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From Wikipedia, the free encyclopedia

Shrews[1]
Fossil range: Middle Eocene–Recent
Southern Short-tailed Shrew
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Soricomorpha
Family: Soricidae
G. Fischer, 1814
Subfamilies

Crocidurinae
Myosoricinae
Soricinae

A shrew or shrew mouse (family Soricidae) is a small mammal classified in the order Soricomorpha. True shrews are also not to be confused with West Indies shrews, treeshrews, otter shrews, or elephant shrews, which belong to different families or orders.

Although its external appearance is generally that of a long-nosed mouse, a shrew is not a rodent, as mice are, and not closely related to rodents. Like mice, shrews have 5 toes. However, shrews have sharp, spike-like teeth, not the familiar gnawing front incisor teeth of rodents.

Shrews are distributed almost worldwide: of the major tropical and temperate land masses, only New Guinea, Australia, and New Zealand do not have native shrews at all; in South America, shrews are relatively recent immigrants and are present only in the northern Andes. In terms of species diversity, the shrew family is the fourth most successful of the mammal families, being rivalled only by the muroid rodent families Muridae and Cricetidae and the bat family Vespertilionidae.

Contents

Characteristics

All shrews are comparatively small, most no more than mouse size. The largest species is the House Shrew (Suncus murinus) of tropical Asia which is about 15 cm long and weighs around 100 grams[citation needed]; several are very small, notably the Etruscan Shrew (Suncus etruscus) which at about 3.5 cm and 2 grams is the smallest living terrestrial mammal.

In general, shrews are terrestrial creatures that forage for seeds, insects, nuts, worms and a variety of other foods in leaf litter and dense vegetation, but some specialise in climbing trees, living underground, in the subniveal layer or even hunting in water. They have small eyes, and generally poor vision, but have excellent senses of hearing and smell.[2] They are very active animals, with voracious appetites and unusually high metabolic rates. Shrews must eat 80-90 % of their own body weight in food daily.

They do not hibernate, but are capable of entering torpor. In winter, many species undergo morphological changes that drastically reduce the animal's body weight. Shrews can lose between 30% and 50% of their body weight, shrinking the size of bones, skull and internal organs.[3]

Whereas rodents have gnawing incisors that grow throughout life, the teeth of shrews wear down throughout life, a problem made more extreme by the fact that they lose their milk teeth before birth, and therefore have only one set of teeth throughout their lifetime. Apart from the first pair of incisors, which are long and sharp, and the chewing molars at the back of the mouth, the teeth of shrews are small and peg-like, and may be reduced in number. The dental formula of shrews is:Upper: 3.1.1-3.3, lower: 1-2.0-1.1.3

Shrews are fiercely territorial, driving off rivals, and only coming together to mate. Many species dig burrows for caching food and hiding from predators, although this is not universal.[2].

Female shrews can have up to ten litters a year, and the animals only stop breeding in the winter in temperate zones, and breed all year round in the tropics. Shrews have a gestation period of 17–32 days. The female often becomes pregnant within a day or so of giving birth, and lactates during her pregnancy, weaning one litter as the next is born[2]. Shrews live for between 12 and 30 months.[4]

Shrews are unusual among mammals in a number of respects. Unlike most mammals, some species of shrew are venomous. Shrew venom is not conducted into the wound by fangs, but grooves in the teeth. The venom contains various compounds and the contents of the venom glands of the American short-tailed shrew are sufficient to kill 200 mice by intravenous injection. One chemical extracted from shrew venom may be potentially useful in the treatment of blood pressure while another compound may be useful in the treatment of neuromuscular conditions and migraines.[5]Also, along with the bats and toothed whales, some species of shrew use echolocation. Unlike most other mammals, shrews lack a zygomatic bone (also called the jugal), and therefore have an incomplete zygomatic arch.

Shrews hold nearly 10% of their mass in their brain, which is the highest brain to body mass ratio of all animals (including humans).[6]

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Echolocation

The Northern Short-tailed Shrew is known to echolocate

The only terrestrial mammals known to echolocate are two genera (Sorex and Blarina) of shrews and the tenrecs of Madagascar. These include the Vagrant Shrew (Sorex vagrans), the Common or Eurasian Shrew (Sorex araneus), and the Northern Short-tailed Shrew (Blarina brevicauda). The shrews emit series of ultrasonic squeaks.[7][8] The nature of shrew sounds unlike those of bats are low amplitude, broadband, multi-harmonic and frequency modulated.[8] They contain no ‘echolocation clicks’ with reverberations and would seem to be used for simple, close range spatial orientation. In contrast to bats, shrews use echolocation only to investigate their habitat rather than additionally to pinpoint food.[8]

Except for large and thus strongly reflecting objects, such as a big stone or tree trunk, they will probably not be able to disentangle echo scenes, but rather derive information on habitat type from the overall call reverberations. This might be comparable to human hearing whether one calls into a beech forest or into a reverberant wine cellar.[8]

Classification

There are 376 species of shrew in 26 genera, which are grouped into three living subfamilies: Crocidurinae (white-toothed shrews), Myosoricinae (African white-toothed shrews) and Soricinae (red-toothed shrews). In addition, the family contains the extinct subfamilies Limnoecinae, Crocidosoricinae, Allosoricinae and Heterosoricinae (although Heterosoricinae is also commonly considered a separate family).

