Orcas in the North Pacific have been seen "massaging" each other - rubbing pieces of kelp between their bodies. Using drones, researchers filmed the animals selecting and biting off the kelp, then placing the tube-shaped piece of seaweed onto the back of another whale.

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,

The whales in question are the southern resident killer whales that live in the Salish Sea between Vancouver Island and Seattle. Unlike other orcas that migrate in and out of the area, this critically endangered population of just over 70 individuals remains in the area year round.