A video of a large, toothy fish biting down on a can of Coke has recently gone viral, namely due to the fact that it is a decapitated head. When the can is forced into the jaw of the dead fish, it chomps down hard, creating a foamy mess.
The video was originally posted to YouTube back in January but was recently shared on Reddit’s WTF channel. Its uploader says the species is a wolf eel (Anarrhichthys ocellatus), a fish that is neither a wolf nor an eel but actually a kind of wolffish, a cantankerous-looking family named for their sharp, wolf-like teeth. However, the species in the video is actually a different type of wolffish, which can be differentiated by its dark spots.
"I would most definitely think that this is a spotted wolffish (Anarhichas minor)," Professor Björn Thrandur Björnsson, head of the fish endocrinology laboratory at the University of Gothenburg, told IFLScience. The spotted wolffish is found in the North Atlantic and Arctic Oceans and can grow to almost 2 meters (6.5 feet) in length. It eats crustaceans as well as mollusks, smaller fishes, and worms.
"The wolffishes have a notorious biting reflex which is well-known by fishermen," said Björnsson. "Thus when e.g. the contents of a bottom trawl is dumped on the deck of a trawler and the fishermen stand knee-deep in various species of fish, working on sorting and separating, an often-used routine was to stick a broom handle or [something] similar into the mouths of the stray wolffish in the catch, so that nobody would be hurt by accidentally sticking a hand or a foot in their gaping jaws. This [is because] they bite down very hard with very sharp teeth, and they don’t let go.
"For other species, a usual way of grasping a fish would be to grasp it by the lower jaw. If you do that with wolffish, your thumb would go the same way as the Coke can."
The person who uploaded the video to Reddit describes the fish as poisonous, but this is inaccurate as wolffishes are neither poisonous nor venomous.
So how did the fish manage to bite the can after being decapitated?
"This is obviously a neuromuscular reflex, with receptors in the jaws and/or mouth cavity which register if anything (a prey, normally) is in the mouth," said Björnsson. Essentially, the jaw is programmed to bite. On detecting something entering the mouth, sensory nerves send signals to the brain, which then sends more nerve signals to the jaw muscles, telling them to contract. Wolffishes have particularly strong jaw muscles as they feed on creatures with solid shells like mussels, clams, and sea urchins.
"The reason for why this reflex can persist after decapitation is because these are cold-water species, and the cold temperature allows tissues, like the brain, nerves, and muscle to 'stay alive' longer, before they die from lack of oxygen, and that the reflex arch from the mouth to the brain and back is unharmed by the decapitation," explained Björnsson. "If you, for example, took out the heart of this fish, it would probably continue to beat for an hour if kept in the correct solution." He ended by criticizing the footage, drawing attention to the lack of respect being paid to the animal as it is just being played with.