Angry octopus punching fish caught on underwater camera, and the reason may be more surprising than you might think

Scientists were spying on marine life in the South Pacific Ocean when they came across something unexpected -- an angry punch from an octopus. Researchers had placed a baited remote underwater video system onto the seafloor at Morton Bank, around 75 miles off the coast of Rotuma -- an island group some 400 miles north of Fiji. They were working to record the number of fish and marine animals in the area when a marine quarrel caught them by surprise.

The footage of the outburst was shared by Nat Geo Pristine Seas in a post on Instagram. In the video, a day octopus (Octopus cyanea) can be seen punching a highfin grouper (Epinephelus maculatus). The octopus also threw a punch at a spotcheek emperor (Lethrinus rubrioperculatus), but narrowly missed it.

"We never really know what we're going to see until we watch the footage back later," Chris Thompson, a marine ecologist at National Geographic Pristine Seas, said, according to Discover Wildlife.

What's behind the behavior?

Why should an octopus punch the fish around it? Thompson said there are a few theories concerning the behavior. "They may be displacing fish to gain access to prey or exerting discipline in a collaborative partnership to spite," the marine ecologist said.

Not the first instance

This was not the first time that an octopus was caught punching fish. According to a 2020 study in Ecology, the same species of octopus got physical while hunting with fish in the Red Sea. The repeated behavior suggests that the smack might be the octopus' way of keeping the group of fish in line.

Thompson said that throwing a punch could be a "way of disciplining the fish into participating actively in the hunt rather than exploiting it and freeloading off the octopus and other fishes' work."

'Up for a bit of biff'

Rotuma and the Red Sea are roughly 1,000 miles away, yet there are clear similarities in the octopuses that inhabit them. "That we are seeing this same behavior in a remote location on the other side of the planet (over 15,000 km away) shows that these octopuses are up for a bit of biff wherever in the world they are," Thompson said.

And fish aren't the only ones at the receiving end of the wrath of octopuses. In 2021, a video surfaced online showing an octopus lashing out at a geologist swimming at a Western Australian beach, leaving red welts on his skin.