Ocean sunfish are the largest bony fish in the world — some species can weigh more than 2,000 pounds and span 14 feet from top to bottom fin. Their impressive size and thick skin usually deter predators.
But off the coast of Baja California, a group of orcas has adopted a brutal way of hunting sunfish: With an unusual maneuver, the orcas pulverize the giants. Erick Higuera, a marine biologist at Conexiones Terramar, a scientific organization, described the attacks as “violent” and “chaotic,” but also “highly calculated.”
Mr. Higuera first witnessed the hunting strategy in 2021. Orcas tossed around a sunfish “like a Frisbee” before making it “explode,” he said. Now, in a study published Thursday in Frontiers in Ethology, Mr. Higuera and his colleagues described two events filmed in 2024 and 2025.
In the two videos, an adult orca held the carcass of a sharp-tail sunfish in its mouth. Then, another adult swam at high speed toward the sunfish. The first orca released it, and the second rammed into it, fragmenting the sunfish. As pieces floated about, a juvenile orca began eating.
“It’s like soccer,” Mr. Higuera said. “Everyone has a role.”
Scientists have documented orcas preying on sunfish, also known as mola, for several decades. In the Gulf of California, the feeding behavior was first reported in the 1990s.
In January, Mr. Higuera and another group of scientists published a study reporting more than 20 encounters between orcas and sunfish. Orca calves were present for eight of them. Female orcas may be using sunfish to train their young, or just for entertainment, the authors wrote in the earlier study.
But the sunfish in the earlier observations were not shredded as much as the prey in the videos, suggesting the fragmentation strategy may be specific to the sharp-tail sunfish.
Robert Pitman, a marine ecologist at Oregon State University who was not involved in the research, saw the behavior as perhaps logical. Sunfish skin is made up of so-called dermal denticles, similar to the rough, toothlike scales that sharks have.
By ramming the fish, Dr. Pitman said, killer whales may get at their prey without wearing down their teeth. “Nothing that they do surprises me anymore,” he said.
Marianne Nyegaard, a marine biologist at Auckland War Memorial Museum who was not involved in the research, has studied ocean sunfish and documented many orca interactions with them.
“I was really pleased to see someone had taken the behavior and kind of described it in detail,” she said.
“Sunfishes are often seen as these big, weird, irrelevant fish that are a bit of a curiosity,” Dr. Nyegaard said. “They’re not really seen as part of the ecosystem.” The new study, she said, helps bring sunfish into “mainstream ecology.”
Luke Rendell, a marine biologist at the University of St. Andrews, said that sunfish know-how might persist in this group of orcas for generations through cultural inheritance.
And ramming behavior is not unique to the sunfish hunt, Dr. Rendell added. He pointed to the widely reported interactions between orcas and boats off the Iberian Peninsula, where orcas have rammed and sunk several vessels.
“In both cases, bashing up something they find in their environment leads to new knowledge,” Dr. Rendell said. “Food, in this study, and fun games, in the case of the boat interactions.”
