Greenland Sharks Can Live 400 Years, and Scientists Say the Proof Is in Their Eyeballs
The Greenland shark is the longest-living vertebrate ever discovered, with an estimated lifespan of 250 to more than 400 years — and scientists cracked the mystery of their age using a protein hidden inside the shark’s eye.
These deep-ocean predators swim through near-freezing Arctic waters at a pace that barely registers. Their growth rate is less than one centimeter per year. Some individuals alive today may have been born before the American Revolution.
The usual method of aging animals — counting rings on teeth or bones — doesn’t work for these slow-growing sharks. So researchers turned to the eye lens. A Greenland shark’s eye contains a protein core that forms before birth and never gets replaced. Carbon from the surrounding environment accumulates in that protein over time. By measuring radiocarbon levels, scientists can calculate how long the protein has existed.
A 2016 study published in Science, led by marine biologist Julius Nielsen, applied this radiocarbon dating method to multiple Greenland sharks. The results shocked the research team.
“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 of the findings.
He was candid about the method’s limitations. “It’s an estimate. It’s not a determination. It is the best we can do,” Nielsen noted. He added that the oldest sharks 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 in the study were centuries old.
Growing Up Takes a Century for Greenland Sharks
Greenland sharks 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.”
Their extreme longevity traces back to a lifestyle that seems almost frozen in time. They inhabit near-freezing waters where their metabolism runs at a fraction of the pace of most other sharks. That slow metabolism minimizes cellular wear and tear, letting their bodies function across centuries. According to NOAA, cold-water species often have slower metabolisms, which can contribute to longer lifespans.
Researchers are also exploring Greenland shark genetics for clues about aging. They have found hints of enhanced DNA repair and cellular maintenance that could slow the process at a fundamental level.
Greenland Sharks Are Effective Hunters
Many Greenland sharks are partially blind due to parasites on their eyes. They hunt anyway, feeding on fish, squid and even seals — relying on stealth and patience rather than speed.
Marine ecologist Kim Praebel explains: “They don’t need to see very well in the deep sea. Smell and other senses are far more important.”
Centuries of Survival Are Threatened by Fishing Nets
Despite surviving for hundreds of years, Greenland sharks face modern threats. They are often caught accidentally in deep-sea fisheries, and their slow reproductive rate makes population recovery difficult.
Nielsen has warned that removing a single centuries-old shark could affect the population’s future. When a species takes a century just to reach maturity, every individual matters.
Their flesh adds another wrinkle to the story. Greenland shark meat is toxic when fresh. In Iceland, it is traditionally fermented and dried to make hákarl, a dish famous for its strong smell and taste.
The Greenland shark’s biology — long life, slow growth, late reproduction — makes it uniquely vulnerable to human interference, even as it endures conditions that would overwhelm most marine species.
Scientists are still studying Greenland shark genetics for insights into aging and DNA repair, but the species’ extreme vulnerability to bycatch means conservation efforts may determine whether these centuries-old animals keep swimming.
This article was created by content specialists using various tools, including AI.
