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Steller Sea Lion Getting “Thiggy” with California Sea Lions

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Animal Updates | Mammals | Volunteering

Thursday, April 25, 2013

Hugh

Parker is the Aquarium of the Pacific’s largest California sea lion. Standing next to him in the pinniped exhibit I am in awe how massive he’s become. This summer he should top out at about 700 pounds! And he’s still growing! Yet this favorite sea lion of mine is a mere Hobbit when compared to the largest of the Otariidae, the Steller sea lion. While up in Moss Landing a few weeks ago I got a first hand look at the difference in size between Zalophus califonianus and Eumetopias jubatus.

A gracious invitation from the Monterey Bay Aquarium to visit my favorite sea otter Gidget aka the Furball in her new surroundings had led me to spend Spring Break in the Monterey area. While exploring Moss Landing I was surprised to encounter a rather large Steller sea lion haul out on a dock surrounded by dozens of California sea lions. It was stunning for me to realize that the smaller sea lions around the Steller which at first I thought were small juveniles were actually Parker size adult males. This Steller Sea Lion was displaying Thigmotaxis behavior with its smaller cousins. Thigmotaxis is the scientific term to describe an animal’s need to be in physical contact with another animal. The staff refers to it as an animal getting “Thiggy” with another critter.

Male Steller sea lions can weigh in at close to 2500 pounds and can reach lengths of 10 feet or more. For comparison a typical full grown adult male California sea lion weighs in at about 800 pounds and reaches a length of just over 7 feet. Sadly the Steller sea lion population is in decline. The Western US stock is listed as Endangered while the rest of the population is listed as Threatened.

More prevalent in Northern waters they are rare visitors to Central and Southern California. I felt fortunate to actually encounter this one at the Moss Landing entrance to Elkhorn Slough. I once saw one at the tip of Catalina 20 years ago and helped rehab a young Steller that stranded in SoCal in the late 90s. This was only the third wild Steller Sea Lion that I’ve seen South of San Francisco and the closest I’ve ever been to an adult male.

On the same day I also saw a female Southern sea otter hanging out on a dock with a group of California sea lions. In this case the otter was not displaying Thigmotaxis behavior. She may have been using the sea lions as a deterrent to aggressive and amorous male sea otters.

As for the Furball she is doing great in her new home and is being cared for by a wonderful, well trained staff up in Monterey. I know she is in good hands.

Steller Sea Lion Getting “Thiggy” with California Sea Lions
Parker the sea lion seems huge when compared to mammalogist Megan. Yet Parker is a mere Hobbit when compared to a Steller sea lion.  | Hugh Ryono
Steller Sea Lion Getting “Thiggy” with California Sea Lions
A slightly wider shot of the Steller sea lion seen on April 8, 2013 at Moss Landing near the entrance to Elkhorn Slough.  | Hugh Ryono
Steller Sea Lion Getting “Thiggy” with California Sea Lions
In this and the previous images the sea lions are displaying Thigmotaxis behavior. The need for one animal to be in physical contact with another. Getting "Thiggy" for short.  | Hugh Ryono
Steller Sea Lion Getting “Thiggy” with California Sea Lions
Not only did I find a Steller sea lion hanging out with California sea lions at Moss Landing, I also saw this female sea otter sharing a dock with them. In this case the otter is not displaying Thigmotaxis behavior. She may be using the sea lions as a deterrent to amorous male sea otters.  | Hugh Ryono

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