Killer whales are really just big dolphins. This behavior was discovered last year, is just now getting press. They're *grooming each other* with broken off pieces of kelp sea weed, like we use a stone to rub off dead skin. Allokelping, it's called, apparently.
Smaller dolphins wear pieces of sponge to protect their snouts when feeding on the ocean floor, so here's another mammal with another tool.
#orca #big #dolphin #kelp #groom #dead #skin #drone #footage #research https://www.science.org/content/article/killer-whales-groom-each-other-pieces-kelp