American water shrew [1] | |
---|---|
An American water shrew on the ice of Pebble Creek | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Eulipotyphla |
Family: | Soricidae |
Genus: | Sorex |
Species: | S. palustris |
Binomial name | |
Sorex palustris Richardson, 1828 | |
Distribution of the American water shrew in Northern America |
The American water shrew or northern water shrew (Sorex palustris) is a shrew found in the nearctic faunal region located throughout the mountain ranges of the northern United States and in Canada and Alaska. [3] The organism resides in semi-aquatic habitats, [4] and is known for being the smallest mammalian diver. [5]
The American water shrew is a sexually dimorphic species in which the males are generally larger and heavier than the females. The size of the shrew is 130–170 mm (5.1–6.7 in) and weight is 8–18 g (0.28–0.63 oz). Their tail length is 57–89 mm (2.2–3.5 in). The shrew exhibits a black and brown pelage which varies in shade depending on the season. [4] When underwater, the animal appears to have a silver veneer on account of its water repellent fur trapping air bubbles. The snout features vibrissae which in the case of water shrews are specialized for aquatic hunting. Like other small mammals who spend part of their time in water, American water shrews have short hairs covering their hind limbs to bolster each paddle with increased surface area, an adaptation not dissimilar to flippers. [5] Externally the American water shrew is indistinguishable from the western water shrew, a genetically distinct species whose morphology differs from the American water shrew strictly over subtle cranial and dental aspects. [6] The American water shrew has a large skull ranging from 21–23 mm (0.83–0.91 in) and width 10–11 mm (0.39–0.43 in) and has a dental formula of 1.5.1.31.1.1.3 × 2 = 32 teeth. [3]
American water shrew populations span the central and eastern regions of Canada and the northern United States, as well as a small isolated section of the Appalachian mountain range. A separate distribution of the population can be found in the western United States and Canada. [4] Because much of the range water shrews occupy today was historically a landscape of continental ice sheets, they considerably expanded their range in the time since the Last Glacial Maximum. [7]
American water shrews prefer to inhabit streams of higher inclines, although they have been observed in a variety of water bodies including more gently sloping streams, springs, mud flats, and even beaver dens. Hence their name, they are rarely found far from water since their diet consists almost entirely of small aquatic invertebrates and fishes. [4]
Shrews are known to hunt land prey depending on the ease of the attack, but mainly target aquatic prey by diving from rocks or elevated banks of streams, making them the smallest of the mammalian divers. Most remarkable about this behavior is that water shrews are mainly nocturnal hunters, meaning they don't use eyesight while locating their prey underwater. While it has been suggested that water shrews may use sonar or electroreception for this purpose, all investigations into these claims have produced no supporting evidence. According to Kenneth C. Catania's research, nocturnally diving shrews manage to locate their prey in the obscured stream by detecting movement along their whiskers or by “underwater sniffing,” a strategy in which they exhale air bubbles onto a perceived target and then re-inhale their own air bubbles to confirm the presence of prey. [5]
Unlike most species of shrews which breed later in the year, American water shrews have been found to breed between the months of February and August based on analysis of wild specimen whose ovarian and testicular activity was at a height during these months. [4] Females usually have a three-week gestation period, and offspring are born in the spring and summer. They usually produce two to three litters during that time. These litters can contain three to 10 offspring. [3]
The American water shrew has nine subspecies: [1]
The red-toothed shrews of the subfamily Soricinae are one of three living subfamilies of shrews, along with Crocidurinae and Myosoricinae. In addition, the family contains the extinct subfamilies Limnoecinae, Crocidosoricinae, Allosoricinae and Heterosoricinae. These species are typically found in North America, northern South America, Europe and northern Asia. The enamel of the tips of their teeth is reddish due to iron pigment. The iron deposits serve to harden the enamel and are concentrated in those parts of the teeth most subject to wear. Members of the genera Chimarrogale, Nectogale, Neomys (Nectogalini) and some members of Sorex (Soricini) are known as water shrews, due to having a semi-aquatic lifestyle.
The northern short-tailed shrew is the largest shrew in the genus Blarina, and occurs in the northeastern region of North America. It is a semifossorial, highly active, and voracious insectivore and is present in a variety of habitats like broadleaved and pine forests among shrubs and hedges as well as grassy river banks. It is notable in that it is one of the few venomous mammals. The specific epithet, brevicauda, is a combination of the Latin brevis and cauda, meaning "short tail".
The cinereus shrew or masked shrew is a small shrew found in Alaska, Canada, and the northern United States. This is the most widely distributed shrew in North America, where it is also known as the common shrew.
The star-nosed mole is a small semiaquatic mole found in moist, low elevation areas in the northern parts of North America. It is the only extant member of the tribe Condylurini and genus Condylura, and it has more than 25,000 minute sensory receptors in touch organs, known as Eimer's organs, with which this hamster-sized mole feels its way around. With the help of its Eimer's organs, it may be perfectly poised to detect seismic wave vibrations.
The American pygmy shrew, also called the eastern pygmy shrew, is a small shrew found throughout much of Alaska, Canada, and the northern contiguous United States, as well as south along the Appalachian Mountains and in a small region in the Colorado and Wyoming Rockies. The species was first discovered in 1831 by naturalist William Cane in Georgian Bay, Parry Sound.
