Steven Senne / AP
The jagged, ragged, pink-gray, spiderless soil dweller is amazing and disgusting.
It's a two-meter-long creature that looks a bit like an eel, but unlike eels, the hailfish lacks a backbone or jaws or eyes. But for all that the monkfish lacks, it makes up for unbelievable amounts of unusual and unusual slime that protects it from predators.
Because of their simple features, scientists have long held that hailfish are primitive but have difficulty finding where to fit the evolutionary timeline for other fish and vertebrates. Ed Yong, an employee of The Atlantic says the evolutionary relationships between hail fish and other fish have long been controversial.
"Many scientists have considered them to be very primitive creatures, like a kind of transition from something like a worm to a fish-like thing, like a precursor to backbone animals like us," Yong said to Scott Simon of NPR.
Part of the problem was that until recently hagfish had virtually no fossil record. In a study published this month in the Proceedings of the National Academy of Sciences a fossil tethymyxine provides new insights. The fossil purchased in 2013 from the Black Hills Institute of Geological Research is referred to in the study as a "unique fossil hail fish".
Found in a Lebanese quarry, the fossil is 12 inches long and contains remnants of mucus obtained 100 million years ago. The chemicals in the preserved mucous glands are consistent with the composition of today's hail fish sludge.
After studying the fossil, the researchers concluded that hagfish are not primitive progenitors for vertebrates, but hypothesized that the creatures are actually vertebrates.
In his contribution to The Atlantic, Yong explained the significance of this discovery:
If it is correct, then hair fishes are not at all primitive evolutionary regression. Instead, they represent a line of vertebrates that differed from others and lost several properties about 550 million years ago.
"They are part of the spine line," Yong said in his interview. "They just seem to have lost a lot of our properties – things like complex eyes and bones and taste buds – so they're not just that weird evolutionary retrogression, they're actually quite specialized."
Your biggest specialization? Her mucus, lots and lots of mucus.
Mucus is an evolutionary trait used by the hag fish to protect itself. They release less than a teaspoon of mucus from the glands on their side when attacked or stressed. But in fractions of a second, this teaspoon expands in liters of mucus.
"If you put a hail fish in a bucket first, it looks as though those thin patches of it are going to clear its flanks like white, cloudy things," Yong said. "And then if you put your hand and whirl around, you'd just pull out like a handful of this stuff, it's almost as if the whole bucket had turned into slime."
The mucus is excellent for penetrating in angles and angles, especially in the mouth and gills of predators. When hail-fish are attacked, they release a slime cloud that suffocates the attacker.
"Hagfish tend to eat dead and dying bodies on the ocean floor, which attract many other things like sharks, so they often get bitten," Yong said. "There were these incredible videos of sharks biting hail fish and then slamming their mouths and gills with mucus and simply choking and forcing them to retreat."
The Museum of New Zealand Te Papa Tongarewa
The thought of a slime cloud is enough to get someone to retreat, but after hearing about the slime from scientists, he said he would like to see how that feels.
"It's not as disgusting as it looks or sounds like," Yong said. "It's not sticky, you could easily wipe it off and it almost feels like I'm not getting comfortable, it's kind of strange, almost ethereal."
Although monkfish lead a somewhat gritty, grotesque life, the new discovery feeds on corpses and slims the things they want to eat, suggesting that there may be more to it than encountering these creatures – or rather on the lack of eyes.
Sophia Boyd and Ed McNulty have produced and edited this story for the show.