Orcas have been observed using tools to engage in what appears to be a delightful, massage-like activity.
The southern resident orca population, or killer whales (Orcinus orca), resides in the northwestern Pacific Ocean’s Salish Sea, near Washington and British Columbia. They primarily feed on fish and are known for their peculiar habit of wearing salmon on their heads.
Recently, they have displayed a behavior that is unprecedented among marine mammals.
Michael Weiss from the Center for Whale Research in Friday Harbor, Washington, along with his team, recorded high-resolution drone footage of the orcas. They observed the whales breaking off pieces of bull kelp (Nereocystis luetkeana), pressing these pieces against one another, and rolling them, seemingly as part of a grooming practice.
The researchers believe this marks the first instance of tool-making by a marine mammal, the first known case of tool use benefiting two individuals simultaneously, and the first documentation of a non-human animal using its body to manipulate a tool instead of using its limbs. Their findings were published on June 23 in the journal Current Biology.
“They break off a two-foot length of kelp’s stem with their teeth and head movements, then approach another whale, flipping the kelp onto their snouts and pressing it against their partner,” Weiss explained to Live Science.
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“They maneuver their bodies to keep the kelp wedged between them and roll it for anywhere from a few seconds to about 15 minutes,” Weiss added.
Deborah Giles, an orca expert at the non-profit SeaDoc Society, who was not part of the study, remarked: “This is really intriguing behavior. They are intentionally crafting the tools they wish to use.”
Weiss’s team observed orcas of all ages and genders engaging in this behavior across various social groups, or pods, within the southern resident community.
Many animals groom each other to reduce stress, maintain health, and strengthen social bonds. Could this be the motivation behind the orcas’ actions?
As social animals, orcas naturally groom one another, as noted by Els Vermeulen, a cetacean specialist at the University of Pretoria in South Africa, who was not involved in the study. “Even though this study is novel and this behavior is being reported for the first time, it doesn’t surprise me.”
The research team found that kelp rubbing occurred more frequently among related individuals and those of similar ages, suggesting a link between grooming and strong social bonds, according to Weiss.
Additionally, they discovered that whales with more dead skin were more likely to engage in rubbing behaviors, indicating a potential benefit for hygiene.
“When discussing animal behavior, we consider both the benefits the animal derives, which relate to health and well-being, and the brain mechanisms that drive these actions,” Weiss stated. “I believe much of it comes down to the fact that it feels pleasant.”
While some animals like chimpanzees, birds, and elephants are known to make and use tools, instances of this among marine creatures are rare. For example, sea otters use stones to crack open shellfish, and dolphins have utilized sponges on their snouts for foraging, but they do not create these tools themselves.
However, kelp grooming is not the only way orcas display their ability to manipulate their environment to create “tools.” They have also been witnessed creating waves to wash seals off ice floes to capture them.
The southern resident orcas are the only group seen using kelp for grooming so far. This may be due to the typical observation method from boats, which makes it difficult to notice small kelp pieces.
“I’ve seen killer whales rolling around with each other from a boat before. It makes me question whether they’ve been performing this behavior for a long time,” remarked Giles. “Drone technology has allowed us a unique glimpse into the lives of these animals that was previously unattainable.”
Regarding the phenomenon of orcas wearing salmon on their heads, experts remain perplexed. “We don’t have an explanation for this behavior,” said Giles. “It seems to happen when prey is more plentiful. They could be playing with their food or simply enjoying the sensation of placing a salmon on their head.”
However, time is critical for studying these extraordinary orcas, as the southern residents are classified as an endangered population under the U.S. Endangered Species Act. The last census recorded only 73 individuals, Weiss noted, and losing these whales would mean “not just the disappearance of 73 whales,” but also the loss of a unique culture and community. “We might never witness this behavior again.”
