Walrus
| Walrus | |
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| The Pacific Walrus | |
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| Family: | Odobenidae Allen, 1880
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| Genus: | Odobenus Brisson, 1762
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| Species: | O. rosmarus
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| Binomial name | |
| Odobenus rosmarus | |
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O. rosmarus rosmarus | |
Walruses also known as Kanika, are large semi-aquatic mammals that live in the cold Arctic seas of the Northern Hemisphere. There are six populations in the Arctic: four in the Atlantic Ocean, one in the Pacific Ocean, and one in the Laptev Sea. Two or three subspecies exist: Odobenus rosmarus rosmarus of the Atlantic, Odobenus r. divergens of the Pacific, and Odobenus r. laptevi of the Laptev Sea, considered by some to be a third subspecies. The Pacific walrus is slightly larger, with males weighing up to 1,900 kg (4,180 lb), but Atlantic males top out at 1,600 kg (3,500 lb). The walrus should not be confused with the elephant seal, another large pinniped, and despite the etymology of its name (variously attributed to combinations of the Dutch words for "whale" walvis and "horse" ros[1] or "shore" wal and "giant" reus[2]), it is not related to the whales. The most likely origin of the word is Old Norse hrossvalr "horse-whale", which was passed in a juxtaposed form to Dutch and the North-German dialects of the Hanseatic league as walros, Walross [Dansk Etymologisk Ordbog, Niels Age Nielsen, Gyldendal 1966].
Walruses are members of the order Carnivora and suborder (or alternatively superfamily) Pinnipedia. They are the only members in the family Odobenidae. The compound Odobenus comes from odous (Greek for "tooth") and baino (Greek for "walk"), based on observations of walruses using their tusks to pull themselves out of the water. Divergens in Latin means "turning apart", referring to the tusks.
Lifestyle and feeding
Walruses spend about half their time in the water and half their time on beaches or ice floes, where they gather in large herds. They may spend several days at a time either on land or in the sea. Diving to depths of 90 m (300 ft), they sometimes stay under for as long as a half hour. They use their pectoral flippers to move along out of water and can stand on all fours with an awkward gait when on rough surfaces.
In the sea they sometimes catch fish, but generally graze along the sea bottom for clams which they suck from the shell. Pacific walruses feed on more than 60 genera of marine organisms including shrimp, crabs, tube worms, soft coral, tunicates, sea cucumbers, various mollusks, and even parts of other pinnipeds. Abrasion patterns of the tusks show that the tusks are dragged through the sediment but are not used to dig up prey and the upper edge of the snout is used instead. Walruses can also spit jets of water to look for clams. Clams and mollusks frequently form the large part of their diet. Large male walruses have been observed to attack seals if they cannot find any other food source.
Walruses have only two natural enemies: the orca and the polar bear. Polar bears hunt walruses by rushing at them, trying to get the herd to flee, then picking off calves or other stragglers. Walruses have been known to kill polar bears.
Walruses use their long tusks (elongated canines) for fighting, dominance, and display and the males will spar with their tusks. They can also use them to form and maintain holes in the ice, or to anchor themselves with the ice.
Physical description and life cycle
Walruses have thick skin and it can get to 5cm (2in) thick around the neck and shoulders of males.
Walruses live around 50 years. The males reach sexual maturity around 10 years yet some as early as 7. They go into rut in January through April, increasing their food intake before the rut, yet then decreasing their food intake dramatically and eating only sporadically during the rut. The females can begin ovulating as soon as 4–6 years old. Interestingly the females are polyestrous, coming into heat in late summer and also around February, yet the males are only fertile around February so the animals are in practicality monoestrous. It is unclear why the females have this second season of potential fertility. By ten years old the females have reached maximum size and all are fertile by then. They breed in January to March with peak conception in February, and perhaps have a delayed implantation for a few months (4-5) with total gestation lasting 15–16 months. Walruses mate in the water and give birth on land or ice floes. The males show off in the water for the females who view them from pack ice. Males compete with each other aggressively for this display-space; the winners in these fights breed with large numbers of females. Older male walruses frequently bear large scars from these bloody but rarely fatal battles. When a calf is born, it is over 1 m (3 ft) long and able to swim. The calves are born on the pack ice generally April to June and then generally nurse for 8–11 months before they begin eating fish on their own and can spend 3 to 5 years with the mothers.
Pacific
About 200,000 Pacific walruses exist. Pacific walruses spend the summer north of the Bering Strait in the Chukchi Sea along the north shore of eastern Siberia, around Wrangel Island, in the Beaufort Sea along the north shore of Alaska, and in the waters between those locations. Smaller numbers of males summer in the Gulf of Anadyr on the south shore of the Chukchi Peninsula of Siberia and in Bristol Bay off the south shore of southern Alaska west of the Alaska Peninsula. In the spring and fall they congregate in the Bering Strait, adjacent to the west shores of Alaska, and in the Gulf of Anadyr. They winter to the south in the Bering Sea along the eastern shore of Siberia south to the northern part of the Kamchatka Peninsula, and along the southern shore of Alaska. The Pacific walruses can have longer tusks and smaller noses.
