Walrus
Encyclopedia
The walrus 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 immediately recognized by its prominent tusk
s, whiskers and great bulk. Adult Pacific males can weigh up to 1700 kilograms (3,747.9 lb) and, among pinniped
s, are exceeded in size only by the two species of elephant seal
s. 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 ecosystem
s.
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.
words walvis ("whale") and ros ("horse") or wal ("shore") and reus ("giant"). However, the most likely origin of the word is the Old Norse
hrossvalr, meaning "horse-whale", which was passed in an inverted form to Dutch and the North-German dialects as walros and Walross.
The now archaic English word for walrus—morse—is widely supposed to have come from the Slavic
. Thus морж (morž) in Russian
, mursu in Finnish
, moršâ in Saami, and morse in French
. Olaus Magnus
, who depicted the walrus in the carta marina
in 1539, first referred to it as the ros marus, likely a Latinization of morž, and this was adopted by Linnaeus in the binomial nomenclature
. The coincidental similarity between "morsus" and the Latin for "death" (mors) and "to bite" (mordere) supposedly contributed to the walrus' reputation as a "terrible monster".
The compound Odobenus comes from odous (Greek
for "tooth") and baino (Greek for "walk"), based on walrus observations using their tusks to pull themselves out of the water. The term divergens in Latin
means "turning apart", referring to the tusks.
Carnivora
. It is the sole surviving member of the family
Odobenidae, one of three lineages in the suborder Pinnipedia along with true seals (Phocidae) and eared seals (Otariidae). While there has been some debate as to whether all three lineages are monophyletic, i.e. descended from a single ancestor, or diphyletic, recent genetic evidence suggests that all three descended from a caniform ancestor most closely related to modern bear
s. Recent multigene analysis indicates that the odobenids and otariids diverged from the phocids approximately 20–26 million years ago, while the odobenids and the otariids separated 15–20 million years ago. Odobenidae was once a highly diverse and widespread family, including at least twenty species in the Imagotariinae, Dusignathinae and Odobeninae subfamilies. The key distinguishing feature was the development of a squirt/suction feeding mechanism; tusks are a later feature specific to Odobeninae, of which the modern walrus is the last remaining (relict
) species.
Two subspecies are commonly recognized: the Atlantic Walrus, O. r. rosmarus (Linnaeus, 1758) and the Pacific Walrus, O. r. divergens (Illiger, 1815). Fixed genetic differences between the Atlantic and Pacific subspecies indicate very restricted gene flow, but relatively recent separation, estimated at 500,000 and 785,000 years ago. These dates coincide with the fossil-derived hypothesis that the walrus evolved from a tropical or sub-tropical ancestor that became isolated in the Atlantic Ocean and gradually adapted to colder conditions in the Arctic. From there, it presumably re-colonized the North Pacific during high glaciation periods in the Pleistocene
via the Central American Seaway
. An isolated population in the Laptev Sea
is considered by some, including Russian biologists and the canonical Mammal Species of the World, to be a third subspecies, O. r. laptevi (Chapskii, 1940), and is managed as such in Russia. Where the subspecies separation is not accepted, whether to consider it a subpopulation of the Atlantic or Pacific subspecies remains under debate.
While isolated Pacific males can weigh as much as 2000 kg (4,409.2 lb), most weigh between 800 and 1800 kg (1,763.7 and 3,968.3 lb). Females weigh about two-thirds as much, sometimes as little as 400 kg (880 lbs). 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
. 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 seal
s: 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.
of walruses is highly variable, they generally have relatively few teeth other than the tusks. The maximal number of teeth is 38 with dentition formula: , but over half of the teeth are rudimentary and occur with less than 50% frequency, such that a typical dentition includes only 18 teeth
beneath is up to 15 cm (5.9 in) thick. Young walruses are deep brown and grow paler and more cinnamon-colored as they age. Old males, in particular, become nearly pink. Because skin blood vessels constrict in cold water, the walrus can appear almost white when swimming. As a secondary sexual characteristic, males also acquire significant nodules, called bosses, particularly around the neck and shoulders.
The walrus has an air sac under its throat which acts like a floatation bubble and allows it to bob vertically in the water and sleep. The males possess a large baculum
(penis bone), up to 63 cm (24.8 in) in length, the largest of any land mammal, both in absolute size and relative to body size.
Gestation
lasts 15 to 16 months. The first 3 to 4 months are spent with the blastula
in suspended development before it implants itself in the placenta. This strategy of delayed implantation, common among pinnipeds, presumably evolved to optimize both the mating season and the birthing season, determined by ecological conditions that promote newborn survival. Calves are born during the spring migration, from April to June. They weigh 45 kilogram at birth and are able to swim. The mothers nurse for over a year before weaning, but the young can spend up to 3 to 5 years with the mothers. Because ovulation is suppressed until the calf is weaned, females give birth at most every two years, leaving the walrus with the lowest reproductive rate of any pinniped.
.
The majority of the Pacific Walrus population summers 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 Siberia's Chukchi Peninsula
and in Bristol Bay off the south shore of southern Alaska west of the Alaska Peninsula
. In the spring and fall they congregate throughout the Bering Strait, reaching from the west shores of Alaska to the Gulf of Anadyr. They winter in the Bering Sea along the eastern shore of Siberia south to the northern part of the Kamchatka Peninsula
, and along Alaska's southern shore. A 28,000 year old fossil walrus specimen was dredged out of San Francisco Bay
, indicating that the Pacific Walrus ranged far south during the last ice age
.
The much smaller Atlantic population ranges from the Canadian Arctic, Greenland
, Svalbard
and the western portion of the Russian Arctic. There are eight presumed sub-populations based largely on geographical distribution and movement data, five to the west of Greenland and three to the east. The Atlantic Walrus once ranged south to Cape Cod
and occurred in large numbers in the Gulf of St. Lawrence. In April 2006, the Canadian Species at Risk Act listed the Northwest Atlantic Walrus population (Québec
, New Brunswick
, Nova Scotia
, Newfoundland and Labrador
) as being extirpated in Canada
.
The isolated Laptev population is confined year-round to the central and western regions of the Laptev Sea
, the easternmost regions of the Kara Sea
, and the westernmost regions of the East Siberian Sea
. Current populations are estimated to be between 5,000 and 10,000 individuals.
Their limited diving ability brings them to depend on shallow waters (and appropriate nearby ice coverage) to enable them to reach their preferred benthic prey.
The Atlantic Walrus was nearly eradicated by commercial harvest and has a much smaller population. Good estimates are difficult to obtain, but the total population is probably below 20,000.
