The polar bear (Ursus maritimus) is a bear Bears are mammals of the family Ursidae. Bears are classified as caniforms, or doglike carnivorans, with the pinnipeds being their closest living relatives. Although there are only eight living species of bear, they are widespread, appearing in a wide variety of habitats throughout the Northern Hemisphere and partially in the Southern Hemisphere native largely within the Arctic circle The Arctic Circle is one of the five major circles of latitude that mark maps of the Earth. For Epoch 2010, it is the parallel of latitude that runs 66º 33′ 43″ north of the Equator encompassing the Arctic Ocean, its surrounding seas and surrounding land masses. It is the world's largest land carnivore A carnivore , meaning 'meat eater' (Latin carne meaning 'flesh' and vorare meaning 'to devour'), is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging. Animals that depend solely on animal flesh for their nutrient requirements are and also the largest bear, together with the omnivorous Omnivores are species that eat both plants and animals as their primary food source. They are opportunistic, general feeders not specifically adapted to eat and digest either meat or plant material primarily. Pigs are one well-known example of an omnivore. Crows are another example of an omnivore that many people see every day. Humans are regarded Kodiak bear, which is approximately the same size.[3] An adult male weighs around 350–680 kg (770–1,500 lb),[4] while an adult female is about half that size. Although it is closely related to the brown bear The brown bear is a large bear distributed across much of northern Eurasia and North America. It can weigh from 300 to 780 kilograms (660 to 1720 lbs) and its largest subspecies, the Kodiak Bear, rivals the polar bear as the largest member of the bear family and as the largest land-based predator, it has evolved to occupy a narrow ecological niche In ecology, a niche is a term describing the relational position of a species or population in its ecosystem to each other; e.g. a dolphin could potentially be in another ecological niche from one that travels in a different pod if the members of these pods utilize significantly different food resources and foraging methods. A shorthand definition, with many body characteristics adapted for cold temperatures, for moving across snow, ice, and open water, and for hunting the seals Pinnipeds or fin-footed mammals are a widely distributed and diverse group of semi-aquatic marine mammals comprising the families Odobenidae (the walrus), Otariidae (eared seals, including sea lions and fur seals), and Phocidae (earless seals) which make up most of its diet.[5] Although most polar bears are born on land, they spend most of their time at sea (hence their scientific name meaning "maritime A sea generally refers to a large body of salt water, but the term is used in other contexts as well. Most commonly, the term refers to a large expanse of saline water connected with an ocean, and is commonly used as a synonym for ocean. It is also used sometimes to describe a large saline lake that lacks a natural outlet, such as the Caspian Sea bear") and can hunt consistently only from sea ice Sea ice is largely formed from seawater that freezes. Because the oceans consist of salt water, this occurs below the freezing point of pure water, at about -1.8 °C, so spend much of the year on the frozen sea.
The polar bear is classified as a vulnerable species A vulnerable species is a species which is likely to become endangered unless the circumstances threatening its survival and reproduction improve. The following is a very small, non-representative fraction of the 8,566 species listed as vulnerable on the IUCN Red List, with 8 of the 19 polar bear subpopulations in decline.[6] For decades, unrestricted hunting[clarification needed] raised international concern for the future of the species; populations have rebounded after controls and quotas began to take effect.[citation needed] For thousands of years, the polar bear has been a key figure in the material, spiritual, and cultural life of Arctic The Arctic is the region around the Earth's North Pole, opposite the Antarctic region around the South Pole. The Arctic includes the Arctic Ocean (which overlies the North Pole) and parts of Canada, Greenland (a territory of Denmark), Russia, the United States (Alaska), Iceland, Norway, Sweden and Finland indigenous peoples Indigenous peoples are people, communities, and nations who claim a historical continuity and cultural affinity with societies endemic to their original territories that developed prior to exposure to the larger connected civilization associated with Western culture. These societies therefore consider themselves distinct from societies of the, and the hunting of polar bears remains important in their cultures.
