Walruses are fascinating marine mammals whose diets are finely tuned to the Arctic ecosystems they inhabit. Their feeding habits are unique, as these large pinnipeds possess specially adapted physical features that allow them to extract their prey from the chilly, often murky depths where their favored meals reside. Notorious for their long tusks, walruses actually rely on their highly sensitive whiskers, or vibrissae, to detect and unearth their food from the ocean floor.
The walrus diet is predominantly composed of benthic invertebrates, which are animals that live on, in, or near the seabed. This includes a variety of organisms, such as clams, mollusks, and worms. While walruses are known to be carnivorous, they seldom chase after mobile prey, preferring instead to suck mollusks from their shells—a feeding method that is both efficient and energy-conserving in their frigid habitat. Occasionally, these massive creatures will supplement their intake with fish or even feed on carcasses, opportunistically taking advantage of the rich nutrients available in their environment.
- Walruses subsist mostly on marine invertebrates like clams, snails, sea cucumbers, tunicates, and worms that dwell on the ocean floor.
- Roughly 97% of their nutritional intake comes from bivalves and other benthic organisms.
- To a lesser degree, they will also feed on fish, seals, whale carcasses, and seabirds.
- Using vibrissae on their snouts, walruses detect prey buried in ocean sediment and rely on suction feeding to extract them.
- Their caloric needs are quite high to maintain blubber reserves for warmth and energy.
What Do Walruses Eat?
Walruses are primarily marine mammals that depend heavily on the bounty of the ocean floor for sustenance. Their diet is largely composed of a variety of shellfish, such as clams and mussels, as well as snails, sea cucumbers, tunicates, and other mollusks that dwell on the ocean floor. They employ their powerful tusks and whiskers to forage for food, whisking away sediment to reveal their prey.
Typical diet of walruses:
- Bivalves: clams and mussels.
- Snails and other mollusks.
- Sea cucumbers
- Occasionally, they consume larger prey, such as seals.
- Fish, worms, crustaceans, and other soft-bodied organisms can also make up a small proportion of their diet.
- Rare instances of eating whale carcasses.
It is estimated that 97% of their diet consists of bivalves and other small invertebrates that dwell on the sea bed. Walruses have an adept foraging behavior, using their sensitive whiskers, or vibrissae, to detect and unearth these organisms.
Given their large body mass, walruses require substantial amounts of food daily. This demand for energy is met through the consumption of vast quantities of shellfish, which serve as a rich source of nutrients. To maintain their body mass and blubber reserves, especially in the cold Arctic habitat, large amounts of these invertebrates are consumed in each meal.
In summary, the walrus diet is focused on marine organisms that reside on or within the sediment of shallow water regions. Their consumption patterns adapt slightly based on availability, showing a preference for abundant, easily accessible, calorie-rich prey items.
How Do Walruses Catch and Eat Their Prey?
Walruses are equipped with sensitive whiskers and footprint sensors, which allow them to detect the presence of food on the murky ocean floor. Their whiskers are particularly adept at sensing the subtle movements of their preferred prey buried in the sediment.
Once potential food is located, walruses use their powerful mouths to create a vacuum-like suction, effortlessly extracting shellfish from their shells. This method is efficient and enables them to consume a significant amount of food with a relatively low energy expenditure.
Despite their intimidating tusks, walruses do not use them to dig up prey directly. Instead, these elongated canines aid in rooting through the sediment, stirring up the ocean floor to disturb hiding mollusks and other invertebrates.
When it comes to ingestion, walruses are not choosy about the form of their food. They typically swallow their findings whole, including the shells, which their robust digestive systems can handle.
For the most part, walruses are not active hunters; they prefer a more sedentary approach to foraging by sweeping the ocean floor and relying on their flippers and water jets to reveal buried shellfish. This method conserves energy, which is crucial in the harsh, cold environments they inhabit.
What Adaptations Help Walruses Feed?
Walruses possess several unique adaptations that facilitate their ability to feed efficiently in their Arctic marine habitat. These features are pivotal in aiding their survival in such a challenging environment.
Sensory Whiskers: Walruses are equipped with highly sensitive whiskers or vibrissae on their muzzles, which are instrumental in detecting their prey. These thick mustaches aid in locating food sources, allowing walruses to find clams and other invertebrates in the murky depths.
