Killer whales have joined the rare club of animals that can make and use tools, for the first time being observed crafting a kind of brush out of kelp and then using it on fellow pod members.
The feat – incredibly rare for marine animals – was seen and captured by researchers from the Center for Whale Research (CWR) based in Washington state, adding to the quirky behaviors already observed in this intelligent and often maligned species.
“We found that southern resident killer whales regularly use lengths of bull kelp during social interactions, apparently as a tool to groom one another,” said Michael Weiss from CWR. “To find that the whales were not 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.”
The scientists saw first-hand how resident orcas off the west coast of North America were sourcing kelp and breaking pieces off the plants, then pressing it against another killer whale's body. The animals were then seen moving so the kelp rolled across their skin, which they believe to be a form of grooming.
What's more, the behavior – which was observed by the researchers gathering images and data from an aircraft above – was seen en masse, across male and female individuals and in young and mature animals. And the orcas that appeared to have more prominent molting or skin issues were most involved in this communal kelp scrub, suggesting that it does indeed have a specific hygiene-related root cause.
“What I find most remarkable is that despite this apparently being a common behavior – we see it most days we fly our drone over these whales – it hadn’t yet been discovered in this population despite nearly 50 years of dedicated observation,” said Weiss. “To me, this demonstrates not just the power of new observation methods but also how much we still have to learn about these animals.”
It's not the first curious behavior that killer whales (Orcinus orca) have exhibited. Besides sinking expensive yachts in Europe, the animals have been observed wearing live salmon as makeshift "hats" – something that was first identified back in 1987 and continues to pop up in populations much like a fashion trend. There are many theories about this particular behavior, with the frontrunner being how they engage in a lot of "social play" even when hunting, but we still like to think it might be simply aesthetics.
The clever manipulation of breaking off kelp and then using it as a deliberate tool is another thing altogether – something very clearly not linked to social hunting. Scientists are yet to learn of any other populations of orcas doing similar.
“This finding highlights yet another way these whales’ society and culture is unique and the importance of recovering the southern resident killer whale population,” added Weiss. “While there are other killer whales around the world, the southern residents represent a genetically, ecologically, and culturally distinct population."
As earlier studies have found, orcas have complex social behaviors that suggest there's a lot about their communication and cognition we are yet to fully understand. Various learned "tricks" specific to different populations of killer whales – the largest species in the dolphin family – have been seen by researchers across the globe, but tool-making is a completely new endeavor for these elusive marine animals.
But these orcas may be onto something – there's emerging evidence that kelp is actually a strong exfoliator, however it's only been studied for use on human skin.
“The bioactive compounds in seaweed offer numerous benefits for skin health, making it an attractive ingredient for skincare products,” noted researchers in a December 2024 paper.
The research was published in the journal Current Biology.
Source: Center for Whale Research via Scimex