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7.25 to 11.5 feet (2.2 to 3.5 m)
Length
up to 3 feet (1 m)
Tusks
1,760 to 3,700 pounds (800 to 1,700 kg)
Weight (Male)
880 to 2,750 pounds (400 to 1,250 kg)
Weight (Female)

About

#Mammals

The Walrus, scientifically known as Odobenus rosmarus, belongs to the Animal Kingdom’s phylum Chordata and class Mammalia. It is a member of the Odobenidae family, which includes only one other species, the extinct Stellar’s sea cow. Walruses are found in the Arctic regions of the Northern Hemisphere, inhabiting the cold waters and ice floes of the Arctic Ocean and adjacent seas.

These marine mammals are known for their large size, robust bodies, and distinctive tusks. Adult walruses can weigh between 600 to 1,500 kilograms and measure up to 3.6 meters in length. They have thick, wrinkled skin that is sparsely covered with coarse hair, which helps insulate them from the cold temperatures of their Arctic environment.

One of the most recognizable features of the walrus is its long tusks, which are elongated canine teeth that can grow up to 1 meter in length in males. These tusks are used for various purposes, including hauling themselves out of the water, breaking ice, and defending against predators.

Walruses are highly adapted for life in the water, with flipper-like limbs that enable them to swim gracefully and dive to great depths in search of food. They primarily feed on a diet of benthic invertebrates such as clams, mussels, and other bottom-dwelling organisms.

Conservation Concerns

Walruses face several conservation concerns, including habitat loss and climate change. Melting sea ice due to global warming threatens their Arctic habitat, reducing the availability of ice floes for resting, breeding, and raising young.

Additionally, walruses are vulnerable to human disturbances such as pollution, habitat degradation, and increased shipping activity in their Arctic range. Oil spills and contamination from industrial pollutants can have devastating effects on walrus populations and their prey.

While the global walrus population is currently stable, some subpopulations are declining due to these threats. The Pacific walrus (Odobenus rosmarus divergens) is listed as “Data Deficient” on the IUCN Red List, indicating a lack of sufficient data to assess its conservation status accurately.

Threatened:
Extinct
Critically Endangered
Endangered
Vulnerable
Near Threatened
Least Concern

Physical Characteristics

The Walrus (Odobenus rosmarus) is a large marine mammal known for its distinctive tusks, whiskers, and considerable bulk, making it an iconic symbol of the Arctic region. Walruses are divided into two subspecies: the Atlantic walrus (Odobenus rosmarus rosmarus) and the Pacific walrus (Odobenus rosmarus divergens). These animals are adapted to the cold Arctic and sub-Arctic marine environment, relying on sea ice for breeding, resting, and protection from predators. Here’s a detailed overview of the physical characteristics of the walrus:

Size

  • Body Length: Adult walruses typically measure between 7.25 to 11.5 feet (2.2 to 3.5 meters) in length, with males being significantly larger than females.
  • Weight: There is a considerable difference in weight between the sexes. Males can weigh between 1,760 to 3,700 pounds (800 to 1,700 kilograms), while females are generally lighter, weighing between 880 to 2,750 pounds (400 to 1,250 kilograms).

Physical Characteristics

  • Skin and Coloration: Walruses have thick, wrinkled skin covered in short, coarse hair. Their skin color can vary from a light brown in younger animals to nearly pink in older individuals, largely due to blood vessel dilation near the skin’s surface to help regulate body temperature.
  • Tusks: One of the most distinctive features of walruses is their long, ivory tusks, which are actually elongated canine teeth. These tusks can grow up to 3 feet (1 meter) in length and are present in both males and females. Tusks are used for defense, dominance displays among males, and to help haul their massive bodies out of the water onto ice or land.
  • Whiskers: Also known as vibrissae, walruses have sensitive whiskers on their snouts that they use to detect prey on the ocean floor. These whiskers are highly sensitive and can help locate mollusks, their primary food source, in the murky Arctic waters.
  • Body Shape: Walruses have a large, cylindrical body with a small head relative to their size, short neck, and flipper-like limbs adapted for swimming in the cold Arctic waters. Their front flippers are used for propulsion while swimming and for support while on land or ice.
  • Blubber: Beneath their skin, walruses have a thick layer of blubber that insulates them from the freezing temperatures of their habitat. This blubber layer can be up to 6 inches (15 centimeters) thick and also serves as an energy reserve.

