Orcas (Orcinus orca) might be even more ferocious predators than we give them credit for. Scientists have discovered orcas that have learned to hunt whale sharks (Rhincodon typus), the largest fish in the world.
Marine biologists documented the never-before-confirmed behavior among orcas living in the Southern Gulf of California, the body of water between the state and country of Mexico. They found evidence of several whale shark attacks that occurred over a six-year-span—most of which involved one particular male orca known as Moctezuma. While much is still unknown about the phenomenon, the findings suggest these killer whales may have acquired and passed on unique knowledge that allowed them to take down their hefty prey.
Despite their friendly reputation from TV shows and movies, orcas are well known to be apex predators wherever they live, hunting a wide variety of fish, rays, and marine mammals, including other dolphins. Orcas have also been recorded hunting various kinds of sharks, including the great white shark, but not whale sharks—an animal that would pose a considerable challenge for any predator. While orcas are the biggest living members of the dolphin family, they’re still far outsized by the whale shark. The average adult orca is around 20-feet-long (6 meters) and weighs six tons, while the average whale shark may extend as long as 45 feet (13.7 meters) and weigh up to 20 tons (some individual whale sharks are even more massive).
Adult whale sharks aren’t thought to have any natural predators, but younger and smaller ones are sometimes hunted by sharks and other large fishes. Whale sharks have been spotted feeding in the Gulf of California, including juvenile sharks, and there have been anecdotal reports of orcas in the area hunting them (even adults). But this new research, published Friday in the journal Frontiers in Marine Science, is the first of its kind to confirm the reports.
Orcas seen here with whale shark carrion in their mouths during an attack on 26 May 2024. © Kelsey Williamson
Marine biologist Erick Higuera Rivas and his colleagues collected photo and video evidence from the public and scientists detailing four hunting events that happened between 2018 to 2024. They found that the orcas cooperated to methodically weaken and ultimately kill their large prey, often by focusing on one particular part of the whale sharks’ bodies: their pelvis.
“We show how orcas displayed a collaboratively hunting technique on whale sharks, characterized by focusing on attacking the pelvic area causing the whale shark to bleed out and allow orcas access to 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 observed at three of these attacks, while another female orca previously seen with Moctezuma also took part in one attack. The repeated presence of these orcas at the attacks, coupled with their precise method of hu