Orcas, commonly known as killer whales, are the ocean’s apex predators, sitting at the top of the marine food chain. Their prey ranges from small fish to large marine mammals, but they are dwarfed by the world’s largest animal, the blue whale, which can reach lengths of over 90 feet and weigh up to 150 tons. Despite this immense size disparity, the answer to the question of whether orcas hunt blue whales is a definitive yes. This rare but documented predatory behavior represents the largest predator-prey interaction on the planet.
The Confirmed Predation Event
For decades, scientists observed orcas harassing blue whales, but a confirmed, successful kill was only recently documented. The first scientifically observed successful predation occurred in March 2019 off the coast of Bremer Bay, Western Australia. Remarkably, the initial victim was estimated to be a healthy, large adult blue whale, approximately 59 to 72 feet long. Subsequent successful attacks in the same region, including one 16 days later and another in 2021, targeted smaller individuals, including a calf and a juvenile whale.
These events demonstrated that while blue whales are massive, they are not invulnerable to a highly coordinated group attack. The sheer scale of the challenge requires the commitment of numerous orcas working together for an extended period.
Coordinated Attack Strategies
The successful hunts rely on sophisticated, cooperative techniques to overcome the blue whale’s size and speed. The initial attack group typically involves a dozen or more orcas, often led by the most experienced adult females in the pod. Their primary goal is to slow and immobilize the giant prey, focusing on the tail flukes and pectoral fins. Orcas repeatedly bite and rake these appendages, causing blood loss and impairing the whale’s ability to swim or maneuver effectively.
Once the blue whale is slowed, the orcas employ a tactic of physical exhaustion and submersion. Multiple orcas will line up side-by-side and ram the whale’s flank, pushing it through the water and forcing it beneath the surface. Others focus their efforts on the head, physically blocking the blowhole to prevent the whale from breathing fresh air. This strategy forces the blue whale to use up its remaining oxygen reserves, leading to fatigue and eventual drowning. In one documented case, a female orca was observed lunging headfirst into the blue whale’s mouth to feed on its nutrient-rich tongue while the animal was still alive.
The Specialized Diet of Transient Orcas
The predation on blue whales is a behavior strictly limited to one specialized group of the species, known as Transient, or Bigg’s, Killer Whales. Orcas are divided into distinct populations, or ecotypes, which differ genetically, socially, and culturally based on their primary food source. Unlike Resident orcas, which feed almost exclusively on fish, Transient orcas are marine mammal specialists.
Their diet consists of seals, sea lions, porpoises, dolphins, and the calves of larger whales, including gray and humpback whales. This carnivorous specialization has driven the evolution of their hunting strategies, favoring stealth and coordinated teamwork over the noisier communication used by fish-eating ecotypes. The social structure and hunting methods of Transient orcas are perfectly suited for tackling large, warm-blooded prey.
Scientific Documentation and Rarity
The formal documentation of orca predation on blue whales is a relatively recent scientific achievement. The three successful attacks observed in 2019 and 2021 off the coast of Western Australia were published in the journal Marine Mammal Science, confirming a long-debated hypothesis. Before these observations, reports of orcas attacking blue whales were anecdotal or involved only harassment, not a confirmed kill.
The rarity of these events explains why scientific evidence was so long in coming. These findings have updated the understanding of the blue whale’s natural mortality, showing that even the largest animals are not free from predation pressure. The observations, which sometimes involved 50 to 75 orcas joining the feast after the kill, provide insight into the complex feeding ecology and group dynamics of these apex predators.