The sea otter, Enhydra lutris, is a marine mammal that spends the vast majority of its life in the water, eating, sleeping, and giving birth in the ocean environment. While sea otters are highly adapted to the cold waters of the North Pacific, they are physically capable of leaving the water and utilizing terrestrial habitats when necessary. Their movement on land, however, is a stark contrast to the graceful maneuvering they display in the sea.
Sea Otter Movement on Land
Sea otters can move on land, but their locomotion is noticeably awkward and uncoordinated compared to a terrestrial mammal. They typically use a clumsy, rolling gait that appears slow and ungainly, usually only sustained for short distances, such as crossing a small beach or navigating intertidal rocks.
When moving quickly, they shift into a bounding or loping motion involving a series of humps and bounds. This bounding movement allows them to cover ground faster than their typical waddle, though they are still slower than most land-based carnivores. Their short legs and heavy, streamlined bodies are not structured for efficient travel outside of the water.
Aquatic Adaptations and Terrestrial Limitations
The features that make the sea otter an exceptional swimmer are precisely what limit its agility on land. Sea otters have evolved to be almost exclusively marine, unlike their relatives, the river otters (Lontra species), which are semi-aquatic and move well in both environments. Their bodies possess a flexible spine and foreshortened limbs, which help to reduce hydrodynamic drag and allow for powerful underwater propulsion.
The sea otter’s hind feet are particularly telling of its aquatic specialization, having evolved into large, flattened, webbed flippers. The fifth digit on each hind foot is the longest, a trait that enhances their ability to scull and propel themselves while floating on their backs, but this morphology makes walking difficult. River otters, by comparison, have a more generalized skeletal structure that allows them to travel significant distances overland.
Why Sea Otters Come Ashore
When a sea otter leaves the water, the behavior is known as “hauling out,” driven by specific biological and behavioral needs. They often come ashore for resting and sleeping, seeking secluded spots on beaches, rocks, or docks. This is especially common during rough seas or high tides when remaining in the water requires more energy.
Hauling out is also connected to thermoregulation, as sea otters lack blubber and rely on dense fur for insulation. Being out of the water allows them to warm up more quickly and conserve body heat, which is essential given their high metabolic rate. Mothers may also haul out to conserve energy while caring for their pups.