| Name | Walrus | Diet | Carnivorous |
| Scientific name | Odobenus rosmarus | Weight | 400-1,700 kilograms (0.44–1.874 tons) |
| Pronunciation | waal-ruhs | Length | 2.2–3.6 meters (7.3–11.8 feet) |
| Classification | Mammalia, Carnivora, Odobenidae | Location | Arctic and Subarctic regions |
The Walrus
The pinnipeds (collectively known as seals) are a group of carnivorous mammals that live a semi-aquatic lifestyle.
The walrus is one of the largest members of this group, weighing up to 1.5 tons.
Of all the pinnipeds, the walrus is only outranked by the sea elephant in terms of size.
They are known for their prominent mustache and long tusks.
The genus name “Odobenus” means “tooth-walking sea horse,” referring to their ability to use their long tusks to haul their body out of the water onto the ice.
They also use their tusks to forage for food and defend themselves in conflict situations.
Walruses spend up to two-thirds of their lives out in the water.
They’re mainly found in the Arctic and subarctic seas of the Northern Hemisphere, with separate populations in the Atlantic and Pacific Oceans.
Walruses are highly social, forming large aggregations on sheets of sea ice or land.
In this article, we’ll explore all the interesting attributes of this giant marine mammal, including their physical characteristics, habits, habitat, and unique adaptations.
Taxonomy and Classification
The scientific name of the walrus is Odobenus rosmarus.
This is a large marine mammal that belongs to the Pinnipedia suborder.
The walrus is the only living species in the family Odobenidae.
It is also the only species in the Odobenus genus.
However, the species is further divided into two subspecies, namely, the Atlantic walrus (Odobenus rosmarus rosmarus) and the Pacific walrus (Odobenus rosmarus divergens).
As the name suggests, the subspecies are found in the Atlantic and Pacific Oceans, respectively.
All pinnipeds (odobenids (walruses), phocids (true seals), and otariids (eared seals)) are carnivorous mammals that evolved from land-dwelling mammals about 50 million years ago.
Walruses and eared seals diverged from the true seals about 20 to 26 million years ago, and the two families separated about 15 to 20 million years ago.
Two walrus subspecies look very similar but are mainly differentiated by their distribution in different oceans.
They separated to form distinct subspecies between 500,000 and 785,000 years ago.
Physical Characteristics
The walrus is a large marine mammal with a robust, barrel-shaped body.
It has a rounded head that grows directly into the body with no distinct neck.
Walruses also have two small eyes but no external ears.
They have short, strong limbs with webbed flippers, which they use for locomotion on land and in the water.
This giant marine mammal has a short and broad muzzle lined with a conspicuous mustache.
The mustache is formed by stiff, quill-like whiskers (vibrissae).
There are about 400 to 700 vibrissae arranged in 13 to 15 rows.
The walrus’ mustache can grow to a length of up to 30 centimeters (12 inches).
Another distinct feature of the walruses is their prominent tusk, which is an extension of their upper canine teeth.
Both male and female walruses have tusks, but males typically have longer tusks than females.
The long tusks, which project downwards from the upper jaws, can grow to lengths of up to one meter and weigh about 5.4 kilograms (12 pounds) in males.
They may have up to 38 more teeth in addition to the tusks.
Walruses are among the largest pinnipeds, only outsized by the elephant seals.
The Pacific walrus subspecies are typically bigger than the Atlantic species, with a 10 to 20% size difference.
Length is typically between 2.2 and 3.6 meters (7.3 to 11.8 feet).
Pacific males have an average weight of about 800 to 1700 kilograms (1800–3700 pounds), while Atlantic species weigh about 900 kilograms (2,000 pounds) on average.
Some Pacific species may also exceed 2,000 kilograms (4,400 pounds) in weight.
Atlantic walruses also tend to have shorter tusks compared to their Pacific relatives, and their snout is somewhat flattened.
Male walruses of both subspecies are about one-third larger than females.
Atlantic females have an average weight of about 560 kilograms (1,230 pounds), while Pacific females weigh 800 kilograms (1,800 pounds).
