In a remarkable scientific breakthrough, researchers have documented endangered killer whales in the Pacific Northwest using kelp as tools to groom one another — a behaviour never before recorded in marine mammals.
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The study, recently published in Current Biology, describes how southern resident killer whales have been observed tearing off strands of bull kelp and rolling them across their bodies during social interactions. Drone footage revealed whales deliberately pressing the kelp against companions and engaging in extended grooming sessions.
“What I find most remarkable is that despite this apparently being a common behaviour – 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 Dr Michael Weiss, lead author and biologist at the Centre for Whale Research in Friday Harbor, Washington.
The critically endangered southern resident orcas comprise fewer than 80 individuals residing in the Salish Sea, a body of water stretching between British Columbia and Washington State.
While tool use is well documented among primates, elephants and certain bird species, it remains an exceptionally rare phenomenon in marine life. Not only were these killer whales observed using tools, but researchers also noted that the kelp was being manufactured into usable shapes — an unprecedented finding in oceanic mammals.
Weiss and his team recorded this grooming behaviour across all age groups and family units, noting that whales were more inclined to groom relatives or peers of similar age. Interestingly, individuals with visible dead skin were more frequently involved, suggesting a possible hygienic motivation.
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“These findings not only shed light on the complexity of orca social lives but also underline the cultural richness of the southern resident population,” added Weiss. “To discover that the whales were not just using but actively creating tools for a purpose not previously known in marine mammals was incredibly exciting.”
The study raises important conservation questions: is this behaviour unique to the southern residents, or does it occur in other orca populations yet to be studied in similar detail?
Researchers say the findings highlight the urgency of protecting this distinctive population, whose cultural behaviours — like tool-assisted grooming — may be lost without robust conservation action. Let me know if you’d like image captions or selected short quotes pulled for use in social media or editorial formats.