Walruses prefer shallow shelf
regions and forage primarily on the sea floor, often from sea ice platforms. They are not particularly deep divers compared to other pinnipeds: the deepest recorded dives are around 80 m (260 ft). They can remain submerged for as long as half an hour.
The walrus has a diverse and opportunistic diet, feeding on more than 60 genera of marine organisms including shrimp
, crab
s, tube worm
s, soft coral
s, tunicate
s, sea cucumbers, various mollusks, and even parts of other pinnipeds. However, it prefers benthic bivalve mollusks, especially clam
s, for which it forages by grazing along the sea bottom, searching and identifying prey with its sensitive vibrissae
and clearing the murky bottoms with jets of water and active flipper movements. The walrus sucks the meat out by sealing its powerful lips to the organism and withdrawing its tongue, piston-like, rapidly into its mouth, creating a vacuum. The walrus palate is uniquely vaulted, enabling effective suction.
Aside from the large numbers of organisms actually consumed by the walrus, its foraging has a large peripheral impact on benthic communities. It disturbs (bioturbates
) the sea floor, releasing nutrients into the water column, encouraging mixing and movement of many organisms and increasing the patchiness of the benthos
.
Seal tissue has been observed in fairly significant proportion of walrus stomachs in the Pacific, but the importance of seals in the walrus diet is under debate. There have been isolated observations of walruses preying on seals up to the size of a 200 kg (440.9 lb) Bearded seal
. There have been rare documented incidents of walruses preying on seabirds, particularly the Brünnich's Guillemot
Uria lomvia.
and the polar bear
. The walrus does not, however, comprise a significant component of either predator's diet. Both the orca and the polar bear are also most likely to prey on walrus calves. The polar bear often hunts the walrus by rushing at beached aggregations and consuming individuals that are crushed or wounded in the sudden exodus, typically younger or infirm animals. The bears also isolate walruses when the walrus overwinter and are unable to escape a charging bear due to inaccessible diving holes in the ice. However, even an injured walrus is a formidable opponent for a polar bear, and direct attacks are rare. Polar bear–walrus battles are often extremely protracted and exhausting and bears have been known to forgo the attack after injuring a walrus. Orcas regularly attack walrus although it is believed that walruses have successfully defended themselves via counterattack against the larger cetacean.
In the 18th and 19th centuries, the walrus was heavily exploited by American and European sealers
and whalers
, leading to the near extirpation
of the Atlantic population. Commercial walrus harvesting is now outlawed throughout its range, although Chukchi
, Yupik and Inuit
peoples, continue to kill small numbers towards the end of each summer.
Traditional hunters used all parts of the walrus. The meat, often preserved, is an important winter nutrition source; the flippers are fermented and stored as a delicacy until spring; tusks and bone were historically used for tools as well as material for handicrafts; the oil was rendered for warmth and light; the tough hide made rope and house and boat coverings; the intestines and gut linings made waterproof parkas; etc. While some of these uses have faded with access to alternative technologies, walrus meat remains an important part of local diets, and tusk carving and engraving remain a vital art form.
Walrus hunts are regulated by resource managers in Russia
, the United States
, Canada
and Denmark
and representatives of the respective hunting communities. An estimated 4–7,000 Pacific Walruses are harvested in Alaska
and Russia, including a significant portion (approx. 42%) of struck and lost animals. Several hundred are removed annually around Greenland
. The sustainability of these levels of harvest is difficult to determine given uncertain population estimates and parameters such as fecundity
and mortality
.
The effects of global climate change are another element of concern. The extent and thickness of the pack ice has reached unusually low levels in several recent years. The walrus relies on this ice while giving birth and aggregating in the reproductive period. Thinner pack ice over the Bering Sea has reduced the amount of resting habitat near optimal feeding grounds. This more widely separates lactating females from their calves, increasing nutritional stress for the young and lower reproductive rates. Reduced coastal sea ice has also been implicated in the increase of stampeding deaths crowding the shorelines of the Chukchi Sea
between eastern Russia and western Alaska. However, there is insufficient climate data to make reliable predictions on population trends.
Currently, two of the three walrus subspecies are listed as "least-concern" by the IUCN, while the third is "data deficient". The Pacific Walrus is not listed as "depleted" according to the Marine Mammal Protection Act
nor as "threatened" or "endangered" under the Endangered Species Act
. The Russian Atlantic and Laptev Sea populations are classified as Category 2 (decreasing) and Category 3 (rare) in the Russian Red Book
. Global trade in walrus ivory
is restricted according to a CITES Appendix 3 listing.
The walrus plays an important role in the religion
and folklore
of many Arctic
peoples. Skin and bone are used in some ceremonies and the animal appears frequently in legends. For example, in a Chukchi
version of the widespread myth of the Raven, in which Raven
recovers the sun and the moon from an evil spirit by seducing his daughter, the angry father throws the daughter from a high cliff and, as she drops into the water, she turns into a walrus — possibly the original walrus. According to various legends, the tusks are formed either by the trails of mucus from the weeping girl or her long braids. This myth is possibly related to the Chukchi myth of the old walrus-headed woman who rules the bottom of the sea, who is in turn linked to the Inuit goddess Sedna
. Both in Chukotka
and Alaska
, the aurora borealis is believed to be a special world inhabited by those who died by violence, the changing rays representing deceased souls playing ball with a walrus head.
Because of its distinctive appearance, great bulk and immediately recognizable whiskers and tusks, the walrus also appears in the popular cultures of peoples with little direct experience with the animal, particularly in English children's literature. Perhaps its best-known appearance is in Lewis Carroll
's whimsical poem The Walrus and the Carpenter
that appears in his 1871 book Through the Looking-Glass
. In the poem, the eponymous anti-heroes use trickery to consume a great number of oyster
s. Although Carroll accurately portrays the biological walrus's appetite for bivalve mollusks, oysters, primarily nearshore and intertidal inhabitants, in fact comprise an insignificant portion of its diet, even in captivity.
Another appearance of the walrus in literature is in the story The White Seal in Rudyard Kipling
's The Jungle Book
, where it is 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".
Walruses also appear in the songs "I Am the Walrus
", "Glass Onion
" and "Come Together
" by The Beatles
.
Pinniped
Pinnipeds or fin-footed mammals are a widely distributed and diverse group of semiaquatic marine mammals comprising the families Odobenidae , Otariidae , and Phocidae .-Overview: Pinnipeds are typically sleek-bodied and barrel-shaped...
marine mammal
Marine mammal
Marine mammals, which include seals, whales, dolphins, and walruses, form a diverse group of 128 species that rely on the ocean for their existence. They do not represent a distinct biological grouping, but rather are unified by their reliance on the marine environment for feeding. The level of...
with a discontinuous circumpolar distribution in the Arctic Ocean
Arctic Ocean
The Arctic Ocean, located in the Northern Hemisphere and mostly in the Arctic north polar region, is the smallest and shallowest of the world's five major oceanic divisions...
and sub-Arctic seas of the Northern Hemisphere
Northern Hemisphere
The Northern Hemisphere is the half of a planet that is north of its equator—the word hemisphere literally means “half sphere”. It is also that half of the celestial sphere north of the celestial equator...
