Photo by: Citron via Wikimedia Commons

A rare frilled shark that has remained unchanged for 80 million years was discovered by a Portuguese trawler off the coast of Algarve in Portugal.The fish remained the same, both inside and out, since the time of the dinosaurs.

Scientists estimated that the said shark, possessing 300 teeth lines in 25 rows, dates back to the Cretaceous Period which was when the Triceratops and Tyrannosaurus Rex roamed Earth, Newsweek reported.A past Japanese research on the fish suggested the frilled shark did not evolve because of the lack of nutrients found in the deep-sea dwellings.

The Japanese team studied a 5.2-foot long female frilled shark in 2007 which they found dying at the surface.However, the fish – occasionally seen off the coasts of Japan, New Zealand, and Australia – survived only for a few hours.The frilled sharks are rarely seen in its natural habitat and are often secluded in the deep waters of the Pacific and the Atlantic, Inquisitr reported.

61% cephalopods diet

When scientists examined the shark, the Chlamydoselachus anguineus, they found that its diet is 61 percent cephalopods.This is the same class to which octopus and squids belong.The remaining 11 percent is made up of different teleost fishes.  The researchers were able to identify the squids, but not the teleost prey because its state of digestion was too advanced to be identified according to species or family.

A 5.3-foot frilled shark caught from the coastal waters of Choshi, Japan, when its stomach was examined, yielded a 590-gram Japanese catshark.It indicates that the frilled shark catches prey near the bottom and far above the water.

However, no one had seen the frilled shark actually feeding.Scientists, however, believe the fish extends along its flanks an open lateral line.It likely uses a vibration-detecting system that is sensitive even to the tiniest movement.

Longest gestation period of any vertebrate animal

The study showed that the frilled shark, pulled from a depth of 700 meters, may have the longest gestation period of 42 months of any living creature, IBT reported.It is almost double the gestation period of an African elephant at 22 months, by far, the longest of any vertebrate animal.

According to a study of 264 frilled sharks from Saruga Bay, Japan, the species breed all-year round.It produces an average litter of six pups, measuring about 55 centimeters long.The female frilled shark has a trunk that is proportionately longer than that of the male, likely to make room for developing its pup in an attenuated body.

Other sharks have separate grills, but the frilled shark's first pair of gills stretch all the way across the throat, one of the six pairs of gills with frilly edges.The jaw, which has over 300 teeth lined in 25 rows, are designed to help it to trap squid, fish, and other sharks in sudden lunges.Professor  Margarida Castro, from the University of Algarve, said that it is where the frilled shark got its name.Other shark species only have five gills.

Dermal denticles create frightening look

Dermal denticles, which lines its spines, when combined with the teeth, give the shark's mouth a frightening look, Castro, said.Some researchers have accidentally injured their fingers examining the teeth of the shark, but the fish is not a threat to humans and has rarely been encountered alive.

The shark is rarely seen and was not discovered before the 19th century by Samuel Garman in 1884 because it is usually found between 390 and 4,200 feet below the surface.According to IFL Science, the shark that was caught in summer measured five feet long, but it could grow as long as six and a half feet.

The fish is believed to have inspired famous stories among sailors of sea serpents because of its movements in the water that are snake-like.The shark is almost neutrally buoyant at depth because of its elongated body cavity that is packed with a huge liver filled with low-density oils and hydrocarbons, Elasmo Research noted.

Researchers working on a European Union project in Algarve discovered the male shark.The project's objective was to minimize unwanted catches in commercial fishing.

Photo by: OpenCage via Wikimedia Commons

A living fossil unchanged for millions of years

The fish was described as a living fossil which Charles Darwin first used to describe living beings which have remained largely unchanged for millions of years because it settled in environmental areas that do not challenge the creature to evolve.Other than the frilled shark, the elephant shark (Callorhinchus mili), a member of the branch of cartilaginous fish known as chimaeras, also hardly changed for 420 million years, according to genome mapping studies, earning it a reputation as another living fossil.

Because its deep-sea habitat is intensely cold, it has slowed the metabolic processes of the frilled shark to a glacial deep.

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