Post by DinosaurMichael on Aug 4, 2012 5:11:53 GMT -5
Northern Elephant Seal - Mirounga angustirostris
The northern elephant seal (Mirounga angustirostris) is one of two species of elephant seal (the other is the southern elephant seal). It is a member of the family Phocidae ("true seals"). Elephant seals derive their name from their great size and from the male's large proboscis, which is used in making extraordinarily loud roaring noises, especially during the mating competition. Sexual dimorphism in size is great: The males can grow to 14 ft (4 m) and 5,000 lb (2,300 kg), while the females grow to 11 ft (3 m) and 1,400 lb (640 kg). Correspondingly, the mating system is highly polygynous; a successful male is able to impregnate up to 50 females in one season. The huge male northern elephant seal typically weighs 1,500–2,300 kg (3,300–5,100 lbs) and measures 4–5 m (13.2–16.5 ft), although some males can weigh up to 3,700 kg (8,152 lbs). Females are much smaller can range from 400 to 900 kg (990-2,000 lbs) in weight, or roughly a third of the male's bulk, and measure from 2.5 to 3.6 m (8.2–11.9 ft). The bull Southern Elephant Seals are, on average, larger than those in the Northern species but the females in both are around the same size, indicating the even higher level of sexual dimorphism in the Southern species. Both adult and juvenile elephant seals are bar-skinned and black before molting. After molting, they generally have a silver to dark gray coat that fades to brownish-yellow and tan. Adult males have hairless necks and chests speckled with pink, white and light brown. Pups are mostly black at birth and molt to a silver gray after weaning. The eyes are large, round and black. The width of the eyes and a high concentration of low light pigments suggest sight plays an important role in the capture of prey. Like all seals, elephant seals have atrophied hind limbs whose underdeveloped ends form the tail and tail fin. Each of the "feet" can deploy five long, webbed fingers. This agile, dual palm is used to propel water. The pectoral fins are used little while swimming. While their hind limbs are unfit for locomotion on land, elephant seals use their fins as support to propel their bodies. They are able to propel themselves quickly (as fast as 8 km/h) in this way for short-distance travel, to return to water, catch up with a female or chase an intruder. Like other seals, elephant seals' bloodstreams are adapted to the cold in which a mixture of small veins surrounds arteries capturing heat from them. This structure is present in extremities such as the hind legs.
Bull Walrus - Odobenus rosmarus
The walrus (Odobenus rosmarus) is a large flippered marine mammal with a discontinuous circumpolar distribution in the Arctic Ocean and sub-Arctic seas of the Northern Hemisphere. The walrus is the only living species in the Odobenidae family and Odobenus genus. It is subdivided into three subspecies: the Atlantic walrus (O. rosmarus rosmarus) which lives in the Atlantic Ocean, the Pacific walrus (O. rosmarus divergens) which lives in the Pacific Ocean, and O. rosmarus laptevi, which lives in the Laptev Sea. The walrus is easily recognized by its prominent tusks, whiskers and great bulk. Adult Pacific males can weigh more than 1,700 kilograms (3,700 lb) and, among pinnipeds, are exceeded in size only by the two species of elephant seals. It resides primarily in shallow oceanic shelf habitat, spending a significant proportion of its life on sea ice in pursuit of its preferred diet of benthic bivalve mollusks. It is a relatively long-lived, social animal and is considered a keystone species in Arctic marine ecosystems. The walrus has played a prominent role in the cultures of many indigenous Arctic peoples, who have hunted the walrus for its meat, fat, skin, tusks and bone. In the 19th and early 20th centuries, the walrus was the object of heavy commercial exploitation for blubber and ivory and its numbers declined rapidly. Its global population has since rebounded, though the Atlantic and Laptev populations remain fragmented and at historically depressed levels. While some outsized Pacific males can weigh as much as 2,000 kg (4,400 lb), most weigh between 800 and 1,680 kg (1,800 and 3,700 lb). The Atlantic subspecies weighs about 10–20% less than the Pacific subspecies. The Atlantic Walrus also tends to have relatively shorter tusks and somewhat more flattened snout. Females weigh about two-thirds as much, with the Atlantic females averaging 560 kg (1,200 lb), sometimes weighing as little as 400 kg (880 lbs), and the Pacific female averaging 794 kg (1,750 lb). Length ranges from 2.2 to 3.6 m (7.2–12 ft). It is the second largest pinniped, after the elephant seals. The walrus' body shape shares features with both sea lions (eared seals: Otariidae) and seals (true seals: Phocidae). As with otariids, it can turn its rear flippers forward and move on all fours; however, its swimming technique is more like that of true seals, relying less on flippers and more on sinuous whole body movements. Also like phocids, it lacks external ears.
