The Greenland shark can live 400 years, older than the country itself

The Greenland shark is a slow-moving predator of the Arctic and North Atlantic that has become famous for a single, startling number: some individuals alive today were already swimming through frigid waters before the founding of the United States, and possibly before many modern nations existed in any recognizable form. A 2016 radiocarbon-dating study estimated that the oldest sharks examined could be pushing 400 years old, making Somniosus microcephalus the longest-lived vertebrate species documented anywhere on Earth. That number has reshaped how scientists think about growth, metabolism, and survival in the deep ocean.

A Radiocarbon Clock Hidden in the Eye’s Lens

Aging a fish that outlives written records required an unusual method. Most sharks are aged using growth rings in calcified vertebrae, similar to counting rings in a tree trunk, but Greenland sharks lack the hard, ring-forming tissue that technique depends on. A shark’s eye lens grows in layers throughout its life instead, and the innermost layer forms before birth and never changes afterward, effectively freezing a chemical snapshot of the year the animal was born. Researchers led by Julius Nielsen at the University of Copenhagen used radiocarbon dating on the lens nuclei of 28 female Greenland sharks caught incidentally in fishing nets, comparing carbon-14 levels to the “bomb pulse,” the sharp spike in atmospheric radiocarbon left behind by nuclear weapons testing in the 1950s and 1960s. The same bomb-pulse principle has been used elsewhere to date human tooth enamel and brain tissue, but applying it to a shark’s eye required first confirming that lens proteins, once formed, never get metabolically replaced. The technique, published in the journal Science, let the team calculate approximate birth years for sharks that had never been tagged or tracked in life.

The Oldest Known Vertebrate on Earth

The results startled even the researchers who produced them. The study estimated an average lifespan of at least 272 years, with the two largest sharks in the sample, measuring 493 and 502 centimeters, calculated at roughly 335 and close to 392 years old. Statistical modeling put the upper bound of the oldest specimen’s age at nearly 400 years, edging out the bowhead whale, the previous longevity record-holder among vertebrates at around 200 years. The team also concluded that female Greenland sharks likely do not reach sexual maturity until around 150 years of age, a reproductive timeline unmatched by any other backboned animal known to science.

Built for Extreme Slowness

The shark’s longevity appears tied directly to how slowly it lives. Greenland sharks grow at a rate of roughly one centimeter a year, a pace so gradual that reaching the species’ typical adult length of four to five meters can take centuries. They inhabit water between about minus 2 and 7 degrees Celsius, conditions that suppress metabolism dramatically, and swim at speeds rarely exceeding one mile per hour, among the slowest of any shark species alive. Biologists studying negligible senescence, a phenomenon in which an organism shows little measurable functional decline with age, point to the Greenland shark’s frigid, low-energy lifestyle as one plausible driver of its extraordinary lifespan.

A Giant of the Arctic Depths

Somniosus microcephalus is the largest fish native to Arctic waters, with the biggest confirmed specimen measuring roughly 6.4 meters and weighing more than 1,000 kilograms. It ranges through the North Atlantic and Arctic Ocean, diving to confirmed depths beyond 1,800 meters, though it is also encountered near the surface in the far north. Many individuals carry a parasitic copepod attached to each cornea, a relationship thought to impair the shark’s eyesight, which may explain its reliance on smell and opportunistic scavenging over active hunting. Stomach-content studies have turned up remains of fish, seals, and even reindeer and polar bear, evidence of both predation and scavenging in the harsh Arctic food web.

A Fragile Future Despite the Long Life

Longevity has not made the species resilient to modern pressures. The Greenland shark is classified as Vulnerable on the International Union for Conservation of Nature’s Red List, a status the organization tightened in 2020 amid evidence of population declines. Because females may not reproduce until age 150, populations recover from overfishing or bycatch losses at a glacial pace compared with faster-maturing species. Greenland sharks were historically hunted for liver oil, and while direct targeting has declined, they remain vulnerable as bycatch in deep-water fisheries across the North Atlantic. Researchers studying the species argue that its extreme longevity is precisely why sustained protection matters: a population that took centuries to accumulate could take just as long, if it is even possible, to rebuild.

How the Age Estimate Compares to Other Long-Lived Animals

Even among nature’s most durable creatures, the Greenland shark’s estimated lifespan stands apart. Bowhead whales, the previous record-holders among mammals, have been estimated at up to roughly 200 years based on harpoon-point evidence and eye-lens chemistry of their own, while giant tortoises typically top out around 150 to 190 years. Ocean quahog clams, a species of long-lived bivalve, have been aged past 500 years using growth-ring counts on their shells, but that record belongs to a mollusk rather than a vertebrate with a backbone, brain, and circulatory system comparable to a shark’s. Popular claims about koi carp living for centuries have been debunked by researchers as based on unreliable scale-ring counts, leaving the Greenland shark’s radiocarbon-verified estimate as the most rigorously documented extreme-longevity case among vertebrates.

This article was produced with the assistance of AI and reviewed by Morning Overview editors.

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