This shark was alive before the American Revolution - and it's still swimming today

 The longest-living vertebrate ever discovered isn’t a whale or a tortoise. It’s a shark - and for beachtown residents who share coastline with dozens of shark species, the science behind its extraordinary lifespan carries weight well beyond the Arctic.

The Greenland shark can live an estimated 250 to more than 400 years, according to a 2016 study published in Science and led by marine biologist Julius Nielsen. Some individuals swimming today may have hatched before the Declaration of Independence was signed.

“We had an expectation that they would be very long-lived animals, but I was surprised that they turned out to be as old as they did,” Nielsen said.

How Researchers Cracked the Greenland Shark Age Mystery

Nielsen’s team used an unconventional method to determine the sharks’ ages. They radiocarbon-dated proteins in the sharks’ eye lenses - proteins formed before birth that remain unchanged throughout life. By measuring how much radiocarbon had accumulated in those proteins, researchers could estimate how long each shark had been alive.

Traditional aging methods, like counting growth rings on teeth or bones, don’t work with Greenland sharks. The animals grow so slowly that such markers are unreliable. The eye lens technique instead measured levels of radiocarbon, a naturally occurring form of carbon that changes over time, embedded in protein cores that never get replaced after formation.

Nielsen was careful about the findings’ precision. “It’s an estimate. It’s not a determination. It is the best we can do,” he said. “The oldest sharks in the study were likely between 272 and 512 years old … But even the lowest part of the age range still makes Greenland sharks the longest-living vertebrate known to science.”

Even the youngest adults examined were centuries old.

Greenland Sharks Have a Glacial Metabolism

The Greenland shark’s lifespan traces back to two factors: near-freezing water and an extraordinarily slow metabolism.

These sharks inhabit waters where their metabolic rate moves at a fraction of the pace of most other shark species. That reduced metabolism minimizes cellular wear and tear, allowing their bodies to function across centuries. Their growth rate is less than one centimeter per year, and they may not reach sexual maturity until 100 to 150 years old.

As National Geographic described it, “The Greenland shark lives life in the slow lane - so slow that it may not even reach adulthood for a century.”

The cold, stable deep-ocean conditions reduce environmental stress and help preserve biological systems over long periods. According to NOAA, cold-water species often have slower metabolisms, which can contribute to longer lifespans. Researchers are now exploring Greenland shark genetics for clues about aging, finding hints of enhanced DNA repair and cellular maintenance that could slow aging at a fundamental level.

Are Greenland Sharks Blind?

Despite barely outpacing a leisurely crawl, the Greenland shark hunts effectively. It feeds on fish, squid and even seals, likely relying on stealth and patience rather than speed. Many Greenland sharks are partially blind due to parasites on their eyes, yet they navigate and hunt using keen senses of smell and vibration detection.

Marine ecologist Kim Praebel said: “They don’t need to see very well in the deep sea. Smell and other senses are far more important.”

Their flesh is toxic when fresh. In Iceland, it is traditionally fermented and dried to make hákarl, a dish famous for its strong smell and taste.

What Are the Modern Threats to This Ancient Species?

Despite surviving for centuries in some of the planet’s harshest waters, Greenland sharks face pressure from deep-sea fisheries that catch them accidentally. Their slow reproductive rate makes population recovery difficult. Nielsen has warned that removing a single centuries-old shark could affect the population’s future.

For folks living alongside one of the world’s most biodiverse marine corridors, the research into Greenland shark longevity and the threats these animals face from commercial fishing mirrors broader concerns about ocean health and shark conservation closer to home.