Shrews

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Shrews
Marsh shrew (Neomys anomalus)

Marsh shrew ( Neomys anomalus )

Systematics
without rank: Synapsids (Synapsida)
Class : Mammals (mammalia)
Subclass : Higher mammals (Eutheria)
Superordinate : Laurasiatheria
Order : Insect eater (Eulipotyphla)
Family : Shrews
Scientific name
Soricidae
Fisherman , 1814

The shrews (Soricidae) are a species-rich family of mammals . Despite the external similarities with the mice , they do not belong to the rodents , but to the order of the insectivores (Eulipotyphla). Worldwide, more than 350 species are distinguished, of which around 10 also live in Central Europe.

description

General

Shrews have a mouse-like appearance, but the snout is elongated and pointed. The limbs are short, the feet each end in five toes and are unspecialized. In some aquatic species, however, the toes have a bristle border that looks like webbing . Shrews are comparatively small mammals, their head body lengths from 3 to 18, mostly between 6 and 10 centimeters. The tail length is variable, in particular some underground burrowing species have a conspicuous short tail. The weight usually varies between 3 and 18 grams, in exceptional cases up to 65 grams. The Etruscan shrew ( Suncus etruscus ) is one of the smallest mammals with a body length of 3.5 to 5 centimeters and a weight of almost 1.8 grams . Many species have scent glands that they use to mark their territory.

The fur is usually dense and short, its coloration varies from yellowish brown through various gray and brown tones to black. The underside is usually lighter, with some species an abrupt transition between the dark top and the light underside can be observed. A shrew's heart beats between 800 and 1000 times per minute.

Head and teeth

Garden shrew ( Crocidura suaveolens )

The skull is elongated and flat, the long, trunk-like nose flexible. The eyes are small and sometimes hidden in the fur. There is an auricle, but it is usually small and often barely or not at all from the fur.

As with all insectivores, the teeth are characterized by pointed cusps and sharp enamel ridges. Shrews have 26 to 32 teeth and thus fewer than the other insectivores. The foremost incisors protrude forward, followed by a row of single-pointed teeth up to the last premolar . Iron deposits in the outer enamel zone ensure a reddish to yellowish coloration in the red-toothed shrews , but also in the water shrews and the American short-tailed shrews . The milk teeth are replaced before the birth so that they are born with the permanent teeth.

Shrews, like the sand weevils and slow loris , are among the few poisonous mammals. Of some genera (neomys and American short-tailed shrew) is known to be in the submandibular gland poison BLTX produce, which allowed them to overwhelm relatively large prey such as frogs and voles. Because of this, shrew bites can also be very painful for humans.

Senses

The shrews' sense of sight is poorly developed; when hunting prey, they tend to rely on the sense of hearing and especially on the sense of smell . A special feature of the shrews is that, alongside bats and toothed whales, they are one of the few mammals in which the ability to echolocation is known. They send out a sequence of high-pitched squeaking sounds that they can use to explore their living space. It is unclear whether echolocation is also used to track down the prey.

distribution and habitat

The southern short-tailed shrew is a well-known species of shrew in North America.

Shrews are distributed almost all over the world and are found in Eurasia , Africa and North and Central America . However, they are absent in South America (apart from the extreme northwest), the Australian-Oceanic region, the polar regions and on remote islands.

They inhabit a wide variety of habitats , but prefer more humid habitats. Most species live in densely populated forest areas, some also occur in grasslands. However, some species such as the pied desert shrew and the representatives of the gray desert shrews also inhabit extremely dry regions.

Way of life

Shrews are predominantly ground dwellers. They are not very good at climbing, and there are no species that live exclusively on trees. Some genera such as the beaver , the mountain stream and the water shrew are adapted to an aquatic way of life. In addition, there are also species that sometimes live underground, such as the stubby-tailed shrews and the molehill shrews , which are adapted to this way of life with enlarged front paws and long claws suitable for digging.

Usually, shrews are solitary animals who avoid contact with conspecifics outside of the mating season; only the small ear shrews are known to behave more socially. Many species are likely to be territorial and mark their territory with glandular secretions.

Some species are both diurnal and nocturnal, while others mainly search for food during the night. As resting places, they dig their own burrows or take over those of other animals or use other protected places such as crevices, holes in the ground or the like. Often they make a nest of dried leaves and grass in it. Some culture-following species are also found in human habitations. They are mostly active all year round, but short periods of slight rigidity ( torpor ) occur in some species.

Shrews have an exceptionally high metabolic rate . When frightened, their heart can beat up to 1200 times per minute, and deaths from shock often occur . Due to their immense metabolism, the shrews have a high need for food, so species of the red- toothed shrews ( Sorex ) eat food on the order of their own body weight every day.

food

Shrews are carnivores that feed primarily on insects and their larvae, earthworms and other invertebrates. Sometimes small vertebrates are also eaten, with their poisonous saliva helping them to overwhelm larger prey. When the opportunity arises, prey animals that are twice as large as voles, toads or small snakes are on the menu. Accordingly, water shrews hunt and eat small fish as well as their main food, beetle larvae and water snails.

