Southern Resident Orcas Use Kelp for First Documented Marine Mammal Toolmaking

Scientists have discovered that southern resident killer whales in the Salish Sea use pieces of kelp as tools to scratch and groom each other, marking the first known tool use by marine mammals. The whales bite off ends of bull kelp stalks and position the fragments between themselves and partners, rolling the kelp along their bodies in a behavior termed "allokelping." This social grooming practice occurs across all age and sex classes and is believed to help strengthen social bonds and maintain healthy skin. Researchers documented multiple instances of this behavior using drone footage, highlighting its widespread nature among the critically endangered population of about 73 individuals. The discovery is notable not only as evidence of tool-making by marine mammals but also as the first recorded instance of wild animals using tools to benefit two individuals simultaneously. Scientists compare this behavior to social grooming seen in primates, emphasizing the importance of touch in moderating stress and building relationships.