. The walrus is the only living species in the Odobenidae family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
and Odobenus genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
. It is subdivided into three subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
: the Atlantic walrus (O. rosmarus rosmarus) which lives in the Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
, the Pacific walrus (O. rosmarus divergens) which lives in the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
, and O. rosmarus laptevi, which lives in the Laptev Sea
Laptev Sea
The Laptev Sea is a marginal sea of the Arctic Ocean. It is located between the northern coast of Siberia, the Taimyr Peninsula, Severnaya Zemlya and the New Siberian Islands. Its northern boundary passes from the Arctic Cape to a point with co-ordinates of 79°N and 139°E, and ends at the Anisiy...
.
The walrus is immediately recognized by its prominent tusk
Tusk
Tusks are elongated, continuously growing front teeth, usually but not always in pairs, that protrude well beyond the mouth of certain mammal species. They are most commonly canines, as with warthogs, wild boar, and walruses, or, in the case of elephants and narwhals, elongated incisors...
s, whiskers and great bulk. Adult Pacific males can weigh up to 1700 kilograms (3,747.9 lb) and, among pinniped
Pinniped
Pinnipeds or fin-footed mammals are a widely distributed and diverse group of semiaquatic marine mammals comprising the families Odobenidae , Otariidae , and Phocidae .-Overview: Pinnipeds are typically sleek-bodied and barrel-shaped...
s, are exceeded in size only by the two species of elephant seal
Elephant seal
Elephant seals are large, oceangoing seals in the genus Mirounga. There are two species: the northern elephant seal and the southern elephant seal . Both were hunted to the brink of extinction by the end of the 19th century, but numbers have since recovered...
s. It resides primarily in shallow oceanic shelf
Continental shelf
The continental shelf is the extended perimeter of each continent and associated coastal plain. Much of the shelf was exposed during glacial periods, but is now submerged under relatively shallow seas and gulfs, and was similarly submerged during other interglacial periods. The continental margin,...
habitat, spending a significant proportion of its life on sea ice in pursuit of its preferred diet of benthic
Benthic zone
The benthic zone is the ecological region at the lowest level of a body of water such as an ocean or a lake, including the sediment surface and some sub-surface layers. Organisms living in this zone are called benthos. They generally live in close relationship with the substrate bottom; many such...
bivalve mollusks
Bivalvia
Bivalvia is a taxonomic class of marine and freshwater molluscs. This class includes clams, oysters, mussels, scallops, and many other families of molluscs that have two hinged shells...
. It is a relatively long-lived, social animal and is considered a keystone species
Keystone species
A keystone species is a species that has a disproportionately large effect on its environment relative to its abundance. Such species play a critical role in maintaining the structure of an ecological community, affecting many other organisms in an ecosystem and helping to determine the types and...
in Arctic marine ecosystem
Ecosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....
s.
The walrus has played a prominent role in the cultures of many indigenous Arctic peoples, who have hunted the walrus for its meat
Meat
Meat is animal flesh that is used as food. Most often, this means the skeletal muscle and associated fat and other tissues, but it may also describe other edible tissues such as organs and offal...
, fat
Fat
Fats consist of a wide group of compounds that are generally soluble in organic solvents and generally insoluble in water. Chemically, fats are triglycerides, triesters of glycerol and any of several fatty acids. Fats may be either solid or liquid at room temperature, depending on their structure...
, skin
Skin
-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...
, tusks and bone
Bone
Bones are rigid organs that constitute part of the endoskeleton of vertebrates. They support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue...
. In the 19th and early 20th centuries, the walrus was the object of heavy commercial exploitation for blubber
Blubber
Blubber is a thick layer of vascularized adipose tissue found under the skin of all cetaceans, pinnipeds and sirenians.-Description:Lipid-rich, collagen fiber–laced blubber comprises the hypodermis and covers the whole body, except for parts of the appendages, strongly attached to the musculature...
and ivory
Walrus ivory
Walrus tusk ivory comes from two modified upper canines. The tusks of a Pacific walrus may attain a length of one meter. Walrus teeth are also commercially carved and traded. The average walrus tooth has a rounded, irregular peg shape and is approximately 5cm in length.The tip of a walrus tusk has...
and its numbers declined rapidly. Its global population has since rebounded, though the Atlantic and Laptev populations remain fragmented and at historically depressed levels.
Etymology
The origin of walrus has variously been attributed to combinations of the DutchDutch language
Dutch is a West Germanic language and the native language of the majority of the population of the Netherlands, Belgium, and Suriname, the three member states of the Dutch Language Union. Most speakers live in the European Union, where it is a first language for about 23 million and a second...
words walvis ("whale") and ros ("horse") or wal ("shore") and reus ("giant"). However, the most likely origin of the word is the Old Norse
Old Norse
Old Norse is a North Germanic language that was spoken by inhabitants of Scandinavia and inhabitants of their overseas settlements during the Viking Age, until about 1300....
hrossvalr, meaning "horse-whale", which was passed in an inverted form to Dutch and the North-German dialects as walros and Walross.
The now archaic English word for walrus—morse—is widely supposed to have come from the Slavic
Slavic languages
The Slavic languages , a group of closely related languages of the Slavic peoples and a subgroup of Indo-European languages, have speakers in most of Eastern Europe, in much of the Balkans, in parts of Central Europe, and in the northern part of Asia.-Branches:Scholars traditionally divide Slavic...
. Thus морж (morž) in Russian
Russian language
Russian is a Slavic language used primarily in Russia, Belarus, Uzbekistan, Kazakhstan, Tajikistan and Kyrgyzstan. It is an unofficial but widely spoken language in Ukraine, Moldova, Latvia, Turkmenistan and Estonia and, to a lesser extent, the other countries that were once constituent republics...
, mursu in Finnish
Finnish language
Finnish is the language spoken by the majority of the population in Finland Primarily for use by restaurant menus and by ethnic Finns outside Finland. It is one of the two official languages of Finland and an official minority language in Sweden. In Sweden, both standard Finnish and Meänkieli, a...
, moršâ in Saami, and morse in French
French language
French is a Romance language spoken as a first language in France, the Romandy region in Switzerland, Wallonia and Brussels in Belgium, Monaco, the regions of Quebec and Acadia in Canada, and by various communities elsewhere. Second-language speakers of French are distributed throughout many parts...
