Scientists have filmed multiple instances of octopuses punching fish in the Red Sea during so-called collaborative hunting expeditions.
An octopus may join forces with several species of fish to increase its chances of nabbing a meal. Groupers patrol the water column, using gestures to signal where prey is hiding. Octopuses can reach into tight cracks with their tentacles. Other species, like goatfishes, may scour the seafloor and join in a pursuit.
To untangle the dynamics of these complex inter-species interactions, researchers filmed several cooperative hunting bouts using underwater cameras. They filmed eight instances of octopus-on-fish violence, finding a number of possible reasons for the octopus picking a fight.
For example, if a fish partner failed to pull its weight or took more than its fair share, they might receive a jab. A sneaky parasitic fish might be shooed away with a tentacle. Sometimes, the octopus punched fish out of the way in order to take the prey for itself.
Collaborative hunting also occurs between reef fish and moray eels—but, eels don’t have arms.