The octopus is viewed as a solitary, if not antisocial, creature, known to keep a distance from its own brethren, but new research suggests at least one species has quite the social life. Researchers recorded 120 hours of footage of 13 big blue octopuses roaming a Red Sea reef off the coast of Israel and noticed the animals congregating with up to 10 fish of various species—and sometimes punching them, per NBC News. According to researchers, the groups appear to be hunting parties, in which the octopus acts as both decision-maker and enforcer. The fish move about, searching the environment for prey, then the octopus chooses one of the options presented, and the fish follow in its wake.
Though there's no sharing of meals among the group, the fish benefit from the octopus' ability to root out prey from crevices, while the octopus benefits because it doesn't have to do the searching for prey itself. It "feeds more than it would on its own and with much less effort," reports NPR. Yet when it isn't experiencing much benefit, the octopus acts out. "If the group is very still and everyone is around the octopus, it starts punching," explains Eduardo Sampaio, a postdoctoral researcher at the Max Planck Institute of Animal Behavior and lead author of the study published Monday in Nature Ecology & Evolution, per NBC.
The octopuses were most often observed punching blacktip groupers—or what Sampaio calls the freeloaders of the group, who tend to ambush prey but not actually search them out—in a move viewed as trying to keep the group on task. This suggests a level of social interaction once thought entirely out of character for octopuses. Sampaio suspects octopus learn this social hunting behavior "because the smaller octopuses seem to have a higher difficulty to collaborate with fish than the large ones," he tells NBC. Though there's no evidence of this, Sampaio also raises the possibility that an octopus might recognize specific fish that it's hunted with previously. (More animal behavior stories.)