The Greenland shark is currently the longest-lived vertebrate known on earth, according to scientists.

The ages of 28 Greenland sharks were determined using radiocarbon dating of eye proteins, which revealed that one female shark was estimated to be about 400 years old. This makes it the oldest known vertebrate on earth, surpassing the previous record holder, a bowhead whale estimated to be 211 years old.

As Julius Nielsen, a marine biologist at the University of Copenhagen and lead author of the study, put it: “We had our expectations that we were dealing with an unusual animal, but I think everyone who did this research was very surprised to learn that the sharks were so old like them.”

Greenland sharks swim through the cold waters of the Arctic and North Atlantic at a pace so slow that it has earned them the nickname “sleeping sharks.” Image credit: Julius Nielsen

Greenland sharks are enormous creatures, capable of reaching up to 5m in length, but they grow at a slow rate of just 1cm per year. They can be found, swimming slowly, in the cold depths of the North Atlantic.

According to the research team, these animals only reach sexual maturity when they reach 4 m in length, which, based on their estimated age range of up to 400 years, would not occur until they are approximately 150 years old.

A freshly tagged Greenland shark returns to the deep, cold waters of Uummannaq Fjord in western Greenland. Image credit: Julius Nielsen

The study was based in part on radiocarbon levels in the sharks’ eye tissue, which was made possible by the large amounts of radiocarbon released into the ocean during atmospheric thermonuclear weapons testing in the 1960s. It was determined that Sharks with higher levels of radiocarbon in eye tissue were younger than 50 years old, while those with lower levels were estimated to be at least 50 years old or older.

The researchers then came up with an estimated age range for the oldest sharks based on their size and previous data on the size of Greenland sharks at birth and the fish’s growth rates.

A Greenland shark swimming near the ocean surface after its release from the research vessel Sanna in northern Greenland. Image credit: Julius Nielsen

According to Nielsen, the analysis has a probability rate of around 95 percent and the sharks were determined to be at least 272 years old, but could be up to 512 years old (!), with the most likely age being 390 years old.

But why do Greenland sharks live so long?

The long lifespan of these animals is attributed to their extremely slow metabolism and the cold waters they inhabit. They move through the waters of the Arctic and North Atlantic at a very slow pace, earning them the nickname “sleeping sharks.” Despite being found with seal parts in their stomachs, the sharks are so slow that experts believe they must have consumed the seals while they were asleep or already dead.The slower you go, the further you will go.