Orcas observed fragmenting sunfish carcasses in Gulf of California
Researchers from Beneath The Waves document two incidents where adult orcas ram dead sunfish to disperse flesh for juveniles, challenging traditional views of cetacean hunting strategies.
Orcas in the Gulf of California have been filmed engaging in a cooperative behaviour where they ram sunfish carcasses with sufficient force to fragment the prey. The observations, published in the journal Frontiers in Ethology, detail two separate incidents in July 2024 and September 2025 where adult orcas held dead sunfish while others struck them, breaking the carcasses into smaller pieces for juveniles to eat.
The first instance occurred off the coast of San Jose del Cabo in Mexico. A tourism operator filmed a group comprising three adult female orcas, one male, and one juvenile. After catching and eating a spine-tail devil ray, an adult female held the carcass of a sunfish with its viscera already removed. A male orca then charged at the carcass, causing it to fragment upon impact, allowing the juvenile to feed on the dispersed flesh while the adults consumed the remainder.
A second incident was recorded in September 2025 in the channel of Isla Cerralvo. An adult orca held a dead sunfish while a second orca rammed it at high speed, splitting the body. The group, which included another adult and a juvenile, fed on the remains. These orcas had been observed preying on a mako shark earlier in the day, indicating the ramming was not a killing blow but a processing technique.
Kathryn Ayres of the nonprofit Beneath The Waves, a co-author of the paper, noted that the behaviour could represent parental investment or social play. The study suggests this "ram-to-fragment" technique may be a sophisticated evolution of the typical three-pronged sunfish hunting strategy, potentially facilitated by the sharp-tail sunfish's rudder-like tail which aids in gripping.
The findings highlight the complexity of orca social structures and learning. While orcas are known for culturally learned behaviours such as herding rays and creating waves to dislodge penguins, this high-impact disintegration of prey tissue appears specific to the structural response of the sunfish. The authors emphasise that collecting identification photographs is key to understanding these evolving techniques.
