It’s no secret that nature can be brutal and violent, but a new Queensland Museum report on the death of some snake eels reads more like the plot of a horror movie than a scientific paper.
Snake eels are a family of eel species that live most of their lives burrowed in the soft sand on the floor of the ocean.
When eaten alive by predators, they will use their hard pointed tail tip, which is for digging, to burst through the fish’s stomach in a bid to escape digestion.
But unfortunately, this isn’t enough to save them. Unable to burrow through a fish’s hard ribcage, they become trapped and die, their body slowly mummified in the gut cavity of their captor.
“They can be trapped in there for quite a while. Sometimes until that fish is eventually caught and fishermen discover them,” said Jeff Johnson, an ichthyologist at the Queensland Museum who co-authored the paper.
“In one instance we actually found one still alive inside a fish. It was one that I had caught off the beach. I took it home and opened it up and out popped this snake eel writing around … I was somewhat shocked to say the least.”
Most snake eel species are around 20cm to 30cm in length, but generally no more than several centimetres wide. Their long thin bodies make it easy for fish to swallow them whole without being killing or even injured.
“Most animals burrow head-first, but snake eels use their hardtail tip to dig straight into the soft sea substrate. When they are swallowed and take exception to that they just use that same mechanism to burst straight out through the stomach wall.”
While this move is almost always fatal for the eel, the large fish may not even notice their stomach being ruptured.
“Fish are able to withstand quite a bit of trauma. Sometimes you’ll see fish with quite sizeable chunks out of their backs and those have healed up, so a small perforation in their stomach wall … they are probably barely aware that it’s happened.”
Johnston said commercial fishers had reported finding fish with multiple eels buried in their gut walls.
Seven species of snake eels were found in the body cavities of a total of 11 species of predatory fishes from various areas around Australia, suggesting this is a widespread occurrence.
“It’s certainly a bizarre process, but it seems it happens far more regularly than we might have thought,” Johnston said.
The report was published by the Queensland Museum in conjunction with Northern Territory Fisheries, CSIRO and the Museum and Art Gallery of the Northern Territory.