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Sea Otter

An endangered species

Order: Carnivora

Family: Mustelidae

Genus & Species: Enhydra lutris


Sea otters are one of the largest of the otter species, with a body length of 3-4 ft and a tail length of 10 in. The males weigh 50-100 lbs, the females 30-70 lbs. The fur is dense and thick and is silky and velvety to the touch. The guard hairs are long, 1.4 in, and the underfur is 0.8 in long. They have no blubber for warmth, unlike other marine mammals, and therefore rely heavily on their fur. Up to 1,600,000 hairs can occupy a square inch on their back. The hair colour is black to dark brown on the back and lighter on the belly. The head and throat are straw-coloured. The hairs on the back are often white-tipped.

The forefeet are stumpy and end in small claws. The back feet are long and webbed and aid the sea otter in swimming. The head is large and blunt and the neck is short. The eyes are small and the ears are short and pointed, almost hidden in the fur. Four incisors are located on the lower jaw, unique among carnivores, and the molars are broad and flat. The nose is large and diamond-shaped, with a "moustache" of whiskers right below it. This gives the sea otter the humorous expression of an old man. The paws are furless. The fur is key to their survival and must be groomed regularly. If it becomes matted with oil, they will die of hypothermia. Sea otters have a strong sense of smell, sight and touch. They have a life span of up to 20 years.


Sea otters are found along the coastal and island waters of the north Pacific from the Aleutian islands of Alaska south to mid-California. On the western side they are found from Russia south to Japan. Today they are flourishing in Checleset Bay and the Baja Reef.

Sea otters spend their entire lives in the water and are rather awkward on land. They live in beds of kelp, which are large plant-like protists, and play a vital role in their society by feeding on the sea urchins that can destroy kelp beds.


Sea otters are strictly carnivorous in nature, feeding on crabs, sea urchins, abalones, fish, octopuses, clams, and mussels. They dive down to depths of 100 ft to catch their meal, and often rise to the surface with a shellfish and a smooth stone. They eat lying on their backs with their belly as the table. Like chimpanzees, they can use tools, and will place the smooth stone on their belly, repeatedly smashing the shellfish on it until the shell breaks off. Unlike river otters, sea otters use their forearms to catch their food, and can stay submerged for up to a minute to dig for clams. Because sea urchins provide little nourishment, they must eat 1/4 of their body weight, 35-40 urchins, each day.


Sea otters have no mating season. Males reach sexual maturity ate 6-9 years of age, females at 4 years. The males mate with more than one female and do not help in raising the young. The females give birth to one pup every two years. The gestation period varies as they can delay the embryo's development to ensure that it is born at a favourable time of the year. The pups are usually born 6-9 months after fertilization. The young are born on the land with fur, eyes open, and a full set of milk teeth. They are taken straight into the water and stay with the mother for one year.


The sea otter has two formidable enemies in the form of killer whales and great white sharks. Because of their fur, they were at one time also hunted close to extinction by European settlers and Russians. By 1911, only 2000 sea otters remained in North America. Today, hunting is illegal, and sea otters are making a slow recovery. Unfortunately, oil spills and chemicals, coupled with their slow reproductive rate, is keeping them on the endangered list.


Sea otters are found in groups called "rafts." Males are in separate rafts then females, and not all sea otters are found in rafts. They range in size from 10-100 individuals and serve no purpose other than to socialize with others.

To sleep, sea otters float on their backs with their paws covering their eyes. They wrap themselves up in kelp so that they do not float away.


There are three subspecies of sea otter: E. l. nereis, E. l. lutris, and E. l. gracilis.


1. "Sea Otter" Wildlife Fact File, IM Pub, USA
2. "Sea Otter" Funk & Wagnall's Wildlife Encyclopedia, pg 2021, vol 17, BPC Pub Ltd, USA, 1974