The marsh shrew, also known as the Pacific water shrew, Bendire's water shrew, Bendire's shrew and Jesus shrew is the largest North American member of the genus Sorex. Primarily covered in dark-brown fur, it is found near aquatic habitats along the Pacific coast from southern British Columbia to northern California. With air trapped in its fur for buoyancy, marsh shrews can run for three to five seconds on top of the water. It measures about 16 cm (6.3 in) in length, including a 7-centimetre (2.8 in)-long tail, and weighs an average of 14.5–16 g (0.51–0.56 oz). The marsh shrew's diet consists mainly of invertebrates, which it hunts on land and in the water. They are rare; their populations are thought to be in decline, and they are considered endangered in parts of their range.
The smoky shrew is a medium-sized North American shrew found in eastern Canada and the northeastern United States and extends further south along the Appalachian Mountains.
The giant otter shrew is a semiaquatic, carnivorous afrotherian mammal. It is found in the main rainforest block of central Africa from Nigeria to Zambia, with a few isolated populations in Kenya and Uganda. It lives in streams, wetlands and slow flowing larger rivers. It is the only species in the genus Potamogale. Otter shrews are most closely related to the tenrecs of Madagascar.
The genus Sorex includes many of the common shrews of Eurasia and North America, and contains at least 142 known species and subspecies. Members of this genus, known as long-tailed shrews, are the only members of the tribe Soricini of the subfamily Soricinae. They have 32 teeth.
The Eurasian water shrew, known in the United Kingdom as the water shrew, is a relatively large shrew, up to 10 cm (4 in) long, with a tail up to three-quarters as long again. It has short, dark fur, often with a few white tufts, a white belly, and a few stiff hairs around the feet and tail. It lives close to fresh water, hunting aquatic prey in the water and nearby. Its fur traps bubbles of air in the water which greatly aids its buoyancy, but requires it to anchor itself to remain underwater for more than the briefest of dives.
The Pyrenean desman or Iberian desman is a small semiaquatic, globally threatened mammal related to moles and shrews, and, along with the Russian desman , is one of the two extant members of the tribe Desmanini. The species occurs in north and central parts of Spain and Portugal, French Pyrenees, and Andorra, but severe range contractions have been documented across its geographic distribution.
Aquatic mammals and semiaquatic mammals are a diverse group of mammals that dwell partly or entirely in bodies of water. They include the various marine mammals who dwell in oceans, as well as various freshwater species, such as the European otter. They are not a taxon and are not unified by any distinct biological grouping, but rather their dependence on and integral relation to aquatic ecosystems. The level of dependence on aquatic life varies greatly among species. Among freshwater taxa, the Amazonian manatee and river dolphins are completely aquatic and fully dependent on aquatic ecosystems. Semiaquatic freshwater taxa include the Baikal seal, which feeds underwater but rests, molts, and breeds on land; and the capybara and hippopotamus which are able to venture in and out of water in search of food.
The Olympic shrew is a rare species of shrew that lives in only 13 spots in northwest Washington state and, a recent discovery, in Burns Bog, located in Delta, BC.
The Glacier Bay water shrew is a species of mammal in the family Soricidae. It is endemic to Alaska in the United States. It can swim underwater, and when it stops swimming, air trapped in its fur lets it float back up to the surface. Owing to small hairs on its feet, the water shrew can run across the water. Its fur is water resistant, although if it does get wet it returns to shore to dry itself with its hind feet. It eats aquatic fly nymphs and terrestrial invertebrates.
The Iberian shrew or Lagranja shrew is a species of mammal in the family Soricidae. It is found in Portugal and Spain.
The ornate shrew is a species of mammal in the family Soricidae (shrews). It is endemic to western North America, ranging from Northern California in the United States to the Baja California peninsula in Mexico. Eight subspecies are known, including the extinct tule shrew, known only from four specimens collected in 1905, and the Suisun ornate shrew, a species of conservation concern in California. Through skull morphology research and genetic testing on Ornate shrew populations, it has been shown that there are three main genetic subdivisions: The Southern, Central and Northern. These three genetic subdivisions of Ornate shrew arose from populations of Ornate shrews getting geographically isolated from other populations.
Preble's shrew is a small shrew distributed across the Great Basin of the United States and southern British Columbia in Canada.
The Inyo shrew is a species of shrew found in the western United States. It is light gray and white in color, with a narrow skull and small body size, very similar in appearance to the related dwarf shrew, but paler and not as large. It can be found in many different habitats, from rocky, mountainous regions to wetlands and riparian areas. Not much is known about its behavioral and reproductive habits. While barely studied, their population is believed to be stable and not under any threat.
Trowbridge's shrew is a species of mammal in the family Soricidae. It is found in southern British Columbia in Canada and in Washington, Oregon, and California in the United States.
The long-tailed shrew or rock shrew is a small shrew found in Atlantic Canada and the Northeastern United States.
John T. Beneski; Derek W. Stinson (12 August 1987). "Sorex palustris" (PDF). Mammalian Species (296): 1–6. doi:10.2307/3503968. ISSN 0076-3519. JSTOR 3503968. Wikidata Q44840815. Archived from the original (PDF) on 6 March 2016.