The Remarkable Longevity of Greenland Sharks
Somewhere a kilometer below the surface of the North Atlantic, in water just above freezing, a Greenland shark drifts. A copepod clings to its cornea like a ragged streamer, yet the eye behind that fouled lens continues to function—more or less—and it has been doing so for centuries.
In fact, the oldest individual ever radiocarbon-dated was a female Greenland shark (Somniosus microcephalus) estimated to be 392 years old, with a broad range of uncertainty. This discovery, published in a landmark 2016 study that dated proteins from Greenland shark eye lenses, established this species as the longest-lived vertebrate known to science (Nielsen et al., 2016).
Unlike the sleek, fast-moving sharks familiar to many, the Greenland shark is built for time, not speed.
How Greenland Sharks Achieve Extraordinary Ages
Greenland sharks grow at a glacial pace, reaching sexual maturity at around 150 years old. They inhabit the near-freezing, deep waters of the North Atlantic, where their entire physiology is adapted to slowness and endurance. Since these sharks lack the calcified vertebrae or otoliths commonly used to age fish, scientists devised an innovative approach: radiocarbon-dating the proteins at the center of their eye lenses. These lens cores are formed before birth and remain unchanged throughout the shark’s life, providing a biological timestamp for age estimation.
Applying this method revealed that even the smallest mature Greenland sharks were over 100 years old. The largest female analyzed was estimated to be 392 years old, with a 95.4% probability range spanning 272 to 512 years. This means some of these sharks were alive during the time of Isaac Newton and far before modern science had taken shape.
The Eye Parasite That Tells a Story
Greenland sharks are often recognized by a curious parasite: Ommatokoita elongata, a copepod that attaches to their corneas, sometimes dangling like a ragged streamer. For decades, researchers assumed the parasite severely impaired the shark’s vision, reasoning that these creatures lived in near-total darkness where sight was less critical and other senses like smell and the lateral line dominated.
However, this long-held assumption has recently come under scrutiny.
Recent Insights Into Greenland Shark Vision
Between 2020 and 2024, researchers from the University of Basel and the University of California, Irvine, studied eyeballs from ten Greenland sharks caught off western Greenland. According to co-author Emily Tom, receiving these samples was a remarkable experience (Smithsonian Magazine).
The team found that the light-sensitive parts of the eyes showed no obvious signs of degeneration despite the sharks’ advanced age. The copepod parasites, while present on the cornea, did not appear to damage the underlying retina. Thus, even sharks over a century old seem capable of some limited vision.
Physiologist Dorota Skowronska-Krawczyk explained that Greenland sharks are not blind but have restricted vision—they can detect light and darkness but likely cannot resolve detailed shapes or rapid movements. The cornea may be scarred and clouded by parasites, yet the retina remains remarkably intact and functional.
Genetic Mechanisms Behind Longevity and Eye Health
What allows these sharks to maintain retinal health over centuries? The answer may lie in their genetics. The Basel and Irvine research teams focused on DNA repair-associated genes, particularly ERCC1 and ERCC4, which encode proteins critical for repairing damaged DNA. Greenland sharks exhibited elevated ERCC4 expression in their retinas compared to other shark species.
Comparative neurobiologist Laura Ryan from Macquarie University noted that this enhanced DNA repair capability could help maintain retinal integrity and mitigate the accumulation of cellular damage over the shark’s extraordinary lifespan, as reported by the Australian Broadcasting Corporation.
The Greenland Shark Genome: Unlocking Secrets of Longevity
In 2026, Shigeharu Kinoshita and colleagues at the University of Tokyo published the first whole-genome sequence of the Greenland shark in PNAS. Covering 96.7% of the shark’s DNA, the study revealed multiple genetic adaptations that may explain its extreme longevity (Live Science).
The Greenland shark’s genome features unique amino acid substitutions in linker histone proteins, which compact DNA into chromosomes. These adaptations likely result in a more stable chromatin structure, slowing the accumulation of DNA damage. Additionally, gene families associated with immune response and DNA repair are expanded, and ferritin genes—which regulate iron storage and protect against oxidative stress—are notably amplified.
Kinoshita concluded that the shark’s extreme longevity is the product of coordinated changes across multiple biological systems, including genome stability, iron metabolism, immune function, and stress resistance. All these factors converge in an animal that moves slowly through cold, dark waters.
The Greenland Shark’s Unique Diet
Greenland sharks are opportunistic feeders, consuming a variety of prey including fish, seals, and carrion. Remarkably, researchers have found remains of terrestrial animals such as reindeer, horses, and polar bears in their stomachs—animals that likely drowned or fell through ice, ultimately sinking into the deep-sea habitat of the sharks.
This dietary flexibility aligns with the shark’s slow metabolic rate and limited movement. Rather than actively chasing prey, they may ambush sleeping or vulnerable seals or scavenge whatever drifts into their environment. In this dark, cold world, patience and opportunism are key survival strategies.
Scientific Skepticism and a Rare Irish Stranding
While the 400-year age estimates have garnered attention, not all experts accept them without question. Aaron MacNeil, a biologist at Dalhousie University, has pointed out that radiocarbon dating in deep-sea environments depends partly on nuclear-bomb fallout from the Cold War era. Slow mixing of these isotopes in deep waters may have skewed age estimates somewhat, potentially inflating them.
Nonetheless, MacNeil acknowledges that Greenland sharks are undoubtedly long-lived, with conservative estimates placing their maximum age at around 200 years or more (Live Science).
Adding to the species’ mystique, a rare Greenland shark stranded on the coast of County Sligo, Ireland, in April 2026. This was the first recorded stranding of the species on Irish shores. The specimen was recovered by the National Museum of Ireland, providing a unique opportunity to study a deep-water animal usually inaccessible to humans.
The Impact of Human Exploitation and Current Status
One reason so few ancient Greenland sharks remain is industrial hunting during the 19th and early 20th centuries, when the sharks were targeted for their liver oil. Given their slow growth and late maturity, populations have been slow to recover, and some marine biologists believe they are still rebounding from this historical exploitation.
Today, most human encounters with Greenland sharks occur accidentally, typically as bycatch in deep-water fisheries. Their deep, cold habitat keeps them largely out of human reach—one of the few advantages of living in such an extreme environment.
What It Means to Witness a Greenland Shark
The life of a Greenland shark unfolds on a timeline unlike nearly any other vertebrate. Growing at roughly one centimeter per year and reaching sexual maturity around 150 years of age, these sharks embody a biological pace measured in centuries. The radiocarbon dating places some individuals’ ages within a range that spans most of recorded modern history.
The aging method, relying on a tiny protein core in the eye lens formed before birth, provides a remarkable biological archive. Complemented by genome sequencing revealing amplified ferritin genes, expanded DNA repair gene families, altered chromatin structure, and elevated retinal ERCC4 expression, the evidence paints a compelling picture of an animal finely tuned for longevity.
These findings are grounded in rigorous scientific measurement, not poetic metaphor. They reveal a creature that thrives quietly in the cold depths, a testament to nature’s capacity for endurance and adaptation.
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