Killer Whales Documented Using Seaweed for Grooming

Marine scientists have captured video evidence showing orcas engaging in an intriguing behavior: using seaweed to groom one another. This intriguing discovery marks a groundbreaking example of tool use among cetaceans, a behavior rarely documented in marine environments.

While tool use is not exclusive to humans, with chimpanzees crafting termite fishing sticks and elephants wielding branches to swat away flies, such behavior within the oceanic realm remains exceptional. Previously, it's mostly been sea otters cracking shellfish with stones or octopuses utilizing coconut shells as portable shelters.

Discovery of Orca Tool Use

Researchers have focused their attention on the population of critically endangered southern resident killer whales located in the Salish Sea, bordered by British Columbia and Washington State, for more than five decades. The revelation came when Rachel John, a master’s candidate at the University of Exeter, U.K., observed peculiar activity while reviewing footage from drone cameras.

Following up on this curiosity, the research team scrutinized earlier recordings and documented the behavior as remarkably common, noting 30 occurrences across eight days. Their observations detailed how one whale snaps a section of bull kelp, likened to a robust yet pliable garden hose, and positions it skillfully between its own body and that of another whale, both using the kelp for several minutes in their interactions.

Allokelping: A Social Ritual

Traditionally, whales have been spotted enjoying seaweed in a recreational activity known as 'kelping', partly for leisure and partly to exfoliate their skin by removing dead cells. The researchers coined this newly documented practice as 'allokelping', a phenomenon involving mutual kelping between two whales.

The team surmised that allokelping bears resemblance to dermal care practices observed among other cetaceans. Though based on limited data, they noted that whales with more dead skin were prone to this activity, often seen paired with kin or age-similar companions, suggesting a mingle of social bonding in these antics.

Cultural Importance and Conservation Concerns

This represents the first documented case of marine mammals engaging in tool manipulation using their bodies rather than extremities. Michael Weiss, from the Center for Whale Research and primary investigator of the study, emphasized its significance as a cultural manifestation within animal societies.

However, the exceedingly reduced numbers of southern resident killer whales, now at a mere 73 individuals, carry ominous implications for preserving this unique cultural behavior if no conservation measures are enacted to support their survival.

Their preferred prey, Chinook salmon, have suffered substantial population declines due to a combination of human activity-influenced factors, including overfishing and climate change, putting additional pressure on orca populations.

Wider Context and Ongoing Challenges

Recent events have also brought killer whales into the public eye, like the surprising appearance of orcas near Seattle and reports of abnormal interactions between ships and orcas in European waters. These incidents add layers to our understanding of their behaviors and highlight the complex challenges facing conservationists in safeguarding these majestic animals.