Thursday, September 29, 2016

Greenland Sharks Set World Record for Longest-Lived Vertebrates

Greenland Sharks Set World Record for Longest-Lived Vertebrates

Julius Nielsen, University of Copenhagen

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An international team of researchers uncovered a mystery of one of the least understood animals in the world, the Greenland shark. They found that not only can these sharks grow to be among the biggest on our planet, they can also live up to 272 years, the longest life expectancy of all known vertebrate animals.

Estimating the Greenland shark’s life expectancy is difficult because employing traditional methods to establish the age of any fish cannot be used with the species. Therefore, the team used carbon dating to determine the shark’s age. The results are now available online in the journal Science.

“Our lifespan study is based on the carbon-14 dating of Greenland shark eye lenses. As with other vertebrates, the lenses consist of a unique type of metabolically inactive tissue. Because the center of the lens does not change from the time of a shark’s birth, it allows the tissue’s chemical composition to reveal a shark’s age,” explains the lead author Julius Nielsen, a PhD student of the University of Copenhagen’s Department of Biology. We use well-established radiocarbon methods, but combine them in a new way. This approach, along with the extraordinary ages for these sharks, makes this study highly unusual.”

Although Greenland sharks are apex predators and among the largest carnivorous sharks, they accidentally get caught by fishing vessels across the North Atlantic. The research team hopes that their discovery can also bring attention to these sharks and help their preservation in the future.

Other researchers include those from the Arctic University of Norway, Aarhus University and the National Aquarium Denmark/Den Blå Planet. Researchers from the Oxford University in the UK, the Indiana University South Bend and the Virginia Institute of Marine Science in the US were also part of the international research team.