Southern Sea Otters: A Keystone Species

Found in California’s offshore waters between Half Moon Bay and Santa Barbara, the southern sea otter is a playful animal which uses its chest both as a dining room table and a place to groom its pups.  

Lolling just beyond the breaking shore waves, rafts of sea otters wrap themselves in kelp for protection from great white sharks, and to keep from drifting while eating, grooming and napping.  Females wrap their pups in kelp to keep them safe from predators while diving for food. 

On a recent visit to Monterey, we saw gulls successfully stealing food from the otters as they were preparing to dine. Using their armpits as pockets, sea otters stash abalone, crabs, clams, mussels and urchins, and use rocks to crack their food open once they get back to the surface. 

As a keystone species*, southern sea otters benefit kelp beds; unchecked, urchins eat kelp quickly enough to create urchin barrens and otters consume urchins.  Interestingly, it is thought that a 2015-2016 increase in sea otter populations is the result of rising urchin counts, as the urchins have lost their primary predator, the sea star, due to wasting disease.  

Members of the weasel family, their double coat is essential to keeping warm in the Pacific waters, as they have no blubber.   

Once abundant in the United States, their diminished range is partly due to hunting for their fur.  The current southern sea otter population is descended from 50 survivors found offshore at Big Sur in 1938. The southern sea otter is listed as endangered by the US Fish and Wildlife Service.

* “A keystone species helps define an entire ecosystem. Without its keystone species, the ecosystem would be dramatically different or cease to exist altogether” per National Geographic.

Published by Mashabu

Earnest observer of our natural world.

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