Walrus

• 1. Introduction

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  At the Tierpark Hagenbeck, walruses easily pulled a five-pound metal plug out of the bottom of their pool, even though it sat under 1.1 metres of water. The animal behind that feat is the walrus, Odobenus rosmarus, a large marine mammal with a patchy distribution around the North Pole. It lives in the Arctic Ocean and in the subarctic seas of the Northern Hemisphere. Adults carry prominent tusks, a thick mat of whiskers and an enormous amount of bulk. Biologists call the walrus a keystone species of the Arctic marine region, and many Arctic peoples have woven it into their cultures. This documentary asks a handful of questions. Why does a word that looks Latin come from the Norse languages? How does an animal find its food in murky water? Why do single walruses sometimes turn up in Spain or Finland? And what happened when whalers and sealers came north for its ivory?

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• 2. Name and Lineage

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  The Old Norse word hrosshvalr, meaning 'horse-whale', is thought to lie behind the English word walrus. Despite its Latin-looking shape, the word is Germanic, and scholars attribute it to Dutch or Old Norse. Its first half comes from hvalr, 'whale', and its second half from hross, 'horse'. The compound probably reached Dutch and the dialects of northern Germany in inverted form, as walros and Walross. A rival theory builds it from the Dutch words wal, 'shore', and reus, 'giant'.

  A Norwegian manuscript called Konungs skuggsjá, thought to date from around AD 1240, gives rosmhvalr as the Icelandic term and rostungr as the Greenlandic one. By then, the source notes, walruses were already gone from Iceland and Norway, while the word kept evolving in Greenland. Place names such as Hvalfjord, Hvallatrar and Hvalsnes may mark old walrus breeding grounds in Iceland, Greenland and Norway.

  Olaus Magnus drew the animal on his Carta Marina in 1539 and called it the ros marus, probably a Latin reworking of the Slavic morž. Linnaeus later adopted that form for his scientific naming. The archaic English word morse shares those Slavic roots, as seen in the Russian морж, the Finnish mursu and the French morse. Ante Aikio traces it back to an unknown language of northern Europe that predates the Finno-Ugric tongues. Morse also happens to resemble the Latin morsus, 'a bite', which supposedly fed the animal's reputation as a terrible monster.

  The genus name Odobenus joins the Greek odous, 'teeth', with baino, 'walk'. Naturalists chose it after watching walruses haul themselves out of the water on their tusks. The Inuktitut word for the animal is aiviq.

  The walrus belongs to the order Carnivora and is the sole survivor of the family Odobenidae. Recent genetic evidence suggests that walruses, true seals and eared seals all descend from a caniform ancestor most closely related to modern bears. A multigene analysis puts the split between true seals and the walrus-and-eared-seal line at 20-26 million years ago. Walruses and eared seals parted ways 15-20 million years ago.

  Odobenidae was once a diverse and widespread family of at least twenty species, grouped in the subfamilies Imagotariinae, Dusignathinae and Odobeninae. Its early defining trait was a squirt and suction style of feeding. Tusks came later and belong only to Odobeninae, of which the modern walrus is the last relict species.

  Two subspecies are widely accepted. The Atlantic walrus, O. r. rosmarus, was named by Linnaeus in 1758, and the Pacific walrus, O. r. divergens, by Illiger in 1815. Fixed genetic differences point to very limited gene flow and a split between 500,000 and 785,000 years ago. That timing fits fossil evidence that the walrus evolved from a tropical or subtropical ancestor, isolated in the Atlantic, that slowly adapted to Arctic cold. An isolated group in the Laptev Sea was once treated as a third subspecies, O. r. laptevi, described by Chapskii in 1940. It has since been shown to be of Pacific walrus origin.

  The fossil record shows walruses living far south of the ice. A large breeding population survived on Sable Island, 100 miles southeast of Nova Scotia, until the early Colonial period. Abundant remains from the southern North Sea date to the Eemian interglacial. Fossils from Vancouver and from the Atlantic coast as far south as North Carolina belong to glacial periods. A 28,000-year-old walrus was even dredged up from the bottom of San Francisco Bay.

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• 3. Built for Ice

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  Most male Pacific walruses weigh between 800 and 1700 kg, and a few outsized bulls reach 2000 kg. In 1909, a hide weighing 500 kg came from an enormous bull in Franz Josef Land. In August 1910, Jack Woodson shot a 4.9 m walrus and harvested a 450 kg hide. A hide usually makes up about 20% of body weight, so these two giants were estimated at 2300 kg or more. A 2015 study by McClain and colleagues found both records hard to verify. Its most reliable maximum was a male measuring 3.8 m and weighing 1883 kg, with 3.95 m as the longest accurate length.