References

  1. ^ Hutterer, Rainer (November 16, 2005). Don E. Wilson and DeeAnn M. Reeder. ed. Mammal Species of the World (3rd ed.). Johns Hopkins University Press. pp. 223–300. ISBN 978-0-8018-8221-0. http://www.bucknell.edu/msw3. 
  2. ^ a b c Barnard, Christopher J. (1984). Macdonald, D.. ed. The Encyclopedia of Mammals. New York: Facts on File. pp. 758–763. ISBN 0-87196-871-1. 
  3. ^ http://books.google.com/books?id=z-XJ-UzdwIgC&pg=PA44&lpg=PA44&dq=seasonal+weight+changes+overwintering
  4. ^ Macdonald (Ed), Professor David W. (2006). The Encyclopedia of Mammals. Oxford University Press. ISBN 0-19-920608-2. 
  5. ^ Piper, Ross (2007), Extraordinary Animals: An Encyclopedia of Curious and Unusual Animals, Greenwood Press.
  6. ^ Brains of White Matter
  7. ^ Thomas E. Tomasi, "Echolocation by the Short-Tailed Shrew Blarina brevicauda", Journal of Mammalogy, Vol. 60, No. 4 (Nov., 1979), pp. 751–759.
  8. ^ a b c d Siemers BM, Schauermann G, Turni H, von Merten S. (2009). Why do shrews twitter? Communication or simple echo-based orientation. Biol Lett. 5(5):593-6. doi:10.1098/rsbl.2009.0378 PMID 19535367
  • Buchler, E.R. 1973. The use of echolocation by the wandering shrew, Sorex vagrans Baird. Diss. Abstr. Int. B. Sci. Eng. 33(7): 3380-3381.
  • Buchler, E.R. 1976. Experimental demonstration of echolocation by the wandering shrew (Sorex vagrans). Anim. Behav. 24(4): 858-873.
  • Busnel, R.-G. (Ed.). 1963. Acoustic Behaviour of Animals. Amsterdam: Elsevier Publishing Company.
  • Forsman, K.A., Malmquist, M.G. 1988. Evidence for echolocation in the common shrew, Sorex araneus. J. Zool., Lond. 216 (4): 655-663. .
  • Gould, E. 1962. Evidence for echolocation in shrews.Ph.D. Thesis, Tulane University.
  • Gould, E., Negus, N., Novick, A. 1964. Evidence for echolocation in shrews. J. Exp. Zool. 156: 19-38.
  • Hutterer, R. 1976. Deskriptive und vergleichende Verhaltensstudien an der Zwergspitzmaus, Sorex minutus L., und der Waldspitzmaus, Sorex araneus L. (Soricidae - Insectivora - Mammalia). Unpublished Ph.D. Thesis, Univ. Wien.
  • Hutterer, R., Vogel., P. 1977. Abwehrlaute afrikanischer Spitzmäuse der Gattung Crocidura Wagler, 1832 und ihre systematische Bedeutung. Bonn. Zool. Beitr. 28(3/4): 218-227.
  • Hutterer, R., Vogel, P., Frey, H., Genoud, M. 1979. Vocalization of the shrews Suncus etruscus and Crocidura russula during normothermia and torpor. Acta Theriol. 24(21): 267-271.
  • Irwin, D.V., Baxter, R.M. 1980. Evidence against the use of echolocation by Crocidura f. flavescens (Soricidae). Säugetierk. Mitt. 28(4): 323.
  • Kahmann, H., Ostermann, K. 1951. Wahrnehmen und Hervorbringen hoher Töne bei kleinen Säugetieren. Experientia 7(7): 268-269.
  • Köhler, D., Wallschläger, D. 1987. Über die Lautäußerungen der Wasserspitzmaus, Neomys fodiens (Insectivora: Soricidae). Zool. Jb. Physiol. 91: 89-99.
  • Sales, G., Pye, D. 1974. Ultrasonic communication by animals. London.
  • Tomasi, T.E. 1979. Echolocation by the short-tailed shrew Blarina brevicauda. J. Mammalogy 60(4): 751-759.

