This is not a fairy tale. In the depths of the dark and cold Atlantic oceans, live shark species with amazing biological abilities.
Greenland sharks or Somniosus microcephalus are the longest-lived vertebrates in the world.
The study, published in the journal Science, shows that the animal can live for at least 272 years. Did not even close the possibility of reaching the age of 500 years.
"We had expected them to be long-lived animals, but I'm really surprised they can get that old," said Julius Nielsen, a researcher and biologist at the University of Copenhagen.
Yet it is not an easy matter to determine how old a shark is.
Age measurements can not be done through testing the bones, because the shark's bones are mostly made up of cartilage.
The researchers found a new way to find out the age of Greenland Sharks, by examining their eyes.
The study was then conducted on 28 female Greenland Sharks who had died accidentally during a fish monitoring program conducted by Greenland Institute for Natural Resources.
"The secret behind the success of this study is that we have sharks ranging from young and old, medium and large, we can compare everything," Nielsen said.
Greenland sharks have a unique eye structure because the lens grows with the age of the animal. The older the sharks, the more layers that increase in the lens.
The researchers could not calculate the layer as in the age circle on the tree. But researchers can remove all the layers that have been increased for years to reach the center or embryonic nucleus of the lens.
This network consists of proteins that form when sharks are still children. That way researchers can analyze the chemical composition of the eye lens's core to estimate the age of the animal.
The radiocarbon dating results from the shark's eye lens revealed that the largest shark in the study, about 5 meters long, was estimated to be around 392 years old.
There are several other things that are revealed.
As their growth is very slow, less than a centimeter per year. So at least we can judge how long the animal's life span.
Or about the sexual maturity of a shark. They are only mature sexually when they have a body length above 4 meters. So we can expect them to start breeding at the age of 156 years.
Secrets of Longevity
Her remote habitat and the still-elusive realm make this giant shark's life little known, including how long her life was.
But the cold environment could be the cause of their long-lived. Cold environments cause low body temperature. That is, their metabolism is slower and will reduce damage to the network.
That's why the results of this study become very important considering the Greenland shark population is not known for sure.
The death of a shark alone can be a big disadvantage.
Moreover, threats can come from anywhere. The presence of unintentional favors to provoke them or increase oil exploration activities and other natural resources, could cause them to go extinct earlier.
"Long life is something extraordinary, but I hope people know the importance of preserving Arctic and deepwater ecosystems," said Aaron Fisk, an ecologist at the University of Windsor who was not involved in the study.
"If Greenland sharks live all this time and do not reproduce until they are 150 years old, then their populations are vulnerable to exploitation, it's important to make policies to protect animals like this," he said.