General Biology

General Biology

Here you will find information about general biology including diet, normal and abnormal sea otter behaviors, and much more!

Sea otters are ravenous eaters because they have to get enough calories to help them stay warm in their cold environment.  In fact sea otters may eat up to 25% of their body weight in food a day!  But what types of food do wild otters like best?

Have you ever spotted a sea otter hauled out on a rock and wondered if that meant the animal was sick?  Just like all wild animals sea otters have a set of normal behaviors including hauling out of the water. 

An ethogram is an inventory list of behaviors performed by a particular species. Ethograms are used to construct activity budgets for an animal which helps researchers catalogue how much time an individual spends doing different activities such as resting, feeding, grooming, or mating in a 24 hour period. When grouped together, many important questions can be addressed simply by comparing whether a population of animals in one location spends more or less time feeding, for example, compared to a population of animals in a different location. The first step in gathering these important data is to decide what the different behavior types are and how they will be defined for a particular species. Below, you will find short videos of the 6 most commonly performed behaviors of sea otters. You can also find links to still images of these behaviors and more here.


Sea otters rest floating on their backs. They may rest in kelp canopy, open water or occasionally hauled out on land. While resting they may form groups known as rafts or rest singly. The resting behavior class may interspersed with low intensity grooming, interacting and traveling behaviors, but the otter’s head and extremities usually remain dry. In California, sea otters tend to spend just under 40% of each 24-hr period resting.


Sea otters groom to maintain the insulating property of their fur coat. The grooming behavior class encompasses a wide range of activities of varying levels of intensity. High intensity grooming can involve vigorous rolling and grooming of fur with paws and flippers, as well as “nosing” into the fur, activities which serve to force air into the fur.  High intensity grooming typically settles in to low intensity rubbing and licking behaviors as the otter transitions to resting. Short bouts of grooming can occur within feeding, traveling and interacting behavior classes. California otters can spend 8-10% of each 24-hr period grooming.


Sea otters interact with one another under a wide range of circumstances. The context of interactions may be related to mating, investigation and recognition of conspecifics, aggressive disputes, or the similar (but less aggressive) play-fighting. Most interactions occur as otters are joining or departing social groups.


Sea otters swim and dive propelled primarily by their hind flippers and tail. They use a combination of surface and underwater swimming behaviors when traveling depending on the context of their locomotion. They may swim between resting and foraging areas, away from threats or disturbances, between centers of use within their greater home-range or, in the case of territorial males, patrol the boundaries of their territory. Traveling dives differ from feeding dives (in which they dive to the bottom to retrieve prey).


Sea otters feed on benthic invertebrates and typically dive to the bottom to forage, although they may also pull prey off emergent rocks, kelp stipes or kelp canopy. Captured prey are brought to the surface for consumption, with the abdomen used as a table. Tools, commonly rocks, may be used by some individuals to break into hard-shelled prey, especially marine snails. Stealing of prey from another otter sometimes occurs, most typically males stealing from females. At the center of the range in California, sea otters spend 40-50% of each 24-hr period foraging, although in more recently occupied areas at the edge of the range they may feed as little as 20% of the time. They may forage at any time during the 24-hr period, day or night.


Sea otters may be disturbed by a number of human activities and tend to display a characteristic series of escalating avoidance behaviors. Recognition of the early stages of disturbance can help those encountering wild otters to avoid disrupting natural behaviors.  In this video you can hear the researchers observing the sea otters and then, once they are disturbed by a canoe, keeping track of the individual animal that is being observed (focal animal) becomes nearly impossible.