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Observations of a Sea Otter Foraging at Moss Landing

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Volunteering | Mammals

Thursday, August 12, 2010

Hugh

While traveling in Northern California a couple of weeks ago I took a side trip to try to catch a glimpse of the sea otters of Moss Landing. I was fortunate to come upon a young male sea otter foraging in the harbor. Watching the behavior of this otter gave me a better insight into the sea otters that I work with at the Aquarium of the Pacific during my Saturday volunteer shifts. In this blog I’d like to share some of my field observations of this Moss Landing otter.

What first caught my eye was a circular light brown cloud of mud swirling at the surface of the water in the harbor of Moss Landing. Right in the middle of this cloud surfaced a young sea otter. He only spent a brief moment on the surface just long enough to take a gulp of air through his mouth before diving straight down into the middle of the now dissipating mud cloud. After stirring up the mud once again the otter surfaced this time with a large clam in its paws. The otter was digging into the mud of the harbor foraging for clams. Floating on his back grasping the shell with one paw on top and the other paw on the bottom he twisted the clam as if he were opening a jar. With one paw turning clockwise and the other turning counterclockwise he broke the seal of the clam and opened it like a locket. Eating every morsel of meat within the clam he let the cleaned out shell fall off his belly into the water. He then dove again and stirred up a cloud of mud while digging down to search for another clam.

After every third or fourth dive the otter would float on the surface and groom himself. He’d start off by first rubbing his paws on his shoulders. It looked like he was trying to clean the mud off his paws. He then rubbed the rest of his body fluffing out his fur followed by a few spins in the water to trap air into his coat to insulate his body.

I recognized this grooming behavior from the many nights that I spent helping to raise an orphan baby sea otter at the Aquarium of the Pacific. Nicknamed the “Furball” young Maggie showed me not only this grooming behavior but also introduced me to another otter behavior that I would watch this Moss Landing otter put to good use. The Furball would occasionally cup her paws together while floating on her back and then bang them repeatedly on her belly which looked like at the time just a playful behavior (you can watch the Furball performing this behavior on the Aquarium’s YouTube video “Adventures in Otter Space”). Watching this otter at Moss Landing showed me the reason for this hammering behavior.

The foraging otter brought up a clam that he could not open with his usual technique. He placed the clam in the folds of his armpits and dove again. When he came up he had a small pointy rock in his paws. Placing the clam on his belly he proceeded to use the pointy end of the rock to crack open the shell by banging it on the clam just like the Furball was exhibiting at the Aquarium. An excellent example of tool use displayed by this otter.

The otter later brought up a large crab. To safely enjoy this meal the critter first bit off both of the crab’s strong claws before munching on the rest of the crustacean. The cracking sound of crab shells being crunched reminded me of when we give our Aquarium otters a treat of crab legs. They make the same cracking noise when they bite into their crabs with their powerful jaws.

Watching this Moss Landing sea otter’s foraging behavior gave me a better insight into the otters that I work with on Saturdays during my volunteer shifts at the Aquarium.

Observations of a Sea Otter Foraging at Moss Landing
After every three or four foraging dives the otter would rub its paws on its shoulders apparently to clean off the mud and then would groom the rest of its body.  | Hugh Ryono
Observations of a Sea Otter Foraging at Moss Landing
The otter would twist the shell in its paws to break the seal of the clam to get at the meat inside.  | Hugh Ryono
Observations of a Sea Otter Foraging at Moss Landing
The location in Moss Landing harbor where the sea otter was foraging in the mud for clams.  | Hugh Ryono
Observations of a Sea Otter Foraging at Moss Landing
Watching the foraging behavior of this Moss Landing sea otter gave me a better insight to the otters that I work with during my volunteer shifts at the Aquarium of the Pacific.  | Hugh Ryono

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