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Scientists have recently discovered a shark that can live up to 400 years, surpassing even the tortoise, earlier believed to be the longest living vertebrate.[/caption]
Scientists have recently discovered a shark that can live up to 400 years, surpassing even the tortoise, earlier believed to be the longest living vertebrate.
Scientists from the University of Copenhagen and University of Oxford have published the discovery of the Greenland shark in a research paper in the life science journal ' Science'.
The discovery was made through radioactive dating of the eye lens nucleus, which remains metabolically inactive throughout the life of the shark, maintaining its chemical composition. The technique has been used for research earlier but never to examine the longevity of an organism.
Previously, the age of sharks were determined by counting the number of growth layers present in calcified structures such as fin spines. The absence of such structures in the Greenland shark urged the scientists to look for a new approach.
Amongst a group of 28 female Greenland sharks that were tested, one was found to be as old as 392 years, making it the oldest living vertebrate in the world. The average life-expectancy of the fish has been found to be 272 years.
The species, that can grow up to be around 21 feet, is indigenous to the North Atlantic.
The lifespan of the animal has been a mystery to marine biologists for decades.
'We used established radiocarbon methods but combined them in a new way. This approach, along with the extraordinary ages for these sharks, makes this study highly unusual,' said lead author of the paper, Julius Nielsen, University of Copenhagen.
Christopher Bronk Ramsey, who co-authored the paper said,'We had to take into account the complexity of the oceans and the growth patterns of the sharks when interpreting the data from this project. Without the advances in statistical analysis made in recent years, it would not have been possible to demonstrate the extraordinary longevity of this species.'
It was conjectured earlier that the fish could live on for centuries considering the slow growth of the fish (1cm in a year) and their large sizes.
The sharks that are estimated to be 335 and 392 years old were 16.17 feet and 16.47 feet long respectively.
It was concluded that a fully grown Greenland shark, that can reach over 16 feet, is at least 272 years old.
Other discoveries in the paper include the findings about the sexual maturity in females, that is attained at 156 years of age.
'Greenland sharks are among the largest carnivorous sharks on the planet, and their role as an apex predator in the Arctic ecosystem is totally overlooked. By the thousands, they accidentally end up as by-catch across the North Atlantic, and I hope that our studies can help to bring a greater focus on the Greenland shark in the future,' said Julius Nielsen.