November 29, 2024, 8:40 am | Read time: 4 minutes
Orcas are skilled hunters and work in teams. Their prey usually includes seals or smaller fish. For the first time, marine biologists have observed that killer whales also prey on the world’s largest sharks. They have developed a specialized hunting strategy to prey on sharks more than twice their size.
Orcas typically hunt marine mammals such as seals, turtles, and fish. But sharks are also part of the prey spectrum of these animals, which are also known as killer whales. However, what scientists have now observed is unique worldwide. In a study, marine biologists from Mexico describe for the first time how a group of animals hunts whale sharks in the Gulf of California. At up to 20 meters long, they are among the largest fish in the world.
But how do orcas manage to hunt these animals, which are twice their size? And what are the advantages of hunting these huge fish? PETBOOK summarizes the exciting results of the study published in the scientific journal Frontiers.
Researchers observed orca group over six years
Killer whales are considered the apex predators in our oceans. It is known from many studies and observations that individual groups specialize in certain prey, such as tuna, and develop their own hunting strategies. These intelligent and social animals usually work as a team. This is how orcas manage to take down large prey such as sharks.
The skillful hunters also work together when attacking whale sharks. Erick Higuera Rivas, marine biologist and lead author of the study, and his team have now been able to document this for the first time. The scientists collected photo and video material over a period of six years and analyzed the footage.
Orcas have developed their own hunting strategy
Whale sharks are – as their name suggests – sharks the size of a whale. It is estimated that the animals can grow up to 20 meters long and weigh more than 34 tons. However, they are not dangerous. They feed on tiny creatures such as plankton.
Whale sharks live mainly in tropical and subtropical areas. In the Gulf of California, there are places where the animals search for food while they are still young and small, the researchers write in their study. In this phase of their lives, the sharks are more vulnerable to predators such as orcas.
The killer whales appear to have developed their own hunting strategy for this. “We show how orcas used a collaborative hunting technique for whale sharks,” says study leader Erick Higuera Rivas in the scientific journal PhysOrg. The whales specifically attack the pelvic area of the sharks.
“All group members work together during the hunt”
Injuries in this area quickly cause the whale sharks to bleed out. The animals’ bodies are presumably less protected here, as the researchers write. There is less muscle and cartilage in this area, which allows easier access to the aorta.
“When hunting, all group members work together and hit the whale shark to turn it upside down,” says Higuera Rivas, describing the orcas’ strategy. “In this position, the sharks enter a state of tonic immobility and can no longer actively move or escape by diving into deeper water.”
Orcas mainly target the shark’s organs
By keeping the large shark under control in this way, the orcas can approach the pelvic area more easily. There, they would primarily remove the organs that are important to them in terms of nutritional physiology. This is because the whale shark’s body consists mainly of cartilage and muscles. Neither contains many nutrients.
Marine biologists suspect that the animals are mainly after the whale shark’s liver. It is an important part of the orcas’ diet. However, the researchers noted, so far, there have been no photographic observations of the whales consuming the organ.
“Orcas could also eat other organs such as the stomach and intestines, but we don’t know 100 percent,” explains marine biologist and study author Francesca Pancaldi in the scientific journal Sciencealert. “I have personally seen the same group of orcas specifically eating only the livers of other shark species in the Gulf of California. We also know from other publications that orcas target this organ because it is rich in lipids, omega-3 fatty acids, and other nutrients.”
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Whale sharks are endangered
The hunting behavior is so far unique to the orcas in the Gulf of California. Whether other groups of killer whales also possess this ability is not yet known. However, the topic should be urgently researched further, as whale sharks are classified as endangered on the Red List of Threatened Species. It is estimated that the population has declined by more than half in recent years. The main reason for this is direct fishing. 1
If more orcas specialize in hunting whale sharks, they could theoretically contribute to the disappearance of the large fish from this region, the researchers warn. Nevertheless, it is very impressive how the killer whales work together strategically and intelligently to reach only a very specific area of the prey, concludes Higuera Rivas. “It shows what great predators they are.”