California Sea Lions Rafting + Thermoregulating

[Photographed from a respectful distance on shore w/tele lens]

California sea lions rafting on Monterey Bay. It’s one of my favorite behaviors to watch, these bubbling rafts of sea lions, floating together with flippers up. And Monterey Bay — when huge numbers of sea lions are present — is a great place to observe them quite easily from the shore and from docks and piers.

The flipper position helps them thermoregulate as they’re resting on the water, a process described here by  NOAA:

” … the flippers are poorly insulated, with the blood vessels close to the surface of the skin. Sea lions often regulate their own body temperature by lifting and exposing one or more flippers as they are floating on the surface of the water. The blood vessels just under the skin dilate and either absorb heat from, or release heat to, the environment. Absorbed heat is then circulated to the rest of the body.”

When a sea lion drifts toward the lens with flipper up, it can look a bit like a dorsal fin for just a split second. Sometimes all you’ll notice at first is the flipper, not the rest of the submerged sea lion. A raised flipper, though, is distinctive in shape and texture. And, even if it’s the only part of the sea lion visible, soon enough a back flipper or a snout raised for breath will break the surface to create these flotillas and silhouettes.

I added one photo at the end of just the sea lion’s flippers visible. I always think this looks like the symbol for Ahimsa — the principle of non-violence toward all beings.

[Image from Wikimedia, public domain]