Greenland shark (Dreamy microcephalus) is the oldest animal to inhabit Earth, according to a new study published in the journal Science. At approximately 390 years old, the animal that lives in the deep waters of the Arctic had the outer layer of the eyes analyzed for age dating.
The leader of the study, Julius Nielsen, a biologist at the University of Copenhagen, concluded that specimens of the species live between 272 and 512 years of age – the most likely is an average life expectancy of 390 years.
“We had the expectation that they would be very long-lived animals, but I was surprised that they turned out to be so old”, explains the biologist.
To arrive at the number, Nielsen did an experiment with 28 female sharks, which had been accidentally killed during the Greenland Institute of Natural Resources’ commercial fish monitoring program.
In other bony fish, it would only be necessary to analyze the otoliths, located in the labyrinth of the inner ear of fish, which are like “stones in the ear”. These crystals formed by calcium carbonate are not present in sharks, which have cartilage instead of the compound.
Together with his team, the biologist analyzed the radiocarbon of the animal’s ocular structure, which has a lens that grows throughout its life. As the creature ages, a new layer of lens makes up the shark’s eye.
It is not possible to count the lenses, as with the rings on tree trunks, but the experts managed to remove all the lenses to reach the embryonic nucleus, that is, the center of the lens, which has existed since the shark was young.
Based on the analysis of the chemical composition of this tissue, the biologist was able to estimate the age of the animal. The study, published Aug. 11, showed that analysis of the 28 sharks concluded that they were all at least 272 years old.
“The secret of the success of this study consisted in the fact that we had young and old animals, medium and large animals, and the possibility of comparing them all”, points out Nielsen.
Other research on the species shows that they are animals that grow quite slowly, about 1 centimeter per year.
Deep waters
The Greenland shark lives in a rather remote habitat in deep water and because of the very cold environments, it is believed that the body temperature is also reduced. This combination leaves the metabolism slow, which generates less damage to the tissues of the animals.
The result of the study promotes a new care for the species — the biologist explains that if a species is rare and has such a long life, any death is quite significant.
Despite being at the bottom of the sea, the Greenland shark does not run away from fishermen who can capture them by accident, the so-called bycatch. The habitat of this species can also be affected by intense climate change and human activities such as fishing and oil extraction in Arctic countries.
In addition, it was understood that the females of the species reach sexual maturity only at 156 years of age, which makes the population of this shark even more vulnerable due to the delay in reproduction.
“Longevity is remarkable, but I hope the public recognizes the importance of this fact when it comes to the management and conservation of ecosystems. If Greenland sharks live that long and don’t reproduce until they are 150 years old, their population is vulnerable to exploitation,” says Aaron Fisk, an ecologist at the University of Windsor who was not involved in the study and was interviewed by National Geographic. .
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