Fossils of the same species have been found that date back millions of years.
The researchers believe that the animal has remained unchanged over the millions of years, and how it managed to survive unchanged when nearly all species were wiped out or forced to evolve to survive is a mystery.
The animal was a male, 1.5 metres in length, and was fished in August at a depth of 700 metres, the Portuguese Institute for the Sea and the Atmosphere (IPMA) said in a statement released on Monday.
After noticing the creature's unusual appearance, the commercial fishermen handed it over to a research team from the Institute for the Sea and Atmospheres, who were working on a project to decrease unwanted catches in commercial fishing. In total, the shark has six pairs of gills that have "frilly" edges.
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However, the shark gets its name from the 300 teeth that line its mouth in a frilled appearance, "which allows it to trap squid, fish and other sharks in sudden lunges", Professor Margarida Castro of the University of the Algarve told Sic Noticias.
According to the scientists, the long, slime, snake-like shark is "little known in terms of its biology or environment", because it lives at great depths in the Atlantic and off the coasts of Australia, New Zealand and Japan, BBC reported. Another study of a Suruga Bay inhabitant showed that frilled sharks may also have the longest gestation period of any living creature, 42 months. Pretty much all other sharks have separate gills, but the frilled shark's first pair of gills stretch all the way across its throat.
Scientists believed it to be a living fossil with a body like a snake but the jaws of a terrifying sea predator.