A Greenland shark alive in the Arctic today may have been born before the United States existed

In the cold waters of the North Atlantic and Arctic Ocean swims a shark that may be older than the United States itself, and possibly older than most of the nations currently on a map. The Greenland shark grows so slowly and lives so long that a specimen caught today could plausibly have been alive when European explorers were still mapping the Americas, making it the longest-lived vertebrate known to science.

A Growth Rate of About a Centimeter a Year

Greenland sharks are among the largest shark species alive, with some individuals reaching lengths of more than six meters, but they achieve that size at a pace almost unmatched among vertebrates, growing at roughly one centimeter per year. That growth rate is dramatically slower than nearly every other large marine animal, a reflection of the extremely cold water and low-energy lifestyle the species has adapted to across its range in the Arctic and North Atlantic. Because growth happens so slowly and predictably, researchers realized decades ago that a Greenland shark’s size alone hinted at an unusually long lifespan, though nobody had a reliable way to confirm exactly how old the largest individuals actually were until relatively recently. The species is also difficult to study in the wild, since it typically inhabits deep, frigid waters far from shore, which meant most historical size and age estimates relied on relatively small numbers of specimens caught incidentally by fishing vessels rather than dedicated research expeditions.

Dating a Shark’s Age Through the Lens of Its Eye

Unlike bony fish, sharks lack the growth rings in ear bones or scales that scientists typically use to age other marine animals, which left the Greenland shark’s true lifespan a mystery for most of the twentieth century. Researchers eventually found a workaround in the shark’s eye: the lens nucleus of a vertebrate eye is metabolically inert, meaning the proteins laid down there during early development remain chemically unchanged for the rest of the animal’s life, effectively locking in a chemical timestamp. A team of scientists used radiocarbon dating on the eye lens proteins of several Greenland sharks, cross-referencing the radioactive carbon signature against known historical spikes from mid-twentieth-century nuclear weapons testing, to calculate the age of each shark far more precisely than size estimates alone could provide.

Two and a Half Centuries Just to Reach Adulthood

The results, published in the journal Science in 2016, estimated Greenland shark lifespans of at least 272 years, with a best statistical estimate landing at roughly 390 years for the study’s largest specimen, a female measuring about five meters long. At that scale, the shark would have needed to survive roughly 150 years before even reaching sexual maturity, an adolescence longer than the entire lifespan of almost any other vertebrate on Earth. A shark born around the estimated birth year of the oldest studied individual would have been alive through centuries of human history most people only encounter in textbooks, a detail that turned an obscure Arctic fish into an unlikely subject of international news coverage.

Toxic Meat That Became a National Dish

Despite its size, Greenland shark flesh is mildly toxic when fresh, containing high concentrations of trimethylamine N-oxide and urea that help the shark regulate buoyancy and osmotic balance in cold, deep water but produce a neurotoxic effect if eaten without preparation. In Iceland, the meat is traditionally fermented and then air-dried for months to break down those compounds, producing a pungent delicacy known as hakarl that remains a part of Icelandic culinary tradition today. The processing method, developed long before the underlying chemistry was understood, effectively turned a fish too dangerous to eat raw into a food safe enough to serve at festive occasions.

A Slow Hunter With Parasites Riding on Its Eyes

Many Greenland sharks carry a parasitic copepod that attaches directly to the cornea, a condition that may impair the shark’s eyesight over time, though the species appears to compensate by relying on other senses to locate food in the near-total darkness of its deep, cold habitat. Long assumed to be a slow-moving scavenger feeding mainly on carrion, the Greenland shark has also been documented with seal remains in its stomach, suggesting it can catch faster-moving prey despite its sluggish reputation, likely through ambush rather than pursuit. Between its extreme age, its near-blindness, and its apparent ability to still hunt seals in total darkness, the Greenland shark remains one of the least understood large predators in the ocean. Its slow metabolism and cold, deep habitat also mean it swims more slowly than almost any other shark of comparable size, which makes the seal remains found in some stomachs especially puzzling to researchers still working out how an animal moving that deliberately manages to catch prey capable of far greater bursts of speed.

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

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