Tuesday, 16 August 2016

Greenland Sharks May Live 400 Years

By Mindy Weisberger, Senior Writer | August 11, 2016 02:21pm ET

Greenland sharks are slow. They swim through the cold waters of the Arctic and the North Atlantic at a sluggish pace that has earned them the nickname "sleeper sharks." Seal parts have been found in their bellies, but the sharks move so slowly that experts have suggested that the seals must have been asleep or already dead when the sharks ate them.

They're also not too swift when it comes to growing, eking out a mere 0.4 inches (1 centimeter) per year, studies have found. Researchers suspected that Greenland sharks' exceptionally slow growth meant that they lived a long time, but they had no idea just how long that might be. That is, until now.

A new study provides the first estimates for Greenland shark longevity, and shows that these slowpokes of the sea stick around a very long time — at least 272 years, and perhaps as long as 390 years on average, making them longer-lived than any other vertebrate in the world.

Finding the age of any type of shark isn't easy, and the Greenland shark (Somniosus microcephalus) is especially challenging, according to study co-author Julius Nielsen, a marine biologist and doctoral candidate at the University of Copenhagen.

Nielsen told Live Science that scientists use bony structures in sharks to track their age — and there aren't many. Some species of sharks have calcified vertebrae or fin spines, and these contain stripes that can be used to calculate how old a shark is, similar to counting growth rings in trees.

Greenland sharks, on the other hand, are "very soft sharks," Nielsen said, and they don't have any bony structures at all.

"Something new had to be taken into consideration to solve this mystery," he said.

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