Overview

• Researchers observed orcas in the Salish Sea manufacturing and rolling lengths of bull kelp between their bodies, marking the first documented tool use in marine mammals.
• The practice, termed “allokelping,” was recorded across all age groups and the three southern resident pods during drone surveys from 2018 to 2024.
• Orcas with more molting or dead skin were more likely to engage in kelp grooming, suggesting a primary role in hygiene by exfoliating skin.
• Bull kelp’s firmness, flexibility and antibacterial properties may enhance both the physical grooming and the social bonding aspects of the behavior.
• With fewer than 80 southern residents remaining, scientists warn that safeguarding this unique cultural practice is vital to the population’s conservation.