Study documents orcas ramming dead sunfish into pieces

Research released on 23 July 2026 says killer whales were filmed ramming a dead sunfish until it broke into pieces, in behaviour researchers said offers unusual insight into orcas.

Video released by the US-based non-governmental organisation Beneath The Waves shows one orca holding the tail of a sunfish while another charges into the rounded mola, causing it to break apart. The research said the sunfish was already dead.

Researcher Kathryn Ayres said the behaviour might have been a way to split the fish into smaller pieces. She also said it could have been play, noting that orcas are known to play with food and often tear prey apart and share it with other members of a group, including calves and juveniles.

The behaviour was documented twice, in 2024 and 2025, off the Gulf of California, according to research published in the peer-reviewed journal Frontiers in Ethology.

Mark Peter Simmonds, director of science at OceanCare, compared the behaviour to human formal meals where socialising and nutrition both play a role. He said it might be similar to a person carving a roast at a formal meal.

Killer whales are described in the report as highly intelligent apex predators. They have been documented playing with prey and using complex hunting tactics, including “wave washing”, in which they cooperate to create choppy water that knocks seals off ice. They have also been seen wearing dead salmon as hats for unknown reasons. Research last year found a critically endangered Salish Sea orca population breaking off pieces of seaweed to rub and groom each other.

Rebecca Wellard, a scientist at Curtin University in Western Australia who was not involved in the research, said the behaviour showed how intelligent orcas are. She said she hoped it would increase respect for the animals as complex predators.

The sunfish can weigh up to 2,000 kilograms and is known for its large, flattened body and fins. The research noted that sunfish do not commonly explode. Wellard said the fish is heavy and bony, so the ramming must have been severe.