Shrew

Shrew (family Soricidae), any of over 350 species of insectivores with a movable nose covered in long sensitive whiskers that extends over the bottom lip. To catch prey, their huge incisor teeth are utilised like forceps; the upper pair is hooked, while the bottom pair extends forward. Smell glands on the flanks, as well as other regions of the body, give shrews an unpleasant odour.

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Shrew mammals are small with cylindrical bodies, narrow limbs, and clawed fingers. Except in short-tailed shrews and water shrews, their eyes are small but visible through the hair, and their ears are rounded and relatively large. The length of the tail varies by species, with some being significantly shorter than the body and others being very long. The testes are kept in the male's abdominal cavity and do not descend, making it difficult to tell the sexes apart. The cerebral hemispheres of the brain are small, while the olfactory lobes are large, indicating lower intelligence and manipulative ability but a better sense of smell.

Scientific Classification

Kingdom: Animalia 

Phylum: Chordata 

Class: Mammalia

Order: Eulipotyphla 

Family: Soricidae 

Subfamilies: Crocidurinae

Myosoricinae

Soricinae

Within the family Soricidae, the 24 genera of "real" shrews are divided into three subfamilies (Crocidurinae, Soricinae, and Myosoricinae). Soricids are members of the Soricimorpha order, which belongs to the insectivores, a wider group of mammals. Elephant shrews and tree shrews are not included in this category of soricids. Shrews have a long evolutionary history in North America, dating back to the Middle Eocene Epoch (48 to 41.3 million years ago); more recent remains have been discovered in Africa, Asia, Europe, and South America.

Natural History 

The majority of shrews are active all year and at different times of the day and night, with regular periods of rest. Insects and other invertebrates are their primary food, but they also eat small vertebrates, seeds, and mushrooms. Toxic saliva is produced by North American short-tailed shrews (genus Blarina) and Old World water shrews (genus Neomys) to immobilise prey. Shrew animals have fast metabolisms and can eat up to double their body weight in food every day; they can't go more than a few hours without eating. As a result, shrew life revolves around a constant search for food. Shrews on land have acute hearing, smell, and touch senses.

The muzzle probes litter and dirt for invertebrates, which are recognised by smell and their sensitive whiskers. The front feet pin large prey, but the mouth grabs it and manipulates it with the flexible muzzle, pushing the meal sideways as it is devoured. To locate prey underwater, amphibious species rely nearly totally on touch. Clicks, twitters, chirps, squeaks, churls, whistles, barks, and ultrasonic sounds are made by shrews in the contexts of warning, defence, aggressiveness, courtship, mother-and-child relationships, and exploration and foraging.

In one or more annual litters, shrews have 2 to 10 blind, hairless young; gestation lasts up to 28 days. The mother is attentive and moves the young from time to time, carrying them by the neck or pushing them to the new nest. When the young are mature enough, they may create a chain, each grabbing the base of the tail of the one ahead of them, and trailing behind the mother as she flees or relocates. Caravanning is the term for this type of behaviour.

Shrews can be found from North America through northwestern South America, Africa, Eurasia, and island groupings east of mainland Asia, all the way to the Aru Islands on Australia's continental shelf. They've adapted to live in tundra, coniferous, deciduous, and tropical woods, savannas, humid and arid grasslands, and deserts, among other places. More than a quarter of all live species (145 out of 325) are found in Africa, with 16 species found in a single site in the southeastern Central African Republic. Suncus murinus, the Asian house shrew, has been imported to Arabia, Africa, Madagascar, and a few Pacific and Indian Ocean islands.

Form and Function 

The average size of most species is the common Eurasian shrew (Sorex araneus), which may weigh up to 14 gram (0.5 ounce) and has a body length of 6 to 8 cm (2 to 3 inches) with a shorter tail (5 to 6 cm). The pygmy white-toothed shrew (Suncus etruscus) of Eurasia and North Africa is one of the smallest mammals known, weighing between 1.2 and 2.7 gram (0.04 to 1 ounce) and about 4 to 5 cm (1.6 to 2 inches) in length with a shorter tail (2 to 3 cm [0.8 to 1.2 inches]). The armoured shrew (Scutisorex somereni) of equatorial Africa is one of the largest, weighing up to 113 grammes (approximately 4 ounces) and measuring 12 to 15 cm (4.7 to 5.9 inches) in length with an 8 to 10 cm (3.1 to 3.9 inch) tail. Shrews have short, dense, silky fur that ranges in colour from grey to black, with slightly milder tones or white on the underside. Sorex species with a dark brown back, greyish-brown sides, and greyish undersides are tricoloured. The head and back of the piebald shrew (genus Diplomesodon) are white with grey.