External links


1911 encyclopedia

Up to date as of January 14, 2010

From LoveToKnow 1911

SHREW,' a term applied to the species of the family Soricidae of the mammalian order insectivora, but in the British Isles to the common and lesser shrews (Sorex araneus and S. minimus). The common shrew, or, properly, shrew-mouse, which in England is by far the commoner of the two, is a small animal 1 This word, whence comes the participial adjective "shrewd," astute, originally meant malicious, and, as applied to a woman, still means a vexatious scold. From their supposed venomous character it was applied to the Soricidae.

about the size of a mouse, which it somewhat resembles in the shape of its body, tail and feet. But here the resemblance ends, for, unlike the mouse, it possesses a long and slender muzzle, with prominent nostrils, which project far beyond the lower lip; the small eyes are almost concealed by the fur; the ears are wide, short and provided internally with a pair of deep folds, capable when laid forwards of closing the entrance; the tail, which is slightly shorter than the body, is quadrangular in section and clothed more or less densely with moderately long hairs, terminating in a short tuft, but in old individuals almost naked; the feet are five-toed, the toes terminating in slender, pointed claws. The dentition is very peculiar and characteristic: there are in all thirty-two teeth, tipped with deep crimson; of which twelve belong to the lower jaw; of the remaining twenty ten occupy each side of the upper jaw, and of these the first three are incisors. The first incisor is large, with a long anterior canine-like cusp and a small posterior one; then follow two small single-cusped teeth; which are succeeded by three similar progressively smaller teeth, the first being a canine and the other two premolars; the next, a premolar, is large and multicuspid, and this is followed by three molars, of which the third is small with a triangular crown. In the lower jaw there are anteriorly three teeth corresponding to the seven anterior teeth above, of which the first is almost horizontal in direction, with its upper surface marked by three notches, which receive the points of the three upper front teeth; then follow two small The Common Shrew (Sorex araneus). teeth and three molars. The body is clothed with closely set fur, soft and dense, varying in colour from light reddish to dark brown above; the under surface of both body and tail being greyish; the basal four-fifths of all the hairs above and beneath are dark bluish grey. On each side of the body, about one-third of the distance between the elbow and the knee, is a gland covered by two rows of coarse inbent hairs, which secretes a fluid with an unpleasant cheesy odour, and which is protective, rendering the creature secure against the attacks of predaceous animals.

The lesser or pigmy shrew (S. minutus) is not so abundant in England and Scotland, but common in Ireland, where the other species is unknown. It appears at first sight to be a diminutive variant of that species, which it closely resembles in external form, but the third upper incisor is shorter, or not longer than the next following tooth, whereas in S. araneus it is longer, and the length of the forearm and foot is less in the former species than in the latter.

