The Audubon Aquarium is the proud home to two rescued Southern sea otters named Clara and Ruby. Clara joined our aquarium family in November 2015 and Ruby joined in March 2017.
The southern sea otter (Enhydra lutris nereis) is the heaviest member of the weasel family and the second smallest marine mammal. While sea otters have limited mobility on land they will typically spend their whole life in the water. Sea otters spend a majority of their day eating, sleeping, and grooming. Sea otters have the thickest fur of any mammal, with approximately one million hairs per square inch. That is equal to 10 heads of human hair in every square inch! They will meticulously pull apart knots and rub their fur to remove loose fur and introduce air to make sure they stay warm. Unlike other marine mammals, sea otters do not have a blubber layer so grooming their fur is very important and takes up about half the otter’s day. They are also the only marine mammals that use tools. Often, they will keep a favorite stone in their deep underarm pockets and use it to open a stubborn shell or break apart food.
Sea otters have a very fast metabolism, and they need to consume 20-30% of their body weight every single day! Such a high metabolic rate helps them maintain body heat. The sea otter's diet consists almost exclusively of marine invertebrates including sea urchins, a variety of bivalves such as clams and mussels, abalone, other mollusks, crustaceans, and snails. Sea otters are one of the few animals that can eat sea urchins, making them a key stone species. A key stone species plays a crucial role in the way the ecosystem functions. For sea otters, their role is maintaining a balance in the kelp forests where they live. Without sea otters to manage the sea urchin population, sea urchins become too numerous and can decimate kelp forests. Kelp forests are a crucial part of the ecosystem because they provide a refuge and food for many fish, invertebrates, and marine mammals. Sea otters are the defenders of the kelp forest!
There are three subspecies of sea otters: southern, northern, and common. The southern otter ranges from south of San Francisco to Santa Barbara County. However, the most concentrated population lives along the central California coast. The northern otter lives along the coasts of Alaska, Canada, and Washington, while the common otter inhabits waters around Asia and Russia.
All three species of sea otters were hunted during the Great Hunt or the Fur Trade which lasted from the late 1700’s to the early 1900’s. During this time, a majority of all three otter populations were depleted. Population estimates before the fur trade range from 100,000-160,000 individuals and was dwindled down to an estimated 1,000-2,000 individuals. It wasn’t until 1911 that sea otters came under protection with the signing of the Fur Treaty of 1911. At that point, it was widely believed the southern otter had become extinct. It wasn’t until 1938, when a group of 30 or so individuals were found off the coast of Big Sur, California that we knew the population had survived. The southern sea otter remains fully protected today under the Endangered Species Act and the Marine Mammal Protection Act. Citizens will face hefty fines and possible jail time for harassment of this endangered species. Sea otter habitat is preserved through several protected areas in the United States. In marine protected areas, polluting activities such as dumping of waste and oil drilling are typically prohibited. Currently, there are estimated to be more than 3,300 southern sea otters. Today, southern sea otters are listed as Threatened under the Endangered Species Act and Endangered under the IUCN Red List. They are still threatened by oil spills, pollution, and parasites.
You can help conserve sea otters by doing a few simple things from home! Remember to reduce, reuse, and recycle. Trash and plastic in the ocean is extremely dangerous for animals, like sea otters, that spend their lives in the ocean. If you have a pet cat at home, make sure you are bagging and throwing away any cat litter. Cat feces can contain the parasite Toxoplasma gondii, which causes Toxoplasmosis. If this parasite makes its way into the ocean it can be very dangerous, even fatal, to sea otters and other marine animals. Support conservation efforts by responsible facilities and groups, like Audubon Nature Institute.
Sea otters have the thickest fur of any animal with approximately one million hairs per square inch. Here at the aquarium, our sea otters enjoy a restaurant-quality diet of gulf shrimp, clam, squid, Pollock, and blue crabs. Our sea otters will consume up to 10 pounds of sea food every day. Sea otters dive to forage for food along the bottom of the kelp forest. They can hold their breath for 3-5 minutes. The deepest dive recorded for a sea otter is 318ft.