To a small extent, they also consume plant material such as seeds and nuts.

Reproduction

Young shrews near their nest

Shrews give birth to up to ten naked and blind young one or more times a year after about three to four weeks of gestation . However, these grow quickly, after 7 to 24 days they open the eyes. In the subfamily of the white-toothed shrews , “moving caravans” sometimes occur, as they bite into the fur at the root of the tail of the front animal. Weaning usually takes two to four weeks, and sexual maturity often occurs after two to three months. The average life expectancy of these animals is one to two years.

Shrews and humans

The musk shrew ( Suncus murinus ) has been able to expand its range as a cultural successor

Shrews were and are not used in particular by humans, nor are they regarded as pests or threats, so that they were rarely hunted. They also do not play a role in pet ownership . Today's threats are primarily based on the destruction of their habitat and the introduction of neozoa into their home regions. As with other groups of mammals, species endemic to small islands are particularly at risk. The shrews of the genus Nesiotites , which lived on several Mediterranean islands, became extinct a few thousand years ago. Today, 14 species are listed by the IUCN as " critically endangered " , a further 71 species are considered critically endangered or endangered; however, precise data are often lacking. In contrast, some species have been able to expand their range in the wake of humans, for example the musk shrew .

In some places, shrews have acquired cultural and historical importance. In ancient Egypt , especially in the later dynasties, they were considered manifestations of the god Horus , and in some cases they were mummified. In China , their squeaks are reminiscent of the Chinese word for money. According to a superstition, the presence of a shrew there means that money will flow into the house. The body parts of the armored shrew , with their unique, particularly resilient structure of the spine , are said to have magical powers in some regions of Africa .

The shrew as a potential carrier of diseases

Bank voles and fire mice are considered to be the main vectors of the Puumala virus and Hantaan virus (species of the Hantavirus ) in Germany. Other species of hantaviruses have also been found in shrews, moles and bats in recent years. It is not yet known whether these newly discovered viruses are pathogenic for humans.

The field shrew ( Crocidura leucodon ) could be the carrier of the Bornavirus (BoDV-1) to other mammals as well as humans.

Systematics and naming

designation

The name Spitz “mouse” should not hide the fact that these animals are not closely related to mice . An amendment adopted renamed by the German Society of Mammalogy at its General Assembly in 1942 in the zoological meaningful, older term Spitzer was Adolf Hitler after becoming aware of by the Berliner Morgenpost of 3 March 1942 under the threat of longer stays "in construction battalions on the Russian front" without delay cancel.

External system

The shrews are incorporated into the insect eater order . This order has a taxonomically highly controversial history, taxa have been incorporated or removed again and again. The molecular genetic studies also do not provide a clear result, so that the parentage relationships within this group remain controversial. The moles (Talpidae) are considered a possible sister group of the shrews , a more distant relationship exists to the slit weevils (Solenodontidae).

Internal system

Two Central European shrew species: above the wood shrew , a representative of the red- toothed shrew , below the house shrew , a representative of the white-toothed shrew

The shrew family is divided into three subfamilies with around 25 genera and over 350 species.

White tooth or eyelash shrews

The members of the subfamily of the white-tooth or eyelash shrews (Crocidurinae) are characterized by white teeth and eyelashes on the tail and on the back of the body. They have fewer teeth (26 to 28) than the red-toothed shrews .

White-toothed shrews are restricted to the Old World, they are found in Eurasia and Africa , and the greatest biodiversity is in central Africa . The following genera are included in this subfamily:

  • The genus of the (actual) white-toothed shrews ( Crocidura ) is the most species-rich mammal genus with around 170 species. Most of them live in Africa or in Southeast Asia, in Central Europe there are three species: the field shrew ( C. leucodon ), the house shrew ( C. russula ) and the garden shrew ( C. suaveolens ).
  • The genus of the thick-tailed shrews ( Suncus ) comprises around 15 species that live in southern Europe, Africa and southern and southeastern Asia. They are characterized by bushy tails. Well-known species are the Etruscan shrew ( S. etruscus ) - which, together with the pig-nosed bat, is considered the smallest mammal - and the musk shrew ( S. murinus ).
  • The Pearson's long-clawed shrew ( Solisorex pearsoni ) is endemic to Sri Lanka.
  • The Kelaart long-clawed shrew ( Feroculus feroculus ) is also only found in Sri Lanka.
  • The pied desert shrew ( Diplomesodon pulchellum ) inhabits steppes and semi-deserts in southern Russia and Central Asia.
  • Palawanosorex muscorum from the Philippine island of Palawan .
  • The three species of the genus Congo eyelash shrews ( Paracrocidura ) are characterized by their relatively large heads and special features in the area of ​​the teeth. You live in central Africa.
  • The Ruwenzori shrew ( Ruwenzorisorex suncoides ) only lives in the Ruwenzori Mountains in Africa.
  • The armored shrews ( Scutisorex ) of Central Africa are characterized by their particularly resilient and flexible spine.
  • The approximately ten species of the genus Sylvisorex inhabit the forests of central and southern Africa. They are characterized by soft, long body hair.

