A shark alive today may have been swimming before the light bulb existed
Scientists dated Greenland sharks using the crystals in their eyes. One came out to roughly 392 years old, give or take a century.
The Greenland shark grows about half a centimeter to a centimeter a year and doesn't reach sexual maturity until around age 150 — a pace so slow that measuring it required a method borrowed from geology rather than marine biology. In 2016, researchers led by Julius Nielsen radiocarbon-dated proteins locked inside the lens of the sharks' eyes, which form in layers during early development and never get replaced afterward, the way tree rings never disappear once laid down.
The results put the species' lifespan at a minimum of about 272 years, with the single oldest shark examined estimated at roughly 392 years old, plus or minus 120 years. Even the low end of that range makes the Greenland shark the longest-lived vertebrate known — a shark born, on that estimate, sometime in the 1600s could plausibly still be alive in the North Atlantic today.
The species' whole biology moves at this pace. Gestation is estimated at 8 to 18 years, among the longest of any vertebrate, and litters can run up to ten pups. Researchers studying why the sharks last this long have pointed to unusually effective DNA repair mechanisms and features that may enhance cancer resistance, though the exact biology is still being worked out.
A fishing boat could be hauling up an animal older than the country it sails from, and nothing about the shark would announce that fact.