Both these shrews live in the neighbourhood of woods, making their nests under the roots of trees or in any slight depression, occasionally even in the midst of open fields, inhabiting the disused burrows of field-mice. Owing to their small size, dark colour, rapid movements and nocturnal habits, they easily escape observation. They seek their food, which consists of insects, grubs, worms and slugs, under dead leaves, fallen trees and in grassy places. They are pugnacious, and if two or more are confined together in a limited space they invariably fight fiercely, the fallen becoming the food of the victorious. They are also exceedingly voracious, and soon die if deprived of food; and it is probably to insufficiency of food in the early dry autumnal season that the mortality among them at that time is due. The breeding-season extends from the end of April to the beginning of August, and five to seven, more rarely ten, young may be found in the nests; they are naked, blind and Abbey in 1083. His first wife was Mabel, daughter of the toothless at birth, but soon run about snapping at everything seigneur of Belesme and Alencon; hence his son Robert, who, within reach. after the death of another son, Hugh, succeeded to the earldoms The alpine shrew (S. alpinus), restricted to the alpine region of ' of Shrewsbury and Arundel, was generally known as Robert de Central Europe, is slightly longer than the common shrew and Belesme (q.v.), one of the most celebrated of the feudal nobles differs in its longer tail, which exceeds the length of the head and in the time of Henry I. Robert having been deprived of all his body, in the colour of the fur, which is dark on both surfaces, English estates and honours in 1102, the earldom of Shrewsbury and in the large size of the upper antepenultimate premolar. was next conferred in 1442 on John, 5th baron Talbot, whose The water-shrew (Neomys fodiens), the third species inhabiting descendants have borne the title to the present day. (See England, differs from the common shrew in being larger with a Talbot; and Shrewsbury, Ist Earl Of, below.) shorter and broader muzzle, smaller eyes and larger feet adapted SHREWSBURY, [[Charles (disambiguation)|CHARLES ]], DUKE OF (1660-1718), for swimming - the sides of the feet and toes being provided with only son by his second wife of Francis Talbot, 11th earl of comb-like fringes of stiff hairs. The tail is longer than the body, Shrewsbury, was born on the 24th of July 1660. His mother and has a fringe of moderately long regularly ranged hairs, which was a daughter of Robert Brudenell, 2nd earl of Cardigan, and extend along the middle of the under surface from the end of the the notorious mistress of the 2nd duke of Buckingham, by whom basal third to the extremity. The fur is long and dense, varying his father was killed in a duel in 1668. Charles was a godson of in colour in different individuals; the prevailing shades are King Charles II., after whom he was named, and he was brought dark, almost black, brown above, beneath more or less bright up as a Roman Catholic, but in 1679 under the influence of ashy tinged with yellowish; but occasionally we find individuals Tillotson he became a member of the Church of England. On his with the under surface dark-coloured. In the number and shape father's death in 1668 he succeeded to the. earldom of Shrewsbury; of the teeth the water-shrew differs from the common shrew: he received an appointment in the household of Charles II., and there is a premolar less on each side above; the bases of the teeth served in the army under James II. But in 1687 he was in are more prolonged posteriorly; and their cusps are less stained correspondence with the Prince of Orange, and he was one of the brown, so that in old individuals they often appear white. This seven signatories of the letter of invitation to William in the species is aquatic in habits, swimming and diving with agility. following year. He contributed towards defraying the expenses It frequents rivers and lakes, making burrows in the banks, of the projected invasion, and having crossed to Holland to join from which when disturbed it escapes into the water. Its food William, he landed with him in England in November 1688. consists of water insects and their larvae, small crustaceans Shrewsbury became a secretary of state in the first administraand probably the fry of small fishes. It is generally distributed tion of William and Mary, but he resigned office in 1690 when the throughout England, is less common in Scotland and not tories gained the upper hand in parliament. While in opposition recorded in Ireland. he brought forward the triennial bill, to which the king refused The geographical range of the common shrew is wide, extending assent. In 1694 he again became secretary of state; but there is eastwards through Europe and Asia to Amurland. The lesser some evidence that as early as 1690, when he resigned, he had shrew extends through Europe and Asia to Sakhalin Island; gone over to the Jacobites and was in correspondence with and specimens of the water-shrew have been brought from James at St Germains, though it has been stated on the other different parts of Europe and Asia as far east as the Altai. In hand that these relations were entered upon with William's Siberia the common shrew is abundant in the snow-clad wastes connivance for reasons of policy. However this may be, William about the Olenek river within ' the arctic circle. Other species appears to have had no suspicion of Shrewsbury's loyalty, of red-toothed shrews are restricted chiefly to North America, for on the 30th of April 1694 the latter was created marquess of where they are found in greater variety than in the Old World, Alton and duke of ,Shrewsbury, and he acted as one of the though Neomys is not represented. Its place is taken by Sorex regents during the king's absence from England in the two palustris east of the Rocky Mountains, and S. hydrodromus in following years. In 1696 definite accusations of treason were Unalaska Island, which, like the water-shrew, have fringes of brought against him by Sir John Fenwick, which William himself hair on the feet, but the unfringed tail and dentition of the communicated to Shrewsbury; and about this time the secretary common shrew. Of the American forms S. bendiri is the largest. of state took but a small part in public business, again professing Other red-toothed shrews belonging to the genus Blarina, dishis anxiety to resign. His plea of ill-health was a genuine one, tinguished from Sorex by the dentition and the shortness of the and in 1700 the king reluctantly consented to his retirement into tail, are common in North America. All red-toothed shrews private life.

(except the aquatic forms) closely resemble one another in habits, For the next seven years Shrewsbury lived abroad, chiefly at. but the short-tailed North American shrew supplements its Rome, whence in 1701 he wrote a celebrated letter to Lord insectivorous fare by feeding on beech nuts. In destroying Somers expressing his abhorrence of public life and declaring numbers of slugs, insects and larvae, shrews aid the farmer that if he had a son he "would sooner bind him to a cobbler and merit protection. Although their odour renders them than a courtier, and a hangman than a statesman." On the safe from rapacious animals, they are destroyed in numbers accession of Queen Anne the whig leaders made an ineffectual by owls. (G. E. D.) attempt to persuade Shrewsbury to return to office. When,


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Simple English

A shrew is a small mammal that resembles a mouse, at first sight. Unlike mice, shrews are not rodents, they feed on Insects mostly, and are in the order Insectivora. Despite the fact, that the name sounds similar, treeshrews are also completely different, and are in the order Scandentia.

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