Myosoricinae

The genera of the subfamily of the Myosoricinae were previously counted among the Crocidurinae. They differ from these in that they have a third lower premolar and other details in the skull structure. The members of this subfamily are restricted to central and southern Africa . The following categories are included:

  • The African wood shrews (genus Myosorex ) primarily inhabit moist forest regions in central and southern Africa.
  • The animals of the genus Congosorex are similar to the African wood shrews. The genus includes three species, two of which were not discovered until the 21st century.
  • The three species of mole shrews ( Surdisorex ) occur exclusively in mountain regions of Kenya that are around 3000 meters high. Typical of them is the short tail and a partially subterranean way of life.

Red-toothed shrews

A wood shrew eating an earthworm

The members of the subfamily of the red- toothed shrews (Soricinae) are characterized by red and yellowish tooth tips. They also have more teeth (30 or 32) than the other subfamilies, and the eyelash hairs on the tail and back of the body are absent.

Red-toothed shrews live in Eurasia , North and Central America and northwestern South America ; in Africa they are absent. A distinction is made between the following genera:

  • The genus of the (actual) red-toothed shrews ( Sorex ) comprises almost 80 species. They are characterized by long tails and small ears and inhabit large parts of Eurasia and North America. The Central European species include: the wood shrew ( S. araneus ) - in 1949 and 2017, their temporary body shrinkage and weight loss were published over the winter; the Alpine shrew ( S. alpinus ), the dwarf shrew ( S. minutus ) and the black- backed shrew ( S. coronatus ).
  • The water shrews ( Neomys ) include three species in Europe and Western Asia. They are adapted to aquatic life by the hairlines on their feet. The water shrew ( N. fodiens ) and the swamp shrew ( N. anomalus ) are known.
  • The stubby-tailed shrews ( Anourosorex ) are adapted to a subterranean way of life similar to the moles with their claw-like front feet and receding eyes. They are found in East and Southeast Asia.
  • The Asian short-tailed shrews ( Blarinella ) live in southwest China and northern Myanmar. Their short body is also adapted to a digging way of life.
  • The four species of the American short-tailed shrew ( Blarina ) occur in southern Canada and the USA. They are relatively well researched and often burrowing animals.
  • The approximately 30 species of small ear shrews ( Cryptotis ) are restricted to the American continent. They live together in groups and are considered more social than most other species of shrew.
  • The six species of beaver shrews ( Chimarrogale ) are similar to the water shrews with bristle fringes on their feet and are adapted to swimming movement. You live in East Asia.
  • The genus Chodsigoa comprises eight species mainly living in China.
  • The four species of the genus Episoriculus inhabit wetlands in Asia.
  • The mountain shrew ( Nectogale elegans ) is the only species of shrew that is webbed . She lives in southern China and the Himalayan region. Fish are likely to make up part of their diet.
  • The genus Nesiotites lived on some Mediterranean islands until a few thousand years ago.
  • The Sikkim big-clawed shrew ( Soriculus nigrescens ) inhabits the Himalayan region.
  • The Mexican desert shrew ( Megasorex gigas ) inhabits southwestern Mexico and lives in forests and semi-deserts.
  • The gray desert shrews ( Notiosorex ) live in arid regions in the southwestern United States and northern Mexico.

Other animals called "shrews"

The shrew family does not include:

Development history

The earliest fossil record of shrews comes from the Upper Eocene of North America. In the Oligocene they immigrated to Asia and Africa , from which time the extinct subfamilies Crocidosoricinae and Heterosoricinae are known. The oldest finds from Africa come from the Miocene , in South America they have only been documented since the Pleistocene .

literature

Web links

Commons : Shrews  - Collection of images, videos and audio files

Individual evidence

  1. ↑ Christel Dötsch and Wighart von Koenigswald: For the red coloring of Soricidenzähnen. Zeitschrift für Mammaliankunde 43 (2), 1978, pp. 65-70
  2. ↑ Behavior: The twittering of shrews is for orientation . ( Spektrum.de [accessed on October 25, 2019]).
  3. ↑ M. Nowak (1999), p. 203
  4. ↑ Figures from the IUCN Red List , accessed January 12, 2007
  5. ↑ Shrews in Ancient Egypt on The Shrew (-ist's) Site
  6. ↑ Information on how to avoid hantavirus infections. (PDF) Robert Koch Institute, Berlin, 2019, accessed on April 28, 2019 .
  7. ↑ Hantavirus disease. RKI, July 2, 2015, accessed April 28, 2019 .
  8. ↑ Bornavirus. Statements by the Blood Working Group of the Federal Ministry of Health. (PDF) Federal Health Gazette, 2019, accessed on April 28, 2019 .
  9. ↑ History of the German Society for Mammalian Science (DGS) (PDF; 1.6 MB)
  10. ↑ See for example: M. Symonds: Phylogeny and life histories of the 'Insectivora': controversies and consequences in Biol. Rev. (2005), 80, pp. 93–128. PDF .
  11. ↑ Rainer Hutterer et al. A new genus and species of shrew (Mammalia: Soricidae) from Palawan Island, Philippines. Journal of, May 8, 2018; doi: 10.1093 / jmammal / gyy041