Orcas (Orcinus orca) may be more ruthless victims than we give them credit for. Scientists have discovered orcas have learned to hunt whale sharks (Rhincodon typus), the largest fish in the world.
Marine biologists have documented behavior that has never been confirmed among orcas that live in the Southern Gulf of California, a body of water between the state and Mexico. They found evidence of several whale shark attacks that occurred over a six-year period—most of which involved a single male orca known as Moctezuma. Although much is still unknown about this phenomenon, the findings suggest that these killer whales may have acquired and passed on unique information that allowed them to take down their large prey.
Despite their friendly reputation for TV shows and movies, orcas are widely known as predators wherever they live, hunting a wide variety of fish, rays, and marine mammals, including some dolphins. Orcas have been reported to hunt various species of sharks, including the white shark, but not whale sharks—an animal that would be a major challenge for any predator. Although orcas are the largest living members of the dolphin family, they are still outnumbered by the whale shark. The average adult orca is 20 meters long (6 meters) and weighs six tons, while the average whale shark can grow to 13.7 meters and weigh up to 20 tons (some whale sharks are even larger.) .
Adult whale sharks are not thought to have natural predators, but young and small ones are sometimes hunted by sharks and other large fish. Whale sharks have been seen feeding in the Gulf of California, including small sharks, and there have been rare reports of orcas in the area preying on them (even adults). But this new study, published Friday in the journal Frontiers in Marine Scienceit is the first of its kind to confirm the reports.
Marine biologist Erick Higuera Rivas and his colleagues collected photo and video evidence from the public and scientists detailing four hunting events that took place between 2018 and 2024. They found that orcas work together to weaken and eventually kill their larger prey, often by targeting one. a particular part of whale sharks’ bodies: their pelvis.
“We show how orcas have shown how to hunt cooperatively a whale sharkswhich is characterized by a focus on attacking the pelvic area that causes a whale shark bleed and allow the orcas to access the lipid-rich liver,” said Higuera Rivas, a scientist at the non-profit marine research organization Conexiones Terramar, in a statement from Frontiers.
The orca Moctezuma was seen in three of these attacks, and another female orca that had been seen with Moctezuma was also involved in one attack. The repeated presence of these orcas in attacks, coupled with their specific hunting style, suggests that they are part of an orca pod that has become specialized in killing whale sharks, the researchers said.
“When hunting, all members of the pod work together, hitting the animal a whale shark to turn it upside down. In that capacity i sharks enter a state of tonic immobility and he can no longer move voluntarily or escape by going deeper,” said Higuera Rivas. “By keeping it under control, the orcas become lighter and faster when approaching the pelvic area shark and they are able to extract vital nutrients for them.”
Both whale sharks and orcas are widely distributed, although whale sharks prefer to stick to warmer, warmer waters. So it is possible that orcas elsewhere have learned to hunt these large fish. At the moment, however, there isn’t much data available to tell us either way. If Moctezuma and his pod are exceptional whale shark hunters, that could have important implications for the conservation of this marine region. Any dangerous changes to whale sharks in the Gulf could affect their chances of survival, for example. And the researchers say that more care is needed to ensure that tourists and other visitors to the area do not disturb the environment too much.
The sea is full of all kinds of mysteries and unknowns, especially in the darkest and deepest crevices of the earth. But it seems that even some of the world’s largest and most famous sea creatures have their secrets yet to be revealed.
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