. Olaus Magnus
Olaus Magnus
Olaus Magnus was a Swedish ecclesiastic and writer, who did pioneering work for the interest of Nordic people. He was reported as born in October 1490 in Östergötland, and died on August 1, 1557. Magnus, Latin for the Swedish Stor “great”, is a Latin family name taken personally, and not a...
, who depicted the walrus in the carta marina
Carta marina
The Carta marina , created by Olaus Magnus in the 16th century, is the earliest map of the Nordic countries that gives details and placenames...
in 1539, first referred to it as the ros marus, likely a Latinization of morž, and this was adopted by Linnaeus in the binomial nomenclature
Binomial nomenclature
Binomial nomenclature is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages...
. The coincidental similarity between "morsus" and the Latin for "death" (mors) and "to bite" (mordere) supposedly contributed to the walrus' reputation as a "terrible monster".
The compound Odobenus comes from odous (Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
for "tooth") and baino (Greek for "walk"), based on walrus observations using their tusks to pull themselves out of the water. The term divergens in Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
means "turning apart", referring to the tusks.
Taxonomy and evolution
The walrus is a mammal in the orderOrder (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
Carnivora
Carnivora
The diverse order Carnivora |Latin]] carō "flesh", + vorāre "to devour") includes over 260 species of placental mammals. Its members are formally referred to as carnivorans, while the word "carnivore" can refer to any meat-eating animal...
. It is the sole surviving member of the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Odobenidae, one of three lineages in the suborder Pinnipedia along with true seals (Phocidae) and eared seals (Otariidae). While there has been some debate as to whether all three lineages are monophyletic, i.e. descended from a single ancestor, or diphyletic, recent genetic evidence suggests that all three descended from a caniform ancestor most closely related to modern bear
Bear
Bears are mammals of the family Ursidae. Bears are classified as caniforms, or doglike carnivorans, with the pinnipeds being their closest living relatives. Although there are only eight living species of bear, they are widespread, appearing in a wide variety of habitats throughout the Northern...
s. Recent multigene analysis indicates that the odobenids and otariids diverged from the phocids approximately 20–26 million years ago, while the odobenids and the otariids separated 15–20 million years ago. Odobenidae was once a highly diverse and widespread family, including at least twenty species in the Imagotariinae, Dusignathinae and Odobeninae subfamilies. The key distinguishing feature was the development of a squirt/suction feeding mechanism; tusks are a later feature specific to Odobeninae, of which the modern walrus is the last remaining (relict
Relict
A relict is a surviving remnant of a natural phenomenon.* In biology a relict is an organism that at an earlier time was abundant in a large area but now occurs at only one or a few small areas....
) species.
Two subspecies are commonly recognized: the Atlantic Walrus, O. r. rosmarus (Linnaeus, 1758) and the Pacific Walrus, O. r. divergens (Illiger, 1815). Fixed genetic differences between the Atlantic and Pacific subspecies indicate very restricted gene flow, but relatively recent separation, estimated at 500,000 and 785,000 years ago. These dates coincide with the fossil-derived hypothesis that the walrus evolved from a tropical or sub-tropical ancestor that became isolated in the Atlantic Ocean and gradually adapted to colder conditions in the Arctic. From there, it presumably re-colonized the North Pacific during high glaciation periods in the Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
via the Central American Seaway
Central American Seaway
The Central American Seaway, also called the Panamanic Seaway or Inter-American Seaway was an ancient body of water that once separated North America from South America...
. An isolated population in the Laptev Sea
Laptev Sea
The Laptev Sea is a marginal sea of the Arctic Ocean. It is located between the northern coast of Siberia, the Taimyr Peninsula, Severnaya Zemlya and the New Siberian Islands. Its northern boundary passes from the Arctic Cape to a point with co-ordinates of 79°N and 139°E, and ends at the Anisiy...
is considered by some, including Russian biologists and the canonical Mammal Species of the World, to be a third subspecies, O. r. laptevi (Chapskii, 1940), and is managed as such in Russia. Where the subspecies separation is not accepted, whether to consider it a subpopulation of the Atlantic or Pacific subspecies remains under debate.
Anatomy
Snout
The snout, or muzzle, is the protruding portion of an animal's face, consisting of its nose, mouth, and jaw.-Terminology:The term "muzzle", used as a noun, can be ambiguous...
. 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 seal
Eared Seal
The eared seals or otariids are marine mammals in the family Otariidae, one of three groupings of Pinnipeds. They comprise 16 species in seven genera commonly known either as sea lions or fur seals, distinct from true seals and the Walrus...
s: Otariidae) and seals (true seals
Earless seal
The true seals or earless seals are one of the three main groups of mammals within the seal superfamily, 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...
: 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.
Tusks and dentition
The most prominent feature of the walrus is its long tusks. These are elongated canines, which are present in both sexes and can reach a length of 1 m (3 ft 3 in) and weigh up to 5.4 kg (12 lb). Tusks are slightly longer and thicker among males, who use them for fighting, dominance and display; the strongest males with the largest tusks typically dominate social groups. Tusks are also used to form and maintain holes in the ice and aid the walrus in climbing out of water onto ice. It was previously assumed that tusks were used to dig out prey from the seabed, but analyses of abrasion patterns on the tusks indicate that they are dragged through the sediment while the upper edge of the snout is used for digging. While the dentitionDentition
Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, the characteristic arrangement, kind, and number of teeth in a given species at a given age...
of walruses is highly variable, they generally have relatively few teeth other than the tusks. The maximal number of teeth is 38 with dentition formula: , but over half of the teeth are rudimentary and occur with less than 50% frequency, such that a typical dentition includes only 18 teeth
Vibrissae
Surrounding the tusks is a broad mat of stiff bristles ('mystacial vibrissae'), giving the walrus a characteristic whiskered appearance. There can be 400 to 700 vibrissae in 13 to 15 rows reaching 30 cm (12 in) in length, though in the wild they are often worn to a much shorter length due to constant use in foraging. The vibrissae are attached to muscles and are supplied with blood and nerves making them a highly sensitive organ capable of differentiating shapes 3 mm (0.118110236220472 in) thick and 2 mm (0.078740157480315 in) wide.Skin
Aside from the vibrissae, the walrus is sparsely covered with fur and appears bald. Its skin is highly wrinkled and thick, up to 10 cm (3.9 in) around the neck and shoulders of males. The blubber layerBlubber
Blubber is a thick layer of vascularized adipose tissue found under the skin of all cetaceans, pinnipeds and sirenians.-Description:Lipid-rich, collagen fiber–laced blubber comprises the hypodermis and covers the whole body, except for parts of the appendages, strongly attached to the musculature...
beneath is up to 15 cm (5.9 in) thick. Young walruses are deep brown and grow paler and more cinnamon-colored as they age. Old males, in particular, become nearly pink. Because skin blood vessels constrict in cold water, the walrus can appear almost white when swimming. As a secondary sexual characteristic, males also acquire significant nodules, called bosses, particularly around the neck and shoulders.
