in adult males and 1247 grams (2.74 lb) in adult females, which is near average. The dental formula is I 1/1 C 0/0 Pm 0/0 M 3/3 = 16. The muskrat received its name because of its inguinal glands, which produce a musky odor. See also: Dentition; Mammalia; Rodentia; Scent gland

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