Scientists Caught an Octopus ‘Punching’ Fish in the Face — and There’s a Surprising Reason for It

Off the coast of Eilat in Israel, a big blue octopus propels itself forward, flailing its tentacles, with a troop of groupers fish following it. At some point during its hunting trip, the octopus extends its tentacles and slaps the fish. Each time, the octopus spots a cheating fish, it extends its tentacles and flings a slap, pushing it back to the task. After a group of researchers documented this bizarre behavior of octopuses in a study published in ESA Ecology, National Geographic explorer Dr. Eduardo Sampaio was too fascinated not to dive into the waters himself. A footage recorded by him of this slapping behavior was shared on YouTube.

The mystery of why an octopus punches a fish lies in a behavioral tendency called the “partner control mechanism,” according to the researchers. This octopus and the fish have partnered with each other to hunt together. The plan goes like this: The octopus will trap the prey in its tentacles and keep it trapped until it dies. If a prey tries to escape from the reef, rocky outcropping, or crevices, then the role of the fish would take charge and prevent the prey from eloping. Octopus usually enters this collaborative relationship with either the blacktip groupers or the blue goatfish. However, in each hunting trip, the octopus itself is the “decider” of the group that leads the social order. 

Collaborating with fish helps him save a lot of energy, which also frees up more time for other activities like reproduction, social interaction, playing, and maintaining the den. The goal of this partnership is mutual benefit, but every member of the hunting group has to put in effort and not just grab the prey by cheating. Call it a coincidence, but a blacktip grouper is a bit lazy by nature. It tends to slow down and wait for the prey during the hunt. This lack of movement agitates the octopus, and it ends up punching the fish to motivate them to perform the task assigned to them for the hunting project. 

Apart from cheaters, an intelligent octopus also tends to slap or punch a fish if it tries to come too close. This blue-blooded creature likes to keep the business clean. As intriguing as it sounds, these complex collaborative dynamics were first observed by scientists while they were combing the Red Sea between 2018 and 2019. After they documented the observations in the study, Sampaio couldn’t hold himself back from diving into the waters and checking out the dynamics unfold with his own eyes. He and his team strapped two camera rigs in the Red Sea and started following the hunting trips of these devils.  

“One of the main questions last time was: Is this really collaboration, or are the fish just following the octopus around?” Sampaio told National Geographic (NG). His team tracked 13 octopuses, capturing 120 hours of footage, following octopuses for 13 hunts. In most of these hunts, they noticed that exactly 10 fish were partnering with the octopus. They observed that the octopus’s punching behavior stems from a lot of different factors, the main factor being lazy and cheating fish. 

“If the group is very still and everyone is around the octopus, it starts punching, but if the group is moving along the habitat, this means that they’re looking for prey, so the octopus is happy. It doesn’t punch anyone,” Sampaio explained to NBC News. Jennifer Mather, an octopus cognition expert, explained to NG that a hunting octopus is like a “bulldozer” that “rolls up the area and scares animals off in all directions.” The predatory fish are his dependent followers who take advantage of the disturbance the octopus provokes in the environment. However, sometimes when a fish takes the octopus too lightly, the octopus doesn’t like that. No free food, it tells them with a slap.

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