  The Atlantic subspecies weighs 10-20% less than the Pacific one, with males averaging 900 kg. Atlantic walruses also tend to have shorter tusks and a flatter snout. Females weigh about two-thirds as much as males, averaging 560 kg in the Atlantic and 800 kg in the Pacific. Overall, only the two elephant seals outweigh the walrus among pinnipeds. Blubber under the skin keeps the animal warm and stores energy.

  Its body mixes traits from two seal families. Like eared seals, it can swing its rear flippers forward and move on all fours. Like true seals, it has no external ears and swims by flexing its whole body rather than leaning on its flippers. Strong eye muscles and a missing orbital roof let it push its eyes outward and look both forward and upward, though its vision suits only short range.

  Tusks are the walrus's most prominent feature. They are elongated canines found in both sexes, reaching 1 m in length and 5.4 kg in weight. Males have slightly longer, thicker tusks and use them for fighting, dominance and display, and the strongest males with the biggest tusks usually rule social groups. Both sexes use their tusks to cut and keep open holes in the ice and to climb out of the water.

  Researchers once believed tusks dug prey from the seabed. Wear patterns show instead that the tusks drag through sediment while the upper edge of the snout does the digging. Beyond the tusks, walruses have few teeth. The maximum is 38, but over half are rudimentary and appear less than half the time, so a typical walrus has only 18.

  Around the tusks sits a broad mat of stiff bristles called mystacial vibrissae. There can be 400 to 700 of them in 13 to 15 rows, growing to 30 cm. In the wild they are often worn much shorter from constant use. Muscles, blood vessels and nerves feed each one, so the whiskers can tell apart shapes 3 mm thick and 2 mm wide.

  Apart from those whiskers, the walrus is sparsely furred and looks bald. Its wrinkled skin is up to 10 cm thick around the neck and shoulders of males, over a blubber layer up to 15 cm deep. Young walruses are deep brown and turn paler and more cinnamon-colored with age, and old males grow nearly pink. In cold water, constricted blood vessels can make a swimming walrus look almost white. Males also develop lumps called bosses around the neck and shoulders.

  An air sac under the throat works like a flotation bubble, letting the walrus bob upright in the water and sleep. Males also carry a baculum up to 63 cm long, the largest of any land mammal in absolute size and relative to body size. Those whiskers do their hardest work on the seabed, where food is hidden.

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• 4. Feeding and Foes

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  Dives beyond 500 m have been recorded in Smith Sound, between northwest Greenland and Arctic Canada, yet walruses mostly stay in shallow water. A study of Atlantic walruses near Svalbard found their deepest dives averaged only 31 m, give or take 17 m. Peak depth seems to depend on where prey lives and how deep the seabed is. Walruses prefer shelf waters and often forage from platforms of sea ice.

  The diet is wide and opportunistic, covering more than 60 genera of marine life. It includes shrimp, crabs, priapulids, spoon worms, tube worms, soft corals, tunicates, sea cucumbers, snails, octopuses, squid and some slow-moving fish. Clams and other bivalves are the favorite. The walrus grazes along the bottom, finds prey with its whiskers and clears murky sediment with jets of water and flipper movements. For the Pacific walrus, benthic invertebrates make up 97 percent of the diet.

  To eat a clam, the walrus seals its powerful lips over the shellfish and yanks its piston-like tongue back into its mouth. That creates a vacuum, and the meat comes out of the shell. A uniquely vaulted palate helps the suction. Researchers measured oral pressures as low as -87.9 kPa in air and -118.8 kPa underwater.

  The feeding does more than fill a stomach. By stirring up the seafloor, walruses release nutrients into the water, mix and move many small organisms, and make the seabed more patchy.

  Seal tissue turns up in a fairly large share of Pacific walrus stomachs, but how much seals matter to the diet is debated. Isolated observations show walruses preying on seals as large as a 200 kg bearded seal. Seabirds, notably Brünnich's guillemot, have rarely been taken. Preying on ice-trapped narwhals or scavenging whale carcasses may happen, though evidence is thin.

  Because of its size and tusks, the walrus has only two natural predators, the orca and the polar bear. Neither relies heavily on it, and both mostly target calves. Polar bears rush beached groups and eat the animals crushed or wounded in the stampede, typically the young or infirm. Bears also isolate walruses in winter when diving holes in the ice are out of reach.

  Direct attacks are rare, because even an injured walrus is a formidable opponent. Walruses have been known to fatally injure polar bears that follow them into the water, where the bear is at a disadvantage. Those battles are protracted and exhausting, and bears have been known to break off after wounding a walrus. Orcas regularly attack walruses. Walruses are believed to have fought off the larger whales with counterattacks, but orcas have also won with little or no injury. Raising young is far harder for the walrus than feeding itself.

