Adult muskrats weigh 0.6–2 kg (1+1⁄4–4+1⁄2 lb), with a body length (excluding the tail) of 20–35 cm (8–14 in).

Their long tails, covered with scales rather than hair, are laterally compressed and generate a small amount of thrust, with their webbed hind feet being the main means of propulsion,[3] and the unique tail mainly important in directional stability.

Muskrats are referred to as "rats" in a general sense because they are medium-sized rodents with an adaptable lifestyle and an omnivorous diet.

[12] An adult muskrat is about 40–70 cm (16–28 in) long, half of that length being the tail, and weighs 0.6–2 kg (1+1⁄4–4+1⁄2 lb).

[13] That is about four times the weight of the brown rat (Rattus norvegicus), though an adult muskrat is only slightly longer.

It is almost certainly[clarification needed] the most prominent and heaviest member of the diverse family Cricetidae, which includes all voles, lemmings, and most mice native to the Americas, and hamsters in Eurasia.

[6][7] Muskrats are covered with short, thick fur, which is medium to dark brown or black, with the belly a bit lighter (countershaded); as the animal ages, it turns partly gray.

[17] Muskrats are found in most of Canada, the United States, and a small part of northern Mexico.

[22] According to an article in Hakai Magazine, from April 2024, the muskrat populations have declined by at least one-half in 34 US states.

Rhode Island's muskrat populations are estimated to be roughly 15 percent of what they were several decades ago.

[25] This implies that this species cannot be imported, bred, transported, commercialized, or intentionally released into the environment in the whole of the European Union.

In many European countries, muskrats have become problematic, damaging flood control systems, crops, and river banks with burrowing activities.

Several European countries have implemented control measures and eradication programs to manage muskrat populations and mitigate their impact.

Muskrats also build feeding platforms constructed in the water from cut pieces of vegetation supported by a branch structure.

Muskrats provide an important food resource for many other animals, including mink, red and gray foxes, cougars, coyotes, wolves, boreal lynxe, Canada lynx bobcats, raccoons, brown and black bears, wolverines, eagles, hawks, large owls, snakes, alligators, and bull sharks.

Otters, snapping turtles, heron,s bullfrogs, large fish such as pike and largemouth bass, and predatory land reptiles such as monitor lizards prey on baby muskrats.

Caribou, moose, and elk sometimes feed on the vegetation which makes up muskrat push-ups during the winter when other food is scarce for them.

Muskrat populations appear to go through a regular pattern of rise and dramatic decline spread over a six- to 10-year period.

Some other rodents, including famously the muskrat's close relatives, such as the lemmings, go through the same type of population changes.

Some predict winter snowfall levels by observing the size and timing of muskrat lodge construction.

[32] In several Native American creation myths, the muskrat dives to the bottom of the primordial sea to bring up the mud from which the earth is created after other animals have failed in the task.

[34] In the southeastern portion of Michigan, a longstanding dispensation allows Catholics to consume muskrat as their Friday penance, on Ash Wednesday, and on Lenten Fridays (when the eating of flesh, except for fish, is prohibited); this tradition dates back to at least the early 19th century.

The preparation involved the removal of the musk glands and the gutting and cleaning of the carcass before the meat was parboiled for four hours with onion and garlic and finally fried.

[7] Royal Canadian Mounted Police winter hats are made from muskrat fur.