When we hear that someone has lived more than 100 years, it kind of blows our minds when we think about all of the things that they’ve lived through. But when we heard about a marine animal that may have been born before William Shakespeare, we were truly shocked. Could it even be true?
There is a mysterious creature living in the dark, frozen waters of the sub-Arctic ocean – a beast that goes by the name, Greenland Shark. This slow-moving animal is absolutely massive, and has managed to avoid humans at all costs, so there’s not much that we know about it. But, recent studies have shown that the Greenland shark just might be the oldest living vertebrae on Earth!
A team of researchers from the University of Copenhagen published a paper last year with the results of a study they conducted in which they tried to determine the age of 28 different female Greenland sharks. Julius Nielsen, the lead author, determined that the oldest of the group could quite possibly be more than 500 years old! If this is true, the Greenland shark would take the title as oldest animal in the world.
Previously, the record holder for the oldest animal alive was the Icelandic clam, also referred to as an ocean quahog. The clam, which also goes by the name Ming, was an incredible 507 years old. Unfortunately, while they were still studying it, Ming died. But Ming wasn’t the first species that was discovered to have lived more than a century.
The race for the longest-living animal seems to be led by the creatures living in the ocean. The Alaskan shortraker rockfish and the Namibian orange are both estimated to live up to roughly 200 years old, maybe even longer. Harriet, a Galapagos tortoise, lived to the incredibly old age of 170! They may be old, but the Greenland sharks definitely have them beat, but only if Nielsen was right about his estimations.
Verifying an animal’s age isn’t an easy task, especially one that has lived such a mysterious life. Researchers were alerted about their possible longevity by witnessing the Greenland shark’s growth rate. They are suspected to grow approximately one centimeter a year! Despite their slow growth rate, they’re one of the largest sharks on the planet, with lengths of up to 20 feet long! You may be surprised, but scientists think this is because of how cold their home is.
“In colder temperatures, growth slows and fish tend to get older,” reported Aaron Fisk, who has studied the Greenland sharks for 20 years. “It’s not hard to imagine that they could be 200 or 400 years old.” Nielsen and his team wanted to test this hypothesis, but they definitely had their work cut out for them.
Some species of fish, like the salmon and cod, have otoliths -tiny bone structures, which have seasonal growth rings, kind of like the rings you can see in tree trunks. These rings allow researchers to figure out the fish’s age. But, unlike the salmon, the Greenland sharks don’t have otoliths, or hardly any calcified material, at all! So, there are no layers for scientists to count. The scientists then turned to a more complicated technique, found in an organ, to determine their age.
All vertebrates have an eye lens that continues to grow throughout their entire life, but the core of the lens is formed before the animal is even born. The core contains a chemical signature from the environment the animal was in during its birth. Scientists use a technique called eye lens radiocarbon to help verify the age.
The first step they needed to take was trying to figure out if the animal was born prior to “the bomb pulse” – a series of thermonuclear weapons tests that occurred in the late 1950s that led to a huge spike in the amount of radiocarbon the atmosphere. Doing this showed the researchers that three of the sharks tested were born after 1960, but they never could’ve imagined how old the rest really were.
Nielsen’s team then took the radiocarbon levels in the 25 sharks and compared them to a chronology of radiocarbon fluctuations that went back 50,000 years. They also assumed that the older the shark was, the longer it was, too. Using these calculations, they found the longest shark – a whopping 16 feet – was around 272 and 512 years old. Not all scientists agree with their conclusions.
Other marine biologists don’t believe that the size of the shark can determine how old it is. A specialist in verifying the age of marine animals, Allen Andrews, has said that previous studies have shown that the largest fish isn’t necessarily the oldest. Nielsen understands the scientist’s concern, but he still stands by the research his team has conducted.
“At the end of the day, we completely agree it is possible that Greenland sharks of the same size can be different ages,” said Nielsen. Since the sharks that were without a doubt younger than 50 years old were also the smallest, he believes their method is working. Also, the information they provided was only an estimation, not a definite answer. Due to those facts, other researchers tend to agree with Nielsen.
“I wouldn’t want to put a date on it, but I think 400 or 500 years is in the realm of possibility,” said Fisk, the Greenland shark expert. “And that’s pretty extraordinary.” What’s more important than their unbelievable longevity, is the findings that Nielsen’s team found about how vulnerable the species truly is.
Since Greenland sharks live for such an incredibly long time, that means they don’t reproduce as often as species with shorter lifespans. So, if humans began exploiting them, their populations wouldn’t bounce back as quickly as other species. And it would be naive to think that there isn’t any commercial interest in the Greenland shark.
In the flesh of the Greenland shark is a high concentration of a chemical, that when eaten is metabolized to produce a similar effect that one feels when extremely drunk. Due to its effects, this shark meat is considered a delicacy in Iceland. Let’s just hope that people don’t start going crazy for their meat, and the Greenland sharks can continue to live their lives in peace, like they’ve done since the dinosaurs roamed the Earth.