The walrus has an air sac under its throat which acts like a floatation bubble and allows it to bob vertically in the water and sleep. The males possess a large baculum
Baculum
The baculum is a bone found in the penis of most mammals. It is absent in humans, but present in other primates, such as the gorilla and chimpanzee.The bone aids in sexual intercourse.-Purpose:...
(penis bone), up to 63 cm (24.8 in) in length, the largest of any land mammal, both in absolute size and relative to body size.
Life history
Reproduction
Walruses live to about 20–30 years old in the wild. The males reach sexual maturity as early as 7 years, but do not typically mate until fully developed around 15 years of age. They rut from January through April, decreasing their food intake dramatically. The females begin ovulating as soon as 4–6 years old. The females are polyestrous, coming into heat in late summer and also around February, yet the males are fertile only around February; the potential fertility of this second period is unknown. Breeding occurs from January to March, peaking in February. Males aggregate in the water around ice-bound groups of estrous females and engage in competitive vocal displays. The females join them and copulate in the water.Gestation
Gestation
Gestation is the carrying of an embryo or fetus inside a female viviparous animal. Mammals during pregnancy can have one or more gestations at the same time ....
lasts 15 to 16 months. The first 3 to 4 months are spent with the blastula
Blastula
The blastula is a hollow sphere of cells formed during an early stage of embryonic development in animals . The blastula is created when the zygote undergoes the cell division process known as cleavage. The blastula is preceded by the morula and is followed by the gastrula in the developmental...
in suspended development before it implants itself in the placenta. This strategy of delayed implantation, common among pinnipeds, presumably evolved to optimize both the mating season and the birthing season, determined by ecological conditions that promote newborn survival. Calves are born during the spring migration, from April to June. They weigh 45 kilogram at birth and are able to swim. The mothers nurse for over a year before weaning, but the young can spend up to 3 to 5 years with the mothers. Because ovulation is suppressed until the calf is weaned, females give birth at most every two years, leaving the walrus with the lowest reproductive rate of any pinniped.
Migration
The rest of the year (late summer and fall) the walrus tends to form massive aggregations of tens of thousands of individuals on rocky beaches or outcrops. The migration between the ice and the beach can be long distance and dramatic. In late spring and summer, for example, several hundred thousand Pacific Walruses migrate from the Bering sea into the Chukchi sea through the relatively narrow Bering StraitBering Strait
The Bering Strait , known to natives as Imakpik, is a sea strait between Cape Dezhnev, Chukotka Autonomous Okrug, Russia, the easternmost point of the Asian continent and Cape Prince of Wales, Alaska, USA, the westernmost point of the North American continent, with latitude of about 65°40'N,...
.
Range and habitat
Bering Strait
The Bering Strait , known to natives as Imakpik, is a sea strait between Cape Dezhnev, Chukotka Autonomous Okrug, Russia, the easternmost point of the Asian continent and Cape Prince of Wales, Alaska, USA, the westernmost point of the North American continent, with latitude of about 65°40'N,...
in the Chukchi Sea
Chukchi Sea
Chukchi Sea is a marginal sea of the Arctic Ocean. It is bounded on the west by the De Long Strait, off Wrangel Island, and in the east by Point Barrow, Alaska, beyond which lies the Beaufort Sea. The Bering Strait forms its southernmost limit and connects it to the Bering Sea and the Pacific...
along the north shore of eastern Siberia
Siberia
Siberia is an extensive region constituting almost all of Northern Asia. Comprising the central and eastern portion of the Russian Federation, it was part of the Soviet Union from its beginning, as its predecessor states, the Tsardom of Russia and the Russian Empire, conquered it during the 16th...
, around Wrangel Island
Wrangel Island
Wrangel Island is an island in the Arctic Ocean, between the Chukchi Sea and East Siberian Sea. Wrangel Island lies astride the 180° meridian. The International Date Line is displaced eastwards at this latitude to avoid the island as well as the Chukchi Peninsula on the Russian mainland...
, in the Beaufort Sea
Beaufort Sea
The Beaufort Sea is a marginal sea of the Arctic Ocean, located north of the Northwest Territories, the Yukon, and Alaska, west of Canada's Arctic islands. The sea is named after hydrographer Sir Francis Beaufort...
along the north shore of Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
, and in the waters between those locations. Smaller numbers of males summer in the Gulf of Anadyr
Gulf of Anadyr
The Gulf of Anadyr, or Anadyr Bay , is a large bay on the Bering Sea in far northeast Siberia.-Location:The bay is roughly rectangular and opens to the southeast. The corners are Cape Navarin , Anadyr Estuary, Kresta Bay and Cape Chukotsky on the Chukchi Peninsula...
on the south shore of Siberia's Chukchi Peninsula
Chukchi Peninsula
The Chukchi Peninsula, Chukotka Peninsula or Chukotski Peninsula , at about 66° N 172° W, is the northeastern extremity of Asia. Its eastern end is at Cape Dezhnev near the village of Uelen. It is bordered by the Chukchi Sea to the north, the Bering Sea to the south, and the Bering Strait to the...
and in Bristol Bay off the south shore of southern Alaska west of the Alaska Peninsula
Alaska Peninsula
The Alaska Peninsula is a peninsula extending about to the southwest from the mainland of Alaska and ending in the Aleutian Islands. The peninsula separates the Pacific Ocean from Bristol Bay, an arm of the Bering Sea....
. In the spring and fall they congregate throughout the Bering Strait, reaching from the west shores of Alaska to the Gulf of Anadyr. They winter in the Bering Sea along the eastern shore of Siberia south to the northern part of the Kamchatka Peninsula
Kamchatka Peninsula
The Kamchatka Peninsula is a peninsula in the Russian Far East, with an area of . It lies between the Pacific Ocean to the east and the Sea of Okhotsk to the west...
, and along Alaska's southern shore. A 28,000 year old fossil walrus specimen was dredged out of San Francisco Bay
San Francisco Bay
San Francisco Bay is a shallow, productive estuary through which water draining from approximately forty percent of California, flowing in the Sacramento and San Joaquin rivers from the Sierra Nevada mountains, enters the Pacific Ocean...
