Researchers have observed a unique behavior among North Pacific orcas: “kelp massage.” Using drone footage, scientists documented orcas selecting and detaching kelp, then using it to rub against other whales.
This behavior, filmed over 12 days in Washington State, involved 30 instances of kelp application. Scientists believe this “allokelping” serves both hygienic and social bonding purposes, representing a novel example of tool use in killer whales.
The findings, published in Current Biology, suggest the orcas intentionally select and utilize the kelp for a specific purpose. “They’re using the kelp to rub between themselves,” explained Professor Darren Croft of the University of Exeter and the Center for Whale Research in Washington State.
Dr. Michael Weiss, lead researcher, noted the frequent occurrence: “When we get a drone over these animals, we’re going to see at least one pair doing this.” This parallels allogrooming in primates, highlighting the importance of physical touch in social dynamics. The researchers hypothesize that whales with irritated skin may be more prone to kelp massage.
The decade-long use of drone technology provided unprecedented insights into orca social interactions, including the details of this novel behavior. “What’s incredible is that with high-quality video, we could see that a lot of this physical contact is happening with the aid of this relatively small piece of kelp,” said one researcher.
While the prevalence of this behavior across other whale populations remains unclear, the discovery of tool use in marine mammals, described as “incredibly exciting” by Dr. Weiss, adds a significant layer to our understanding of orca culture. This research builds upon over 50 years of study on the Southern Resident killer whale population, initially focused on survival threats, and now illuminates the complexities of their social structure, including the crucial roles of grandmothers and female support for their sons. Previous research highlighted the significant sacrifices made by female whales.
The discovery underscores the uniqueness of orca society and the importance of conservation efforts for this threatened population.