Researchers have discovered that endangered killer whales in the Pacific Northwest use tools made from kelp to groom one another – a behaviour never before seen in marine mammals.
In a new study published in Current Biology, scientists observed southern resident killer whales manufacturing tools by tearing off pieces of bull kelp and rolling them between their bodies during social interactions.
Drone footage captured whales pressing the kelp against their companions and using it in prolonged grooming sessions.
“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 lead author Dr Michael Weiss of the Center for Whale Research in Friday Harbor, WA.
The critically endangered southern resident population consists of fewer than 80 individuals living in the Salish Sea, that lies between British Columbia and Washington State.
While tool use is well documented in primates, elephants and birds, it remains rare among marine animals.
Weiss and colleagues observed this behaviour across all age groups and social units, noting that whales were more likely to groom relatives or similarly aged partners.
Individuals with more dead skin were also more frequently involved, suggesting a hygienic function.
The findings highlight the cultural uniqueness of southern residents and underscore the importance of conservation efforts. It remains unknown whether this tool-assisted grooming is unique to this group or occurs in other whale populations.
Weiss added, “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.”
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