It might be inconceivable to think about how we share the same Earth with other living beings who have been here way before us or even our ancestors. And they will continue to live even after you have gone. Other than trees, there are also deep-sea creatures like jellyfish who have lived for what could be considered as “forever.” Even though this sea creature is not as old as the almost immortal jellyfish, she is still several centuries years old. And she is a Greenland shark. According to scientists this species of sharks is considered to be the longest-living vertebrates known on Earth.
When researchers set off to determine the ages of 28 Greenland sharks, it was estimated that one female was about 400 years old, reported the BBC. They utilized the method of radiocarbon dating to determine the age, which was otherwise considered to be very difficult to do. The researchers who published their findings in Science Magazine stated that they used the pulse of carbon-14 produced by nuclear tests in the 1950s for this purpose. Specifically, studying the carbon dating that incorporated into the eye during development was used to determine the age of the Greenland sharks.
Lead author Julius Nielsen, a marine biologist from the University of Copenhagen, said, “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.” This species is large yet but grows very slowly. They were able to conclude that this species of sharks reach maturity only at about 150 years of age. They also found that the life span of a Greenland shark could be at least 272 years. Since these Arctic Sea creatures grow very slowly and reach about 500 cm in total length, it could mean that their life span is well beyond those of other vertebrates.
“The Greenland shark’s eye lens is composed of a specialized material – and it contains proteins that are metabolically inert,” explained Neilson. “Which means after the proteins have been synthesized in the body, they are not renewed any more. So we can isolate the tissue that formed when the shark was a pup, and do radiocarbon dating.” This was the procedure that helped determine the age of these particular sharks. Determining the ages of some fish can be easily done by analyzing their otoliths, or ear stones. just like one would count the rings of a tree. But for sharks, which are made mostly of cartilage, calcified tissue may be hard to come by, reported National Geographic.
“The secret behind the success of this study is that we had young and old animals, medium-sized and large animals, and we could compare them all,” Nielsen stated. Greenland sharks have a unique eye structure in that the lens grows throughout an animal’s lifetime. The older an animal gets, the more layers are added to the lens. But unlike counting the tree rings, scientists remove all the layers that have been added over the years until they reach the center, or the embryonic nucleus, of the lens instead. The largest shark in their study was five meters in length. She was estimated to be approximately 392 years old but this could not be definitely determined.
So according to Nielsen, she could be aged anywhere between 272 and 512 years old, and it was most likely around 390. “It kicks off the bowhead whale as the oldest vertebrate animal,” he stated.