Like other seal species, walruses have grayish skin.
Their skin is about two to four centimeters (1–2 inches) thick and has deep folds around the shoulders.
This helps with insulation and reduces drag while swimming.
Their skin also has a covering of short reddish hair, which gives the walrus an overall cinnamon or reddish brown appearance.
The skin coloration can vary based on factors like blood flow, diet, and the presence of marine organisms on the skin.
Habitat and Distribution
Walruses are native to the Northern Hemisphere.
Their range extends from the North Pole to the Arctic and Subarctic regions.
The Atlantic and Pacific subspecies occupy different areas within this region.
Atlantic walruses are less common, with a small population of about 25,000.
They are found primarily in the seasonally ice-covered waters of Russia, Norway, Greenland, and Canada.
The Pacific walrus has a wide range and a higher population of up to 200,000 in the wild.
Their range extends from Russia to Alaska in the United States.
They’re typically found in the waters of the Bering, Chukchi, and Laptev Sea.
Walruses are migratory, so their range tends to vary at different times of the year.
For instance, most populations of the Pacific species spend their summers in the Chukchi Sea along the northern coast of eastern Siberia.
In the spring and fall, they migrate to the Bering Strait, with a range that may extend from the western coast of Alaska to the Gulf of Anadyr.
Pacific walruses also spend their winter in the Bering Sea, along the eastern coast of Siberia, all the way down to the northern edge of the Kamchatka Peninsula (southern coast of Alaska).
Walruses are often described as semi-aquatic because they spend time partly in the water and partly on land.
Although they can dive to depths of more than 500 meters, walruses prefer to spend their time in shallow waters where they forage for food.
They are mainly found on the coast and in the margins of ice shelves.
Behavior and Social Structure
Generally, walruses spend up to two-thirds of their life underwater.
On land, the walrus can turn its flippers forward underneath its body.
This allows it to crawl on all four limbs like sea lions and fur seals.
They move better on land compared to the true seals.
Their flippers are not very useful in the water.
Instead, they move by undulating their entire body.
Walruses use their long tusks to pull their body out of the water.
The length of the rusk also makes it appear like they use them for walking while on land.
The tusks are also used for breaking breathing holes while swimming below the ice.
They also have an air sac underneath their throat.
This acts like a flotation bubble, allowing the seal to bob its body vertically in the water and sleep.
Walruses are diurnal, which means they’re more active during the day than at night.
However, their daily routines may also be influenced by the availability of food and the season of the year.
Walruses are highly social animals.
They are known to rest and congregate in large numbers on ice floes, rocky shores, or coastal beaches.
Walruses spend most of their time underwater foraging for food, while they use the land or ice floes to rest between feeding bouts, breed, give birth, and nurse their young.
They may also come on land to escape predators or rough sea conditions.
Walruses are not territorial animals.
They gather in large numbers in areas with abundant food resources and are known to tolerate one another.
However, they may get aggressive occasionally, especially during mating season.
Walruses are migratory, with their movements tied to the seasonal changes in ice cover and prey availability.
They move into more open waters in the summer months and return to ice-bound regions during the winter.
Walruses are found in various group sizes, ranging from just a few individuals to thousands living together in large herds.
In male herds, walruses may establish a dominance hierarchy based on their size and age.
Dominant males get better access to females during the breeding season.
Diet and Feeding
Walruses are carnivorous mammals with a diverse diet.
They’re opportunistic feeders, which means they prey on various animals depending on what’s available within their range.
The walrus diet consists of up to 60 genera of marine organisms, which may include different species of shrimps, crabs, corals, tube worms, and sea cucumbers.
They may also prey on mollusks, slow-moving fish, and even other pinnipeds, such as seals.
The preferred prey of most walrus species is benthic bivalve mollusks, especially clams.
Walruses forage in shallow marine environments, typically at depths of about 10 to 50 meters (30 to 160 feet).
They search for prey on the sea bottom, using their sensitive vibrissae to find them in the murky waters.
