This 512-Year-Old Shark Is Now The Oldest Vertebrate On The Planet.
Does Cold Water Preserve Them?
“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.
Not An Easy Task
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.
Looking Into Their Eyes
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.
Radiation In The Water
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.
Happy 512th Birthday!
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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.
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