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Lobodon
The crabeater seal (''Lobodon carcinophaga''), also known as the krill-eater seal, is a true seal with a circumpolar distribution around the coast of Antarctica. They are medium- to large-sized (over 2 m in length), relatively slender and pale-colored, found primarily on the free-floating pack ice that extends seasonally out from the Antarctic coast, which they use as a platform for resting, mating, social aggregation and accessing their prey. They are by far the most abundant seal species in the world. While population estimates are uncertain, there are at least 7 million and possibly as many as 75 million individuals. This success of this species is due to its specialized predation on the abundant Antarctic krill of the Southern Ocean, for which it has uniquely adapted, sieve-like tooth structure. Indeed, its scientific name, translated as "lobe-toothed (''lobodon'') crab eater (''carcinophaga'')", refers specifically to the finely lobed teeth adapted to filtering their small cr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lobodontine Seals
The true seal tribe Lobodontini, collectively known as the Antarctic seals or lobodontin seals, consist of four species of seals in four genera: the crabeater seal (''Lobodon carcinophaga''), the leopard seal (''Hydrurga leptonyx''), the Weddell seal (''Leptonychotes weddelli''), and the Ross seal (''Ommatophoca rossii''). All lobodontine seals have circumpolar distributions surrounding Antarctica. They include both the world's most abundant seal (the crabeater seal) and the only predominantly mammal-eating seal (the leopard seal). While the Weddell seal prefers the shore-fast ice, the other species live primarily on and around the off-shore pack ice. Thus, though they are collectively the most abundant group of seals in the world, the combination of remote range and inaccessible habitat make them among the least well studied of the world's seals. Adaptations The Lobondontini are thought to have diverged from the elephant seals (''Mirounga'') during the late Miocene in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lobodontini
The true seal tribe Lobodontini, collectively known as the Antarctic seals or lobodontin seals, consist of four species of seals in four genera: the crabeater seal (''Lobodon carcinophaga''), the leopard seal (''Hydrurga leptonyx''), the Weddell seal (''Leptonychotes weddelli''), and the Ross seal (''Ommatophoca rossii''). All lobodontine seals have circumpolar distributions surrounding Antarctica. They include both the world's most abundant seal (the crabeater seal) and the only predominantly mammal-eating seal (the leopard seal). While the Weddell seal prefers the shore-fast ice, the other species live primarily on and around the off-shore pack ice. Thus, though they are collectively the most abundant group of seals in the world, the combination of remote range and inaccessible habitat make them among the least well studied of the world's seals. Adaptations The Lobondontini are thought to have diverged from the elephant seals (''Mirounga'') during the late Miocene in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
True Seal
The earless seals, phocids or true seals are one of the three main groups of mammals within the seal lineage, Pinnipedia. All true seals are members of the family Phocidae (). They are sometimes called crawling seals to distinguish them from the fur seals and sea lions of the family Otariidae. Seals live in the oceans of both hemispheres and, with the exception of the more tropical monk seals, are mostly confined to polar, subpolar, and temperate climates. The Baikal seal is the only species of exclusively freshwater seal. Taxonomy and evolution Evolution The earliest known fossil earless seal is ''Noriphoca gaudini'' from the late Oligocene or earliest Miocene ( Aquitanian) of Italy. Other early fossil phocids date from the mid-Miocene, 15 million years ago in the north Atlantic. Until recently, many researchers believed that phocids evolved separately from otariids and odobenids; and that they evolved from otter-like animals, such as ''Potamotherium'', which inhabited ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ross Seal
The Ross seal (''Ommatophoca rossii'') is a true seal (family Phocidae) with a range confined entirely to the pack ice of Antarctica. It is the only species of the genus ''Ommatophoca''. First described during the Ross expedition in 1841, it is the smallest, least abundant and least well known of the Antarctic pinnipeds. Its distinctive features include disproportionately large eyes, whence its scientific name (''Ommato-'' meaning "eye", and ''phoca'' meaning "seal"), and complex, trilling and siren-like vocalizations. Ross seals are brachycephalic, as they have a short broad muzzle and have the shortest fur of any other seal. Taxonomy and evolution The Ross seal shares a recent common ancestor with three other extant Antarctic seals, which are together known as the lobodontine seals. The other species are the crabeater seal (''Lobodon carcinophaga''), leopard seal (''Hydrurga leptonyx'') and Weddell seal (''Leptonychotes weddelli''). These species, collectively belonging to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weddell Seal
The Weddell seal (''Leptonychotes weddellii'') is a relatively large and abundant true seal with a circumpolar distribution surrounding Antarctica. The Weddell seal was discovered and named in the 1820s during expeditions led by British sealing captain James Weddell to the area of the Southern Ocean now known as the Weddell Sea. The life history of this species is well documented since it occupies fast ice environments close to the Antarctic continent and often adjacent to Antarctic bases. This is the only species in the genus ''Leptonychotes''. Description Weddell seals measure about 2.5–3.5 m (8 ft 2 in–11 ft 6 in) long and weigh 400–600 kg (880–1,320 lb). They are amongst the largest seals, with a rather bulky body and short fore flippers relative to their body length. Males weigh less than females, usually about 500 kg (1,100 lb) or less. Male and female Weddell seals are generally about the same length, though females can be slightly l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leopard Seal
