The Greenland shark may be the oldest living vertebrate

In 2016 marine biologists reported a startling result: the Greenland shark is the longest-lived vertebrate on Earth. Because the species lacks the calcified bones scientists normally use to read age, the team turned to an unlikely clock — the eye lens, which forms before birth and never stops storing protein.

By radiocarbon-dating lens nuclei from 28 sharks, they estimated lifespans of at least 272 years, with the largest individual put at roughly 392 years (and possibly as old as ~500). That comfortably beats the bowhead whale, the previous record holder at around 211 years.

A 5-metre Greenland shark alive today may have been a pup in the 1600s.

The trade-off is a glacially slow life. These sharks grow about 1 centimetre a year and do not reach sexual maturity until around 150 years old — a pace that makes the species acutely vulnerable to overfishing and bycatch.