water rat


water rat
1. any of various rodents having aquatic habits.
2. the muskrat, Ondatra zibethica.
3. (in Australia and New Guinea) any of the aquatic rats of the subfamily Hydromyinae, esp. of the genus Hydromys.
4. Slang. a vagrant or thief who frequents a waterfront.
[1545-55]

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rodent
Introduction

      any of 18 species of amphibious carnivorous rodents (rodent). They exhibit many adaptations associated with hunting in water for food and burrowing along streams, rivers, and lakes. The eyes are small, the nostrils can be closed to keep water out, and the external portion of the ears is either small and furry or absent. Highly sensitive whiskers are abundant on the fleshy blunt muzzle. The long thick fur is gray or brown, dense and woolly, and water-repellent. The tail is usually densely haired, and in some species the hairs form a keel along the underside. The rats' long, wide hindfeet are fringed with stiff hairs and have bald soles with conspicuous webbing between the digits.

Natural history
      One of the smallest species is a South American fish-eating rat (Neusticomys monticolus) with a body length of 10 to 12 cm (4 to nearly 5 inches) and a tail of about the same length. The golden-bellied water rat (Hydromys chrysogaster) of Australia and New Guinea is the largest, with a body 20 to 39 cm long and a slightly shorter tail (20 to 33 cm). Living by freshwater lakes, estuaries, and rivers and in coastal mangrove swamps, it is tolerant of heavily polluted aquatic habitats. Its prey includes a variety of invertebrates, such as large aquatic insects, snails, mussels, crabs, and crayfish. Vertebrates taken include fish, frogs, turtles, young and adult birds, bird eggs, bats, and mice. The other 17 species typically require clear, unpolluted freshwater streams. The animals' diet consists primarily of a variety of aquatic insects, but they also eat crustaceans (crustacean) and occasionally small fish. All water rats locate prey underwater by touch with their sensitive whiskers. Most are adept swimmers and aggressive underwater predators, but the African water rat (Colomys goslingi) wades through shallow water or sits at the water's edge with its muzzle submerged; it is reported to eat some terrestrial insects and snails. Although most water rats are nocturnal, some species are active during the day.

      Water rats of the genus Hydromys live in the mountains and coastal lowlands of Australia, New Guinea, and some nearby islands. The earless water rat (Crossomys moncktoni) inhabits mountains of eastern New Guinea, where it prefers cold, fast-flowing streams bordered by tropical forest (tropical rainforest) or grass. The African water rat is also found along streams bordered by tropical forest. The 11 water rats of the Western Hemisphere are found from southern Mexico into South America, where they typically live along streams in rainforests from sea level upward to mountain pastures above the tree line.

Classification
      Although all water rats are members of the mouse family ( Muridae), they belong to two different subfamilies. The genera Hydromys, Crossomys, and Colomys are classified in the subfamily Murinae (Old World mice and rats), whereas the American species are members of the subfamily Sigmodontinae (New World mice and rats). No water rats exist in the Asian tropics or at nontropical latitudes. Instead, carnivorous amphibious shrews (shrew) and moles occupy the water rat's ecological niche. The European water voles (vole) (genus Arvicola) are sometimes called water rats.

Genus Hydromys (water rat)
 5 species.Genus Neusticomys (neotropical, or fish-eating, rats)
 5 species.Genus Ichthyomys (crab-eating water rats)
 3 species.Genus Chibchanomys (Chibchan water mice)
 2 species.Genus Crossomys (earless water rat)
 1 species.Genus Colomys (African water rat)
 1 species.Genus Anotomys (Ecuador fish-eating rat)
 1 species.

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Universalium. 2010.

Look at other dictionaries:

  • Water rat — Wa ter rat 1. (Zo[ o]l.) (a) The water vole. See under {Vole}. (b) The muskrat. (c) The beaver rat. See under {Beaver}. [1913 Webster] 2. A thief on the water; a pirate. [1913 Webster] …   The Collaborative International Dictionary of English

  • Water Rat — may refer to:*Water Vole, an European rodent *Rakali, an Australian rodent *Round Tailed Muskrat, sometimes called the Florida water rat *Rat (zodiac) …   Wikipedia

  • water rat — ► NOUN 1) a large semiaquatic rat like rodent. 2) Brit. a water vole …   English terms dictionary

  • water rat — n an animal like a big mouse that can swim and lives near water …   Dictionary of contemporary English

  • water rat — n. 1. any of various rodents that live on the banks of streams and ponds ☆ 2. MUSKRAT …   English World dictionary

  • water rat — noun 1. common large Eurasian vole • Syn: ↑water vole, ↑Arvicola amphibius • Hypernyms: ↑vole, ↑field mouse • Member Holonyms: ↑Arvicola, ↑genus Arvicola …   Useful english dictionary

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  • water rat — vandeninis pelėnas statusas T sritis zoologija | vardynas taksono rangas rūšis atitikmenys: lot. Arvicola terrestris angl. European water vole; ground vole; vole rat; water rat; water vole vok. Erdratte; große Erdmaus; große europäische Wühlmaus; …   Žinduolių pavadinimų žodynas

  • water rat — vandeninis žiurkėnukas statusas T sritis zoologija | vardynas taksono rangas rūšis atitikmenys: lot. Scapteromys tumidus angl. South American water rat; water rat rus. водяной хомячок ryšiai: platesnis terminas – vandeniniai žiurkėnukai …   Žinduolių pavadinimų žodynas

  • water rat — Muskrat Musk rat , n. 1. (Zo[ o]l.) A North American aquatic fur bearing rodent ({Ondatra zibethica} formerly {Fiber zibethicus}). It resembles a rat in color and having a long scaly tail, but the tail is compressed, the hind feet are webbed, and …   The Collaborative International Dictionary of English


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