Atlantic
About 15,000 Atlantic walruses exist: they live in the Canadian Arctic, in the waters of Greenland, of Svalbard and of the western portion of the Russian Arctic. The Atlantic walrus once enjoyed a range that extended south to Cape Cod and occurred in large numbers in the Gulf of St. Lawrence.
Medical problems
Eye problems for the walrus are common and they sometimes experience intestinal disease. They sometimes get tusk infections, and in captivity are prone to ingesting foreign objects. Also various common fungal and bacterial sometimes cause minor infections. Trampling and tusk injuries occur during interactions and sometimes females are harassed and show bruises and laceration.
The Atlantic walruses show exposure to the bacteria Brucella and sometimes will show infection with Trichinella and also lice. Caliciviruses are thought to sometimes affect Pacific walruses causing skin lesions and they are thought to have a wide exposure to the viruses. These viruses are thought to interact between terrestrial and aquatic mammals, with marine mammals showing antibodies to many caliciviruses that affect land mammals. Herpesviruses can also be seen sometimes in the walrus population.
Walruses in captivity often suffer tusk injuries from banging them against their enclosures, which do not have the "give" of their natural habitat. This chipping or breaking frequently leads to infection and often removal of the tusks, as large-scale infections in the tusks can become life-threatening. The removal is usually not a problem for the captive walruses, as they have no need to climb on ice and typically only one male is kept per group, so there is no competition.
The walrus in popular culture
In western culture, fiction often depicts the species—with its plump body, bushy mustache, and peacefully sleepy expression—as a happy, lovable and friendly animal, and its appearance may be interpreted as somewhat comical.
In literature and music
- Farley Mowat's book Sea of Slaughter has a large section dedicated to the effects of hunting on eastern Canada's walrus population.
- Lewis Carroll's famous poem "The Walrus and the Carpenter" inspired the 1967 song "I Am the Walrus" by The Beatles. In the song John Lennon is "the Walrus". However, in order to deliberately confuse his fans, Lennon sings in the later song "Glass Onion" that "the Walrus was Paul". In the solo song "God," Lennon sings "I was the Walrus, but now, I'm John."
- The Walrus is a Canadian news magazine.
- In Salman Rushdie's children's book Haroun and the Sea of Stories, The Walrus is the name of the imposing Grand Controller of Gup.
- Walrus is also the name of Captain Flint's ship in Robert Louis Stevenson's Treasure Island.
In other media
The Walrus is a very commonly seen animal in animation. They are usually portrayed as rugged but experienced and lovable characters, or as aristocratic characters due to the animal's snout looking somewhat like a mustache.
- Rotor the Walrus, a.k.a "Boomer", is a prominent character in SatAM Sonic the Hedgehog animated series as well as the ongoing Sonic the Hedgehog comic book continuity. Rotor is the protagonist group's brave but shy mechanical super-genius and intellectual. He is very friendly and generally fits the archetypal personality of the walrus.
- The Captain of the Thames is an anthropomorphic walrus from the video game Xenogears. He is a demi-human, captain, and all around man of the sea.
- Frost Walrus is one of the Maverick bosses in the video game Mega Man X4.
- EverQuest has many walruses in the world of Norrath.
- Chumley is the sidekick of the title character in the cartoon series Tennessee Tuxedo and His Tales. He is good natured if a bit dim.
- Wally Walrus is a character from the Woody Woodpecker cartoons. He was the nemesis as well as rival of the title character.
- McSweeny, a large and muscular walrus, is a very minor character from the Sly Cooper series of video games.
- Walrein, a Monster Blue Walrus in Pokémon
- Bletch is the name of the walrus of the film by director Peter Jackson, Meet The Feebles. Unlike the passive image of walruses, Bletch is very mean and cheats on his hippopotamus lover with a cat.
- Wendell is the starving walrus in the Animal Crossing video game series.
- Wozza the Walrus is a purple walrus from Banjo-Kazooie who lives in Freezeezy Peak inside a cave.
- Craig Stadler, a golfer formerly on the PGA Tour in the United States who now competes on the Champions Tour for golfers age 50 and over, is nicknamed the Walrus for his portly build and mustache.
- Tuskernini is an anthropomorphic walrus villain on the Darkwing Duck cartoon.
- Jocco is the walrus pal to Henry in the movie 50 First Dates.
- Tusky is Aquaman's pet in The Superman/Aquaman Hour of Adventure cartoons.
Trivia
- Savoonga, Alaska calls itself the "Walrus Capital of the World".
- A male walrus' penis is completely internal; however, it has one of the largest bacula (penis bones) of the animal kingdom.
References
- Template:IUCN2006
- Marine Mammal Medicine, Leslie Dierauf and Frances Gulland, CRC Press 2001, ISBN 0-8493-0839-9
- Annales des sciences naturelles. Zoologie et biologie animale. Paris, Masson. ser.10:t.7
- Tagging and tracking Atlantic walrus (BBC Walrus tracker).