The walrus, Odobenus rosmarus, is a massive marine mammal inhabiting the Arctic and subarctic seas of the Northern Hemisphere. These pinnipeds spend their lives navigating two contrasting environments: the cold ocean water and the solid terrain of land or ice floes. The difference in medium requires specialized physical adaptations, which dictate their movement and speed capabilities.
Walrus Anatomy and Locomotion
Adult male Pacific walruses can weigh over 1,700 kilograms (3,700 pounds), with a thick layer of blubber that provides insulation and buoyancy. This large, fusiform body shape is well-suited for movement through water, but it presents a challenge on solid ground.
A distinguishing anatomical feature that enables terrestrial movement is the ability to rotate the hind flippers forward. Unlike true seals, walruses can position these rear limbs under their pelvic girdle, allowing them to support their weight and move on all fours. Their fore-flippers are turned at right angles to the body, providing traction and assistance during locomotion on ice or rock. This rotation capability allows the walrus to employ a more active, four-limbed movement instead of dragging its heavy body.
Swimming Speed and Aquatic Movement
Water is the walrus’s primary medium, and its body is optimized for efficient aquatic travel. The typical cruising speed is generally sustained around 4 to 4.3 miles per hour (3.5 to 3.7 knots). This deliberate pace conserves energy for long-distance migrations and extended foraging dives.
When a sudden burst of speed is necessary, such as evading a predator, the walrus can achieve speeds up to 21 to 22 miles per hour (18 to 19 knots). This high-speed propulsion is generated primarily by alternating powerful strokes of the large hind flippers. The fore-flippers are used for steering and maneuvering, but they are often held against the body during sustained swimming, reducing drag.
Terrestrial Speed and Movement
Despite their size and seemingly clumsy appearance, walruses can move with surprising speed on land or ice when motivated. Their ability to rotate their hind flippers allows them to run on all fours, similar to a dog’s gait. This movement is often described as a lumbering gallop or run, which they use for short distances.
The maximum terrestrial speed a walrus can achieve is approximately 4 to 7 miles per hour, which can match the running speed of an average human being. However, this speed is not sustainable due to their massive body weight and anatomical limitations. Their land movement is typically reserved for brief dashes, such as when they are startled or moving to a haul-out site. When not rushed, their motion is a slow, shuffling walk.