, indicating that the Pacific Walrus ranged far south during the last ice age
Wisconsin glaciation
The last glacial period was the most recent glacial period within the current ice age occurring during the last years of the Pleistocene, from approximately 110,000 to 10,000 years ago....
.
The much smaller Atlantic population ranges from the Canadian Arctic, Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...
, Svalbard
Svalbard
Svalbard is an archipelago in the Arctic, constituting the northernmost part of Norway. It is located north of mainland Europe, midway between mainland Norway and the North Pole. The group of islands range from 74° to 81° north latitude , and from 10° to 35° east longitude. Spitsbergen is the...
and the western portion of the Russian Arctic. There are eight presumed sub-populations based largely on geographical distribution and movement data, five to the west of Greenland and three to the east. The Atlantic Walrus once ranged south to Cape Cod
Cape Cod
Cape Cod, often referred to locally as simply the Cape, is a cape in the easternmost portion of the state of Massachusetts, in the Northeastern United States...
and occurred in large numbers in the Gulf of St. Lawrence. In April 2006, the Canadian Species at Risk Act listed the Northwest Atlantic Walrus population (Québec
Quebec
Quebec or is a province in east-central Canada. It is the only Canadian province with a predominantly French-speaking population and the only one whose sole official language is French at the provincial level....
, New Brunswick
New Brunswick
New Brunswick is one of Canada's three Maritime provinces and is the only province in the federation that is constitutionally bilingual . The provincial capital is Fredericton and Saint John is the most populous city. Greater Moncton is the largest Census Metropolitan Area...
, Nova Scotia
Nova Scotia
Nova Scotia is one of Canada's three Maritime provinces and is the most populous province in Atlantic Canada. The name of the province is Latin for "New Scotland," but "Nova Scotia" is the recognized, English-language name of the province. The provincial capital is Halifax. Nova Scotia is the...
, Newfoundland and Labrador
Newfoundland and Labrador
Newfoundland and Labrador is the easternmost province of Canada. Situated in the country's Atlantic region, it incorporates the island of Newfoundland and mainland Labrador with a combined area of . As of April 2011, the province's estimated population is 508,400...
) as being extirpated in Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
.
The isolated Laptev population is confined year-round to the central and western regions of the Laptev Sea
Laptev Sea
The Laptev Sea is a marginal sea of the Arctic Ocean. It is located between the northern coast of Siberia, the Taimyr Peninsula, Severnaya Zemlya and the New Siberian Islands. Its northern boundary passes from the Arctic Cape to a point with co-ordinates of 79°N and 139°E, and ends at the Anisiy...
, the easternmost regions of the Kara Sea
Kara Sea
The Kara Sea is part of the Arctic Ocean north of Siberia. It is separated from the Barents Sea to the west by the Kara Strait and Novaya Zemlya, and the Laptev Sea to the east by the Severnaya Zemlya....
, and the westernmost regions of the East Siberian Sea
East Siberian Sea
The East Siberian Sea is a marginal sea in the Arctic Ocean. It is located between the Arctic Cape to the north, the coast of Siberia to the south, the New Siberian Islands to the west and Cape Billings, close to Chukotka, and Wrangel Island to the east...
. Current populations are estimated to be between 5,000 and 10,000 individuals.
Their limited diving ability brings them to depend on shallow waters (and appropriate nearby ice coverage) to enable them to reach their preferred benthic prey.
Population
There were roughly 200,000 Pacific Walruses according to the most recent (1990) census-based estimate.The Atlantic Walrus was nearly eradicated by commercial harvest and has a much smaller population. Good estimates are difficult to obtain, but the total population is probably below 20,000.
Diet
Continental shelf
The continental shelf is the extended perimeter of each continent and associated coastal plain. Much of the shelf was exposed during glacial periods, but is now submerged under relatively shallow seas and gulfs, and was similarly submerged during other interglacial periods. The continental margin,...
regions and forage primarily on the sea floor, often from sea ice platforms. They are not particularly deep divers compared to other pinnipeds: the deepest recorded dives are around 80 m (260 ft). They can remain submerged for as long as half an hour.
The walrus has a diverse and opportunistic diet, feeding on more than 60 genera of marine organisms including shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
, crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
s, tube worm
Tube worm
A tube worm is a worm-like sessile invertebrate that anchors its tail to an underwater surface and secretes around its body a mineral tube, into which it can withdraw its entire body.Tube worms are found among the following taxa:...
s, soft coral
Coral
Corals are marine animals in class Anthozoa of phylum Cnidaria typically living in compact colonies of many identical individual "polyps". The group includes the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton.A coral "head" is a colony of...
s, tunicate
Tunicate
Tunicates, also known as urochordates, are members of the subphylum Tunicata, previously known as Urochordata, a group of underwater saclike filter feeders with incurrent and excurrent siphons that is classified within the phylum Chordata. While most tunicates live on the ocean floor, others such...
s, sea cucumbers, various mollusks, and even parts of other pinnipeds. However, it prefers benthic bivalve mollusks, especially clam
Clam
The word "clam" can be applied to freshwater mussels, and other freshwater bivalves, as well as marine bivalves.In the United States, "clam" can be used in several different ways: one, as a general term covering all bivalve molluscs...
s, for which it forages by grazing along the sea bottom, searching and identifying prey with its sensitive vibrissae
Vibrissae
Vibrissae , or whiskers, are specialized hairs usually employed for tactile sensation. The term may also refer to the thick hairs found inside human nostrils, but these have no sensorial function and only operate as an airborne particulate barrier...
and clearing the murky bottoms with jets of water and active flipper movements. The walrus sucks the meat out by sealing its powerful lips to the organism and withdrawing its tongue, piston-like, rapidly into its mouth, creating a vacuum. The walrus palate is uniquely vaulted, enabling effective suction.
Aside from the large numbers of organisms actually consumed by the walrus, its foraging has a large peripheral impact on benthic communities. It disturbs (bioturbates
Bioturbation
In oceanography, limnology, pedology, geology , and archaeology, bioturbation is the displacement and mixing of sediment particles and solutes by fauna or flora . The mediators of bioturbation are typically annelid worms , bivalves In oceanography, limnology, pedology, geology (especially...
) the sea floor, releasing nutrients into the water column, encouraging mixing and movement of many organisms and increasing the patchiness of the benthos
Benthos
Benthos is the community of organisms which live on, in, or near the seabed, also known as the benthic zone. This community lives in or near marine sedimentary environments, from tidal pools along the foreshore, out to the continental shelf, and then down to the abyssal depths.Many organisms...
.
