The orca, or killer whale, is the largest member of the oceanic dolphin family, recognized by its striking black and white coloration. They are classified as obligate carnivores, meaning their diet consists entirely of meat. This makes the orca an apex predator, sitting at the very top of the marine food web with no natural enemies. Found in every ocean worldwide, from the Arctic to the Antarctic and in tropical waters, their global distribution is second only to humans among mammals.
Defining the Orca Diet
Orcas require food to sustain their large bodies, with an individual sometimes consuming up to 500 pounds of prey each day. Their diet is varied across the species, allowing them to thrive in diverse marine environments. Prey categories include bony fish, marine mammals, seabirds, and cephalopods like squid.
The consumption of marine mammals sets them apart from most other large oceanic predators. They regularly target seals, sea lions, dolphins, porpoises, and even large whales. Orcas have also been documented preying on sea turtles and various species of shark and ray.
Specialized Feeding Strategies
The broad diet of the orca species is composed of specialized diets followed by distinct populations known as ecotypes. These ecotypes are groups that have genetically and culturally adapted to specific prey types, hunting techniques, and habitats. Despite sometimes sharing the same waters, ecotypes rarely interbreed or interact, and they strictly adhere to their learned dietary traditions.
The North Pacific features the most studied ecotypes. Resident orcas primarily eat fish, with some populations consuming up to 96% salmon, particularly the high-fat Chinook variety. Transient orcas feed almost exclusively on marine mammals. Offshore orcas consume sharks and schooling fish, a diet often resulting in significant tooth wear.
Similar specialization is observed globally. Some North Atlantic populations focus on large runs of herring and mackerel, utilizing specific herding methods. Antarctic orcas are separated into multiple types, with one specializing in minke whales, another targeting seals, and a third focused on Antarctic toothfish. This learned specialization means a fish-eating orca will not switch to marine mammals, even if fish become scarce.
Hunting Methods and Intelligence
Orcas use complex, coordinated hunting strategies. They operate in close-knit, matrilineal family groups called pods, where hunting knowledge is passed down through generations. This collaborative behavior allows them to successfully pursue prey much larger and faster than themselves.
One cooperative technique is “wave-washing,” where several orcas swim in unison to create a powerful wave that washes a seal or penguin off an ice floe. When hunting schooling fish like herring, pods may employ “carousel feeding,” circling the fish to condense them into a tight ball before stunning them with powerful tail-slaps. For larger prey, such as a gray whale calf, the entire pod works together to separate the young whale from its mother through coordinated ramming and biting. Orcas also use echolocation to find prey and have been observed using disorienting tactics, like creating underwater turbulence.