Post by DinosaurMichael on Sept 24, 2013 23:59:19 GMT 5
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.
Tiger Shark - Galeocerdo cuvier
The tiger shark, Galeocerdo cuvier, is a species of requiem shark and the only member of the genus Galeocerdo. Commonly known as sea tiger, the tiger shark is a relatively large macropredator, capable of attaining a length of over 5 m (16 ft). It is found in many tropical and temperate waters, and is especially common around central Pacific islands. Its name derives from the dark stripes down its body which resemble a tiger's pattern, which fade as the shark matures. The tiger shark is a solitary, mostly night-time hunter. Its diet involves a wide range of prey, including crustaceans, fish, seals, birds, smaller sharks, squid, turtles, sea snakes, and dolphins. The tiger shark is considered a near threatened species due to finning and fishing by humans. While the tiger shark is considered to be one of the sharks most dangerous to humans, the attack rate is surprisingly low according to researchers. The tiger is second on the list of number of recorded attacks on humans, with the great white shark being first. They often visit shallow reefs, harbors and canals, creating the potential for encounter with humans. One of the largest sharks living today, the tiger shark commonly attains a length of 3 to 4.2 m (9.8 to 13.8 ft) and weighs around 385–635 kilograms (849–1,400 lb). Sometimes a male tiger shark can grow up to 4.5 meters (14-15 feet long) and females to 5.5 meters (18 feet long). A tiger shark can sometimes rival a great white shark in size. The tiger shark can grow up to 14-20 feet long. The skin of a tiger shark can typically range from blue to light green with a white or light yellow underbelly. Dark spots and stripes are most visible in young sharks and fade as the shark matures. Its head is somewhat wedge-shaped, which makes it easy to turn quickly to one side. They have small pits on the side of their upper bodies which hold electro-receptors called the ampullae of Lorenzini which enable them to detect electric fields, including the bio-electricity generated by prey. Tiger sharks also have a sensory organ called a lateral line which extends on their flanks down most of the length of their sides. The primary role of this structure is to detect minute vibrations in the water. These adaptations allow the tiger shark to hunt in darkness and detect hidden prey. A reflective layer behind the tiger shark's retina called the tapetum lucidum allows light-sensing cells a second chance to capture photons of visible light, enhancing vision in low light conditions. A tiger shark generally has long fins to provide lift as the shark maneuvers through water, while the long upper tail provides bursts of speed. Tiger sharks normally swim using small body movements. Its high back and dorsal fin act as a pivot, allowing it to spin quickly on its axis, though the shark's dorsal fins are distinctively close to its tail. Its teeth are specialized to slice through flesh, bone, and other tough substances such as turtle shells. Like most sharks, however, its teeth are continually replaced by rows of new teeth.
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.
Tiger Shark - Galeocerdo cuvier
The tiger shark, Galeocerdo cuvier, is a species of requiem shark and the only member of the genus Galeocerdo. Commonly known as sea tiger, the tiger shark is a relatively large macropredator, capable of attaining a length of over 5 m (16 ft). It is found in many tropical and temperate waters, and is especially common around central Pacific islands. Its name derives from the dark stripes down its body which resemble a tiger's pattern, which fade as the shark matures. The tiger shark is a solitary, mostly night-time hunter. Its diet involves a wide range of prey, including crustaceans, fish, seals, birds, smaller sharks, squid, turtles, sea snakes, and dolphins. The tiger shark is considered a near threatened species due to finning and fishing by humans. While the tiger shark is considered to be one of the sharks most dangerous to humans, the attack rate is surprisingly low according to researchers. The tiger is second on the list of number of recorded attacks on humans, with the great white shark being first. They often visit shallow reefs, harbors and canals, creating the potential for encounter with humans. One of the largest sharks living today, the tiger shark commonly attains a length of 3 to 4.2 m (9.8 to 13.8 ft) and weighs around 385–635 kilograms (849–1,400 lb). Sometimes a male tiger shark can grow up to 4.5 meters (14-15 feet long) and females to 5.5 meters (18 feet long). A tiger shark can sometimes rival a great white shark in size. The tiger shark can grow up to 14-20 feet long. The skin of a tiger shark can typically range from blue to light green with a white or light yellow underbelly. Dark spots and stripes are most visible in young sharks and fade as the shark matures. Its head is somewhat wedge-shaped, which makes it easy to turn quickly to one side. They have small pits on the side of their upper bodies which hold electro-receptors called the ampullae of Lorenzini which enable them to detect electric fields, including the bio-electricity generated by prey. Tiger sharks also have a sensory organ called a lateral line which extends on their flanks down most of the length of their sides. The primary role of this structure is to detect minute vibrations in the water. These adaptations allow the tiger shark to hunt in darkness and detect hidden prey. A reflective layer behind the tiger shark's retina called the tapetum lucidum allows light-sensing cells a second chance to capture photons of visible light, enhancing vision in low light conditions. A tiger shark generally has long fins to provide lift as the shark maneuvers through water, while the long upper tail provides bursts of speed. Tiger sharks normally swim using small body movements. Its high back and dorsal fin act as a pivot, allowing it to spin quickly on its axis, though the shark's dorsal fins are distinctively close to its tail. Its teeth are specialized to slice through flesh, bone, and other tough substances such as turtle shells. Like most sharks, however, its teeth are continually replaced by rows of new teeth.
