Octopuses punch fish in the face
Octopuses punch fish in the face when they step out of line while hunting together, a study has found.
The jab to the head demotes a fish to the outside of the group and helps maintain order and discipline in the two-species pack, scientists said.
Scuba-diving scientists in the Red Sea watched octopuses and fish working in partnership to catch molluscs and shellfish and found the species share leadership duties depending on the role.
The fish, such as the goldsaddle goatfish and the Blacktip grouper, take the lead in deciding where the coalition will hunt, but the octopus is in charge of if, and when, an attack is launched.
But the relationship is not always smooth and both fish and octopus have methods of dishing out punishments for members of the pack that transgress.
Fish will dart towards other fish that have erred, observations show, while octopuses punch fish in the face to restore control.
Octopus often hunt with a blacktip grouper and gold-saddle goatfish – EDUARDO SAMPAIO
Scientists from the Max Planck Institute of Animal Behavior in Germany partnered with researchers at the University of Lisbon and recorded more than 120 hours of octopus and fish hunts in the Red Sea in October 2018.
“Punching involves an explosive motion of one arm directed at a specific hunting partner, which actively displaces it to outer areas of the group temporarily or permanently,” the authors write in their study.
“We found that the octopus was the main interspecific regulator of the group, perpetrating a disproportionate number of aggressive actions towards fish partners.”
The scientists believe that the fish choose to work with an octopus because it is a specialist hunter that can reach prey they would be unable to catch themselves.
An octopus works with the fish because the large number of individuals in a school allows it access to a larger area than it would be able to cover itself, saving energy and maximising hunt efficiency.
The intelligent eight-legged cephalopod is “the main controller and leader in the group”, the scientists say.
Octopus-fish hunting partnerships are unusual in nature, but similar cross-species dynamics do exist, including with badgers and coyotes and moray eel and groupers.
The “functional complexity” and “dynamic nature” of the octopus-fish dyad made this partnership different to the others, scientists say.
“The exhibited range of partner-dependent behavioural flexibility, especially concerning the use of social information when deciding to switch foraging strategies and whom and when to punch, indicates that day octopuses have hallmarks of (heterospecific) social competence and cognition,” the authors add.
The study is published in the journal Nature Ecology and Evolution.
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