Walruses are large marine mammals well-suited to life in the polar regions. They spend approximately two-thirds of their lives in the water, deeply intertwined with the ocean’s resources. While they use sea ice and land for resting and reproduction, their physical characteristics and behaviors enable them to navigate and survive in frigid waters.
How They Move Through Water
Walruses possess physical adaptations that enable efficient movement through water. Their thick layer of blubber provides insulation against the cold and contributes to buoyancy. This blubber also contributes to their streamlined body shape, reducing drag and making swimming more efficient. Walruses primarily use their powerful hind flippers for propulsion, employing alternate strokes. Their foreflippers assist with steering and maintaining balance.
Walruses typically swim at about 7 kilometers per hour (4.3 mph), with bursts up to 35 kilometers per hour (21.7 mph). They can hold their breath for extended periods, often up to 10 minutes, and sometimes as long as 25-30 minutes. During dives, they exhibit physiological adaptations like a slowed heart rate, which conserves oxygen by redirecting blood flow to essential organs. Their muscles also contain high levels of myoglobin, a protein that binds and stores oxygen, enhancing underwater endurance. Specialized pharyngeal muscles prevent water from entering their trachea when their mouths are open underwater.
Activities in Their Watery Habitat
Walruses engage in various activities within their watery habitat. A primary activity is foraging for benthic invertebrates, organisms living on or in the seafloor. Their diet largely consists of bivalve mollusks like clams and mussels, as well as snails, sea cucumbers, and worms. Walruses use their highly sensitive whiskers to locate prey buried in the ocean sediment, even in dark or murky waters. They can also squirt jets of water from their mouths to clear away sediment and uncover food.
Walruses can consume a substantial amount of food, eating 5 to 7% of their body weight daily, or up to 60 clams in a single dive. They generally forage in shallow waters, usually no deeper than 80 meters (262 feet). In addition to feeding, walruses exhibit social behaviors in the water, often swimming in large groups for safety and efficiency. Mating occurs in the water during winter months. Walruses also undertake long-distance migrations, following seasonal changes in sea ice and food availability.
Why Walruses Thrive in the Ocean
The ocean is the primary habitat for walruses due to their reliance on its resources and unique adaptations. Their diet is almost exclusively marine invertebrates found on the ocean floor, making a stable marine environment essential for their sustenance. The vastness of the ocean also provides refuge from predators like polar bears and killer whales, which are among their few natural threats. Their substantial size, with adult males weighing over 2,000 kilograms (4,400 pounds), deters many potential dangers.
Walruses depend on sea ice as a mobile platform for resting between foraging trips, breeding, and raising their young. Their ability to swim long distances and dive efficiently allows them to access widespread feeding grounds and follow the shifting ice. The combination of their specialized feeding mechanisms, robust physical insulation, and physiological diving adaptations ensures their survival in the Arctic’s challenging conditions. These features collectively enable walruses to thrive in their aquatic lifestyle.