Behavior and Adaptations

  • Diet: Walruses primarily feed on benthic invertebrates, especially mollusks like clams. They use their powerful snouts to create suction and dislodge prey from the ocean floor, then use their tongue to extract the meat.
  • Social Structure: Walruses are social animals, often found in large herds that can number in the thousands during certain times of the year. These herds are generally segregated by sex outside of the breeding season.
  • Habitat: They depend on sea ice for various life processes, including breeding, nursing calves, and resting between foraging bouts. As such, the walrus is directly impacted by the loss of sea ice due to climate change.

The walrus’s unique physical traits, from its tusks and whiskers to its adaptations for life in cold marine environments, highlight its evolutionary success in the Arctic. Conservation efforts are crucial to ensure the survival of walruses, as they face increasing threats from climate change and human activities.

Reproduction

The reproductive cycle of the walrus, a large marine mammal inhabiting the Arctic and sub-Arctic regions, involves several key stages:

Sexual Maturity: Walruses reach sexual maturity at different ages depending on gender and environmental factors. Males typically reach maturity between 7 to 10 years of age, while females reach maturity between 4 to 6 years of age.

Breeding Season: Breeding in walruses typically occurs from January to March, although the exact timing may vary depending on location and environmental conditions. During this time, males establish dominance hierarchies and compete for access to breeding females.

Mating Behavior: Male walruses, known as bulls, engage in aggressive displays to establish dominance and secure mating opportunities with females, known as cows. These displays often involve vocalizations, posturing, and physical combat between rival males.

Gestation Period: After successful mating, female walruses undergo a gestation period of approximately 15 to 16 months, one of the longest gestation periods among mammals. This extended period allows for the development of a single calf in the womb.

Birth and Maternal Care: Walrus calves are typically born between April and June, during the warmer months when ice conditions are more favorable. Calves are born on land or ice floes and are nursed by their mothers for about 2 years. Female walruses exhibit strong maternal bonds and provide extensive care and protection to their offspring.

Juvenile Development: Walrus calves are born with a layer of blubber to help insulate them in the cold Arctic waters. They quickly learn to swim and dive under the guidance of their mothers. Juvenile walruses remain with their mothers for several years, gradually learning essential skills for survival in their marine environment.

Reproductive Cycle and Reproductive Success: Female walruses typically give birth to a single calf every 2 to 3 years. Factors such as food availability, environmental conditions, and the health of the mother can influence reproductive success. Walrus populations face threats from climate change, habitat loss, and human activities, highlighting the importance of conservation efforts to protect these iconic Arctic mammals.

Lifespan

The walrus (Odobenus rosmarus) is a large marine mammal known for its distinctive tusks and prominent whiskers. Found primarily in the Arctic region, walruses spend much of their time on sea ice and in coastal areas, where they feed on benthic invertebrates like clams and mussels. Understanding the lifespan of walruses and the threats they face is crucial for their conservation. Here’s an overview:

Lifespan in the Wild: In the wild, walruses have a lifespan of approximately 30 to 40 years, although some individuals may live longer. Their lifespan can vary depending on factors such as predation, food availability, and environmental conditions. Female walruses tend to live longer than males on average.

Lifespan in Captivity: Walruses are rarely kept in captivity due to their specialized habitat requirements, large size, and complex social behavior. As a result, there is limited information about their lifespan in captivity. However, it is generally believed that walruses may not thrive well in captivity compared to their natural habitat, and their lifespan may be shorter due to the challenges of replicating their natural environment in captivity.

