We return to the ocean to one of the most beloved marine mammals, the Sea Otter. Sea otters were almost hunted to extinction for their lustrous fur coats. By the early 20th century they numbered just a few thousand . Through international cooperation, Sea Otters were protected and now number over 100,000 animals in the wild. However, Sea Otters are still endangered and under incredible pressure. This species is also critical to a healthy coastal ecosystem around the northern Pacific rim. We hope you enjoy learning more in this week’s podcast about Sea Otters and all their mustelid hijinks.
Sea Otter Natural History
Sea otters are carnivores and members of the Mustelid family. As otters, they are members of the Lutrinae subfamily. This includes the 13 species of otters found throughout the world. The scientific name for sea otters is Enhydra lutris.
Within sea otters, there are three subspecies:
- Southern Sea Otter (California,) Enhydra lutris nereis
- Northern Sea Otter (Washington, Canada, Alaska), E. l. kenyoni
- Asian Sea Otter (Russia, Japan), E. l. lutris
The mustelids all date back to the Myacids, which existed roughly 55 million years ago. As a family, mustelids did not really proliferate until about 30 million years ago. During that time, with climate change, which was natural over thousands of years, forests gave way to grasslands. With that, rodents and lagomorphs (rabbits et al.) began to proliferate. Mustelids were the main predator of these animals and thus also proliferated.
Sea otters were almost hunted to extinction in the 1800s, prized for their fur. So much so, by the early 20th Century, there were only one to two thousand left. Today, there are an estimated 100,000 or more sea otters in the Pacific Ocean. However, they are still endangered and under threat.
Sea Otter Facts
One of the most amazing facts is sea otters have the thickest coat of any mammal on earth. It is estimated their fur is so dense that there are 1,000,000 hairs per square inch. It is this pelt which helps the sea otter stay warm in its aquatic environment. Sea otters do not have any blubber or fat like other marine mammals to help them stay warm in water that is anywhere from 34 to 50 F (1 to 10 C). Rather, the outer guard hairs help trap air in their dense fur. This air is actually more effective at keeping a sea otter warm when compared to the thick layer of blubber of other marine mammals.
Sea otters can live up to 25 years but typically only live 10 to 12 years in the wild. Their hearing and eyesight are average, but they do have a good sense of smell. During their dives for food, they can stay under for up to 6 minutes, but usually are only under for around 1 minute. They also can dive as deep as 120 feet (37 meters). When hunting, sea otters eat a variety of food to include sea urchins, mussels, clams, abalone, crabs, and even fish. They also are one of the rare mammals that have been observed to use tools. Sea otters will often carry a rock or other hard object in the folds of their skin and use it to crack open its prey.
Sea Otter Conservation
Sea otters are still considered Endangered. They are facing multiple pressures throughout the world, most of which climate change and plastics in our oceans. The Southern Sea Otter is the most in trouble off the California coast. With an estimated population of only 2300 animals, they are in trouble. Recent studies have shown that climate change is driving juvenile great white shark populations up into the Central California coastal range of sea otters. These sharks are the #1 direct cause of Southern sea otter deaths. The sharks usually do not consume the otter, but rather bite them and then realize it is not a good prey item.