Beware! If you're a fish, don't swim too close to an octopus during collaborative hunts. Those eight-limbed creatures have been known to punch at fish.
Called "active displacement" of fish, this behaviour usually takes place during collaborative hunting efforts that both the octopus and fish engage in.
In such a situation with multiple parties, a complex network is created where investment and payoff can be unbalanced, and this gives rise to partner control mechanism, said marine biologist Eduardo Sampaio from the University of Lisbon in Portugal. A paper on this behaviour was published in the Ecology journal.
Simply put, the octopus was keeping the fishes in line, and maintaining a sense of control and dominance. According to a Science Alert article, it might be deterring them away from the prey, relocating their position in the pack or even excluding them from the hunt altogether.
The researchers came to this conclusion after observing interactions between octopuses (Octopus cyanea) and different fish species (like the tailspot squirrelfish, blacktip and lyretail groupers) in the Red Sea.
During the research, there were two occasions when the punch was given seemingly for no reason. The researchers proposed two possible reasons for this: the octopus might have punched the fish out of spite or it did so to ensure that the fish “behaved” itself during future hunts.
Whatever the reason, there's certainly a lot more to find out about this intriguing behaviour.