A viral clip of an octopus being ambushed and eaten by a giant fish has been catching out Reddit users all week. And you're probably not going to see this one coming either.  

Originally uploaded to YouTube back in 2012 by Steve Winkworth, the video starts with the unsuspecting octopus – purported to be a veined octopus (Amphioctopus marginatus) – gliding elegantly along the seafloor. Based on its defensive behaviour, experts suspect the cephalopod was fleeing from the diver.

"It's pretty clear the octopus is being chased by the diver, so this isn't a natural situation,” Dr Zoe Doubleday, a marine biologist at the University of Adelaide, tells Australian Geographic.

Sadly, the octopus's day is about to go from bad to worse. As it glides over an innocuous-looking patch of sand, it's attacked by a concealed predator: an oversized flat fish that explodes from the seabed. Cue a burst of ink and debris and an almighty struggle between the two foes. Finally, relative calm is restored as the octopus disappears beneath the body of the victorious, yet mysterious, assailant. 

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The identity of the giant flat fish that ambushed, attacked and presumably devoured the hapless octopus was hotly debated by Reddit users. But Dr Neil C. Aschliman, Assistant Professor in the Biology Department at St. Ambrose University, and an expert on sharks and rays, is confident that the unknown assailant is a coffin ray (Hypnos monopterygius).

“The clip is brief and the cloud of sand doesn't help, but there are several features that indicate this to be the most likely culprit,” he tells Earth Touch. “The overall disc shape, tail anatomy and colour are consistent with Hypnos.”

Even though the two animals are pretty evenly matched in size, there is nothing unusual about a coffin ray ambushing and eating such large prey (just look at what this guy had for breakfast!). According to Dr Aschliman, the rays are "known for tackling surprisingly large prey" and "the octopus in the video certainly would be fair game." Since the cephalopods are "famously compressible" (they really, really are), swallowing one shouldn’t be a problem for the hungry ray. 

What the video doesn't show is exactly how this ambush predator was able to overpower – and likely dispatch – the octopus so quickly. “[Coffin rays] can generate and discharge powerful electric current using modified gill muscles,” explains Dr Aschliman. “It can use this to subdue prey (for example, an otherwise feisty and dexterous cephalopod) and deter predators.”

So it looks like this unfortunate octopus has become an internet sensation thanks to its (quite literally) shocking demise. 


Top header image: Bernard DUPONT, Flickr