Footage from the Red Sea shows octopuses hunting side by side with fish — and when a fish partner hangs back instead of flushing prey out on cue, the octopus has been filmed punching it with an extended arm, sometimes for no food reward at all

Footage from the Red Sea shows octopuses hunting side by side with fish — and when a fish partner hangs back instead of flushing prey out on cue, the octopus has been filmed punching it with an extended arm, sometimes for no food reward at all

A day octopus flashes black and white for a fraction of a second, extends an arm, and strikes its hunting partner across the head. In some of the documented cases, the researchers could tell exactly why: the fish had been crowding the octopus’s next meal, or dragging its feet. In others, they couldn’t connect the punch to anything the fish had done. The footage is part of a small but pointed body of work led by Eduardo Sampaio, now a postdoctora…