Etruscan shrew
| Etruscan shrew[1] | |
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| Conservation status | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Soricomorpha |
| Family: | Soricidae |
| Genus: | Suncus |
| Species: | S. etruscus |
| Binomial name | |
| Suncus etruscus (Savi, 1822) |
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| Etruscan Shrew range (blue — native, black — probably extant origin uncertain) |
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The Etruscan shrew (Suncus etruscus), also known as the Etruscan pygmy shrew or the white-toothed pygmy shrew is the smallest known mammal by mass, weighing only about 1.8 grams (0.063 oz) on average[3][4][5][6][7] The bumblebee bat is regarded as the smallest mammal by skull size).[3][8]
The Etruscan shrew has a body length of about 4 centimetres (1.6 in) excluding the tail. It is characterized by very rapid movements and a fast metabolism, eating about 1.5–2 times its own body weight per day. It feeds on various small vertebrates and invertebrates, mostly insects, and can hunt individuals of the same size as itself. These shrews prefer warm and damp climates and are widely distributed in the belt between 10° and 30°N latitude stretching from Europe and North Africa up to Malaysia. They are relatively rare and are endangered in some countries.
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[edit] Description
The Etruscan shrew has a slender (not truncated) body, with a length between 3 and 4.5 centimetres (1.2 and 1.8 in) excluding the tail. The tail is longer than half of the body. The body mass varies between 1.3 grams (0.046 oz)[8] and 2.4 grams (0.085 oz)[4] and is usually about 1.8 grams (0.063 oz).[3] The head is relatively large, with a long, mobile proboscis, and the hind limbs are relatively small.[9] The Etruscan shrew has a very fast heart beating rate, up to 1511 beats/min (25 beats/s) and a relatively large heart muscle mass, 1.2% of body weight.[3] The fur color on the back and sides is pale brown, but is light gray on the stomach. The shrew usually has 30 teeth, but the 4th upper intermediate tooth is very small (rudimentary), and is absent in some individuals.[6] Near the mouth growth a dense array of short whiskers, which the shrew actively uses in searching for prey, especially in the night.[7] Dimorphism in body features between males and females is absent.[9]
[edit] Activity
Etruscan shrews live alone, except during mating periods. Their lifespan is estimated as two years, but with a large uncertainty.[10] They protect their territories by making chirping noises and signs of aggressiveness.[11] They tend to groom themselves constantly when not eating, and are always moving when awake and not hiding. The hiding periods are short, and typically last less than half an hour. Clicking sounds are heard when these shrews are moving, which cease when they rest.[9] The shrews are more active during the night when they make long trips; during the day, they stay near the nest or in a hiding place.[6] They reach their maximum level of activity at dawn.[2]
The movements of the Etruscan shrew are rapid, with a rate of about 780 min−1 (13 s−1). In cold seasons and during shortages of food, the shrews lower their body temperatures down to about 12 °C (54 °F) and enter a state of temporary hibernation to reduce energy consumption. Recovery from this state is accompanied by shivering with the frequency of about 3500 min−1 (58 s−1).[3] This induces heating, with the rate up to 0.83 °C/min, which is among the highest values recorded in mammals; the heart rate increases exponentially with time from 100 to 800–1200 beats/min, and the respiratory rate rises linearly from 50 to 600–800 beats/min.[4]
Etruscan shrews apparently breed all year round, the gestation period is about 28 days, and they have 2–6 cubs per litter. Most pregnancies occur between October and December.[2] Cubs are born naked and blind, but quickly develop, becoming independent and sexually mature at three to four weeks of age.[5][9]
[edit] Distribution
The Etruscan shrew inhabits a belt extending between 10° and 40°N latitude across Eurasia.[3] In Southern Europe, it has been found in Albania, Bosnia and Herzegovina, Bulgaria, Croatia, Cyprus, France, Macedonia, Malta, Montenegro, Greece, Italy, Portugal, Slovenia, Spain, and Turkey, with unconfirmed reports in Andorra, Gibraltar and Monaco; it has been introduced by humans to some European islands, such as Canary Islands.[2]
