Orcas Observed Using Novel Technique to Dismember Sunfish

Researchers in the Gulf of California have documented a previously unrecorded hunting behavior by orcas. The marine mammals were observed using a coordinated strategy to break apart large sunfish. This behavior involves one orca holding a dead sunfish while another charges into it at high speed. The impact fragments the sunfish into smaller pieces.

This technique was recorded during two separate incidents. In both cases, the sunfish were already deceased. Scientists believe the ramming serves to process the prey rather than kill it. The force of the collision breaks the sunfish tissue into thousands of fragments.

Dr. Kathryn Ayres, a scientist at Beneath The Waves, co-authored the study. She noted that this method might help younger orcas feed more easily. Orcas are known to share food with calves and juveniles. The behavior could also be a form of play, as orcas are known for playing with their food.

Sunfish can reach over three meters in length and weigh up to 2,000 kilograms. They often rest at the ocean surface, making them vulnerable to predators. The newly documented behavior suggests a specialized method for handling this large prey.

This fragmentation may also influence the microbial environment. Sunfish have a gelatinous outer layer and skin with a distinct microbiome. Breaking the tissue disperses these microbial taxa, potentially altering nutrient composition in the water. This exposure could offer nutritional or immune benefits to the orcas.

Researchers are still investigating whether the same orcas were involved in both documented events. More footage and identification photographs are needed to confirm individual animals. This new observation highlights the complex and evolving hunting strategies of orcas.