Time travel: Scientists discover 400-year-old Greenland shark born in the 17th century.s
Residing in the deep, cold waters of the North Atlantic, the Greenland shark can live a minimum of 272 years and potentially reach a staggering… 500 years. The Greenland shark is the “oldest” vertebrate on this planet, according to a recent study published in National Geographic.
Leading the research, biologist Julius Nielsen from the University of Copenhagen (Denmark) stated, “From the start, we suspected that they were long-lived creatures, but we never imagined they would live this long.” One reason that surprised scientists is that Greenland sharks live in remote areas, limiting human knowledge about them, including their lifespan.
Previous studies hypothesized that this shark species develops extremely slowly, growing less than 1 cm per year. The slow growth rate is believed to contribute to their longer lifespan compared to other vertebrates, according to scientists’ reasoning.
Typically, determining the age of a bony fish is not a challenging task – analyzing their ear stones is sufficient. However, sharks have a predominantly cartilaginous structure without the hard tissue, including the mentioned ear stones. Consequently, scientists found an alternative method to determine the age of Greenland sharks: looking into their eyes!
Throughout the Greenland Institute of Natural Resources’ commercial fish monitoring program, researchers analyzed 28 female sharks that had previously died. “The secret behind the success of this study is that we had the opportunity to examine both young and old sharks, as well as medium-sized and large ones. This allowed us to compare the data,” shared Mr. Nielsen.
The eyes of Greenland sharks have a unique structure, with crystalline lenses developing throughout their lives. As the sharks age, more layers form in the lenses. Scientists can separate each layer until they reach the core (nucleus) of the lens, which includes proteins formed when the shark was just a pup. The chemical composition of the lens nucleus is then analyzed to estimate the shark’s age.
According to the research published in the journal Science in August last year, the radiocarbon levels in the lens nuclei of the aforementioned 28 Greenland sharks indicated a minimum lifespan of 272 years.
The exact reasons behind the remarkable longevity of Greenland sharks are not yet fully understood, but the frigid environmental conditions in which they reside may play a part. The icy environment lowers their body temperature, consequently slowing down their metabolic processes – meaning less damage to their tissues. Moreover, female Greenland sharks are believed to reach sexual maturity when their bodies reach over 4 meters in length, which occurs at the age of… 156.
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