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Several years ago various arms of the the media ran a story about the stupendous longevity of the Greenlandic (or Greenland) shark, claiming that some of its species surviving to this day may have been around prior to Christopher Columbus’ discovery of America in 1492! The difficulty with such claims was that they could not be scientifically tested. Estimation of age was a stumbling block because, unlike other species of Chrondrichthyes which you can calculate age by counting the growth bands (compared to tree rings) on their fin spines and vertebrae, the Greenlandic shark has no hard tissue at all on its body.
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| Greenlandic shark (source: americanoceans.org) |
To tackle the conundrum Danish scientists applied the methodology of radiocarbon dating to the species. Greenlandic sharks or Somniosus microcephalus have a lifelong special protein in their eye lenses which can be carbon dated. The result, in 2016 scientists were able to estimate the lifespan of these lumbering sea creatures at up to 400 years!§ Life isn’t exactly eventual for the Greenlandic shark however. Confined to the deep and freezing waters of the Arctic and North Atlantic, everything happens with them and to them in slow motion. Their metabolisms are agonisingly slow. Although capable of growing to more than 20 foot, the growth is painstaking slow (less than 1cm a year!), as is these monsters’ movement through the ocean waters. Sexual maturity for the shark doesn’t come until it is 150 years old!
The key to the Greenlandic shark’s extraordinary capacity for longevity would seem to lie in its cancer-fighting powers. The shark’s genome is twice the size of a human’s, containing multiple copies of genes which play a role in DNA repair and the suppression of tumours.
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‘6 of the Longest-Living Creatures on Earth’, Dave Roos, History, 02-Dec-2024, www.history.com
‘The Strange and Gruesome Stort of the Greenland Shark, the Longest-Living Vertebrate on Earth’, M.R. O’Connor, The New Yorker, 25-Nov-2017, www.newyorker.com
§ at 400+ years the Greenlandic shark still isn’t the Earth’s longest-living creature, the ocean quahog, a clam species located in the North Atlantic, have been found to live up to 500+ years…its secret of phenomenally long life apparently lies in its ability for almost total inactivity! So much for the benefits of exercise.