The shrew also occurs in North Africa (Algeria, Egypt, Libya, Morocco, Tunisia) and around Arabian Peninsula (Bahrain, Israel, Jordan, Lebanon, Oman, Syria, and Yemen including Socotra). In Asia, it was observed in Afghanistan, Azerbaijan, Borneo, Bhutan, China (Gengma County only), Burma, Georgia, Guinea, India, Iran, Iraq, Kazakhstan, Laos, Malaysia (Malaysian part of Borneo island), Nepal, Pakistan, Philippines, Sri Lanka, Tajikistan, Thailand, Turkey, Turkmenistan and Vietnam. There are unconfirmed reports of the Etruscan shrew in West and East Africa (Guinea, Nigeria, Ethiopia) and in Armenia, Brunei, Indonesia, Kuwait and Uzbekistan.[1][5]
The shrew is relatively rare, especially in Azerbaijan, Georgia (included into the Red Book), Jordan and Kazakhstan (Red Book).[5] Even where not endangered, its density is always lower than of the other shrews living in the area.[2]
[edit] Habitat
The Etruscan shrew favors warm and damp habitats covered with shrubs, which it uses to hide from predators. It is usually confined to the foothills and lower belts of mountain ranges, though has been found up to 3,000 m above sea level. It colonizes riparian thickets along the banks of lakes and rivers, as well as human-cultivated areas (abandoned gardens, orchards, vineyards, olive groves and edges of fields). The shrew, however, avoids intensively cultivated areas, as well as dense forests and sand dunes.[2] It is poorly adapted to digging burrows, so arranges its nests in various natural shelters, crevices and others uninhabited burrows.[5][6]
[edit] Hunting and feeding
Because of its high ratio of surface area to body volume, the Etruscan shrew has an extremely fast metabolism and must eat 1.5–2.0 times its body weight in food per day. It feeds up to 25 times per day, mostly on various invertebrates (insects, their larvae, earthworms, etc.), as well as small vertebrates (young frogs, lizards and rodents), and can hunt prey of nearly the same body size as itself. It prefers species with a soft, thin exoskeleton, so avoids ants when given a choice. It kills large prey by a bite to the head and eating it immediately, but takes small insects back to its nest.[5][6][7] When hunting, the Etruscan shrew mostly relies on its sense of touch rather than vision, and may even run into its food at night.[9]
[edit] Predators and threats
The largest threat to Etruscan shrews originates from human activities, particularly destruction of their nesting grounds and habitats as a result of farming. Etruscan shrews are also sensitive to weather changes, such as cold winters and dry periods.[5] Major predators are birds of prey, especially owls.[6][9]
[edit] References
- ^ a b Hutterer, Rainer (16 November 2005). Wilson, Don E., and Reeder, DeeAnn M.. ed. Mammal Species of the World (3rd ed.). Baltimore: Johns Hopkins University Press, 2 vols. (2142 pp.). p. 258. ISBN 978-0-8018-8221-0. OCLC 62265494. http://www.bucknell.edu/msw3. direct link
- ^ a b c d e f Aulagnier, S.; Hutterer, R.; Jenkins, P.; Bukhnikashvili, A.; Kryštufek, B.; and Kock, D. (2008). "Suncus etruscus". IUCN Red List of Threatened Species. Version 2010.3. International Union for Conservation of Nature. http://www.iucnredlist.org/apps/redlist/details/29671. Retrieved 25 October 2010.
- ^ a b c d e f Klaus D. Jürgens (2002). "Etruscan shrew muscle: the consequences of being small". The Journal of Experimental Biology 205 (Pt 15): 2161–2166. PMID 12110649.
- ^ a b c Fons R., Sender S., Peters T., Jürgens K. D. (1997). "Rates of rewarming, heart and respiratory rates and their significance for oxygen transport during arousal from torpor in the smallest mammal, the Etruscan shrew Suncus etruscus". Journal of Experimental Biology 200 (Pt 10): 1451–1458. PMID 9192497. http://jeb.biologists.org/cgi/reprint/200/10/1451.pdf.
- ^ a b c d e f g Suncus etruscus, Red Book of Kazakhstan (in Russian)
- ^ a b c d e f Белозубка карликовая (Suncus etruscus) (in Russian)
- ^ a b c Scholarpedia: Vibrissal touch in the Etruscan shrew
- ^ a b Jonathan I. Bloch, Kenneth D. Rose and Philip D. Gingerich (1998). "New species of Batodonoides (Lipotyphla, Geolabididae) from early eocene of Wyoming: Smallest known mammal". Journal of Mammalogy 79 (3): 804–827. doi:10.2307/1383090. JSTOR 1383090.
- ^ a b c d e f Suncus etruscus. White-toothed pygmy shrew University of Michigan, Museum of Zoology
- ^ Longevity Records. Table 1. Record Life Spans (years) of Mammals
- ^ R. David Stone (1995) Eurasian insectivores and tree shrews: status survey and conservation action plan, IUCN, ISBN 2831700620 p. 30
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