Mouth Structure: They exhibit strong jaws and a robust palate that are essential for suction feeding. This adaptation enables them to generate a powerful vacuum to extract soft-bodied prey from shells, a feeding method that demands substantial strength and resilience in their oral structures.
|Locating prey in murky waters
|Strong Jaws & Palate
|Withstanding suction feeding pressures
|Digging and unearthing buried prey
|Surviving periods without food
Tusks: The walrus’s iconic tusks also play a significant role in feeding. These long, protruding canines are not just for show or self-defense; they’re used to dislodge prey that is buried in the sea floor.
Metabolic Efficiency: Finally, walruses have the capability to withstand long periods without food when necessary. This ability to fast is crucial during times when food is scarce, ensuring their resilience in an ecosystem where food availability can fluctuate drastically.
Walruses’ Food Intake and Foraging Habits
Walruses are known for their distinctive diet, primarily comprising benthic invertebrates. Foraging for food, they display unique habits influenced by seasonal changes and reproductive states. Adult walruses typically consume about 3,000 to 6,000 clams during a single meal, and they tend to feed twice a day. This significant intake is a testament to their large size and the energy requirements it entails.
Pregnant females, on the other hand, demonstrate a notable increase in their food consumption. To support their developing offspring, they increase their intake by approximately 30-40%, ensuring they have the necessary nutrients for fetal growth.
The foraging depth for walruses is generally between 10 to 50 meters, but they stay within 80 meters of the water’s surface to breathe. These mammals are adept at navigating through the water and use their vibrissae, or whiskers, to detect prey on the ocean floor.
Walruses tend to migrate seasonally to optimize their access to prey. They spend more time foraging when they move south in the fall than when they move north in the spring.
Why Do Walruses Require So Much Food?
Walruses are mammoth marine mammals whose diets are imperative to sustain their significant body mass. Adult walruses can weigh up to 2,000 pounds, necessitating a substantial amount of food to maintain this weight. Their environment compels them to amass thick layers of blubber, which act as energy reserves vital for survival during the brutal Arctic winters.
During the summer months, walruses take advantage of the abundant food sources to build up blubber reserves. This fat layer is not just for insulation against the frigid waters, but it also functions as a crucial energy supply during periods when food is scarcer. Conditions in the Arctic can be extreme, and available food sources fluctuate markedly with the seasons. Their blubber is critical for walruses as it delivers the necessary energy to endure long periods of fasting, especially during their southward migration in the fall.
For female walruses, the need for high caloric intake is even greater when they are nursing. Nursing females require more calories to produce rich milk to support the rapid growth of their calves. The demands of lactation mean that these females must consume a more significant amount of food to not only sustain their own energy needs but also to ensure the well-being of their offspring.
In summary, the immense dietary requirements of walruses are a direct result of their need to maintain their considerable mass, their reliance on blubber reserves for energy and warmth, and the increased demands placed on nursing females.
What Threats Do Walruses Face Regarding Food?
Walruses rely heavily on a stable marine environment to maintain an adequate food supply. Climate change poses a significant threat as it leads to the decline of sea ice. These mammals use ice as resting platforms between feeding bouts; when ice diminishes, it affects their ability to reach abundant feeding grounds.
The access to coastal feeding areas is increasingly restricted. Human activities, such as shipping and industrial operations, compound this issue, forcing walruses to travel greater distances for food. It also leaves them susceptible to disturbances that can affect their feeding efficiency.
With increased competition for food sources, walruses may find themselves vying with other marine species for the same prey. The competition can become fiercer as fish and other animals that walruses depend on also become scarcer due to overfishing or changes in the ecosystem.
Decline in Sea Ice:
- Impact: Reduces resting platforms
- Result: Longer travels for food
Restricted Coastal Access:
- Impact: Human activities limit spaces
- Result: Disrupted feeding practices
Competition for Food:
- Impact: Other species vie for the same resources
- Result: Potential reduction in food availability
These factors not only threaten the walrus’s ability to feed but can also affect their overall health and reproductive success. Conservation efforts are crucial to mitigate these threats and ensure the long-term survival of walrus populations.
- Contemporary diets of walruses in Bristol Bay, Alaska suggest temporal variability in benthic community structure. Search NCBI databases. https://www.ncbi.nlm.nih.gov.
- Female and young walruses depend on disappearing Arctic sea ice for food sources. University of Maryland Center for Environmental Science (UMCES). https://www.umces.edu.
- Female Pacific walruses (Odobenus rosmarus divergens) show greater partitioning of sea ice organic carbon than males: Evidence from ice algae trophic markers. PLOS. https://journals.plos.org.
- Climate change puts the Pacific Walrus population on thin ice. World Wildlife Fund (WWF). https://www.worldwildlife.org.