Orcas are known for surprising behaviors. A new study documents two cases of orcas ramming sunfish so hard that the fish explode.
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“Don’t play with your food” is a rule orcas don’t seem to follow.
Off the shores of Cabo San Lucas, Kathryn Ayres, a scientist at the ocean-health nonprofit Beneath The Waves, saw a surprising orca behavior: one orca holds a sunfish in its mouth while another lines up and then rams it at high speed — leaving behind thousands of sunfish bits scattered like confetti.
Ayres and her coauthors documented this “stabilize-and-ram” behavior in a paper published Thursday.
“Seeing a large animal burst into fragments looks shocking,” says study co-author Erick Higuera, a marine biologist at Conexiones Terramar.
But “it isn’t ‘crazy’ or ‘cruel,'” he says, but rather “highly specialized biology.”
“We think this may help younger orcas feed more easily — or it could also just be for fun,” Ayres says. “Orcas are known for playing with their food.”
In fact, these marine mammals have been documented displaying all kinds of “playful” behaviors. Orcas off of Washington state have been seen wearing salmon as hats. And some adolescent orcas take up a hobby of sinking ships.
They’re like cats, Robert Pitman says, a marine ecologist at Oregon State University who wasn’t involved with the study. He says, like cats, orcas like to “torment prey and non-prey alike.”
But Pitman thinks this is primarily a feeding behavior. He notes some older orcas that eat sharks have trouble eating later in life due to teeth worn down to their gums — as do young orcas without teeth. Sunfish, like sharks, can be tough to eat. They can weigh thousands of pounds and have incredibly dense, rubbery, and collagenous skin several inches thick. And if that wasn’t trouble enough, “there just doesn’t seem to be much to eat on a sunfish,” he says.
“I think this behavior is a clever way to deal with a difficult prey item,” he says. Given the context, the ramming behavior could be a more efficient method to eat sunfish than meticulously pulling it apart.
Higuera came to the same conclusion. “Orcas do not possess hands or tools to tear apart their prey,” he says — so ramming sunfish to “bite-size pieces” is “incredibly practical.”
Whether this behavior is “fun” is still an open question. For the behavior to be “fun,” Higuera says, it needs to be voluntary, rewarding and involve modified or exaggerated behaviors. There are two documented cases of this behavior: one caught by Ayres in July 2024, and another filmed by a tourism operator last September. And in both examples, he notes it has aspects of being a social game like a sport with one orca teeing up another to ram it. But he says it could also be a kind of parental care, with the adults preparing food for teething juveniles.
He says it is likely a feeding-plus-fun social activity, but would like to see more examples of this behavior before drawing any conclusions. For example, Higuera says if scientists saw adults doing it without toothless orcas present and not eating the shredded sunfish at all, that would support the case that it’s simply entertainment.
While both of the documented cases took place in Baja California, Pitman says it remains to be seen if other orcas around the world practice this “innovation” too. Higuera is also interested. He doesn’t know if it was the same orcas involved in the two cases, but thinks it is likely a “cultural knowledge” restricted to a handful of pods in the area.
Pitman applauds the authors for elucidating this behavior. He says he’s seen orcas carrying sunfish like “a large pizza box in its mouth” many times before and did not know what they were doing. “Maybe now I know,” he says.
He warns, however, “for some snorkeling thrill seeker” hoping to see the orcas, that they should be careful not to end up as the pizza box themselves.
This story originally appeared on NPR
