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- National Geographic said it captured the first footage of killer whales rubbing up against an iceberg.
- The orcas may be using the iceberg to exfoliate their skin, which also had a build up of algae.
- The orcas also migrate thousands of miles potentially just to molt their skin, scientists say.
Orcas living in the freezing waters of Antarctica have been captured in footage rubbing up against icebergs in what could be an innovative skincare technique.
Drone footage taken by National Geographic showed a pod of orcas performing the rare ritual in the new documentary series "Incredible Animal Journeys." National Geographic said it was the first time the behavior had been captured on video. A clip of the footage was also shared by Newsweek.
In the footage, which is featured in the episode "Home at the end of the Earth" that aired on November 20, several killer whales can be seen approaching an iceberg and then rubbing and rolling up against it. The clip even appears to show a mother guiding a calf toward the ice and then rolling over in order to show the calf how to do it. The whales also have a yellow-green algae built up on their skin.
The docuseries says the orcas are rubbing up against the ice in order to exfoliate their skin, a temporary solution until they migrate thousands of miles north to warmer waters so they can properly molt.
Like humans, whales and dolphins typically shed their skin continuously, and most of them have no problem doing this in warmer waters. However, for orca populations in colder waters, like the Antarctic, thermoregulation can become an issue, making it difficult to keep blood flowing to their skin and potentially preventing the whales from molting properly.
In response, the whales could be migrating in order to molt, according to a 2019 paper published in the journal Marine Mammal Science. The study found that some antarctic killer whales make an essentially nonstop, nearly 7,000-mile migration to warmer waters that takes six to eight weeks.
While the reasons whales migrate remain a mystery, the study argued the evidence suggests "deferred skin molt could be the main driver of long-distance migration for antarctic killer whales." National Geographic called it "the world's longest migration solely for skincare."
Robert Pitman, a marine ecologist at Oregon State University's Marine Mammal Institute and lead author of the 2019 paper, told Business Insider he agreed that the orcas could be using the icebergs for exfoliation.
Similar to humans after a sunburn, a killer whale shedding its skin may feel itchy, Pitman said, and so they could be seeking relief by rubbing against the iceberg, particularly if the migration to warmer waters is delayed.
"They probably don't need to do rubbing on the ice," he said, but added that they may be doing it if they haven't fed enough yet to leave on the migration, during which they mostly fast.
The algae buildup could also play a role and may hasten the orcas' desire to shed their skin, thus leading them to rub up against the ice.
"It's not a good thing for algae to accumulate," Pitman said. "It drags on the body. They have to carry it around and don't swim as efficiently."
Pitman added that when the whales go to the tropics and shed their skin, the algae build-up comes off with it.
Similar behavior to rubbing up against icebergs has also been observed in orca populations in the Pacific Northwest and British Colombia, Canada. Northern Resident orcas, for instance, will swim to the seafloor and rub their bodies up against rocks.
Andrew Trites, director of the Marine Mammal Research Unit at the University of British Columbia, told Business Insider that the killer whales may also enjoy the sensation of rubbing themselves up against the cold iceberg, noting the species is very tactile and sensitive to touch.