If you think living to 100 years is old, think again. A Greenland shark at that age is still a youngster, according to research released on Thursday.
These remarkable fish live to at least 400 years, making them the longest-living vertebrates on planet Earth.
They pass out other marine and land oldsters, including bowhead whales, turtles and tortoises.
The Greenland shark does not even begin to have offspring until it reaches about 150 years.
They can grow to at least 5m in length, making them one of the largest carnivore sharks, but they grow exceedingly slowly, usually only 1cm per year, the researchers found.
"Greenland sharks are among the largest carnivorous sharks on the planet and their role as an apex predator in the Arctic ecosystem is totally overlooked," said doctoral student Julius Nielsen, of the University of Copenhagen.
“By the thousands, they accidentally end up as by-catch across the north Atlantic.”
He led the research with colleagues from the Greenland Institute of Natural Resources, the Arctic University of Norway, Aarhus University and the University of Oxford.
Scientific mystery
The Greenland shark has remained a bit of a scientific mystery for decades, as has the part they play in the food web of the north Atlantic.
The sharks are not uncommon and are found in the cold, deep waters of the north Atlantic, but the researchers admitted they knew very little about the creature’s biology and habits before the study.
They examined 28 female sharks caught as accidental by-catch and were able to determine their age in an unusual way – their eyes.
The centre of the shark’s eye is inactive tissue that changes very little over its lifetime.
This allowed the researchers to study the chemistry of the eye using radiocarbon dating facilities at Oxford.