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• 5. Calves and Migration

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  Slowpoke, a captive walrus at SeaWorld Orlando, died at 49, the oldest on record. In the wild, walruses live about 20-30 years. Males can reach sexual maturity as early as 7 years but usually do not mate until they are fully developed at about 15. Females may begin ovulating at 4-6 years and reach physical maturity at 10-12, while males reach it at 15-16.

  From January through April, males rut and sharply cut their food intake. Breeding runs from January to March and peaks in February. Males gather in the water around groups of females on the ice and compete with vocal displays. The females then join them, and mating takes place in the water. Females come into heat twice, in late summer and around February, but males are fertile only around February.

  Gestation lasts 15 to 16 months, and for the first three to four months the blastula sits in suspended development before implanting in the uterus. This delayed implantation is common among pinnipeds. It presumably evolved to time mating and birth to conditions that help newborns survive.

  Calves arrive during the spring migration, from April to June. They weigh 45-75 kg at birth and can already swim. Mothers nurse for over a year, and young may stay with them for up to five years. Walrus milk has more fat and protein than the milk of land animals but less than that of true seals. That leaner milk slows growth and lengthens the mother's nursing commitment.

  Walruses are the only pinnipeds known to suckle young at sea as well as during long stays on ice or land. Ovulation is suppressed until the calf is weaned, so a female gives birth at most every two years. That is the lowest reproductive rate of any pinniped. Males may help inexperienced young learn to swim and have even been recorded caring for orphans. When a group is threatened, all the adults may protect the young.

  Several hundred thousand Pacific walruses migrate from the Bering Sea into the Chukchi Sea each late spring and summer. They pass through the narrow Bering Strait. For the rest of the year, in late summer and fall, walruses form massive aggregations of tens of thousands on rocky beaches and outcrops. The move between ice and shore can be long and dramatic. A few individuals go much further than that, drifting thousands of kilometres from home.

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• 6. Wanderers

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  Between 1815 and 1954-25 walruses were recorded in Scotland, one in England and one in Ireland. Another six turned up in Scotland and one in England from 1955 to 1986. Mainland Norway sees them more often, with 31 recorded between 1900 and 1967. Svalbard is not counted there, since walruses live in it year-round. Walruses tend to wander southwards from their usual range.

  In recent years, western Europe's visiting walruses have drawn large crowds and heavy press coverage. People give the animals popular names and follow their travels. Individuals can be recognised from scars and from the size of their tusks.

  Wally, a male, was first seen at Valentia Island, Ireland, in March 2021. He moved on to the Pembrokeshire coast in Wales, then western France and Bilbao in Spain. He later went back north to the Isles of Scilly, returned to Ireland and finally headed to Iceland.

  Freya, a five-year-old female, was first sighted in the northern North Sea in 2019. She received her name only after appearing in the Netherlands in October 2021. She then visited several North Sea sites until she was shot near Oslo in Norway on the 13th of August 2022.

  Stena, a female thought to be over 20 years old, was first seen at Vigra near Ålesund on Norway's west coast in March 2022. From there she traveled via Denmark and southwest Sweden to Rügen, Germany, by June 2022. She then visited several Baltic Sea sites and ended up in Kymenlaakso, Finland, still in 2022. That was the first record of a walrus in the northern Baltic Sea. She was healthy at first but could not find enough food in the Baltic. She became emaciated and died when rescuers tried to transport her for treatment.

  Thor, a male of about 8 years, was first seen in the Netherlands on the 6th of November 2022. He moved west to Brittany in northern France, crossed the English Channel and then headed north along England's east coast. He reached Northumberland on the 2nd of January 2023. He then returned to the Arctic and was last seen at Breiðdalsvík, Iceland, on the 24th of February 2023. Iceland had a walrus story of its own long before Thor arrived.

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• 7. Hunted and Counted

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  Flippers fermented and stored until spring were a delicacy for traditional walrus hunters, who used nearly every part of the animal. Preserved meat was an important winter food. Tusks and bone became tools and handicrafts, and rendered oil gave warmth and light. The tough hide made rope and coverings for houses and boats, and gut linings made waterproof parkas. Walrus meat is still an important local food, and tusk carving and engraving remain a vital art form.

  Around 1213-1330 AD, a genetically distinct walrus population in Iceland was wiped out after Norse settlement. Much later, in the 18th and 19th centuries, American and European sealers and whalers heavily exploited the species and nearly destroyed the Atlantic subspecies. As early as 1871, traditional hunters voiced concern about how many walruses whaling fleets were taking. The Adolf Erik Nordenskiöld account adds that European hunters and Arctic explorers found the meat unappealing and ate it only from necessity, though they treated walrus tongue as a delicacy.

