In the cold, dark waters of the North Atlantic and Arctic Oceans swims an animal that may have been alive before the founding of the United States. The Greenland shark, a sluggish deep-water predator that most people will never see, holds the record as the longest-lived vertebrate known to science. Estimates drawn from a single individual suggest that some members of the species could be pushing past four centuries of age, a lifespan that reframes what biologists thought was possible for an animal with a backbone.
How researchers arrived at a 400-year estimate
The claim rests on an unusual dating method. Sharks do not have the bony structures, such as ear stones or growth rings, that scientists typically use to age fish. Greenland sharks are especially difficult because their bodies are soft and slow-growing. To get around this, a team of researchers turned to the lens of the eye, whose central proteins form before birth and remain chemically unchanged for the rest of the animal’s life. By applying radiocarbon dating to those proteins, they could estimate when each shark was born.
The results, published in a widely cited 2016 study, placed the average lifespan of the sampled sharks in the range of several centuries. The largest female in the group, measuring roughly five meters, was estimated to be around 392 years old, with a statistical margin that stretched from about 272 to more than 500 years. Even at the conservative end, that figure comfortably exceeds the lifespan of the bowhead whale, the previous vertebrate record holder. The National Oceanic and Atmospheric Administration’s species profile for the Greenland shark reflects the scientific consensus that the animal is among the most long-lived on the planet.
A life lived in the slow lane
Extreme longevity in the Greenland shark appears to be tied to the extreme conditions of its habitat. The species lives in frigid water, often at depths where temperatures hover near freezing. Cold slows metabolism, and a slow metabolism appears to slow nearly everything else about the animal’s biology. Greenland sharks grow at a glacial pace, adding roughly a centimeter to their length each year. An adult that reaches four or five meters has therefore been growing for a very long time.
That unhurried pace extends to reproduction. Researchers estimate that female Greenland sharks may not reach sexual maturity until they are around 150 years old, which would make them among the latest-maturing animals known. A creature that takes a century and a half simply to begin reproducing is poorly suited to bouncing back from population declines, a vulnerability that has consequences for conservation.
An apex scavenger of the deep
Despite its size and predatory reputation, the Greenland shark is not a fast hunter. Its top swimming speed is measured in a few kilometers per hour, slower than the seals it sometimes eats. Scientists have long puzzled over how such a slow animal captures agile prey, with one leading hypothesis being that it ambushes seals while they sleep in the water. The shark is also a committed scavenger, and its stomach contents have included the remains of fish, other sharks, and even land mammals such as reindeer and polar bears that likely entered the water as carcasses.
Many individuals carry a further peculiarity: parasitic copepods that attach to the surface of their eyes, sometimes leaving the shark partially blind. Because the animal relies heavily on smell and other senses to navigate the lightless deep, impaired vision does not appear to be a serious handicap. The shark’s flesh contains high concentrations of a compound that is toxic when eaten fresh, which is why traditional preparations in Iceland involve fermenting and drying the meat for months before it is considered safe.
Why an ancient shark matters to modern science
The Greenland shark’s longevity is more than a trivia-quiz superlative. Biologists studying aging are interested in how the species avoids the cancers and cellular breakdowns that limit the lifespans of most animals. An organism that can sustain functioning tissues for centuries may hold clues about cellular repair, genetic stability, and the biology of senescence. Research into the shark’s genome is ongoing, and scientists hope it may reveal mechanisms that protect long-lived cells from damage.
The same traits that make the shark scientifically fascinating also make it fragile. A species that grows slowly, matures after a century, and reproduces infrequently cannot easily withstand pressure from fishing, whether targeted or accidental as bycatch. Individuals hauled up in nets today may have been born in an era of wooden sailing ships. That perspective has driven calls for careful management of the deep-water fisheries where the sharks are most likely to be caught.
A living link to the past
The idea that a single animal alive today could have been swimming through Arctic waters when the first telescopes were being built captures something rare in the natural world. The Greenland shark is a reminder that the deep ocean still harbors organisms whose basic biology defies easy explanation. Its unhurried existence, spanning the rise and fall of empires above the surface, has made it an enduring symbol of just how much remains unknown about life in the planet’s coldest and darkest places.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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