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What Makes Some Orca Whales Love a Good Belly Rub?

Some pods have been observed rubbing themselves on rocky beaches; scientists are still working to understand why

(Frans Lanting/Corbis)
smithsonian.com

On a beach in British Columbia’s Discovery Islands, a group orca whales were exhibiting an unusual and kind of adorable behavior. Mere feet from the land, the pods was rushing the shoreline with the apparent goal of rubbing their bellies and sides on the beach’s smooth stones. You can see for yourself—a group of whale watchers captured the whales' self-administered belly rubs on video.

Such behavior is thought to be almost entirely unique to certain resident northern populations, CBC reports, and is so rare that researchers have had a hard time studying it. But this likely isn’t a new phenomenon: even before science got wind of the rub-downs in the 1970s, Aboriginal tribes were witness to them.

So, what’s inspiring these whales to risk beaching for a mere marine massage?

Graham Templeton over at Motherboard worked to tease out the answer. He found that, though science is still left guessing about the whales' exact motivations, there are some good indications that the behavior is “a prime example of genuine animal culture—the idea that sub-populations of species can form and maintain learned behaviours over generations.”

In other words, it is likely (though not yet proven to be) a social, rather than an instinctual activity. This theory is strengthened by the fact that the rubbing appears to be taught to younger generations. Furthermore, even after years of absence, pods tend to return the beaches their families used, which appear to be carefully selected for their loose rocks and steep incline toward land. Unlike animals like sea turtles, which use magnetic fields to guide them to familiar beaches, orca whales may instead be using memory.

Templeton interviewed Lance Barrett-Lennard, a zoologist and whale researcher, who has personally seen the behavior on multiple occasions. He notes that the thrill of rubbing—and the risk of getting caught out of the surf—may play a role:

“The danger [of beaching] may be part of what the whales enjoy,” said Barrett-Lennard. “Shared risk is what gives these sorts of activities value, that’s what we know in humans... Pushing [themselves] up onto a beach is inherently risky, and that may be part of the excitement.” Similarly rare and isolated Patagonian pods engage in the much more dangerous practice of shallow water seal hunting, as seen in this video.

Another indication that belly rubs are more social than practical: it's unlikely that the whales are either grooming themselves or relieving itching. Orcas are known to rapidly shed their skin without the need for more friction than swimming affords.

More compelling reasoning suggests that the whales “may simply be enjoying the cold stone massage,” writes Templeton, and that they may do it to further strengthen social bonds between pod members.

All of this theorizing means that videos like the one filmed in Canada may be important to helping scientists nail down just what inspires northern orcas to display such conduct. But if they are really just doing it for fun, then they aren’t the only creature on earth to go to extreme measures for a good massage

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