Killer whales are known for exceptional intelligence, displaying complex social structures and sophisticated communication. New research provides fresh evidence for this, documenting how these marine mammals use stalks of seaweed as tools to groom each other — as in, "You scratch my back and I'll scratch yours."
Using drones to observe a population of killer whales in the Salish Sea, part of the Pacific Ocean between Washington state and British Columbia, researchers noticed that these predators engaged in a behavior they named "allokelping," one of the few known examples of tool use by marine mammals.
The killer whales find large stalks of a type of seaweed called bull kelp, either attached to the seabed or floating at the surface. They then bite off the end of the stalk, position it between themselves and another killer whale and roll the kelp between their bodies.
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