Orcas are known to be smart and ruthless hunters. They've been observed hunting a variety of prey, with some species, such as whales, larger than them. They use a wide range of strategies to hunt and kill prey, but now, in the Gulf of California, researchers have observed one that hasn't been described before.
"We document how one orca holds the sunfish and lets go just before another orca hits it at high speed, causing the tissue to break apart into thousands of pieces," said first author of the Frontiers in Ethology article, Dr Kathryn Ayres, a scientist at Beneath The Waves, a non-profit organization promoting ocean health. "We think this may help younger orcas feed more easily or it could also just be for fun. Orcas are known for playing with their food."
Sunfish blown to bits
Sunfish can grow over three meters long and weigh up to 2,000 kg. They move through various depth layers but come to the surface to rest, thermoregulate, or seek parasite removal. In surface waters, they are vulnerable to predation. In the Gulf of California, they are one of the species most commonly hunted and eaten by orcas. The current observations are based on two independent hunting events that occurred a little more than one year apart.
In July 2024, Ayres observed how a group of orcas, including a juvenile, interacted with a dead sharp-tail sunfish, which they had killed previously. A female orca held the sunfish by its large tail fin – an effective point of grip – while a male orca accelerated and swam toward both. Shortly before impact, the female released the sunfish. The ramming caused the sunfish's tissue to fragment and float in the water. The juvenile of the group then began consuming smaller bits of sunfish. The adults fed on what remained of the body but didn't consume the smaller fragments.
In September 2025, a similar event, which was filmed by Héctor Franz, followed the same hold-to-ram and feeding behavior.
Small bites
The high-impact ramming behavior caused substantial disintegration of prey tissue. Ramming has not been previously described as a predation strategy by orcas. Both events suggest that the orcas followed a coordinated and cooperative strategy, with one orca stabilizing the carcass so the other could hit it more precisely. The sunfish were already deceased in both events, so the ramming is thought to be a processing technique rather than a means to deliver a killing blow.
The gelatinous layer that covers sunfish, known as capsule, and their skin host a distinct microbiome. If this tissue is shattered, the microbial taxa inhabiting it are dispersed into the water where they alter the nutrient composition. Tissue fragmentation could therefore facilitate contact between sunfish and orca microbiomes, which could provide nutritional or other benefits, such as immune regulation.
The observed behavior could be interpreted as a form of parental investment, the researchers pointed out. Dividing the carcass into more manageable pieces for the calf aligns with previously observed behaviors.
"Orcas often tear apart prey and share it with other members of the group, including calves and juveniles," said Ayres.
'They continue to surprise us'
Yet, this doesn't mean that this interaction could not also have served other social purposes: it could simply have been a game for the killer whales.
As far as the sunfish are concerned, the interaction could provide new insights into the species' characteristics. So far, fragmentation of tissue has only been observed in sharp-tail sunfish. This suggests that disintegration could be a species-specific structural response of sharp-tail sunfish tissue to high-energy impacts that may not apply to other, larger sunfish species.
It's unclear if the same orcas were involved in both events. This highlights the need for more high-quality footage – especially of orca's dorsal fins and eye patches – to be able to identify individuals.
"Collecting good identification photographs whenever possible is key: we are still seeing new techniques of how orcas hunt and process their prey," concluded Ayres. "They're one of the most iconic marine predators in the world, yet they continue to surprise us."