The northern elephant seal (Mirounga angustirostris) is one of two species of elephant seal (the other is the southern elephant seal). It is a member of the family Phocidae ("true seals"). Elephant seals derive their name from their great size and from the male's large proboscis, which is used in making extraordinarily loud roaring noises, especially during the mating competition. Sexual dimorphism in size is great: The males can grow to 14 ft (4 m) and 5,000 lb (2,300 kg), while the females grow to 11 ft (3 m) and 1,400 lb (640 kg). Correspondingly, the mating system is highly polygynous; a successful male is able to impregnate up to 50 females in one season. The huge male northern elephant seal typically weighs 1,500–2,300 kg (3,300–5,100 lbs) and measures 4–5 m (13.2–16.5 ft), although some males can weigh up to 3,700 kg (8,152 lbs). Females are much smaller can range from 400 to 900 kg (990-2,000 lbs) in weight, or roughly a third of the male's bulk, and measure from 2.5 to 3.6 m (8.2–11.9 ft). The bull Southern Elephant Seals are, on average, larger than those in the Northern species but the females in both are around the same size, indicating the even higher level of sexual dimorphism in the Southern species. Both adult and juvenile elephant seals are bar-skinned and black before molting. After molting, they generally have a silver to dark gray coat that fades to brownish-yellow and tan. Adult males have hairless necks and chests speckled with pink, white and light brown. Pups are mostly black at birth and molt to a silver gray after weaning. The eyes are large, round and black. The width of the eyes and a high concentration of low light pigments suggest sight plays an important role in the capture of prey. Like all seals, elephant seals have atrophied hind limbs whose underdeveloped ends form the tail and tail fin. Each of the "feet" can deploy five long, webbed fingers. This agile, dual palm is used to propel water. The pectoral fins are used little while swimming. While their hind limbs are unfit for locomotion on land, elephant seals use their fins as support to propel their bodies. They are able to propel themselves quickly (as fast as 8 km/h) in this way for short-distance travel, to return to water, catch up with a female or chase an intruder. Like other seals, elephant seals' bloodstreams are adapted to the cold in which a mixture of small veins surrounds arteries capturing heat from them. This structure is present in extremities such as the hind legs.
Bull Walrus - Odobenus rosmarus
The walrus (Odobenus rosmarus) is a large flippered marine mammal with a discontinuous circumpolar distribution in the Arctic Ocean and sub-Arctic seas of the Northern Hemisphere. The walrus is the only living species in the Odobenidae family and Odobenus genus. It is subdivided into three subspecies: the Atlantic walrus (O. rosmarus rosmarus) which lives in the Atlantic Ocean, the Pacific walrus (O. rosmarus divergens) which lives in the Pacific Ocean, and O. rosmarus laptevi, which lives in the Laptev Sea. The walrus is easily recognized by its prominent tusks, whiskers and great bulk. Adult Pacific males can weigh more than 1,700 kilograms (3,700 lb) and, among pinnipeds, are exceeded in size only by the two species of elephant seals. It resides primarily in shallow oceanic shelf habitat, spending a significant proportion of its life on sea ice in pursuit of its preferred diet of benthic bivalve mollusks. It is a relatively long-lived, social animal and is considered a keystone species in Arctic marine ecosystems. The walrus has played a prominent role in the cultures of many indigenous Arctic peoples, who have hunted the walrus for its meat, fat, skin, tusks and bone. In the 19th and early 20th centuries, the walrus was the object of heavy commercial exploitation for blubber and ivory and its numbers declined rapidly. Its global population has since rebounded, though the Atlantic and Laptev populations remain fragmented and at historically depressed levels. While some outsized Pacific males can weigh as much as 2,000 kg (4,400 lb), most weigh between 800 and 1,680 kg (1,800 and 3,700 lb). The Atlantic subspecies weighs about 10–20% less than the Pacific subspecies. The Atlantic Walrus also tends to have relatively shorter tusks and somewhat more flattened snout. Females weigh about two-thirds as much, with the Atlantic females averaging 560 kg (1,200 lb), sometimes weighing as little as 400 kg (880 lbs), and the Pacific female averaging 794 kg (1,750 lb). Length ranges from 2.2 to 3.6 m (7.2–12 ft). It is the second largest pinniped, after the elephant seals. The walrus' body shape shares features with both sea lions (eared seals: Otariidae) and seals (true seals: Phocidae). As with otariids, it can turn its rear flippers forward and move on all fours; however, its swimming technique is more like that of true seals, relying less on flippers and more on sinuous whole body movements. Also like phocids, it lacks external ears.