Threats to the Walrus:

  1. Climate Change: Climate change poses a significant threat to walruses by causing loss of sea ice habitat, which they rely on for resting, breeding, and accessing food. As sea ice retreats due to warming temperatures, walruses are forced to haul out onto land in larger numbers, leading to overcrowding, increased competition for limited space, and higher mortality rates, especially among calves.
  2. Human Disturbance: Human activities such as shipping, oil and gas exploration, tourism, and industrial development can disturb walrus populations, causing them to abandon haul-out sites, disrupt feeding behavior, and increase stress levels. These disturbances can have negative impacts on walrus health and reproduction, ultimately affecting population dynamics.
  3. Overharvesting: Historically, walruses were heavily hunted for their blubber, tusks, and skin, leading to population declines in some regions. While commercial hunting has been largely regulated or banned, illegal poaching still occurs in some areas, posing a threat to walrus populations, especially in regions with limited enforcement of regulations.
  4. Pollution: Pollution from oil spills, chemical contaminants, plastics, and other pollutants can accumulate in the Arctic marine environment, contaminating walrus habitat and prey species. Exposure to pollutants can have detrimental effects on walrus health, including reproductive issues, immune suppression, and behavioral changes.
  5. Loss of Prey: Walruses primarily feed on benthic invertebrates such as clams, mussels, and other bottom-dwelling organisms. Overfishing, habitat degradation, and changes in prey abundance and distribution due to climate change can reduce the availability of prey for walruses, impacting their nutritional status and overall health.

Conservation efforts for walruses include habitat protection, regulation of hunting and human activities in walrus habitats, research to understand population dynamics and threats, and international cooperation to address climate change and other global challenges facing Arctic ecosystems. By addressing these threats and implementing effective conservation measures, it is possible to protect and sustain walrus populations for future generations.

Eating Habits

The walrus, with its iconic tusks and massive size, is a marine mammal known for its unique feeding habits. Understanding its eating habits provides insight into its role as a specialized predator in the Arctic ecosystem.

Diet: Walruses are primarily carnivorous and feed on a variety of marine organisms found in Arctic waters. Their diet includes a wide range of prey, such as clams, mussels, snails, shrimp, crabs, fish, and occasionally seals. They are particularly adept at feeding on benthic (bottom-dwelling) invertebrates, using their sensitive whiskers to detect prey buried in the sediment.

Foraging Behavior: Walruses are benthic feeders, meaning they search for food on the ocean floor. They use their highly specialized vibrissae (whiskers) to detect the presence of prey in the murky waters of the Arctic. Once they locate a potential food source, such as a clam bed or mussel bed, they use their strong tusks to excavate and dislodge the prey from the substrate.

Feeding Strategies: When feeding on benthic organisms like clams and mussels, walruses often employ a suction feeding technique. They use their powerful lips and muscular tongue to create a vacuum, sucking the soft tissues of their prey out of their shells. Walruses may also use their tusks to pry open shellfish or to defend themselves against predators.

Grazing on Seabed: In addition to benthic feeding, walruses are known to graze on the seafloor for other types of prey, such as sea cucumbers and worms. They use their sensitive whiskers to detect these organisms in the sediment and their flexible lips to grasp and ingest them.

Haul-Outs and Feeding Sites: Walruses often congregate in large numbers at haul-out sites, which are areas of land or ice where they come ashore between feeding bouts. These haul-out sites provide resting and socializing opportunities for walruses. From these sites, walruses may venture out to nearby feeding areas, such as clam beds or shallow coastal waters, to forage for food.

Seasonal Variation: The feeding habits of walruses can vary seasonally based on factors such as ice cover, prey availability, and reproductive cycles. During the summer months, when sea ice retreats, walruses may travel long distances in search of suitable feeding grounds. In contrast, during the winter, when sea ice reforms, they may rely on breathing holes and cracks in the ice to access food.

Conservation Concerns: Walruses face various threats to their feeding habits and overall survival, including climate change, habitat loss, pollution, and disturbance from human activities such as shipping and oil exploration. Protecting their critical feeding habitats, managing fisheries sustainably, and mitigating the impacts of climate change are essential for ensuring the long-term viability of walrus populations in the Arctic.

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Sources
  • Britannica, Walrus, https://www.britannica.com/animal/walrus, retrieved March 2024.
  • Burnie, David & Wilson, Don, Animal, Smithsonian Institute, Washington DC.
  • Clutton-Brock, Juliet and Wilson, Don, Mammals, Smithsonian Handbooks, New York, NY.
  • Hickman et al, Integrated Principle of Zoology, McGraw Hill, Boston.