They may also agitate the sea bottom with their flippers to expose clams and other benthic organisms.
Walruses feed on clams by sucking the meat out of the clamshell.
They do this by creating suction with their powerful lips and piston-like tongues.
Contrary to the assumption that walruses use their tusks to dig out prey on the sea bottom, findings suggest that they do not play a significant role in feeding.
Walruses can prey on seals up to 200 kilograms (440 pounds) in size.
They have also been known to attack sea birds, although this occurs infrequently.
Walruses may also prey on ice-trapped whales or scavenge on whale carcasses occasionally.
Reproduction and Life Cycle
Male walruses become sexually mature at about age seven but will not mate until they’re about 15 years of age.
Females, on the other hand, start mating when they’re about four to six years old.
Males rut (become sexually excited) between January and April of each year.
During this period, they eat less and tend to be more aggressive.
Female walruses are diestrous, meaning they only ovulate twice a year.
Although males are only fertile around January, females come into heat around February and Late Summer.
The breeding season for both Pacific and Atlantic walruses is between January and March, with February being the peak period.
During this period, estrous females aggregate on sea ice while males swim around them in the water.
Males engage in competitive displays to attract females.
They display their body and tusk size to establish dominance and also make clicking or bell-like sounds underwater.
When a female is attracted, she’ll join the male in the water.
Copulation occurs underwater.
Males have a large penis bone (baculum) which can be up to 63 centimeters (25 inches) in length.
This is the largest penis of any land mammal.
Gestations in walruses last for about 15 to 16 months.
Walruses can delay implantation for three to four months.
This strategy ensures that their young are born during the most favorable season (usually during the spring migration between April and June).
Walrus calves are quite big at birth, with an average length of one to 1.4 meters (3.3 to 4.7 feet) and an average weight of about 33 to 85 kilograms.
Calves can swim as soon as they’re born, but they’re still totally dependent on the mother.
They nurse for up to more than a year before they’re weaned but may remain with the mother for up to five years after birth.
Walruses have the slowest growth rate of all the seals.
Although their milk contains high amounts of fats and proteins, it has lower nutrients compared to the milk of other seal species.
Female walruses are protective of their calf.
When threatened on land, the female picks up her calf with her flippers and dives into the water to escape predators.
Walruses reproduce infrequently, with females giving birth once every two years.
This means they have the lowest reproductive rate of all the seal species.
They do have a long span, which can be up to 40 years in captivity and about 20 to 30 years in the wild.
Ecological Role and Interactions
As predatory carnivores with a diverse diet, the feeding activities of walruses have a significant impact on their ecosystem.
Adult walruses may eat up to about 3 to 6% of their body weight, feeding their stomachs twice daily.
They mainly feed on benthic organisms, with clams forming the bulk of their diet.
An individual may eat 3,000 to 6,000 clams within a single feeding season.
By preying on these mollusks, walruses help control their populations.
In addition to consuming a large number of prey organisms, the foraging activities of walruses have a significant impact on the benthic environment where they live.
They disturb the sea floor as they feed, releasing nutrients into the water column, which promotes the growth of phytoplanktons.
The discarded part of their prey also serves as food for smaller animals and returns nutrients to the environment.
Given their size and formidable tusks, walruses have very few natural predators.
In fact, only orcas and polar bears are large enough to prey on walruses.
These predators only attack walruses occasionally, typically attacking younger or infirm individuals.
When attacked, walruses are known to injure polar bears, especially in the water.
Conservation Status and Threats
The walrus is currently listed as a vulnerable species on the IUCN Red List of endangered animals.
Although their current population trend is unknown, the two subspecies face significant threats within their respective ecosystems.
People used to pose the most significant threats to walruses through overharvesting and poaching.
American and European sealers and whalers heavily harvested walruses in the 18th and 19th centuries.
Consequently, the Atlantic subspecies almost neared extirpation, and the Pacific subspecies experienced a significant decline in their numbers.
Most places have outlawed commercial walrus harvesting
In the United States, native American tribes like the Chukchi, Yupik, and Inuit peoples have permission to harvest them in small numbers, especially towards the end of summer each year.
