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American Water Shrew
The American water shrew (''Sorex palustris'') or northern water shrew, is a shrew found in the nearctic faunal region located throughout the mountain ranges of the northern United States and in Canada and Alaska. The organism resides in semi-aquatic habitats, and is known for being the smallest mammalian diver. Anatomy and morphology 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 and weight is . Their tail length is . The shrew exhibits a black and brown pelage which varies in shade depending on the season. 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Richardson (naturalist)
Sir John Richardson FRS FRSE (5 November 1787 – 5 June 1865) was a Scottish naval surgeon, naturalist and Arctic explorer. Life Richardson was born at Nith Place in Dumfries the son of Gabriel Richardson, Provost of Dumfries, and his wife, Anne Mundell. He was educated at Dumfries Grammar School. He was then apprenticed to his maternal uncle, Dr James Mundell, a surgeon in Dumfries. He studied medicine at Edinburgh University, and became a surgeon in the navy in 1807. He traveled with John Franklin in search of the Northwest Passage on the Coppermine Expedition of 1819–1822. Richardson wrote the sections on geology, botany and ichthyology for the official account of the expedition. Franklin and Richardson returned to Canada in 1825 and went overland by fur trade routes to the mouth of the Mackenzie River. Franklin was to go as far west as possible and Richardson was to go east to the mouth of the Coppermine River. These were the only known points on the central co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shrew
Shrews (family Soricidae) are small mole-like mammals classified in the order Eulipotyphla. True shrews are not to be confused with treeshrews, otter shrews, elephant shrews, West Indies shrews, or marsupial 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. It is, in fact, a much closer relative of hedgehogs and moles; shrews are related to rodents only in that both belong to the Boreoeutheria magnorder. Shrews have sharp, spike-like teeth, whereas rodents have gnawing front incisor teeth. Shrews are distributed almost worldwide; among the major tropical and temperate land masses, only New Guinea, Australia, and New Zealand have no native shrews; in South America shrews appeared only relatively recently, as a result of the Great American Interchange, and are present only in the northern Andes. The shrew family has 385 known species, making it the fourth- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nearctic
The Nearctic realm is one of the eight biogeographic realms constituting the Earth's land surface. The Nearctic realm covers most of North America, including Greenland, Central Florida, and the highlands of Mexico. The parts of North America that are not in the Nearctic realm are Eastern Mexico, Southern Florida, coastal Central Florida, Central America, and the Caribbean islands, which, together with South America, are part of the Neotropical realm. Major ecological regions The World Wildlife Fund (WWF) divides the Nearctic into four bioregions, defined as "geographic clusters of ecoregions that may span several habitat types, but have strong biogeographic affinities, particularly at taxonomic levels higher than the species level (genus, family)." Canadian Shield The Canadian Shield bioregion extends across the northern portion of the continent, from the Aleutian Islands to Newfoundland. It includes the Nearctic's Arctic Tundra and Boreal forest ecoregions. In terms of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dental Formula
Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiology (that is, the relationship between the shape and form of the tooth in question and its inferred function) of the teeth of an animal. Animals whose teeth are all of the same type, such as most non-mammalian vertebrates, are said to have ''homodont'' dentition, whereas those whose teeth differ morphologically are said to have ''heterodont'' dentition. The dentition of animals with two successions of teeth (deciduous, permanent) is referred to as ''diphyodont'', while the dentition of animals with only one set of teeth throughout life is ''monophyodont''. The dentition of animals in which the teeth are continuously discarded and replaced throughout life is termed ''polyphyodont''. The dentition of animals in which the teeth are set in sock ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Last Glacial Maximum
The Last Glacial Maximum (LGM), also referred to as the Late Glacial Maximum, was the most recent time during the Last Glacial Period that ice sheets were at their greatest extent. Ice sheets covered much of Northern North America, Northern Europe, and Asia and profoundly affected Earth's climate by causing drought, desertification, and a large drop in sea levels. Based on changes in position of ice sheet margins dated via terrestrial cosmogenic nuclides and radiocarbon dating, growth of ice sheets commenced 33,000 years ago and maximum coverage was between 26,500 years and 19–20,000 years ago, when deglaciation commenced in the Northern Hemisphere, causing an abrupt rise in sea level. Decline of the West Antarctica ice sheet occurred between 14,000 and 15,000 years ago, consistent with evidence for another abrupt rise in the sea level about 14,500 years ago. Glacier fluctuations around the Strait of Magellan suggest the peak in glacial surface area was constrained to betw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sorex
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'' (red-toothed shrews). They have 32 teeth. These animals have long, pointed snouts, small ears, which are often not visible, and scent glands located on the sides of their bodies. As their eyesight is generally poor, they rely on hearing and smell to locate their prey, mainly insects. Some species also use echolocation. Distinguishing between species without examining the dental pattern is often difficult. In some species, a female shrew and her dependent young form "caravans", in which each shrew grasps the rear of the shrew in front, when changing location. Species * Genus ''Sorex'' – most basal of the genera ** Kashmir pygmy shrew (''S. planiceps'') – India and Pakistan ** Tibetan shrew (''S. thibetanus'') â ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mammals Of The United States
About 490 species of mammals are recorded in the United States. Unincorporated territories like for example Puerto Rico, Guam or Northern Mariana Islands are not covered. Mammals introduced and extinct in the Holocene except Pleistocene/Holocene boundary are included. According to the IUCN Red List 3 of these species are critically endangered, 20 endangered, 15 vulnerable, 20 near threatened and 4 extinct. Some species are identified as indicated below: *(A) - Accidental *(E) - Extinct *(Ex) - Extirpated (extinct in the US, but exists elsewhere in the world) *(I) - Introduced The following tags are used to highlight each species' conservation status as assessed by the International Union for Conservation of Nature: (v. 2013.2, the data are current as of March 5, 2014) and the Endangered Species Act: (the data are current as of March 28, 2014) Subclass: Theria Infraclass: Metatheria Order: Didelphimorphia (common opossums) ---- Didelphimorphia is the order of common ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