Seal tissue has been observed in fairly significant proportion of walrus stomachs in the Pacific, but the importance of seals in the walrus diet is under debate. There have been isolated observations of walruses preying on seals up to the size of a 200 kg (440.9 lb) Bearded seal
Bearded Seal
The bearded seal , also called the square flipper seal, is a medium-sized pinniped that is found in and near to the Arctic Ocean. It gets its generic name from two Greek words that refer to its heavy jaw...
. There have been rare documented incidents of walruses preying on seabirds, particularly the Brünnich's Guillemot
Brünnich's Guillemot
The Thick-billed Murre or Brünnich's Guillemot is a bird in the auk family . This bird is named after the Danish zoologist Morten Thrane Brünnich...
Uria lomvia.
Interspecies predatory relationships
Due to its great size and tusks, the walrus has only two natural predators: the orcaOrca
The killer whale , commonly referred to as the orca, and less commonly as the blackfish, is a toothed whale belonging to the oceanic dolphin family. Killer whales are found in all oceans, from the frigid Arctic and Antarctic regions to tropical seas...
and the polar bear
Polar Bear
The polar bear is a bear native largely within the Arctic Circle encompassing the Arctic Ocean, its surrounding seas and surrounding land masses. It is the world's largest land carnivore and also the largest bear, together with the omnivorous Kodiak Bear, which is approximately the same size...
. The walrus does not, however, comprise a significant component of either predator's diet. Both the orca and the polar bear are also most likely to prey on walrus calves. The polar bear often hunts the walrus by rushing at beached aggregations and consuming individuals that are crushed or wounded in the sudden exodus, typically younger or infirm animals. The bears also isolate walruses when the walrus overwinter and are unable to escape a charging bear due to inaccessible diving holes in the ice. However, even an injured walrus is a formidable opponent for a polar bear, and direct attacks are rare. Polar bear–walrus battles are often extremely protracted and exhausting and bears have been known to forgo the attack after injuring a walrus. Orcas regularly attack walrus although it is believed that walruses have successfully defended themselves via counterattack against the larger cetacean.
Conservation
Seal hunting
Seal hunting, or sealing, is the personal or commercial hunting of seals. The hunt is currently practiced in five countries: Canada, where most of the world's seal hunting takes place, Namibia, the Danish region of Greenland, Norway and Russia...
and whalers
Whaling
Whaling is the hunting of whales mainly for meat and oil. Its earliest forms date to at least 3000 BC. Various coastal communities have long histories of sustenance whaling and harvesting beached whales...
, leading to the near extirpation
Local extinction
Local extinction, also known as extirpation, is the condition of a species which ceases to exist in the chosen geographic area of study, though it still exists elsewhere...
of the Atlantic population. Commercial walrus harvesting is now outlawed throughout its range, although Chukchi
Chukchi people
The Chukchi, or Chukchee , ) are an indigenous people inhabiting the Chukchi Peninsula and the shores of the Chukchi Sea and the Bering Sea region of the Arctic Ocean within the Russian Federation. They speak the Chukchi language...
, Yupik and Inuit
Inuit
The Inuit are a group of culturally similar indigenous peoples inhabiting the Arctic regions of Canada , Denmark , Russia and the United States . Inuit means “the people” in the Inuktitut language...
peoples, continue to kill small numbers towards the end of each summer.
Traditional hunters used all parts of the walrus. The meat, often preserved, is an important winter nutrition source; the flippers are fermented and stored as a delicacy until spring; tusks and bone were historically used for tools as well as material for handicrafts; the oil was rendered for warmth and light; the tough hide made rope and house and boat coverings; the intestines and gut linings made waterproof parkas; etc. While some of these uses have faded with access to alternative technologies, walrus meat remains an important part of local diets, and tusk carving and engraving remain a vital art form.
Walrus hunts are regulated by resource managers in Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
, the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
and Denmark
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...
and representatives of the respective hunting communities. An estimated 4–7,000 Pacific Walruses are harvested in Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
and Russia, including a significant portion (approx. 42%) of struck and lost animals. Several hundred are removed annually around Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...
. The sustainability of these levels of harvest is difficult to determine given uncertain population estimates and parameters such as fecundity
Fecundity
Fecundity, derived from the word fecund, generally refers to the ability to reproduce. In demography, fecundity is the potential reproductive capacity of an individual or population. In biology, the definition is more equivalent to fertility, or the actual reproductive rate of an organism or...
and mortality
Mortality rate
Mortality rate is a measure of the number of deaths in a population, scaled to the size of that population, per unit time...
.
The effects of global climate change are another element of concern. The extent and thickness of the pack ice has reached unusually low levels in several recent years. The walrus relies on this ice while giving birth and aggregating in the reproductive period. Thinner pack ice over the Bering Sea has reduced the amount of resting habitat near optimal feeding grounds. This more widely separates lactating females from their calves, increasing nutritional stress for the young and lower reproductive rates. Reduced coastal sea ice has also been implicated in the increase of stampeding deaths crowding the shorelines of the Chukchi Sea
Chukchi Sea
Chukchi Sea is a marginal sea of the Arctic Ocean. It is bounded on the west by the De Long Strait, off Wrangel Island, and in the east by Point Barrow, Alaska, beyond which lies the Beaufort Sea. The Bering Strait forms its southernmost limit and connects it to the Bering Sea and the Pacific...
between eastern Russia and western Alaska. However, there is insufficient climate data to make reliable predictions on population trends.
Currently, two of the three walrus subspecies are listed as "least-concern" by the IUCN, while the third is "data deficient". The Pacific Walrus is not listed as "depleted" according to the Marine Mammal Protection Act
Marine Mammal Protection Act
The Marine Mammal Protection Act of 1972 was the first article of legislation to call specifically for an ecosystem approach to natural resource management and conservation. MMPA prohibits the taking of marine mammals, and enacts a moratorium on the import, export, and sale of any marine mammal,...
nor as "threatened" or "endangered" under the Endangered Species Act
Endangered Species Act
The Endangered Species Act of 1973 is one of the dozens of United States environmental laws passed in the 1970s. Signed into law by President Richard Nixon on December 28, 1973, it was designed to protect critically imperiled species from extinction as a "consequence of economic growth and...
. The Russian Atlantic and Laptev Sea populations are classified as Category 2 (decreasing) and Category 3 (rare) in the Russian Red Book
Red Data Book of the Russian Federation
Red Data Book of the Russian Federation , also known as Red Book or Russian Red Data Book is a state document established for documenting rare and endangered species of animals, plants and fungi, as well as some local subspecies that exist within the territory of the Russian Federation and its...
. Global trade in walrus ivory
Walrus ivory
Walrus tusk ivory comes from two modified upper canines. The tusks of a Pacific walrus may attain a length of one meter. Walrus teeth are also commercially carved and traded. The average walrus tooth has a rounded, irregular peg shape and is approximately 5cm in length.The tip of a walrus tusk has...
is restricted according to a CITES Appendix 3 listing.
