In pricey spas, kelp facials and body wraps can set the esthetically inclined human back hundreds of dollars.
But in the Salish Sea off British Columbia’s coast, southern resident killer whales are also using the sea plants for what scientists suspect are grooming purposes.
Researchers who have spent years studying the endangered whales say higher-quality drones helped them spot the whales regularly breaking off pieces of kelp to use as a tool, pressed between their bodies.
Michael Weiss, chair of the Center for Whale Research based in Washington state, is the lead author on a recent study published in the journal Current Biology, which hypothesizes both hygienic and social purposes.
While the center has been observing the southern resident killer whales for almost half a century, they were able to get a new drone in 2024 — through a research grant — with a zoom lens that allowed them to notice behaviours like this one.
“It’s not all that surprising that they’re able to do it; what’s surprising is that we didn’t know about it from over 50 years of study,” he said.
“What I think it says is that there’s a lot more to learn from these whales, and there’s a lot to learn from other less well-studied populations as well.”
While primates and birds are known to use tools, Weiss told CBC News that it’s a lot less common in the marine environment — partly because they don’t have grasping limbs.
“Despite having these big brains and these complex behaviours, reports of them using tools are rarer than you’d expect, given what you see in terrestrial animals,” he said.
“And we also have seen whales and dolphins rub on each other to potentially remove parasites and dead skin.”
But the southern residents’ use of both types of behaviour at once has not been seen in other whales, Weiss said.
“We haven’t seen any reports of whales combining those two things and using an object to enhance this kind of social touch.”
The researchers observed the behaviour in southern residents across all social groups, both sexes and all age classes.
“We saw 30 different instances of it, which is a limited sample size in terms of statistical power, but in terms of demonstrating that it’s not just a one-off quirky thing — that it is an important kind of part of their social lives — it’s quite robust,” said Weiss.
Dr. Andrew Trites, a professor at the UBC Institute for the Oceans and Fisheries, told CBC News that in reading the study, he sees sufficient observations between individuals for it to be significant.
“We’ve been looking at interactions between killer whales and dolphins, but we’ve never, ever looked at interactions with kelp, and so this is something new for me, and I was quite excited,” said Trites.
“Some of it is speculative about what the purpose might be, but I think it’s a good starting point to bring attention to what I think is very unique behaviour. You’re not born with this behaviour. You learn it and with interactions with others, it’s reinforced.”
Weiss said other mammals, including primates, do use tools and groom each other, but the whales’ situation is distinct, in part because two animals are getting shared benefits.
“We don’t have one whale with a stick scratching the other one. We have two whales with kelp between them, simultaneously rubbing it against each other. And that’s really unique,” he said.
He said primates rarely use grooming tools unless given them by humans.
“This kind of widespread, common behaviour in the population — everyone seems to be doing it in the southern residents, they’re doing it all the time — there’s not really any examples of anything like that, where it’s become commonplace in social interactions to use a tool to enhance that interaction,” he said.
“So I think it’s really special and it’s a brand new context for tool use in marine mammals. It’s not something we’ve seen marine mammals use tools for before.”
Weiss said the next steps for researchers are seeing how the skill is learned, understanding more about the whales’ skin conditions and taking a closer look at the social bonds the use of the kelp helps create.
“Seeing if whales who perform this behaviour together are more likely to then co-operate in other ways later. Are they more likely to chase fish together? Are they more likely to share food with one another, or do other social interactions?” he said.
Southern resident orcas along the West Coast are categorized into three families known as the J, K and L pods, each of which has its own dialect and calls that differ from the others. There are also transient orcas in the region known as Bigg’s killer whales, which feed primarily on marine mammals.
Fisheries and Oceans Canada and Parks Canada, in consultation with Transport Canada and Environment and Climate Change Canada, completed an assessment of the southern resident population last year, finding the population had dwindled to 73, with only 23 breeding females.
The Center for Whale Research also said the population had dipped to 73 in its July 1, 2024, census following the death of two adult male orcas.
Weiss said the research is another example of why it is important to protect the population.
“When we’re talking about conserving this population, we’re not talking just about conserving 73 individual animals. We’re talking about conserving a unique culture with unique behaviours that if we lost them, we’d never see again,” he said.
“This is just another example of the fact that these separate populations of whales are not interchangeable, they’re not fungible. They are special and losing them is a loss for the world. It’s a loss of something unique from the world.”
