Sea Otter (Enhydra lutris)


Class: Mammalia
Order: Carnivora
Family:    Mustelidae
Size:    3 to 4 feet (0.9 to 1.2 meters)
Weight: 30 to 100 pounds (13.6 to 45 kg)
Diet: Fish, crustaceans, shell fish, sea urchins, mussels and snails 
Distribution: Coastal and island waters of the north Pacific from California to Alaska and Japan to Russia  
Young:  1 pup per 2 years
Animal Predators:  White sharks, bald eagles and killer whales
IUCN Status: Endangered
Terms: Young: Pup   Group: Raft
Lifespan: 23 years in the wild



·         Sea otters’ lungs are 2.5 times the dimension found in land mammals of the same size.

·         Sea otters can swim as fast as 14.5 miles (9 km) per hour underwater.

·         Enhydra” comes from the Greek “en hydra,” meaning “in the water,” and the Latin “lutris,” meaning otter.

·         Sea otters spend up to 48 percent of the daylight hours grooming their fur. 

·         Foraging dives usually last 50 to 90 seconds, but otters can remain submerged for nearly six minutes. 



Sea otters have the thickest fur of any mammal, with about 600,000 hairs per square inch. They are brown in colour and because they have no fat they must rely on their thick, insulating fur for warmth. Their hind legs are long and the paws are broad, flat, and webbed. Their forelimbs are short and have retractable claws that they use for grooming and eating. Sea otters have webbed feet that help them when diving to catch their prey. Their tail is less than one third of their body length. 



Sea otters live in temperate, coastal waters along the north Pacific from California to Alaska and Japan and Russia in the west. They spend the majority of their life at sea, approximately one half mile (0.8 km) from the shore. 


Feeding Habits

Besides abalone, sea otters eat sea urchins, mussels, snails, octopus, squid and many other types of fish. To crack open a shell, sea otters place a flat rock on their stomachs and lie on their backs in the water, then bring the shell down with force on the rock. Their use of tools makes them distinct from most other mammals. They also sometimes use a rock when diving for food, to pry a hidden mollusc out from between a crevice on the sea bottom. Sea otters help the kelp industry by eating sea urchins and other animals that live in and eat kelp. When sea otters feed they stay in very shallow waters.  



Otters form groups called “rafts” made up of solely males or of females. Females and males pair up during mating, but the males then leave to return to their raft and give no parental support. Nine months later, the female gives birth to one pup, who is born with his eyes open, a full set of teeth and fur. She supports the pup on her chest, nursing him and grooming him frequently. When mothers dive down to hunt for food, they leave the pups wrapped in kelp. The pups bob up and down on the surface, and male otters (who often steal food from females) have been known to hold a pup hostage for the food the mother has gathered. Once she hands over the food, the pup is freed, unharmed. Pups need 24-hour care from their mothers to survive in the wild. At six weeks, the pups learn to dive and find food, but they keep nursing until the age of six to eight months, when they are full grown. When they are able to hunt for their own food, pups often have a preference for and hunt for the same type of food as their mothers, using the same techniques.



Otters spend almost all their time in the water, eating, sleeping and even giving birth there. They wind themselves up in kelp to keep warm and to keep from floating away while sleeping. Unlike other marine mammals, sea otters do not have blubber to insulate them from cold water, instead, their fur holds air bubbles which keep them warm. As well, they need to eat 25 percent of their body weight per day to generate a high metabolism. Otters usually rest or sleep on their backs with their paws folded over the chest or over their eyes during the day to block the light while sleeping.  Sea otters are extremely playful and social animals and will frolic not only with other otters, but with seals as well. Some mischievous otters have been known to hitch rides by suddenly jumping onto kayaks or rowboats, startling the human occupants.



Sea otters lived in abundance along the Pacific Rim from Japan to California until the 1700s, when fur traders began to hunt them for their rich, soft pelts. By the early 1900s, the population had dropped from several hundred thousand to less than 2,000. Sea otters are now protected under the Marine Mammal Protection Act and the Endangered Species Act, as well as being fully protected under California law, where sea otters were totally decimated at one time. The work of conservationists has brought the population up to more than 150,000 worldwide.  Oil spills have been extremely detrimental to this species for two reasons: oil damages the function of their fur to keep them warm; and otters groom themselves often, so when they get oil in their mouths they become poisoned. They are listed as Threatened by Environment Canada. 



Sea Otter Wildlife Fact File, IM Pub, US