Killer whales, also known as orcas, are highly intelligent and adaptable marine mammals at the top of the ocean’s food chain. These powerful predators are recognized for their distinctive black and white markings and complex social structures. While their diet varies by population, sharks are a part of what they eat. Orcas employ sophisticated hunting strategies, demonstrating their remarkable cognitive abilities.
Preferred Shark Species
Killer whales prey on various shark species, including great white, mako, thresher, and blue sharks. In New Zealand, sharks and rays are important prey, including eagle rays, stingrays, common threshers, smooth hammerheads, blue sharks, basking sharks, and shortfin makos. Orca populations off South Africa and Australia have been observed targeting great white sharks.
Orcas sometimes target younger or smaller sharks. A significant preference for the high-fat livers of sharks has been noted in various interactions. For example, a great white shark carcass found in Victoria, Australia, was missing its liver, digestive, and reproductive organs, with DNA confirming killer whale predation. This selective consumption highlights the nutritional value of shark livers, which are rich in fats and oils, providing a dense source of calories.
Unique Hunting Strategies
Killer whales exhibit coordinated hunting tactics when pursuing sharks. One strategy involves ramming sharks or flipping them upside down to induce tonic immobility. When inverted, a shark becomes temporarily paralyzed and helpless. This allows orcas to precisely remove the shark’s lipid-rich liver.
Cooperative hunting is a hallmark of killer whale behavior, enabling them to tackle large prey. Pods work together, with some individuals driving the shark while others position themselves for the tonic immobility technique. Off South Africa, Port and Starboard, a pair of killer whales, have attacked great white sharks since 2017. Starboard can even perform a solo attack, grabbing a great white’s pectoral fin and flipping it over to access the liver in under two minutes.
Orcas utilize echolocation to locate prey and identify specific organs. By emitting clicks, they create a mental image of their surroundings, discerning the size and composition of internal structures. This allows them to pinpoint the nutrient-dense liver, avoiding less digestible parts like cartilage and tendons. Such precision in hunting underscores the advanced cognitive abilities and problem-solving skills of these marine predators.
Dietary Significance
While killer whales are opportunistic predators with a diverse diet, the role of sharks varies among populations. Some orca ecotypes specialize in specific prey; for instance, “resident” killer whales in the U.S. Pacific Northwest primarily consume fish, particularly salmon. In contrast, “transient” orcas, also known as Bigg’s killer whales, mainly prey on marine mammals, including seals, dolphins, and sometimes sharks.
Shark predation is not a common occurrence for all killer whale populations. It is often opportunistic, localized, or specific to ecotypes that have developed these specialized hunting techniques. The high nutritional value of shark livers makes them a valuable target when available. This rich energy source is important for larger orcas or those engaged in energy-intensive activities.
Sharks typically form only part of a killer whale’s broad diet, which also includes other marine mammals, fish, and seabirds. The presence of shark-hunting orcas can lead to changes in shark distribution, as great white sharks, for example, have been observed to flee and forage elsewhere when orcas are present. This demonstrates the significant impact killer whales, as apex predators, can have on marine ecosystems.