lemming

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lemming,

name for several species of mouselike rodentsrodent,
member of the mammalian order Rodentia, characterized by front teeth adapted for gnawing and cheek teeth adapted for chewing. The Rodentia is by far the largest mammalian order; nearly half of all mammal species are rodents.
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 related to the volesvole,
name for a large number of mouselike rodents, related to the lemmings. Most range in length from 3 1-2 to 7 in. (9–18 cm) and have rounded bodies with gray or brown coats, blunt muzzles, small ears concealed in the long fur, and short tails.
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. All live in arctic or northern regions, inhabiting tundra or open meadows. They frequently nest in underground burrows, particularly in winter, although they do not hibernate. They feed on grasses, mosses, and roots, and probably on insects. All are about 5 in. (13 cm) long, with stout bodies, thick fluffy fur, small ears, very short tails, and long claws. The brown to black Norway lemming, Lemmus lemmus, of Scandinavia, is the best known, because of its spectacular periodic swarming. Two or three times per decade, this species undergoes a population explosion of such proportions that the lemmings set out in all directions in search of food. They cross bodies of water by swimming and occasionally some reach and enter the ocean, where they drown. This behavior has given rise to folklore about lemmings committing mass suicide, but the population crashes mainly because lemming predators increase in number in response. Other species of the genus Lemmus are found in the northern portions of Eurasia and North America and sometimes exhibit similar swarmings. The snow, or collard, lemmings, Dicrostonyx, found in the arctic regions of Asia and North America, are pure white in winter and brown, gray, or reddish in summer; this color change is unique among rodents. They are also distinguished by the growth in winter of an extremely long two-pronged claw on the third and fourth finger of each forefoot; these claws may function in shoveling snow. Bog lemmings, members of the genus Synaptus, are found in marshy places in North America as far south as the N United States. The wood lemming, Myopus schisticolor, is found in N Eurasia. The steppe lemmings, members of the genus Lagarus, of S Russia and Mongolia, are properly classified as voles; the North American species of this genus, Lagarus curtatus, is found in the W United States and is known as the sagebrush vole. Lemmings are classified in the phylum ChordataChordata
, phylum of animals having a notochord, or dorsal stiffening rod, as the chief internal skeletal support at some stage of their development. Most chordates are vertebrates (animals with backbones), but the phylum also includes some small marine invertebrate animals.
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, subphylum Vertebrata, class Mammalia, order Rodentia, family Cricetidae. See mousemouse,
name applied to numerous species of small rodents, often having soft gray or brown fur, long hairless tails, and large ears. The chief distinction between these animals and the variety of rodents called rats is in size: mice are usually smaller.
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Lemming

 

any one rodent of the tribe Lemmini of the subfamily Microtinae. The body measures approximately 15 cm long, and the tail approximately 2 cm long. The coloration is a uniform gray-brown or mixed. In the winter, the fur of some lemmings turns very light or white and the claws of the forelimbs grow longer. There are four genera, comprising 20 species. The genera are Myopus (wood lemmings), Synaptomys (bog lemmings), Lemmus (true lemmings), and Diacrostonyx (collared, or hoofed, lemmings).

Lemmings inhabit the forests, mountain tundras, and plains of Eurasia and North America. There are three (or four) species in the USSR. They are distributed from the Kola Peninsula and Central Russia to the Chukchi Peninsula and the Far East. The most common species are the arctic lemming (D. torquatus); the Ob’, or Siberian, lemming (L. obensis, or L. sibiricus); and the Norway lemming (L. lemmus). The animals are active year-round. In the tundra in some years they reproduce in vast numbers, achieving a high abundance, and undertake distant migrations during which they even cross rivers. Lemmings feed on sedges, subshrubs, and mosses. They are the principal food of the arctic fox. Lemmings transmit the causative agents of several viral diseases.

REFERENCES

Mlekopitaiushchie fauny SSSR, part 1. Moscow, 1963.
Marsden, W. The Lemming Year. London, 1964.

lemming

[′lem·iŋ]
(vertebrate zoology)
The common name for the small burrowing rodents composing the subfamily Microtinae.

lemming

any of various volelike rodents of the genus Lemmus and related genera, of northern and arctic regions of Europe, Asia, and North America: family Cricetidae. The Scandinavian variety, Lemmus lemmus, migrates periodically when its population reaches a peak