Culture
Religion
Religion is a collection of cultural systems, belief systems, and worldviews that establishes symbols that relate humanity to spirituality and, sometimes, to moral values. Many religions have narratives, symbols, traditions and sacred histories that are intended to give meaning to life or to...
and folklore
Folklore
Folklore consists of legends, music, oral history, proverbs, jokes, popular beliefs, fairy tales and customs that are the traditions of a culture, subculture, or group. It is also the set of practices through which those expressive genres are shared. The study of folklore is sometimes called...
of many Arctic
Arctic
The Arctic is a region located at the northern-most part of the Earth. The Arctic consists of the Arctic Ocean and parts of Canada, Russia, Greenland, the United States, Norway, Sweden, Finland, and Iceland. The Arctic region consists of a vast, ice-covered ocean, surrounded by treeless permafrost...
peoples. Skin and bone are used in some ceremonies and the animal appears frequently in legends. For example, in a Chukchi
Chukchi people
The Chukchi, or Chukchee , ) are an indigenous people inhabiting the Chukchi Peninsula and the shores of the Chukchi Sea and the Bering Sea region of the Arctic Ocean within the Russian Federation. They speak the Chukchi language...
version of the widespread myth of the Raven, in which Raven
Kutkh
Kutkh , is a Raven spirit traditionally revered in various forms by various indigenous peoples of the Russian Far East. Kutkh appears in many legends: as a key figure in creation, as a fertile ancestor of mankind, as a mighty shaman and as a trickster...
recovers the sun and the moon from an evil spirit by seducing his daughter, the angry father throws the daughter from a high cliff and, as she drops into the water, she turns into a walrus — possibly the original walrus. According to various legends, the tusks are formed either by the trails of mucus from the weeping girl or her long braids. This myth is possibly related to the Chukchi myth of the old walrus-headed woman who rules the bottom of the sea, who is in turn linked to the Inuit goddess Sedna
Sedna (mythology)
In Inuit mythology, Sedna is the goddess of the sea and marine animals such as seals. A creation myth, the story of Sedna shows how she came to rule over Adlivun, the Inuit underworld...
. Both in Chukotka
Chukotka Autonomous Okrug
Chukotka Autonomous Okrug , or Chukotka , is a federal subject of Russia located in the Russian Far East.Chukotka has a population of 53,824 according to the 2002 Census, and a surface area of . The principal town and the administrative center is Anadyr...
and Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
, the aurora borealis is believed to be a special world inhabited by those who died by violence, the changing rays representing deceased souls playing ball with a walrus head.
Because of its distinctive appearance, great bulk and immediately recognizable whiskers and tusks, the walrus also appears in the popular cultures of peoples with little direct experience with the animal, particularly in English children's literature. Perhaps its best-known appearance is in Lewis Carroll
Lewis Carroll
Charles Lutwidge Dodgson , better known by the pseudonym Lewis Carroll , was an English author, mathematician, logician, Anglican deacon and photographer. His most famous writings are Alice's Adventures in Wonderland and its sequel Through the Looking-Glass, as well as the poems "The Hunting of the...
's whimsical poem The Walrus and the Carpenter
The Walrus and the Carpenter
"The Walrus and the Carpenter" is a narrative poem by Lewis Carroll that appeared in his book Through the Looking-Glass, published in December 1871. The poem is recited in chapter four, by Tweedledum and Tweedledee to Alice. The poem is composed of 18 stanzas and contains 108 lines, in an...
that appears in his 1871 book Through the Looking-Glass
Through the Looking-Glass
Through the Looking-Glass, and What Alice Found There is a work of literature by Lewis Carroll . It is the sequel to Alice's Adventures in Wonderland...
. In the poem, the eponymous anti-heroes use trickery to consume a great number of oyster
Oyster
The word oyster is used as a common name for a number of distinct groups of bivalve molluscs which live in marine or brackish habitats. The valves are highly calcified....
s. Although Carroll accurately portrays the biological walrus's appetite for bivalve mollusks, oysters, primarily nearshore and intertidal inhabitants, in fact comprise an insignificant portion of its diet, even in captivity.
Another appearance of the walrus in literature is in the story The White Seal in Rudyard Kipling
Rudyard Kipling
Joseph Rudyard Kipling was an English poet, short-story writer, and novelist chiefly remembered for his celebration of British imperialism, tales and poems of British soldiers in India, and his tales for children. Kipling received the 1907 Nobel Prize for Literature...
's The Jungle Book
The Jungle Book
The Jungle Book is a collection of stories by British Nobel laureate Rudyard Kipling. The stories were first published in magazines in 1893–4. The original publications contain illustrations, some by Rudyard's father, John Lockwood Kipling. Kipling was born in India and spent the first six...
, where it is 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".
Walruses also appear in the songs "I Am the Walrus
I Am the Walrus
"I Am the Walrus" is a 1967 song by The Beatles, written by John Lennon and credited to Lennon–McCartney. Lennon claimed he wrote the first two lines on separate acid trips. The song was in the Beatles' 1967 television film and album Magical Mystery Tour, and was the B-side to the #1 hit "Hello,...
", "Glass Onion
Glass Onion
"Glass Onion" is a song by The Beatles from their 1968 double-album The Beatles primarily written by John Lennon and credited to Lennon–McCartney. This is the first track on the White Album to feature Ringo Starr on drums...
" and "Come Together
Come Together
"Come Together" is a song by The Beatles written by John Lennon and credited to Lennon–McCartney. The song is the opening track on The Beatles' September 1969 album Abbey Road....
" by The Beatles
The Beatles
The Beatles were an English rock band, active throughout the 1960s and one of the most commercially successful and critically acclaimed acts in the history of popular music. Formed in Liverpool, by 1962 the group consisted of John Lennon , Paul McCartney , George Harrison and Ringo Starr...
.
Further reading
- Heptner, V. G.; Nasimovich, A. A; Bannikov, Andrei Grigorevich; Hoffmann, Robert S, Mammals of the Soviet Union, Volume II, part 3. Washington, D.C. : Smithsonian Institution Libraries and National Science Foundation
External links
- Biologist Tracks Walruses Forced Ashore As Ice Melts – audio report by NPRNPRNPR, formerly National Public Radio, is a privately and publicly funded non-profit membership media organization that serves as a national syndicator to a network of 900 public radio stations in the United States. NPR was created in 1970, following congressional passage of the Public Broadcasting...
- Thousands Of Walruses Crowd Ashore Due To Melting Sea Ice – video by National Geographic