3D field tracking and field experiments of octopuses and fish reveal the secrets of multi-species hunting

Diving gear on, cameras ready: biologist Eduardo Sampaio and his colleagues are ready to go. They dive into the Red Sea, scanning the water left and right, wondering: Where can you find an octopus hunting? Finally, they spot one. The team turns on the two cameras they have with them and sets up many more to collect data. Then it’s time to wait.

Months later, after analyzing more than 100 hours of video taken during dives in Israel, Egypt and Australia, Sampaio is more than satisfied with the images. The dual camera perspectives allowed him to create a 3D view of the scene and gave him new insights into multi-species hunting.

Using advanced 3D tracking and field experiments, Sampaio observed that multi-species groups exhibit unique, composition-dependent properties.

“In groups of Octopus cyanea and various fish species, social influence is not uniformly distributed but rather hierarchically structured across multiple dimensions, reflecting specialized roles within the group,” the biologist explains. Fish, especially red mullet, are particularly responsible for environmental exploration, dictating the direction of the group, while octopuses determine the timing and start of group movements.

In an intriguing display of ecological synergy, fish act as an extended sensory system for octopuses, covering larger areas and improving the efficiency of prey detection.

“This beneficial interaction allows fish to acquire otherwise inaccessible prey and octopuses to conserve energy by focusing on high-quality food sources, while exerting control and providing feedback within the group, highlighting the sophisticated dynamics of marine life collaboration,” Sampaio says.

The results are published in the journal Nature Ecology and Evolution.

A New Perspective on Leadership

Leadership in animal groups, whether fish, birds or monkeys, is typically associated with the desire to move the group forward. However, this study shows that leadership can emerge from both the stimulation and inhibition of movement in others, with the octopus acting as the primary influencer of movement through inhibition.

Furthermore, group composition significantly influences individual investment and collective action, revealing exploitation by different group members. This triggers partner control mechanisms, mainly by the octopus, which strikes at exploiters, reinforcing its de facto leadership position. These actions help the octopus maintain the benefits it receives from collaborative partners.

Concretely, in terms of the hunting situation, this means that “when the octopus catches its prey, it also kills it,” explains Sampaio.

“A prey is not divided, it is taken by the one who catches it first. However, because the interaction between the fish and the octopus is repeated several times during a hunt, the prey is “shared” in the sense that sometimes it is the octopus that catches the prey, and other times it is the fish that catches the prey.”

This research demonstrates that Octopus cyanea, a solitary species, exhibits remarkable social competence and cognitive flexibility, adapting its behavior in response to the actions of different species.

“These results expand our understanding of leadership and sociality, highlighting the complexity and adaptability of social interactions in nature,” Sampaio says.