Orcas Use Kelp as a Possible Grooming Tool

New York Times

5 hours ago

A hundred feet or more above the Salish Sea — high enough to avoid spooking any marine mammals below — a drone camera recorded orcas periodically pairing up to perform a sort of swimming, rolling hug.
That was nothing new for the Southern Residents, a group of orcas in the Pacific Northwest that lives south of other groups. But when researchers inspected the drone videos, which were filmed last year, they noticed something they had not seen before: A little piece of kelp was often sandwiched between the creatures' bodies.
The research, published this week in the journal Current Biology, is among the most compelling evidence yet that marine mammals make and use tools, a skill more commonly attributed to terrestrial animals like monkeys, humans and crows.
Michael Weiss, an author of the study who is the research director for the Center for Whale Research in Washington State, said that the Southern Residents had long used their intelligence and social skills to adapt to a challenging environment. The group of 73 orcas, which are often called killer whales, has been shrinking for decades and was listed as endangered in 2005.
'I'm not surprised that we eventually found tool use in killer whales,' Dr. Weiss said. 'But it was obviously a surprise to see this particular behavior, because we just had no idea it was happening.'
Kelp is not that hard to find in the waters near British Columbia and Washington State, where these orcas generally stay. But they were not just grabbing any old floating stalk. They were using their teeth to break off pieces, which were almost always about two feet long.
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