All shrews have a similar body shape, but structural differences indicate various lifestyles. Most shrews, for example, dwell on the ground, but some tropical species, such as Africa's forest musk shrews (genus Sylvisorex) and Asia's white-toothed shrews (genus Crocidura), forage and travel beneath the forest canopy in shrubs, vines, and small trees. These animals have long toes and feet, as well as a tail that is substantially longer than the body.

Other shrews have digging adaptations. The short-tailed shrews of North America (genus Blarina), Kenyan shrews (genus Surdisorex), Asian mole shrews (Anourosorex squamipes), and Kelaart's long-clawed shrew (Feroculus feroculus) of Sri Lanka are among them. All have small eyes buried below their fur, very small ears, long digging claws on their forefeet, and short tails. They build and forage in subterranean burrows, only coming to the surface for short periods of time.

The eyes of water shrews are particularly tiny (covered with skin in genus Nectogale). These are land-dwelling amphibious creatures that forage in water. The African Scutisorex somereni has a strange and unexplained speciality. It has more and larger lumbar vertebrae, which are interconnected by multiple bony spines to produce a flexible and robust backbone. This shrew can sustain a person's weight.

Common Shrew 

The Eurasian shrew (Sorex araneus) is the most common shrew and one of the most frequent animals in Northern Europe, including Great Britain but excluding Ireland. It has velvety dark brown fur with a light underside and is 55 to 82 millimetres (2.2 to 3.2 in) in length and weighs 5 to 12 grammes (0.2 to 0.4 ounce). Until their first moult, juvenile shrews have lighter fur. Small eyes, a pointed, movable nose, and red-tipped teeth distinguish the common shrew. It has a life expectancy of about 14 months. Shrews are active during all hours of the day and night, with only brief intervals of rest in between surges of activity.

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Territory

The Woodlands, meadows, and hedgelands of Britain, Scandinavia, and Eastern Europe are home to common shrews. Each shrew builds a 370 to 630 m2 (440 to 750 yd2) home range. During the breeding season, males frequently push the boundaries in order to find females. Shrews are fiercely territorial and will protect their territory against other shrews. They build their nests beneath the ground or in dense foliage.

Diet 

Insects, slugs, spiders, worms, amphibians, and small rodents make up the common shrew's carnivorous and insectivorous diet. To survive, shrews must ingest 200 to 300 percent of their body weight in food each day. To attain this goal, a shrew must eat every 2 to 3 hours. If a shrew goes without food for more than a few hours, it will starve. They don't hibernate in the winter because their bodies are too small to retain enough fat reserves and they only last for a brief period of time.

Shrews have evolved adaptations to help them survive the winter. Their skulls shrink by approximately 20 percent, and their brains shrink by up to 30 percent. Their spines become shorter and their other organs lose bulk. As a result, total body mass falls by roughly 18%. When spring arrives, they will expand to about their former size. Dropping temperatures, according to scientists, cause their systems to break down and absorb bones and tissues. As the weather warms up with the arrival of spring, their bodies begin to restore the bones and tissues that have been destroyed. This cuts their feeding requirements in half and boosts their chances of surviving the winter. In addition, common shrews have three unique seasonal morphologies that, despite varying temperatures, have the same relative oxygen consumption. Shrews have limited vision and rely on their keen senses of smell and hearing to locate food.

Differences Between Shrew Mouse 

Some of the differences between shrew mouse are: Shrews are typically smaller than mice and have significantly more pointed noses. Mice have huge eyes, whereas shrews have tiny eyes that are nearly invisible beneath their fur. Meat-eaters have pointed teeth and small ears, whereas mice have grooved incisors and huge ears.

Asian House Shrew

The Asian house shrew (Suncus murinus) is a shrew species native to South and Southeast Asia that has been included on the IUCN Red List as Least Concern since 2008 due to its high population and widespread distribution. It has been adopted in a number of countries in West Asia and East Africa. It's an invasive species that's been blamed for the extinction of some island lizard species.

