The record for the longest-living vertebrate was broken two years ago, as biologists used groundbreaking radiocarbon dating to age ancient marine life in the Arctic. The Greenland shark that smashed the record was aged at 400 years, or, to put that into slightly more dramatic language, four centuries.
Our enduring Arctic friend has unknowingly hunted, swum, and slumbered through four centuries’ worth of major historical events. The shark was born under the reign of King James I and was navigating its adolescence through the inauguration of King George II. She would have reached adulthood around the time of the American Revolution.
The world of vertebrates is littered with incredible lifespans. The oldest elephant ever discovered, Lin Wang, passed away at the age of 86. The oldest human (according to records) was 122-year-old French woman Jeanne Louise Calment, who passed away in 1997.
The Greenland shark is a record breaker and no doubt about it, but an Icelandic “ocean quahog” (that’s “clam,” to most of us) once studied managed to live for 507 years. The clam’s impressively long life was cut short in 2006 when a team of British researchers, unaware of the creature’s age, opened it up to examine it.
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The Greenland shark’s strategy when it comes to longevity may be quite simple: growth. The animal grows less than 1 centimeter per year. But their exact age is often hard to determine. University of Iceland shark expert Steven Campana explained: “Fish biologists have tried to determine the age and longevity of Greenland sharks for decades, but without success.”
Newly developed radiocarbon dating principles were what made the accurate ageing of these sea creatures possible.
Many fish can be age-assessed by counting rings of calcium carbonate production within their ears. Yes, sort of like ageing a tree.
But sharks do not have this feature. Instead, scientists looked to their eyes. The Guardian newspaper covered their progress: “The lens of the eye is made of proteins that build up over time … Work out the date of these proteins, the scientists say, and it is possible to achieve an estimate of the shark’s age.”
Greenland shark in the St. Lawrence Estuary / Requin du Groenland dans l'estuaire du Saint-Laurent / Photo © Jeffrey Gallant (GEERG.ca)
This is when scientists turned to radiocarbon dating, a method whereby the levels and rate of carbon decay in a material, or body, could be measured.
A historical anomaly affected their findings dramatically: atomic bomb testing in the 1950s increased the levels of carbon-14 in the atmosphere by a significant amount. This surge of non-naturally occurring carbon-14 entered the North Atlantic marine food chain in the early 1960s, affecting, amongst other things, the ocean’s shark population.
Scientists found out that the two youngest sharks in their study must have been born after the 1960s: their ocular lens proteins contained the most carbon-14. And our record-smashing female Greenland shark was then discovered to be, give or take a decade or two (and we’ll forgive the margin of error), a staggering four centuries old.
What would you remember if you’d lived through the last four centuries? Did you enjoy this amazing story? Keep up with science and share with friends and relatives!
Thumbnail Credit: YouTube Screenshot | One World One Ocean