In the cold, dark waters of the North Atlantic and Arctic swims a shark that may have been alive when Isaac Newton was working out the laws of motion. The Greenland shark grows so slowly and lives so long that scientists now consider it the longest-lived vertebrate on Earth, with individuals estimated to survive for several centuries. That extraordinary longevity, hidden for generations in a sluggish deep-sea predator, reshaped how researchers think about the outer limits of animal lifespan.
Centuries measured in a shark’s eye
The breakthrough came from an unusual dating method. Greenland sharks lack the hard, layered structures used to age most fish, so a research team turned instead to the lens of the eye, whose central tissue forms before birth and never renews. By applying radiocarbon dating to the eye lenses of sharks collected as bycatch, scientists could estimate each animal’s age. As reported in the journal Science, the largest specimen examined, a female roughly five meters long, was estimated to be about 400 years old, with a possible range spanning several centuries on either side of that figure.
Those numbers placed the Greenland shark far beyond any other known vertebrate. The findings implied that the biggest individuals swimming today were born in the seventeenth or early eighteenth century and have been growing quietly ever since.
A life lived in slow motion
The secret to such longevity appears to be extreme slowness in nearly every biological process. Greenland sharks inhabit frigid, deep waters where temperatures hover near freezing, and their metabolism is correspondingly sluggish. They grow at only about a centimeter per year and can reach lengths of four to five meters. The U.S. National Ocean Service, part of NOAA, notes that this glacial pace of growth is closely tied to the animal’s exceptional lifespan, with the cold environment slowing aging itself.
The same slow tempo carries a striking consequence for reproduction. Research summarized by NOAA Fisheries indicates the species may not reach sexual maturity until around 150 years of age, meaning a Greenland shark can spend more than a century growing before it ever reproduces. Few animals invest so long in reaching adulthood.
An enigmatic Arctic predator
For all its fame as a record-holder, the Greenland shark remains poorly understood. It ranges across the North Atlantic and into Arctic waters, often at great depths, and moves slowly enough that it was long assumed to be primarily a scavenger. Yet remains of seals and fast-swimming fish have been found in the stomachs of these sharks, raising unresolved questions about how such a lethargic hunter captures agile prey, possibly by ambushing animals as they sleep.
Many individuals also carry parasites attached to their eyes, which can impair vision, though in the lightless deep this may matter little. The species’ flesh is naturally toxic when fresh because of compounds in its tissue that help it cope with cold and pressure, a trait that has shaped traditional Arctic food preparation for centuries.
Why extreme age raises conservation stakes
The Greenland shark’s longevity is a scientific marvel, but it also leaves the species acutely vulnerable. An animal that takes 150 years to reproduce cannot recover quickly from population losses, so bycatch in commercial fisheries and other pressures pose a serious long-term threat. Because the biggest sharks alive today began their lives centuries ago, any decline in their numbers would take an extraordinarily long time to reverse.
That combination of vulnerability and mystery keeps the Greenland shark at the frontier of marine research. Each new study of its biology and behavior fills in another piece of a life measured not in years or decades but in the span of human history itself, offering a rare window into how life can persist across the centuries.
How radiocarbon dating unlocked the age
The eye-lens method that revealed the Greenland shark’s age borrows a technique more often associated with archaeology. The core of the eye lens forms before the animal is born and its proteins are never replaced, so it preserves a chemical snapshot from the start of life. Radiocarbon levels in the environment spiked during atmospheric nuclear testing in the mid-twentieth century, leaving a detectable marker in tissues formed afterward. Sharks whose lens cores carried that signal had to have been born relatively recently, while those without it were far older, and calibrating against the known timeline allowed researchers to bracket each animal’s age. The uncertainties are wide, which is why estimates span ranges of decades or more, but the conclusion that the largest sharks are centuries old has held up.
The finding rewrote expectations for vertebrate longevity and prompted new interest in the genetics behind such extreme lifespans. Later work sequencing the species’ unusually large genome has sought clues to how its cells resist the accumulated damage that limits the lives of most animals, a question with potential relevance far beyond the deep Atlantic.
A predator built for the cold and dark
The Greenland shark’s biology is shaped throughout by the extreme environment it inhabits. Living in near-freezing water at depths where sunlight never reaches, it moves with a famously languid pace that earned it a reputation for sluggishness. Its body chemistry is adapted to withstand the cold and immense pressure of the deep, and those same adaptations make its raw flesh toxic to eat unless carefully processed, a fact that has shaped Arctic culinary traditions for generations. Widely distributed but rarely seen, the shark spends most of its enormous life span in a realm that humans can barely observe, which is part of why so much about its feeding and reproduction remains uncertain even now.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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