The leopard seal (''Hydrurga leptonyx''), also referred to as the sea leopard, is the second largest species of seal in the Antarctic (after the southern elephant seal). Its only natural predator is the orca. It feeds on a wide range of prey including cephalopods, other pinnipeds, krill, fish, and birds, particularly penguins. It is the only species in the genus ''Hydrurga''. Its closest relatives are the Ross seal, the crabeater seal and the Weddell seal, which together are known as the tribe of Lobodontini seals. The name ''hydrurga'' means "water worker" and ''leptonyx'' is the Greek for "thin-clawed". Taxonomy French zoologist Henri Marie Ducrotay de Blainville described the leopard seal in 1820. Description The leopard seal has a distinctively long and muscular body shape when compared to other seals, but it is perhaps best known for its massive jaws, which allow it to be one of the top predators in its environment. The front teeth are sharp like those of other carnivores, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leopard Seals
The leopard seal (''Hydrurga leptonyx''), also referred to as the sea leopard, is the second largest species of seal in the Antarctic (after the southern elephant seal). Its only natural predator is the orca. It feeds on a wide range of prey including cephalopods, other pinnipeds, krill, fish, and birds, particularly penguins. It is the only species in the genus ''Hydrurga''. Its closest relatives are the Ross seal, the crabeater seal and the Weddell seal, which together are known as the tribe of Lobodontini seals. The name ''hydrurga'' means "water worker" and ''leptonyx'' is the Greek for "thin-clawed". Taxonomy French zoologist Henri Marie Ducrotay de Blainville described the leopard seal in 1820. Description The leopard seal has a distinctively long and muscular body shape when compared to other seals, but it is perhaps best known for its massive jaws, which allow it to be one of the top predators in its environment. The front teeth are sharp like those of other carnivores ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Southern Ocean
The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the World Ocean, generally taken to be south of 60° S latitude and encircling Antarctica. With a size of , it is regarded as the second-smallest of the five principal oceanic divisions: smaller than the Pacific, Atlantic, and Indian oceans but larger than the Arctic Ocean. Over the past 30 years, the Southern Ocean has been subject to rapid climate change, which has led to changes in the marine ecosystem. By way of his voyages in the 1770s, James Cook proved that waters encompassed the southern latitudes of the globe. Since then, geographers have disagreed on the Southern Ocean's northern boundary or even existence, considering the waters as various parts of the Pacific, Atlantic, and Indian oceans, instead. However, according to Commodore John Leech of the International Hydrographic Organization (IHO), recent oceanographic research has discovered the importance of Southern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Argentina
Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, the fourth-largest country in the Americas, and the eighth-largest country in the world. It shares the bulk of the Southern Cone with Chile to the west, and is also bordered by Bolivia and Paraguay to the north, Brazil to the northeast, Uruguay and the South Atlantic Ocean to the east, and the Drake Passage to the south. Argentina is a federal state subdivided into twenty-three provinces, and one autonomous city, which is the federal capital and largest city of the nation, Buenos Aires. The provinces and the capital have their own constitutions, but exist under a federal system. Argentina claims sovereignty over the Falkland Islands, South Georgia and the South Sandwich Islands, and a part of Antarctica. The earliest recorded human prese ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molting
In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is the manner in which an animal routinely casts off a part of its body (often, but not always, an outer layer or covering), either at specific times of the year, or at specific points in its life cycle. In medieval times it was also known as "mewing" (from the French verb "muer", to moult), a term that lives on in the name of Britain's Royal Mews where the King's hawks used to be kept during moulting time before becoming horse stables after Tudor times. Moulting can involve shedding the epidermis (skin), pelage (hair, feathers, fur, wool), or other external layer. In some groups, other body parts may be shed, for example, the entire exoskeleton in arthropods, including the wings in some insects. Examples In birds In birds, moulting is the periodic replacement of feathers by shedding old feathers while producing new ones. Feathers are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lanugo
Lanugo is very thin, soft, usually unpigmented, downy hair that is sometimes found on the body of a fetus or newborn. It is the first hair to be produced by the fetal hair follicles, and it usually appears around sixteen weeks of gestation and is abundant by week twenty. It is normally shed before birth, around seven or eight months of gestation, but is sometimes present at birth. It disappears on its own within a few weeks. It is replaced by hair covering the same surfaces, which is called vellus hair. This hair is thinner and more difficult to see. The more visible hair that persists into adulthood is called terminal hair. It forms in specific areas and is hormone-dependent. The term is from the Latin ''lana'', meaning "wool." Humans Fetal development During human development, the lanugo grows on fetuses as a normal part of gestation, but it is usually shed and replaced by vellus hair at about thirty-three to thirty-six weeks of gestational age. As the lanugo is shed from the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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