page_title: Muskrat
section_title: Description
hierarchical_section_title: Muskrat / Description
caption_attribution_description: Deutsch: Bisamratte Ondatra zibethica, Schädel, Coll. Museum Wiesbaden English: muskrat , skull, Coll. Museum Wiesbaden
context_page_description: The muskrat, the only species in genus Ondatra and tribe ondatrini, is a medium-sized semiaquatic rodent native to North America and an introduced species in parts of Europe, Asia, and South America. The muskrat is found in wetlands over a wide range of climates and habitats. It has important effects on the ecology of wetlands, and is a resource of food and fur for humans.
  The muskrat is the largest species in the subfamily Arvicolinae, which includes 142 other species of rodents, mostly voles and lemmings. Muskrats are referred to as "rats" in a general sense because they are medium-sized rodents with an adaptable lifestyle and an omnivorous diet. They are not, however, members of the genus Rattus.
context_section_description: An adult muskrat is about 40–70 cm (16–28 in) long, half of that is the tail, and weighs from 0.6–2 kg (1.3–4.4 lb). That is about four times the weight of the brown rat (Rattus norvegicus), though an adult muskrat is only slightly longer, and are almost certainly the largest and heaviest members of the diverse family Cricetidae, which includes all voles, lemmings, and most mice native to the Americas. Muskrats are much smaller than beavers (Castor canadensis), with which they often share their habitat.
  Muskrats are covered with short, thick fur, which is medium to dark brown or black in color, with the belly a bit lighter (countershaded); as the age increases, it turns a partly gray in color. The fur has two layers, which provides protection from  cold water. They have long tails covered with scales rather than hair. To aid them in swimming, their tails are slightly flattened vertically, a shape that is unique to them. When they walk on land, their tails drag on the ground, which makes their tracks easy to recognize.
  Muskrats spend most of their time in the water and are well suited for their semiaquatic life. They can swim under water for 12 to 17 minutes. Their bodies, like those of seals and whales, are less sensitive to the buildup of carbon dioxide than those of most other mammals. They can close off their ears to keep water out. Their hind feet are semiwebbed, although in swimming, their tails are their main means of propulsion.
caption: A muskrat skull
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