A trip to the newly-discovered undersea spa, where humpback whales go for skin care : NPR

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Scratching that hard-to-reach spot can sometimes feel so good. But other species, they’ve got to get creative. Dogs can roll on their backs. Birds can take a dust bath. But what do you do if you live underwater? Is skin care even a thing? For our series, Weekly Dose of Wonder, NPR’s Carrie Feibel relays a new discovery involving humpback whales going to the undersea spa.

CARRIE FEIBEL, BYLINE: Skin care is definitely a thing underwater. For one, the ocean is teeming with microbes. And then there are hitchhikers, like the barnacles and sucker fish that love to latch onto whales and dolphins.

OLAF MEYNECKE: The whales definitely don’t want those barnacles on them. Like, the swim speed is reduced, and it’s weighing them down.

FEIBEL: Olaf Meynecke is a marine scientist with Griffith University in Brisbane, Australia.

MEYNECKE: And I’ve seen them eyeballing these sucker fish, and they don’t like them at all.

FEIBEL: Whales are big, and their skin care challenges can be big too. Meynecke says they need to constantly shed skin to ward off the threat of infection.

MEYNECKE: But of course, you know, if you’re just swimming through the ocean, skin doesn’t just easily come off.

FEIBEL: This is where a trip to a spa would be a big help. And that’s exactly what Meynecke came across while researching humpback migration along the Australian coast. He follows whales in a boat and attaches digital tags to them. The tags record where they go underwater and how they move. After a few hours, the tags pop off and get picked up. The data includes video footage from that whale’s point of view. One day, while reviewing some video, Meynecke’s team saw the humpback whales diving down to the bottom and sort of rolling over while pushing and scraping against the sand and gravel.

MEYNECKE: I remember sitting there with my colleagues, and we were laughing about it. And we’re like, what? What are the whales doing? Like, why are they rolling on the sand?

FEIBEL: It reminded him of a horse rolling on its back, except humpback whales are so huge that their body rolls seem to happen in majestic, slow motion.

MEYNECKE: But we thought maybe this was just a one-off.

FEIBEL: It wasn’t a one-off. On later expeditions, videos showed different whales also spiraling through the sand about 12 stories underwater.

MEYNECKE: And we could see the skin flying off.

FEIBEL: Some videos show little fish rushing in to help.

MEYNECKE: And the whales were holding so still that those fish could just come and started picking off the skin.

FEIBEL: This had never been documented before in humpbacks. They named the behavior sand rolling. Now, when you look at mammals up on land, scratching and rolling and other skin care behaviors are well known. Bruce Schulte is a biologist at Western Kentucky University who studies elephants. He says elephants have to deal with biting bugs, like mites and ticks and even sunburn. Obviously, they’ve got their trunks to spray water on themselves.

BRUCE SCHULTE: But then they also do things like bathe, mud bath, rub on trees.

FEIBEL: Schulte says these skin care routines, while good for health, can have other functions.

SCHULTE: I think the interesting extension of this for both species is how much is this a social act?

FEIBEL: Elephants often wallow in mud together, and that’s what Meynecke found with his whales, too. In this recording, you can hear a male and a female humpback communicating after a visit together to the sand spa.

(SOUNDBITE OF WHALES COMMUNICATING)

FEIBEL: In one of the expeditions, three male humpbacks fought over a female.

MEYNECKE: And it was a very severe, like, heavy fighting. It was ramming into each other. It looked definitely brutal.

FEIBEL: After an hour, they stopped fighting, dove down, and started sand rolling near each other. Meynecke says, if the whales got cut or scraped up in the fight, then the sand could help clean out the wounds, but he imagines it might also be a way for them to settle down and reset.

MEYNECKE: Also, a feel-good feeling like, I really just had a strong fight with these guys, but now I’m just rolling in the sand. And then I just swim off and fight with the next guys.

FEIBEL: Meynecke wants to learn more about how the whales use sand rolling for their health or socially and map the locations they prefer so these whale spas can be protected and preserved.

Carrie Feibel, NPR News.

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