Researchers have found that a specific group of killer whales uses seaweed as a tool, marking the first documented instance of tool use among marine mammals.
The identified whales belong to the “Southern Resident” population. Their behavior has attracted attention from scientists recently. These whales chip away at the edges of kelp stems, placing the pieces between themselves and their partners, and then rolling the kelp against their bodies for extended periods.
Using drone footage for their observations, the research team published their findings on Monday.
This small community of orcas resides in the Salish Sea, situated between Washington and British Columbia.
“What surprises me about this behavior is how prevalent it seems across the population,” remarked Michael Weiss, the lead author from the Whale Research Center in Washington.
Weiss and his team stumbled upon this unexpected behavior while conducting aerial surveys. This population comprises just 73 endangered individuals.
The researchers had been observing these whales since 2018 to gain deeper insights into their social interactions and foraging methods.
While there are other killer whale populations worldwide, Weiss pointed out that the Southern Residents are distinct genetically, ecologically, and culturally.
Through high-quality drone footage, they discovered that the whales were creating the tool by breaking off stalks of burkelp.
The team noted that whales of various social groups, regardless of sex or age, engaged in this grooming behavior, particularly with closely related individuals or partners of a similar age.
Interestingly, they found that whales with increased molting or dead skin were more inclined to participate in grooming, hinting at a potential hygiene function.
“The burkelp stems are sturdy yet flexible, like a garden hose, which makes it ideal for grooming,” Weiss explained.
The researchers identified a behavior they termed “Allokelping” during eight of the twelve days covered in their study.
Weiss emphasized the unexpected nature of these discoveries, noting that they had been observing this group for nearly fifty years.
“This not only demonstrates the advantages of new observational techniques but also highlights how much more there is to learn about these creatures,” he stated.
Co-author Rachel John, a master’s student at the University of Exeter, echoed this sentiment, observing that even with extensive research on orcas, new findings continue to emerge.
On the subject of why Allokelping occurs, senior author Darren Croft highlighted the importance of tactile interactions. He pointed out that while killer whales frequently contact one another, using kelp in this way could enhance that experience.
He also mentioned potential benefits to skin health and noted the antibacterial and anti-inflammatory properties of the bull kelp.
If Allokelping is indeed a “culturally significant behavior” for the Southern Resident killer whales, scientists stress the need to protect this endangered population.
Weiss warned that the fate of these killer whales appears grim, as their current birth rates aren’t sustainable long-term. This decline is linked to their struggle to find enough fatty chinook salmon for survival.
“Losing them means more than just the loss of 73 individual animals or genetic lines,” Weiss pointed out. “It would signify the loss of a complex society and a rich tapestry of cultural practices.”
