Sea otters are the heaviest members of the weasel family, and their fur is deeply luxurious and dense. And for good reason. Unlike most marine mammals, they don’t have a layer of blubber under their skin to keep them warm, Defenders of Wildlife reports. That beautiful fur is so dense, in fact, that it consists of 250,000 to up to one million hairs per square inch, and that insulates them.
But beauty is more than fur deep and sea otters are considered to be a keystone species in the environments in which they live.
With that in mind, what are five fascinating facts about sea otters?
1. Otters help reduce levels of atmospheric carbon dioxide. How do they do this? By preying upon undersea creatures that feast on the kelp forests that provide crucial cover and food for many other sea animals. Kelp forests also play a key role in capturing carbon in marine ecoystems, Defenders notes.
Because otters eat sea urchins and other animals that graze the giant kelp, these beautiful forests can thrive and support a rich plant and animal community, The Monterey Bay Aquarium notes. Since otters also eat crabs, this also helps to keep estuary ecosystems in good shape because it allows sea slugs to proliferate and eat the algae that would otherwise smother eelgrass, which provides important food and shelter for fish.
2. Sea otters spend most of their lives in the water and can dive as deep as 330 feet when searching for a meal, Defenders reports. Alongside primates, they are one of the only mammals to use tools. They grip small rocks or other hard objects to pry shellfish from the rocks and then smash them open.
3. Sea otters are found in the shallow coastal waters of the northern Pacific. Historically, they ranged from Japan, along coastal Siberia and the Aleutian Islands on down the coasts of Alaska, British Columbia, Washington, Oregon, down the California coast to Baja California. They can now be found in Canada, Russia, Japan, California, and Washington. The majority of all wild sea otters are found in Alaskan waters, but there have even been reported sightings in Mexico.
In the past, sea otters ranged from several hundred thousand to more than one million. Tragically, the fur trade reduced their numbers worldwide to only a total of 1,000-2,000 in the earlier part of the 1900s, Defenders reports. There are now estimated to be about 106,000 worldwide. In California, there are just under 3,000.
There are three distinct subspecies of sea otters — the Northern sea otter (Enhydra lutris kenyoni) is found in the Aleutian Islands, Southern Alaska, British Columbia, and Washington — and the Southern sea otter (Enhydra lutris nereis), or California sea otter, which ranges along the California coast from San Mateo County in the north to Santa Barbara county in the south. A third subspecies, the Russian sea otter (Enhydra lutris lutris) is found in the western north Pacific, Arkive notes.
4. Sea otters metabolize their food rapidly. They gorge themselves in order to keep warm, crunching up as much as 25 to 40 percent of their body weight each day, the World Wildlife Fund Reports.
5. Sea otters are polygynous, and adult males typically defend territories that include the ranges of several females, Arkive notes. During mating, the male bites the female’s nose, leaving her with a bloody reminder of their embrace. Females usually give birth to one pup at a time, and she carries her little one on her chest, nursing and grooming the baby so that the youngster remains buoyant with well-insulated fur. Young pups wait on the surface while mom hunts for food. As they get older, they follow their mother and learn to forage by watching her. A pup stays with its mom for three to six months and then they’re ready to be off on their own.
Otters are very gregarious and like to hang around in large same-sex groups, or “rafts.” In California, these rafts don’t usually exceed more than 50 individuals. It’s a different story in Alaska, where the otter population density is higher. Here, rafts can consist of as many as 2,000 otters. These meticulously clean creatures spend more time grooming their fur than any other mammal. They do this by rubbing, rolling, and blowing air into their fur. When air is trapped in the creature’s underfur, it is heated by the body and this provides insulation. It also gives otters a silvery appearance underwater.
While sea otter populations have rebounded somewhat, other human activities, such as coastal development and pollution pose a threat, Arkive notes. During the Exxon Valdez oil spill in Alaska’s Prince William Sound, hundreds, and perhaps thousands of otters died as direct result of the disaster. Another oil spill (always a possibility) is a continual threat to these engaging creatures and could very well have devastating consequences should one occur. Other threats include entanglement in fishing gear, especially gill nets, and competition with commercial fisheries.
Another problem: Otter populations in the central Aleutian Islands have declined by up to 90 percent, and evidence suggests that this sharp decline is the result of predation by killer whales. Populations of Steller’s sea lions and harbor seals have crashed, forcing the orcas to depend on the otters.
Sea otters are legally protected in the U.S. under the Marine Mammal Protection Act. In Canada, they are protected under the Species at Risk Act. Despite this protection along with other conservation measures, the Californian population has been slow to increase. A new recovery plan is underway via the U.S. Fish and Wildlife Service and the aim is to manage destructive human activities in order to give the population a chance to recover, hopefully to a point where it can be taken off the List of Endangered and Threatened Wildlife.
Fortunately, there’s been some good news: Efforts to reintroduce sea otters along the U.S. west coast have been successful, and have managed to restore these adorable and inquisitive creatures to much of their former range, Arkive notes.
Hopefully, these engaging and playful creatures will be with us for many more years to come.
Note: The video above shows just how delightful baby sea otters are.
