"The Greenland shark's eye lens is composed of a specialised material - and it contains proteins that are metabolically inert," explained Mr Neilson.
"Which means after the proteins have been synthesised in the body, they are not renewed any more. So we can isolate the tissue that formed when the shark was a pup, and do radiocarbon dating."
The team looked at 28 sharks, most of which had died after being caught in fishing nets as by-catch.
Using this technique, they established that the largest shark - a 5m-long female - was extremely ancient.
Because radiocarbon dating does not produce exact dates, they believe that she could have been as "young" as 272 or as old as 512. But she was most likely somewhere in the middle, so about 400 years old.
Saturday, August 13, 2016
400-year-old Greenland Shark ‘Longest-Living Vertebrate’