Admittedly, hagfish are not the most beautiful animals. They are reminiscent of pink tubes. During the day they usually remain buried in the seabed and only come out at night. Instead of dandruff she wraps a thick layer of mucus. They do not have eyes, a jaw or teeth, instead they tear pieces of meat from their prey with a sort of horn-occupied tongue. When an enemy invades, they can quickly turn the water around them into a slime cloud that clogs the enemy's gills.
This way of life is so successful that the animals have hardly changed in the last millions of years. Ammonites, dinosaurs, giant sloths: the hagfish have all survived. And that is what makes the animals so interesting for zoologists, because they are considered the origin of vertebrates. Although hagfish have a skeletal structure, this is limited to only a few cartilaginous structures.
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hagfish
Was the ancestor of all vertebrates a hagfish?
Researchers have been arguing passionately for decades about the place of the hawks in the pedigree of the animals. Some, who rely mainly on fossil finds, consider it a kind of prototype of vertebrates. That would mean that all fish and vertebrates - including humans - had a common ancestor that looked much like a hagfish.
The others argue that hagfish are so strange that they have to get their own diversion in the tree of the animals. The researchers relied mainly on DNA analyzes, which put the hagfish more in line with the lamprey. Lamprey is also one of the original vertebrates and does not have a jaw. (The evolution of the jaw is an exciting story, read more here.) The common ancestor of vertebrates would have looked more like a fish.
Now researchers at the University of Chicago have discovered a 100-million-year-old fossil that could clarify this issue, they report in the journal Proceedings of the National Academy of Sciences.
The find is extremely rare. Normally, the rather soft hagfish are not preserved. In the now examined specimen even residues of the mucus layer were found. It contained a lot of keratin, a substance that also contains fingernails.
"We now have a fossil dating back to the original plan for hawfinals by 100 million years," says researcher Tetsuto Miyashita. Now there is also the fossil evidence that the structure of the animals was similar to that of the bloodsucking lampreys millions of years ago.
The researchers therefore assume that the round mouths developed their eel-like physique and their unusual diet only when they had already separated from the pedigree of the vertebrates. Thus our great-great-great-ancestor would not be a slimy primal animal, but a fish.