Scientists have for the first time seen orcas hunting whale sharks, the biggest fish on the planet, new research has revealed.
The question of how orcas are able to kill the enormous fish is resolved by the dramatic video above, which also demonstrates that whale sharks are probably a common food source for some pods.
Shark ecologist Kathryn Ayres spotted a group of orcas circling on May 26 when she was leading visitors on an ocean safari close to La Paz, Mexico. Ms Ayres remarked, “I knew some poor animal was being tormented. They like to play with their food.”
Although there has previously been anecdotal evidence that orcas could kill whale sharks, marine scientists have now thoroughly recorded the behaviour for the first time by examining four distinct hunting incidents that were captured on camera.
The study, which was released Friday (November 29) in the journal Frontiers in Marine Science, details hunts that took place between 2018 and 2024, and were documented in photos and videos recorded by scientists and the public.
First, the orcas strike a whale shark quickly with their bodies. The whale shark is then turned over and is unable to dive to escape, floating belly-up. The orcas then consume the prey's internal organs after biting its abdomen, causing blood to spill.
“You can clearly see how all the members of the orca pod are trying to bring down the whale shark,” the study’s author, Higuera Rivas, said.
“While one orca was bumping him on the ventral (belly) side, the other one was bumping him on the head. Then, eventually, the whale shark is taken into an upside-down position,” he added.
The whale shark enters a condition known as “tonic immobility”, which is essentially a momentary paralysis brought on by intense fear and is observed in other animals.
Three of the four documented predation occurrences involved a male orca named Moctezuma, who was first observed in 1992. One of the pod's matriarchs may have been the father of this male orca, and he may have picked up his shark-eating skills from her.
Four or five female or juvenile whales frequently accompany him; in one documented case, they launched an attack without him.
The Moctezuma pod is a group of orcas that appear to be experts at hunting cartilaginous fish. Off the coast of southern Baja, they also hunt bull sharks, pygmy devil rays, and stingrays. The renowned Aztec emperor is the inspiration behind Moctezuma's name.
Additionally, the females in the pod have been given Aztec names such as Quetzali, Niich, and Waay, which in Majan means “witch” due to the shape of her dorsal fin resembling a witch's cap.
This pod may have a distinct penchant for whale sharks.
Simon Pierce, the executive director of the Marine Megafauna Foundation and a whale shark conservation specialist who was not involved in the study, told the National Geographic: “I've never heard of whale sharks being targeted by orcas anywhere else in the world. But, if a pod of killer whales focuses on one, I don't think a whale shark has much of a chance.”
Why are orcas wearing salmon hats?
In related news, orcas across Puget Sound, in the Pacific north-west, were spotted with dead salmon on their heads recently. This was first spotted in 1987 but, the following year, the orcas decided there was no need for more.
The reason for the “salmon hats” are unknown, but links have been made to the unusually large number of salmon this year.
It could also be a strategy to catch prey; as evidenced in this article, orcas do have terrifying intelligence.
