A remarkable new study has uncovered how a pod of orcas in the Pacific Ocean, off the coast of Mexico, has developed an effective strategy for hunting and killing whale sharks — the world’s largest fish, capable of growing up to 18 meters (60 feet) in length.
While previous reports and observations had suggested that orcas were capable of preying on whale sharks, this study offers the first detailed documentation of such hunting behavior, capturing four separate events on camera. These hunts were conducted in the Gulf of California, where whale sharks gather in feeding areas. However, the orcas specifically target younger, smaller sharks, typically measuring between 3 to 7 meters (10 to 23 feet) in length, as these juveniles are more vulnerable to predators.
Despite the potential for an intense battle, the orcas are able to easily overpower the gentle giants. According to Francesca Pancaldi, the study’s lead author and a researcher at Mexico’s Centro Interdisciplinario de Ciencias Marinas, the whale shark is no match for the orcas due to its slow movement and small brain, which is about the size of an egg. The whale shark’s defense mechanisms are limited to flailing or diving, but these are often ineffective against the orcas’ coordinated strategy.
The study, published in the journal Frontiers in Marine Science on Friday, details how the orcas use a series of precise maneuvers to subdue the whale sharks. First, the orcas strike the sharks with high-speed body blows. Next, they flip the shark upside down, rendering it unable to dive and escape. Once the shark is immobilized, the orcas bite into the belly, causing the shark to bleed out. They then consume its internal organs, particularly the nutrient-rich liver.
In the analysis of the four hunting events observed between 2018 and 2024, researchers identified the orcas involved by distinctive marks such as dorsal fins and scars. In three of the hunts, a male orca named Moctezuma, who measures around 8 meters (26 feet), was observed. The presence of a female orca, seen previously with Moctezuma, suggests that they may belong to the same pod or be closely related.
This strategic hunting behavior begins with one orca striking the whale shark’s belly while another targets its head. The shark eventually enters a state called “tonic immobility,” a form of temporary paralysis caused by extreme fear. This technique is seen in other animals, which also become immobilized when turned upside down.
The study suggests that the orcas are likely hunting for the whale shark’s large, fatty liver, a highly nutritious organ that makes up a significant portion of the shark’s body weight. While the researchers did not observe the orcas eating the liver, it is known that killer whales often target sharks for their rich livers.
This new behavior is particularly significant because it marks the first clear documentation of orcas hunting the largest species of shark on the planet. Orcas, also known as killer whales, are apex predators in the ocean and are known for hunting a wide variety of prey, including fish, marine mammals, sea turtles, and cephalopods.
The orcas of the Gulf of California could represent a new ecotype of orcas that specialize in hunting sharks and rays. Researchers are eager to conduct more studies to determine whether these orcas are developing a distinct hunting strategy. In comparison, orcas in South Africa have been observed developing techniques to hunt great white sharks, another apex predator, leading to significant changes in the local ecosystem.
Despite this unique hunting strategy, the researchers believe that the predation on whale sharks has not had a major impact on their populations in the Gulf of California or the broader ecosystem.