Climate change remains the biggest threat to walruses today.
As global temperatures continue to rise, ice floes are melting faster, forcing a larger number of walruses to a limited area.
This increases the risk of trampling and disturbances that can lead to stampedes, causing the death of calves and vulnerable individuals.
The proximity of walruses to continental shelves also puts them at risk of pollution, such as oil spills and the accumulation of contaminants in their ecosystem.
Many countries actively protect walruses in their habitats through legal means.
International agreements, such as the Marine Mammal Protection Act in the United States and the Agreement on the Conservation of Polar Bears and their Habitat, also protect the species.
Unique Adaptations and Survival Strategies
Walruses have developed a set of remarkable adaptations that help them survive their semi-aquatic lifestyle.
These adaptations also aid their survival in the cold waters of their Arctic and subarctic home.
One of their most prominent features is their long ivory tusks.
Walruses use these elongated canine teeth to pull their bodies out of the water onto ice floats, where they rest in between hunts underwater.
They also use the tusk to break through the ice to create breathing holes and for defense against predators like polar bears.
The size of the tusk also plays a role in establishing dominance within their social groups.
Like other marine animals adapted to life in the cold arctic regions, walruses have a thick layer of fat beneath their skin.
The layer of fat can be up to 15 centimeters (6 inches) thick and is an excellent insulator against the frigid Arctic waters.
The fat later also serves as an energy reserve that aids their survival during periods of scarcity.
Walruses have whiskers around their snouts, also known as vibrissae.
This sensitive mustache helps them detect prey, such as clams and other benthic invertebrates, in the dark, murky waters where they live.
Cultural Significance and Human Interactions
The walrus is a well-known animal, especially to the people of the Arctic and subarctic regions where it lives.
Local legends and folklore frequently mention the animal, and it also plays a vital role in the religion of certain cultures.
People use the skin and bones of the walrus in various religious ceremonies.
They also hunted walruses for other purposes.
Traditional hunters harvested and kept all parts of the walrus for various purposes.
They used the tusks and bones as tools and fashioned the tough hide into ropes and coverings for shelters and boats.
Local tribes preserved the meat, and it constituted a significant portion of their winter nutrition.
People also harvested oil from the walrus for use in lighting lamps and other purposes.
In recent years, most of these uses have diminished due to the availability of advanced alternatives.
However, walrus meat is still a part of many local delicacies, with the tongue being the tastiest part of the meat.
Future Prospects and Research
As a species native to the Arctic region, most studies relating to walruses in recent years have focused on the impact of climate change on their habitat and behavior.
The reduction in floating sea ice forces walruses to haul out on land in larger numbers, resulting in increased stress and higher risks of stampedes.
Future research in this area will aid in the development of conservation strategies and protect the walrus and other sea-ice-dependent species.
Research is also ongoing to monitor the health of walrus populations and assess the impact of contaminants, such as heavy metals and pollutants, in their environment on their population.
Understanding the health of these animals is vital for both their conservation and for assessing the overall health of Arctic marine ecosystems.
Conclusion
The walrus is a large marine mammal native to the Arctic and subarctic regions of the Northern Hemisphere.
It is a pinniped, meaning it is related to the true seals and eared seals.
People know walruses for their impressive size and oversized ivory tusks.
Historically, walruses played a prominent role in the culture of various indigenous tribes of the Arctic who hunted them for their meat, fat, skin, tusks, and bone.
Today, most places prohibit the commercial hunting of this marine mammal, which has helped their population bounce back.
However, climate change, pollution, and other factors still threaten them.
This is why we have to pay more attention to the species and invest more effort into learning more about them and protecting them.
Sources:
- https://en.wikipedia.org/wiki/Walrus
- https://en.wikipedia.org/wiki/Pinniped
- https://www.britannica.com/animal/walrus
- https://www.wwf.org.uk/learn/fascinating-facts/walrus
- https://seaworld.org/animals/facts/mammals/walrus/
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