Scientists believe they have discovered the oldest vertebrate animal on Earth: a female Greenland shark that lived to be nearly 400 years old.
The shark, which measures over 16 feet in length, lived for an estimated 392 years, but could have an age range between 272 to 512 years, according to research recently published in the journal Science.
The centuries old shark takes the title of longest-living vertebrate from a bowhead whale that was estimated to be 211 years old. Though the shark was probably born in the 17th century, she could have been born some time between 1501 and 1744, the BBC points out.
But that doesn't make the shark the oldest animal to have lived - that record is held by a clam named Ming, which lived to turn 507, The Guardian reports.
"Even with the lowest part of this uncertainty, 272 years, even if that is the maximum age, it should still be considered the longest-living vertebrate," said Mr Nielsen.
The study, led by biologists from the University of Copenhagen, used radiocarbon dating to find the ages of 28 deceased Greenland sharks, studying their lenses to determine their age. The species of shark is now the world's longest-living vertebrate.
Here's what a Greenland shark looks like in action:
When they're born, Greenland sharks measure 42 centimetres and grow at a rate of 1 centimetre each year. The largest sharks end up measuring over 16 feet long, while female sharks reach sexual maturity on their 150th birthday, the study found.
To find the sharks' ages, scientists measured the carbon levels in the lenses of their eyes, and looked for carbon-14 - which entered the ocean in the 1960s in the wake of nuclear bomb testing from the mid-1950s - to figure out which sharks were born before and after that time, a Science article explains.
Then, the researchers compared their radiocarbon dating findings with the sharks' estimated growth patterns, to determine how long the sharks born before the 1960s lived.
"We had our expectations that we were dealing with an unusual animal, but I think everyone doing this research was very surprised to learn the sharks were as old as they were," Julius Nielsen, the marine biologist from the University of Copenhagen who led the study, told the BBC.
Business Insider has contacted the Marine Biological Association for comment.