New research documents that octopuses found in the Red Sea have been lashing out at their hunting partners. This phenomenon takes the form of swift, explosive punches aimed at nearby fish––previously undocumented and highly unusual behavior in the animal kingdom.
Researchers from the University of Lisbon in Portugal and the Max Planck Institute of Animal Behavior in Germany have gathered footage of several octopuses in various parts of the Red Sea exhibiting this behavior. They believe that during collaborative hunting with fish, octopuses punch them as a consequence of negative behavior or as a means to steal prey for themselves. This is one of very few cases of animals, other than humans, acting in this way, and even this is a sporadic event, having been captured a mere 8 times on camera.
One of the only other species known to exhibit similar behaviors is the Capuchin monkey. Recent research conducted by Yale University analyzed their tendency to punish their peers who received more than their fair share of food, even when it came with a cost to themselves. They placed food onto a table with a collapsible extension, and if the monkeys pulled the rope, the food would fall into an inaccessible container. Consistently, they chose to collapse the table when the monkey with whom they were sharing received more than them. The researchers observed that despite losing access to their own portion, the monkeys acted out of spite as it is understood in game theory, wherein behavior generates a double negative.
While the monkeys’ actions were seemingly in response to broken social norms, the octopuses did not always have clear reasons for lashing out at the fish. Octopuses and fish hunt together to take advantage of the other’s specialized hunting skills.
The hunting group scours the seafloor and nearby corals to locate its next meal, and the fish alert the octopus to the nearby prey. Once the octopus emerges victorious from the fight, the spoils are free to be claimed by the group. Each species has specialized roles to follow, and researchers have concluded that when a fish breaks those rules, the octopus is sure to reprimand it. While further analysis is required, the researchers have theorized that this punishment in response to transgressions may promote cooperation between the group, as well as discouraging future exploitation. If this were to be the case, the energetic cost to the octopus would be profitable.
Selfish as it may be, the octopus may also lash out when it wants immediate access to nearby prey, giving it the chance to hoard the prize all for itself. In response to this seemingly exploitative behavior, the fish can choose to abandon the hunting group, disincentivizing the octopus from frequently taking advantage of its hunting partners: “If one fish feels that they are not getting enough food and that the interaction with the group is being harmful to them, they just leave the group,” said lead study author Eduardo Sampaio, a Ph.D. student at the University of Lisbon and the Max Planck Institute of Animal Behavior.
While the fish may leave and hunt with another group if it feels this interaction is not mutually beneficial, the octopus’ choices are far more limited. Sampaio disclosed that if the octopus is being taken advantage of and would refrain from using partner control mechanisms – in this case, punching – its only other option would be to stop hunting or go back to the den, both of which impose a large cost on the octopus.
Sampaio was especially intrigued by the occurrence of these divergent species working together: “This is a very rare case in nature because usually we study flocks of birds or shoals of sardines, and they have similar weight in the decision making of the group. And here it’s different.” Unlike the monkeys, there are added variables to consider in these interspecies interactions.
Since each species has a distinct function in the group, Sampaio noted that it was difficult to analyze exactly how instances of punching impacted the group because not every fish species reacted identically. For example, the researchers have observed that some fish species, like the Lyretail Grouper, will continue hunting if one of their own has been punched and expelled from the group. However, if the aforementioned happened to a Goldsaddle Goatfish, the entire species would exit with its ousted peer.
The rarity of instances of multiple species hunting together makes it far more difficult to understand the impact of their behavior. But one thing is for sure: both the monkeys and the octopuses lash out to control their partner. Animals, it seems, have more complex characters than humans give them credit for.
Theresa Barth for Times Media Mexico