At more than 16 feet long, the Greenland shark is one of the world’s largest sharks. It is also one of the least understood.
Now, scientists have discovered that with a life expectancy of at least 272 years, it also has the longest life expectancy of all vertebrate animals known to science.
More than 50 years ago, scientists reported that Greenland sharks only grow a few centimeters over several years. Since then, researchers could only speculate about the shark’s lifespan. But now, using carbon-14 dating, scientists have discovered the answer in the shark’s eye lenses. Their findings appear in the journal Science.
“Our lifespan study is based on the carbon-14 dating of Greenland shark eye lenses,” says Julius Nielsen, a PhD student of biology at the University of Copenhagen.
“As with other vertebrates, the lenses consist of a unique type of metabolically inactive tissue. Because the center of the lens does not change from the time of a shark’s birth, it allows the tissue’s chemical composition to reveal a shark’s age. We use well-established radiocarbon methods, but combine them in a new way.”
Eye lenses have previously been used to discover the age of whales, but it is the first time that the carbon-14 dating of eye lenses has been used to estimate the life expectancy of fish.
The study also marks an important milestone for the establishment of sustainable management plans for Greenland sharks, Nielsen says.
“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. By the thousands, they accidentally end up as by-catch across the North Atlantic and I hope that our studies can help to bring a greater focus on the Greenland shark in the future.”
Researchers at Aarhus University conducted the carbon-14 analyses. Additional researchers from the University of Copenhagen, Greenland Institute of Natural Resources, Arctic University of Norway, Oxford University, Indiana University, and the Virginia Institute of Marine Science are coauthors of the study.
Source: University of Copenhagen