Orcas filmed grooming each other with seaweed in rare case of ocean mammal tool use
Researchers studying a population of orcas living in waters off the United States and Canada have recorded them breaking off pieces of bull kelp stalks to groom each other by rolling the kelp across their skin.
While tool use among primates, elephants and birds (including Australia’s palm cockatoo) has been extensively documented, the researchers say this orca behaviour is a rare example of marine mammal tool use.
One of the world’s most powerful predators, the orca (Orcinus orca), also known as a killer whale, is actually the largest member of the dolphin family.
The new study, published in the journal Current Biology, was conducted by recording drone video footage of an orca population that lives in a section of the Pacific Ocean between Canada’s British Columbia and the US state of Washington.
Video credit: Center for Whale Research
Grooming was observed among male and female orcas, with closely related or similarly aged individuals apparently more likely to groom each other. The researchers say the behaviour could have a hygienic purpose, with some of the orcas showing moulting or dead skin.
“To find that the killer whales weren’t just using but also manufacturing tools, and that these objects were being used in a way never before reported in marine mammals, was incredibly exciting,” said Michael Weiss from the Centre for Whale Research in Friday Harbor, Washington.
“To me this demonstrates not just the power of new observation methods but also how much we still have to learn about these animals.”
The kelp grooming study is the latest piece of research to expand scientific understanding of orca behaviour. Earlier this year scientists researching the killing of a great white shark in western Victoria confirmed the first instance of orcas’ selective eating of shark liver in Australian waters.
Are Australia’s orcas also grooming each other?
Australian orca experts say more research is needed to know whether local orcas are behaving in the same way.
“Tool use in marine mammals is rare, and this discovery adds yet another layer to our understanding of killer whale intelligence,” marine scientist Dr Bec Wellard, an adjunct research fellow at Western Australia’s Curtin University and founder of Project Orca, told Australian Geographic.
“These aren’t just apex predators; they’re socially complex, curious, and culturally rich animals capable of remarkably sophisticated behaviours. This kind of grooming interaction challenges us to keep expanding how we study, interpret, and value animal behaviour.
“I’ve seen humpback whales in Australian waters play with seaweed by grasping it in their mouths and draping it over their fins, possibly for tactile pleasure or even to remove parasites. But I haven’t yet observed killer whales here doing the same. It’s exciting to think how much more there is to discover here.”
Dr Olaf Meynecke, who leads the whales and climate program at Queensland’s Griffith University, agrees the orca behaviour documented in the new research is different from that observed among other cetaceans, including whales.
“What I really find surprising and very interesting is the fine-tuned and delicate behaviour that they are undertaking. Kelp is part of their daily environment, and they have started utilising it,” Dr Meynecke told Australian Geographic.
“Clearly there is a strong social bonding aspect to this behaviour. And as an add-on, it benefits some of their skin properties as well.
“We don’t know if this kind of behaviour exists in other groups or if it is quite specific to that family pod. The research opens up lots of questions.”
Dr Meynecke said the research could also expand awareness of the importance of kelp, which is declining globally, including in Australia.
“If kelp has properties that benefit marine mammals by reducing skin condition problems or bacterial growth, then that is a very important thing to understand.
“Having a more complete understanding of how marine mammals interact with their environment helps give us a better picture of life in the ocean.”