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The house shrew is also known as the grey musk shrew, Asian musk shrew, or Indian shrew. It is known in India as chuchunder and is mentioned as a nocturnal inhabitant of Indian households in Rudyard Kipling's The Jungle Book as chuchundra. However, Kipling's incorrect usage of the term "muskrat" has caused confusion with the unrelated North American muskrat (Ondatra zibethicus), which is not found in India and was (incorrectly) shown in The Jungle Book.

Taxonomy

Carl Linnaeus coined the scientific name Sorex murinus for a house shrew from Java in 1766. Several house shrew zoological specimens were reported as different species between the late 18th and early 20th centuries, however, they are now regarded synonyms.

• Sorex myosurus by Peter Simon Pallas in 1781.

• Sorex viridescens by Edward Blyth in 1859 was a house shrew from the Malabar coast, India.

Description 

The house shrew has homogeneous, short, thick fur that ranges in colour from mid-grey to brownish-grey. The tail is thick at the base and narrows at the tip, with a few long, bristle-like hairs thinly dispersed throughout. They have five clawed toes and short legs. They have extended snouts and short external ears. They also have a strong musk odour, which comes from musk glands that can be seen on each side of the body. During the breeding season, the odour is most prominent.

The Asian house shrew is plantigrade and has a long nose, like all shrews. The teeth are a set of sharp points that are used to pierce the exoskeletons of insects. It is the largest of the shrew species, weighing between 50 and 100 g and measuring approximately 15 cm from snout to tail tip.

Behaviour 

When entering human habitations, the house shrew has a propensity of travelling fast around the borders of the walls. It emits a chattering sound that resembles jingling money as it runs, earning them the nickname "money shrew" in China. When the house shrew is disturbed, it emits an ear-piercing, high-pitched shriek that sounds like nails scraping a chalkboard or a metal fork scraping glass, and which repels house cats. Predators avoid the house shrew because of its foul odour, and even if they do catch one by accident, they rarely consume it.

Another interesting feature of this shrew (which it shares with Europe's white-toothed shrews) is that it forms a "caravan" with its young, in which the young line up behind the mother and follow her while she walks. The first young will use its teeth to grasp the mother's fur, and the following young will do the same with the sibling in front of them.

shrew is frequently misidentified as a rat or mouse and treated as pests. It is good for humans in general because it eats largely dangerous insects like cockroaches and even house mice. As a result, it can be classified as a biological pesticide. Unlike rodents, the population of house shrews has remained stable. Despite its utility as an insecticide, the pungent odour of its droppings, which it may deposit in human residences beneath kitchen cupboards and other places, might make it undesirable. It can also eat human food, such as meat from kitchens, as well as dog or cat food. It is known to kill young chicks on occasion, making it unpopular with farmers; nevertheless, rats kill more chicks and do so more quickly. Its method of attacking chicks, which includes chewing a tendon, immobilising it, then killing and eating it, could imply that it has a poisonous bite that paralyses, as at least two other shrew species have (i.e. the Eurasian water shrew and the Northern short-tailed shrew).

Interesting Facts About Shrew 

• They have the fastest metabolic rate of any mammal. The masked shrew's heart, Sorex cinereus, beats 800 times per minute, far quicker than the hummingbird's.

• Shrews need to consume 80-90 percent of their body weight in food on a daily basis. If they are not fed for half a day, they will starve to death. They consume anything, but prefer tiny animals; they are economically essential as insect and slug destroyers that threaten crops.

• Shrews are easily frightened and will jump, faint, or die if they hear something unexpected.

• The Etruscan Shrew (Suncus etruscus) is the smallest living terrestrial mammal, measuring around 3.5 cm and weighing 2 grams.

• Shrews, unlike most mammals, have poisonous species. Shrew venom is delivered to the wound by grooves in the teeth rather than fangs. The contents of the venom glands of the American short-tailed shrew are enough to kill 200 mice by intravenous injection, and the venom comprises a variety of chemicals.

Conclusion 

From this article, it is very clear that shrews are mouse sized and it also resembles the shape of the mouse and we have come across the scientific classification, natural history and forms and function. There are different types of shrews discussed in this article Asian house shrew and common shrew which has been discussed briefly in this article.