The Greenland shark may not grow up until 150, and one was dated at nearly 400 years old

One shark measured by scientists was so old its lifespan stretched across centuries, and that was only part of the surprise. The same species appears to take around 150 years just to reach sexual maturity, and researchers are now looking into its DNA to understand how it ages so slowly.

A shark with an age estimate that changed the conversation

The number that made people stop and look twice was 392. That was the estimated age of the oldest Greenland shark in a 2016 study led by biologist Julius Nielsen, based on a sample of 28 female sharks that had been caught accidentally in fishing nets.

The animal was also the largest in the group, measuring just over 16 feet. Scientists did not present that age as an exact birthday. The estimate came with a wide margin of error, putting the shark somewhere between 272 and 512 years old. Even so, the lower end of that range was enough to push it past the previous record holder, a bowhead whale thought to have lived around 211 years.

That made the Greenland shark the longest lived vertebrate known to science from the animals that have been aged this way. It also left researchers with a startling possibility. If the estimate is close, one individual shark may have been alive for nearly 400 years.

The species grows at an unusually slow pace, about one centimeter a year. By that measure, even a six foot Greenland shark has likely already been alive for centuries.

Why scientists looked at the eye instead of the skeleton

Working out the age of a Greenland shark was never going to be straightforward. Many sharks can be aged using hard structures that show growth marks, but Greenland sharks do not have those same ring marked clues available to researchers.

So Nielsen's team turned to a part of the body that sounds almost improbable at first: the nucleus of the eye lens. That tissue forms before a shark is born and changes very little afterward, making it useful for radiocarbon dating.

Using that method on the sharks in their sample gave scientists a way to estimate ages that had previously been difficult to pin down. It also opened up a debate that has not entirely gone away. Scientists still cannot give a precise maximum lifespan for the species. A 2025 Canadian assessment noted that the eye lens method has not been independently confirmed, and a recent review said uncertainty in ocean radiocarbon levels adds another layer of difficulty when researchers try to narrow down a birth year.

So the headline figure is extraordinary, but it also comes with a scientific asterisk. The shark may be nearly 400 years old. It may be younger or older within that very broad range. What is clear is that this species lives for an exceptionally long time.

It may take 150 years just to be ready to reproduce

The same study delivered another figure that may be even harder to wrap your head around. Female Greenland sharks likely do not reach sexual maturity until they are around 150 years old.

That estimate came from the size at which females are known to begin reproducing. Put simply, the species appears to spend an incredibly long time getting to the point where it can produce young. A shark born today could live through the entire history of email, two world wars, and the invention of the car, and still not be ready to have pups.

That slow pace matters far beyond curiosity. Nielsen has said policymakers need to keep in mind that Greenland sharks are extremely long lived and slow to mature. A population that may need a century and a half just to begin breeding is not one that can quickly bounce back from losses.

Seen together, the age estimate and the maturity estimate change the way the animal is understood. This is not just a large shark that happens to live a long time. It is a species whose whole timeline runs on a scale that is unusual even by the standards of long lived animals.

Now scientists are searching the shark's DNA for the reason

The next big step has come from genetics. A separate team led by fisheries chemist Shigeharu Kinoshita at the University of Tokyo published the first nearly complete map of a Greenland shark's genetic code in the journal PNAS, covering about 97 percent of its DNA.

Instead of trying to estimate the age of one individual, this research looks for clues to why the species may age so slowly in the first place. The team found unusually expanded gene families linked to immune defense and DNA repair. They also identified a notable increase in genes involved in iron storage.

Those findings do not point to a single longevity gene, and the researchers have been careful not to claim more than the data can support. The genome used in the study came from just one animal, so it is a starting point rather than a final answer.

Still, it gives scientists a new way to investigate one of the strangest timelines in the vertebrate world. The Greenland shark is already remarkable for an age estimate that could exceed any whale, tortoise, or fish aged by other methods, and for a reproductive schedule that may not begin until 150. Now researchers have a nearly complete genetic map that could help explain how an animal can move through life at such a different speed, and why that might matter for studies of aging and age related disease in other species as well.