  As late as the 18th century, the Greater Gulf of St. Lawrence held large numbers of Atlantic walruses, sometimes in colonies of 7,000-8,000. Commercial harvest nearly eradicated them. In April 2006, Canada's Species at Risk Act listed northwestern Atlantic walruses in Québec, New Brunswick, Nova Scotia, Newfoundland and Labrador as eradicated in Canada. Atlantic walrus numbers, though hard to estimate, probably remain below 20,000.

  The Pacific walrus also fell, to between 50,000 and 100,000 in the 1950s and 1960s. Limits on commercial hunting let numbers climb to a peak in the 1970s and 1980s, with aerial surveys every five years from 1975 to 1985 each estimating more than 220,000. There were roughly 200,000 in 1990, and an aerial census combined with satellite tracking put the figure near 129,000 in 2006. By 2018, the global estimate stood at 112,500 mature individuals. The isolated Laptev Sea population is estimated at 5,000-10,000.

  In 1952, ivory hunting over 300 years had left Svalbard's walruses nearly gone. Norway then banned commercial hunting there, and by 2018 the area held an estimated 5,503 walruses. Commercial harvesting is now outlawed across the whole range. Chukchi, Yupik and Inuit peoples may still take small numbers near the end of each summer.

  Resource managers in Russia, the United States, Canada and Greenland regulate hunts together with hunting communities. An estimated 4,000-7,000 Pacific walruses are taken each year in Alaska and Russia, about 42% of them struck and lost. Several hundred more are removed annually around Greenland. Uncertain population estimates make it hard to judge whether these levels are sustainable.

  Climate change adds a further worry. Pack ice has fallen to unusually low extent and thickness in several recent years, yet walruses rely on it for giving birth and gathering to breed. Thinner ice over the Bering Sea has cut resting habitat near good feeding grounds. That separates nursing females from their calves, which raises nutritional stress for the young and lowers reproduction. Less coastal sea ice has also been linked to more stampede deaths on the crowded Chukchi Sea shores between eastern Russia and western Alaska. A 2012 analysis of ice trends suggests Pacific walruses will keep declining and shift further north, though careful management might limit the damage.

  Official status varies. Two of the three walrus subspecies are listed as least concern by the IUCN, and the third is data deficient. The Pacific walrus is not listed as depleted under the Marine Mammal Protection Act, nor as threatened or endangered under the Endangered Species Act. The Russian Atlantic and Laptev Sea populations are Category 2 (decreasing) and Category 3 (rare) in the Russian Red Book. A CITES Appendix III listing restricts global trade in walrus ivory. In October 2017, the Center for Biological Diversity said it would sue the U.S. Fish and Wildlife Service to force a threatened or endangered listing for the Pacific walrus. Hunters' trophies still chase the biggest tusks, and the Boone and Crockett record book lists Atlantic and Pacific entries just over 30 inches and 37 inches long.

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• 8. Walrus in Story

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  In a Chukchi version of the widespread Raven myth, a daughter is thrown from a high cliff and turns into a walrus as she falls into the water. Her angry father throws her after Raven recovers the sun and the moon from an evil spirit by seducing her. Legends say the tusks are either the trails of her mucus as she weeps or her long braids. The myth may be related to a Chukchi tale of an old walrus-headed woman who rules the seabed, who in turn is linked to the Inuit goddess Sedna.

  In both Chukotka and Alaska, the aurora borealis is believed to be a special world for people who died by violence. The shifting rays are their souls playing ball with a walrus head. Skin and bone are used in some ceremonies, and the walrus appears often in legends across the Arctic.

  Most of the distinctive 12th-century Lewis Chessmen of northern Europe were carved from walrus ivory, although a few were found to be made of whales' teeth.

  Because of its tusks, bulk and whiskers, the walrus also turns up in the popular cultures of peoples with little direct experience of it. English children's literature is the best example. Lewis Carroll's poem "The Walrus and the Carpenter" appeared in his 1871 book Through the Looking-Glass. In it, the two title characters trick a great number of oysters and eat them. Carroll captured the walrus's appetite for bivalves, but oysters live mostly near shore and in the intertidal zone and make up an insignificant part of its diet in captivity. The Beatles' cryptic song "I Am the Walrus" refers to Carroll's poem.

  Rudyard Kipling's story "The White Seal" in The Jungle Book offers another portrait. Kipling calls his walrus the old Sea Vitch, the "big, ugly, bloated, pimpled, fat-necked, long-tusked walrus of the North Pacific, who has no manners except when he is asleep". Few readers of that line have ever seen the animal in the wild.

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