The IUCN The International Union for Conservation of Nature is an international organization dedicated to natural resource conservation. The stated goal of the organization is to help the world find pragmatic solutions to the most pressing environment and development challenges. The group publishes a "Red List" compiling information from a now lists global warming Global warming is the increase in the average temperature of Earth's near-surface air and oceans since the mid-20th century and its projected continuation. According to the 2007 Fourth Assessment Report by the Intergovernmental Panel on Climate Change , global surface temperature increased 0.74 ± 0.18 °C (1.33 ± 0.32 °F) during the 20th as the most significant threat to the polar bear, primarily because the melting of its sea ice habitat reduces its ability to find sufficient food. The IUCN states, "If climatic trends continue polar bears may become extirpated from most of their range Categories: Demography | Ecology | Population | within 100 years."[7] The polar bear was listed as a threatened species Threatened species are any species which are vulnerable to extinction in the near future. World Conservation Union (IUCN) is the foremost authority on threatened species, and treats threatened species not as a single category, but as a group of three categories: vulnerable, endangered, and critically endangered, depending on the degree to which under the Endangered Species Act The Endangered Species Act of 1973 is one of the dozens of United States environmental laws passed in the 1970s. As stated in section 2 of the act, it was designed to protect critically imperiled species from extinction as a "consequence of economic growth and development untempered by adequate concern and conservation." by the United States Department of the Interior The United States Department of the Interior is the United States federal executive department of the U.S. government responsible for the management and conservation of most federal land and the administration of programs relating to Native Americans, Alaska Natives, and Native Hawaiians, and to insular areas of the United States in 2008.
Contents |
Naming and etymology
Constantine John Phipps was the first to describe the polar bear as a distinct species.[7] He chose the scientific name The formal system of naming species is called binomial nomenclature , binominal nomenclature (since 1953, the technically correct form in zoology), or binary nomenclature. The essence of it is that each species name is in (modern scientific) Latin and has two parts, so that it is popularly known as the Latin name of the species, although this Ursus maritimus, the Latin Latin or sometimes Roman is an Italic language originally spoken in Latium and Ancient Rome. Although often considered a dead language, in view of the fact that it has no native speakers, a small number of scholars can fluently speak it and it continues to be taught in schools and universities and has been, and currently is, used in the process of for 'maritime bear',[8] due to the animal's native habitat. The Inuit The Inuit are a group of culturally similar indigenous peoples inhabiting the Arctic regions of Canada , Denmark (Greenland), Russia (Siberia) and the United States (Alaska). The Inuit language is grouped under Eskimo-Aleut languages. An Inuk is an Inuit person refer to the animal as nanook In Inuit mythology, Nanook or Nanuq , which is from the Inuit language for polar bear, was the master of bears, meaning he decided if hunters had followed all applicable taboos and if they deserved success in hunting bears[9] (transliterated Transliteration is the practice of converting a text from one writing system into another in a systematic way. An example of transliteration is typing an e-mail using a qwerty keyboard and sending it in a non-qwerty script as nanuuq in the Inupiaq language).[10] The Yupik The Yupik or, in the Central Alaskan Yup'ik language, Yup'ik, are a group of indigenous or aboriginal peoples of western, southwestern, and southcentral Alaska and the Russian Far East. They include the Central Alaskan Yup'ik people of the Yukon-Kuskokwim delta, the Kuskokwim River, and coastal Bristol Bay in Alaska; the Alutiiq of the Alaska also refer to the bear as nanuuk in Siberian Yupik.[citation needed] The bear is umka in the Chukchi language The Chukchi language also known as Luoravetlan, Chukot and Chukcha is a Palaeosiberian language spoken by Chukchi people in the easternmost extremity of Siberia, mainly in Chukotka Autonomous Okrug. According to the Russian Census of 2002, about 7,700 of the 15,700 Chukchi people speak Chukchi; knowledge of the Chukchi language is decreasing, and. In Russian, it is usually called бе́лый медве́дь (bélyj medvédj, the white bear), though an older word still in use is ошку́й (Oshkúj, which comes from the Komi The Komi language is a Finno-Permic language spoken by the Komi peoples in the northeastern European part of Russia. Komi is one of the two members of the Permic subgroup of the Finno-Ugric branch. The other Permic language is Udmurt, to which Komi is closely related oski, "bear").[11] In French, the polar bear is referred to as ours blanc ("white bear") or ours polaire ("polar bear").[12] In the Norwegian-administered Svalbard Svalbard is an archipelago in the Arctic, constituting the northernmost part of Norway. Located north of mainland Europe, it is about midway between mainland Norway and the North Pole. The group of islands range from 74° to 81° north latitude (and thus inside the Arctic Circle), and from 10° to 35° east longitude. Spitsbergen is the largest archipelago, the polar bear is referred to as Isbjørn ("ice bear").
