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Octopuses Join Forces with Fish in Surprising Group Hunts

A recent study has unveiled a fascinating discovery that certain octopuses hunt alongside fish, working in organized groups to capture prey. This challenges the long-held belief that octopuses are solitary hunters, revealing a more complex social structure than previously thought.

The research, which focused on the species Octopus cyanea, also known as the big blue or day octopus, captured video evidence of these cephalopods collaborating with different fish species to hunt on the seafloor. What’s more, the study observed an unexpected behavior—octopuses punching their fish partners to keep them on task during the hunt. This suggests that octopuses play a more active role in coordinating group efforts, a surprising level of social interaction for a species long considered solitary.

Researchers followed 13 octopuses for 120 hours off the coast of Eilat, Israel. Their footage revealed octopuses working in teams with groups of up to 10 fish, including species like goatfish and blacktip groupers. Although the octopuses did not lead these hunting parties, they frequently nudged and punched fish to maintain order, particularly when fish weren’t contributing to the hunt. Blacktip groupers, often less active during the chase, seemed to receive the most punches, as if the octopus was ensuring everyone pulled their weight.

Fish benefit from these hunts by relying on the octopus’s ability to flush prey out of hidden spots. In turn, octopuses save energy by following the fish to potential prey locations, avoiding the need for speculative searching. The arrangement appears mutually beneficial, although there’s no evidence the animals share their catch—each species eats what it manages to capture.

One of the researchers, Eduardo Sampaio, explained that the octopus plays a central role in the group’s movements. If the hunting party remains stationary, the octopus might punch its companions to encourage movement. On the other hand, if the group is actively seeking prey, the octopus remains content and refrains from any punching.

To better understand the group dynamics, the research team used 3D tracking software to analyze their video footage, allowing them to map the positions of each animal and see how they influenced one another’s movements. They discovered that goatfish, in particular, would often venture off to explore, potentially leading the group, but the octopus ultimately determined when and where the hunt would progress. While the study sheds light on the collaborative behavior between octopuses and fish, many questions remain. For instance, do individual octopuses prefer to hunt with certain fish? Could an octopus have a “favorite” companion based on past successful hunts? It’s also unclear whether this behavior is learned over time or instinctual.

Sampaio leans toward the idea that younger octopuses may struggle more with group coordination, suggesting that the skill is learned with experience. As octopuses grow larger, they might become more adept at collaborating with fish to optimize their hunting strategies.

This study has implications beyond marine biology. It adds complexity to the understanding of animal intelligence and social behavior, potentially supporting the social brain hypothesis, which posits that intelligence in animals evolved due to the need for complex social interactions. Previously, octopuses were considered an exception to this theory due to their perceived solitary nature. However, these new findings indicate that scientists might have underestimated the social intricacies of octopus behavior.