Orcas Cleansing Each Other with Bits of Kelp

Orcas off the coast of North America have been observed engaging in a unique behavior, grooming each other with kelp—showcasing an intriguing instance of marine mammals utilizing tools.

For several years now, scientists have closely monitored a population of 80 endangered killer whales in the Pacific region between British Columbia and Washington. Researchers employed drones to capture a bird’s-eye view of these whales’ activities.

Since analyzing the footage from summer 2024, they have noted Orcas manipulating kelp chains in a peculiar manner. “It’s quite strange,” states Rachel John from the Whale Research Center in Washington, “but whales are known for their quirky behaviors.”

The footage reveals Orcas snapping off kelp stems at the seabed by using their teeth and rocking back and forth on their heads. The segments they break off are approximately the length of their beak-like snout. Remarkably, the Orcas consistently target specific parts of the kelp rather than randomly selecting pieces.

After breaking the kelp, the whales rub it between their heads and the sides of their pod mates, taking turns to groom each other for extended periods—sometimes lasting up to 12 minutes.

“What’s fascinating is that they lack appendages like hands, so they accomplish this using deliberate body movements,” adds John.

Known as “kelping,” this behavior, observed among Orcas, could be a social variation of existing grooming habits. “The social bonds in this group are exceptionally strong, and physical contact is a known way to reinforce these ties,” explains John.

This behavior was observed across all ages and genders within the pod, with the data suggesting that whales of similar ages were more likely to engage in this “kelping” behavior together. Importantly, it may serve as a form of hygiene, says John. The team found that Orcas were more inclined to scrub each other with kelp if they had any skin issues.

While it’s premature to ascertain any health benefits from this behavior, Olaf Meynecke from Griffith University in Australia expresses interest in having researchers compare the skin bacteria of Orcas with kelp properties to identify any correlations.

“It makes perfect sense that they would explore what resources the oceans provide to mitigate skin infections,” comments Meynecke. He believes this behavior may be prevalent among other Orca pods as well as various whale species.