The polar bear was previously considered to be in its own genus In biology, a genus is a low-level taxonomic rank (a taxon) used in the classification of living and fossil organisms, which is an example of definition by genus and differentia. The term comes from Latin genus "descent, family, type, gender", cognate with Greek: γένος – genos, "race, stock, kin", Thalarctos.[13] However, evidence of hybrids between polar bears and brown bears, and of the recent evolutionary divergence of the two species, does not support the establishment of this separate genus, and the accepted scientific name is now therefore Ursus maritimus, as Phipps originally proposed.[14]
Taxonomy and evolution
Polar bears depend on sea ice Sea ice is largely formed from seawater that freezes. Because the oceans consist of salt water, this occurs below the freezing point of pure water, at about -1.8 °C as a platform for hunting seals. Large feet and short, sharp, stocky claws are adaptations to this environment.The bear family What does and does not belong to each family is determined by a taxonomist. Similarly for the question if a particular family should be recognized at all. Often there is no exact agreement, with different taxonomists each taking a different position. There are no hard rules that a taxonomist needs to follow in describing or recognizing a family, Ursidae, is believed to have split off from other carnivorans about 38 million years ago. The Ursinae subfamily originated approximately 4.2 million years ago. According to both fossil and DNA evidence, the polar bear diverged from the brown bear, Ursus arctos, roughly 150,000 years ago.[15] The oldest known polar bear fossil Fossils are the preserved remains or traces of animals, plants, and other organisms from the remote past. The totality of fossils, both discovered and undiscovered, and their placement in fossiliferous (fossil-containing) rock formations and sedimentary layers (strata) is known as the fossil record. The study of fossils across geological time, how is a 130,000 to 110,000-year-old jaw bone, found on Prince Charles Foreland in 2004.[15] Fossils show that between ten to twenty thousand years ago, the polar bear's molar teeth Molars are the rearmost and most complicated kind of tooth in most mammals. In many mammals they grind food; hence the Latin name mola, "millstone" changed significantly from those of the brown bear. Polar bears are thought to have diverged from a population of brown bears that became isolated during a period of glaciation in the Pleistocene The Pleistocene is the epoch from 2.588 million to 12,000 years BP covering the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek πλεῖστος (pleistos "most") and καινός (kainos "new").[16]
More recent genetic studies have shown that some clades A clade[note 1] is a group consisting of an organism and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological classification. In of brown bear are more closely related to polar bears than to other brown bears,[17] meaning that the polar bear is not a true species according to some species concepts In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are often used, such as similarity of DNA, morphology or.[18] In addition, polar bears can breed with brown bears to produce fertile grizzly–polar bear hybrids,[16][19] indicating that they have only recently diverged and are genetically similar.[20] However, because neither species can survive long in the other's ecological niche, and because they have different morphology In biology "morphology" is the study of the form, structure and configuration of an organism. This includes aspects of the outward appearance [citation needed] as well as the form and structure of the internal parts like bones and organs. This is in contrast to physiology, which deals primarily with function, metabolism, social and feeding behaviors, and other phenotypic A phenotype is any observable characteristic or trait of an organism: such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior . Phenotypes result from the expression of an organism's genes as well as the influence of environmental factors and the interactions between the two characteristics, the two bears are generally classified as separate species.[20]
When the polar bear was originally documented, two subspecies Subspecies in biological classification, is either a taxonomic rank subordinate to species, or a taxonomic unit in that rank (plural: subspecies). A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one were identified: Ursus maritimus maritimus by Constantine J. Phipps in 1774, and Ursus maritimus marinus by Peter Simon Pallas Peter Simon Pallas was a German zoologist and botanist who worked in Russia in 1776.[21] This distinction has since been invalidated.
One fossil subspecies has been identified. Ursus maritimus tyrannus—descended from Ursus arctos—became extinct during the Pleistocene. U.m. tyrannus was significantly larger than the living subspecies.[16]
Polar bears investigate the submarine USS Honolulu 280 miles (450 km) from the North Pole The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is, subject to the caveats explained below, defined as the point in the northern hemisphere where the Earth's axis of rotation meets the Earth's surface. It should not be confused with the North Magnetic Pole.
|
Thu, 26 Aug 2010 09:41:37 GMT+00:00
Worries Russian Experts Inter Press Service As a result, polar bears and their natural habitat are seriously threatened. "The climate changes seem to be caused partly by natural factors about which we ...
341px x 500px | 111.80kB
[source page]
Friends C Day is a team effort Choose from the drop down menu to see what we re talking about
unknown
hu, 29 Apr 2010 00:59:00 GM
The Russian premier took part in an expedition organized by the Russian government and the Russian Geographical Society, which was launched to assess how global warming affects . polar bears. .
