#allokelping

KILLER WHALES CRAFT KELP TOOLS FOR SOCIAL GROOMING

In a remarkable discovery, researchers have documented wild Resident killer whale (Orcinus orca ater) manufacturing and using tools in a social context. Observed in the Salish Sea from April to July 2024, members of the endangered southern resident population were seen detaching short lengths of bull kelp (Nereocystis luetkeana) and using them during tactile interactions with a partner, a behavior the authors call allokelping. This behaviour differs from playful kelp draping commonly seen in cetaceans, whales in this study deliberately fashioned kelp segments using their teeth, positioned them between their bodies, and coordinated their movements to roll the kelp across one another’s skin.

This represents a potential case of tool-assisted allogrooming, a behaviour rarely documented in non-primates and never before in marine mammals. Statistical analyses suggest that allokelping may serve both hygienic and affiliative functions, being more common among close kin and individuals of similar age, and possibly linked to skin molting. The whales’ use of their entire bodies, rather than limbs, to manipulate the kelp, and the mutual benefit of the interaction, make this a unique form of tool use in the animal kingdom. If confirmed, it would expand our understanding of cetacean intelligence, culture, and the evolutionary roots of cooperation.

Photo: Orca grasps a bull kelp stalk by the holdfast end and detaches a short stipe segment for use in allokelping.

A social behavior found in the Southern Resident population of killer whales (orcinus orca), allokelping is found when two killer whales hold a piece of bull kelp between their trunks, arching against each other, resulting in the rolling of the kelp between the two.

The Southern Resident population of killer whales (or, a population of killer whales in the eastern North Pacific found off of the coast of British Columbia, Oregon state, and Washington state) were the first observed. As of writing this and to our knowledge, this might be a behavior unique to this population.

This behavior is interesting because it can count as "tool usage" (building tools) due to the intentional creation of the kelp as a tool. It's also interesting as a social behavior, as Southern Resident killer whales do this consistently!

This was discovered in 2024 and released at the end of June, 2025.

Links and other information:

While this was the first article we read about it, this article is on a site that gives you "two free articles a month"; in other words, it's paywalled.

Here's a site page about the Southern Resident Killer Whales specifically, if you'd like to learn more about this population of killer whales!

Another article that we skimmed through.