A shark found dead on an Irish shore has left scientists astonished — it may have been only 150 years old but not mature, and its species can live 400 years

A dead Greenland shark found on Ireland’s storm-battered west coast has given researchers a rare look inside the longest-living vertebrate known to science. The roughly 10-foot animal appeared in County Sligo in April 2026, marking the first recorded stranding of the species in Ireland.

It weighed more than 440 lb. and may have been between 150 and 200 years old. That sounds ancient, but for a shark capable of living for several centuries, it may only recently have become mature enough to reproduce.

A 150-year-old young adult

Greenland sharks can live for about 400 years, although their exact maximum lifespan remains debated. Estimates generally range from 300 to 500 years, meaning some animals alive today may have been swimming when Shakespeare was writing.

Emilie De Loose, a marine biologist with the Irish Whale and Dolphin Group, said the discovery was both astonishing and sad. “This specimen took 150 years to reach the point where it could have reproduced,” she said, suggesting it may never have had the chance to help the population recover.

The beige-gray shark was not fully grown, since the species can reach around 16 ft. Even so, getting it off the marshy shore required volunteers, a crane, and a truck.

What the necropsy revealed

Volunteers first covered the body with seaweed to keep gulls and other scavengers away. A recovery operation supervised by the National Museum of Ireland then moved it to a regional veterinary laboratory.

Researchers wore masks, gloves, and protective clothing during the necropsy, an animal autopsy used to investigate health and cause of death. Jasmine Stavenow Jerremalm, a marine ecology doctoral researcher at University College Cork, said a centuries-old animal had to be handled carefully because nobody knew what diseases or microbes it might carry.

Every major organ was measured, weighed, examined, and sampled. The liver weighed about 110 lb., while the heart weighed roughly 75 lb., compared with about 11 ounces for a human heart.

Built for dark Arctic waters

Greenland sharks live in the North Atlantic and Arctic near Greenland, Canada, and Iceland. They are slow, solitary swimmers that feed on carcasses but can also capture living prey such as seals.

How does such a slow shark catch a fast marine mammal? Lily Fogg, an evolutionary biology researcher at the University of Basel, suggested it may ambush seals that are sleeping, injured, resting, or trapped near ice. Powerful suction then helps pull prey into the mouth.

The shark had sharp upper teeth and saw-like lower teeth suited to tearing flesh from carcasses. Its stomach appeared empty, but a full section of the intestine suggested recent digestion, while a slow metabolism may help it survive long periods when Arctic food is scarce.

Eyes that may work for centuries

For years, Greenland sharks were often described as almost blind because small tassel-like parasites attach to the front of their eyes. A 2026 study that included her found a very different picture.

The eyes and retinas appeared intact and specialized for extremely low light, even in sharks more than a century old. The visual system works much like a low-light camera built for the cold darkness of the deep Arctic, with the parasites apparently causing less damage than once assumed.

Researchers also found strong activity in genes involved in repairing damaged DNA. Since DNA damage is closely connected to aging, that repair system may help explain how the shark’s vision remains healthy for so long.

A scarred heart that kept working

Recent research on Greenland shark hearts found signs normally linked to aging, including widespread tissue scarring and cellular stress. Yet the animals appeared healthy, suggesting that their extraordinary lifespan may not depend on avoiding damage completely.

Instead, the species may be unusually good at continuing to function despite wear accumulated over centuries. That is a striking contrast with humans, whose eyesight and heart health often decline as age-related damage builds.

The Irish team removed the eye lenses for radiocarbon dating, which estimates age using carbon captured early in life. A muscle sample will also be studied through telomeres, protective structures at the ends of DNA that tend to shorten with age and environmental stress.

Why one dead shark matters

Brynn Devine, an Arctic fisheries scientist with Oceans North, said basic facts about the species remain unknown despite its broad range and enormous size. Scientists still do not know where these sharks mate, where they give birth, how often females reproduce, or how many young they produce.

Only one pregnant female has been directly documented, according to the available research. Without reliable breeding and population data, conservationists cannot easily identify critical habitats or measure the danger posed by accidental capture in fishing gear.

The Sligo shark showed no obvious cuts or wounds linked to nets, so further testing may be needed to explain its death. The museum hopes the specimen can eventually be preserved for public display, while its skin, organs, eyes, and tissue samples continue answering questions about an animal that may spend centuries beneath the ice-cold sea.

The main studies on Greenland shark vision and cardiac aging were published in Nature Communications and Aging Cell.