"This was probably the most fun I had writing a paper," writes Eduardo Sampaio of the University of Lisbon. And the study in the journal Ecology is indeed a weird one: Sampaio and his team observed that octopuses appear to sucker punch fishes, reports Gizmodo. You can see for yourself in video here and here. The researchers note that octopuses and fish are known to collaborate as hunters, and the punches might be a case of an octopus trying to punish a fish who got out of line, at least in the view of the octopus. Or in researcher-speak, it's all about "partner control mechanisms," per the Smithsonian. However, in some cases, the researchers couldn't figure out any reason the octopuses had to punch, meaning they might be doing so simply "because [they] can," in the words of Live Science.
"I laughed out loud, and almost choked on my own regulator," Sampaio tells Live Science. "But I still marveled at it every time I saw it." As the researchers describe it in the study, an octopus lashes out using "a swift, explosive motion with one arm" at a fish that happens to be passing by, "which we refer to as punching." And what happens to the fish? Sometimes it leaves the group and doesn't return, or sometimes it waits awhile to come back, presumably chastened. Given that it's a little difficult to get inside the head of an octopus, it's possible the seemingly no-reason punches might have a reason that merely isn't understood yet. (Another surprising octopus discovery took place earlier this year on the ocean floor.)