It was 1744, Nature reports, when this sleepy, small-headed Somniosus microcephalus … when this long-swimming, short-sighted Greenland shark came into the world – if not a century or two earlier. And it could keep going until it’s more than 500 years old, the oldest vertebrate on the planet:
Marine scientists already knew that the Greenland shark was long-lived, says Peter Bushnell, a marine physiologist at Indiana University South Bend and a co-author of the study, published in Science. The fish are enormous but grow slowly, suggesting a long lifespan. Adult Greenland sharks have been measured at more than 6 metres long — and researchers think that they could grow even longer. One 1963 study estimated that the species grows at less than 1 centimetre per year.
…[T]he team decided to measure levels of radioactive carbon-14 in fibres in the centre of the shark’s eye lens. Such measurements reflect levels of radiocarbon in the ocean when the lens was first formed. Measurements of 28 female Greenland sharks, made during surveys in 2010–13, suggested that the largest of them (at 5.02 metres long) must have been between 272 and 512 years old at the time.
The shark’s longevity probably arises because it expends very little energy, owing to its cold body temperature and enormous size, Bushnell says. Not all cold, large species live to such an exceptional age, so it would be intriguing to know whether the shark has any particular quirks or molecular tricks that contribute to its long lifespan, says Mario Baumgart, a biologist at the Leibniz Institute on Aging in Jena, Germany.
The study also shows that Greenland shark females don’t reach sexual maturity until around 150 years old — suggesting that a century of heavy fishing could wipe out the entire species, says Bushnell. Although the sharks aren’t themselves being overfished, a greater threat comes from the way climate change is affecting fishing practices in their environment, says Aaron MacNeil, a marine biologist at the Australian Institute of Marine Science near Townsville, Queensland.