Facts About Sea Otters

Sea otters, the smallest marine mammal, nevertheless can grow to be between four and five feet long and weigh between 60 and 70 pounds. They typically eat between 25 and 30 percent of their body weight per day. Pregnancies last between five and eight months and result in one pup born an average of once per year. Pups are dependent upon their mothers for up to one year. The average sea otter lives between 10 and 12 years, though they can live up to 25 years. In the early 20th century hunting had reduced the number of sea otters to at most 2,000, but today there are as many as 150,000 off the coasts of Alaska, California and British Columbia.

Sea otters spend nearly all their time in the water, mostly near the surface. They will, however, dive as much as 250 feet to gather food, which they bring to the surface to eat. Their diet includes lots of sea urchins as well as snails, clams, shrimp, crabs, fish and other sea creatures. They can be seen floating in the water in groups of 10 to 100, called rafts. Sea otters typically float, sleep, rest and eat while lying on their backs, but may turn on their stomachs when travelling and entangle themselves in kelp beds in order to stay anchored in place. They are the only otters to give birth in the water.

The lush, silky, black or brown fur is the sea otter's calling card. The thick fur consists of long guard hairs and shorter, fine hairs -- between 600,000 and one million hairs per square inch. Compare that with the 100,000 hairs on the average human head, and it's clear the sea otter's fur is dense and full. Lacking the layer of blubber that other sea animals have, the sea otter's fur coat keeps him warm by trapping a layer of air under the fur. Sea otters maintain their sleek and silky coats with constant grooming using their clawed forepaws and mouths.

Killer whales prey on Alaskan sea otters, and great white sharks sometimes kill California sea otters. But humans remain the major threat to sea otters. By the late 1800s hunting them for their fur had made sea otters extinct. In the 1900s fishing nets and oil spills killed many sea otters. Conservation measures restored their numbers to Oil mats their fur, which allows their skin to get wet and the sea otters to freeze. Then, during their meticulous cleaning and grooming, they die from ingesting the oil and its toxins. Other chemicals and pollutants in the water also are eaten during regular grooming.

When the numbers of sea otters are down, sea urchins take over the kelp beds, eating away their stems and destroying the kelp forests. This displaces all the other creatures that make up the ecosystem of the kelp beds. But this destruction also contributes to climate change. Kelp beds absorb and hold onto carbon, which keeps greenhouse gasses from being released into the atmosphere. So when sea otters are available to eat the sea urchins, they are slowing the rate of climate change.