|
WASHINGTON, Aug. 11 (Xinhua) -- With a life expectancy of at least 272 years, the Greenland shark could be the longest-lived vertebrate on Earth, a new study said Thursday.
The Greenland shark is an iconic species of the Arctic Seas, with adults reaching four to five meters in total length, but their extremely slow growth rates, at about one centimeter per year, hint that their longevity is likely to be exceptional, according to the study published in the U.S. journal Science.
To determine the average age of this species, an international team of researchers applied radiocarbon dating techniques to the eye lenses of 28 females caught as by-catch between 2010 and 2013.
Their analysis calculated an age of 392 years for their largest specimen, a 502-centimeter behemoth, with an uncertainty of plus or minus 120 years.
This means that the animal has a life span of at least 272 years and at most 512 years.
"Our results demonstrate that the Greenland shark is among the longest-lived vertebrate species, surpassing even the bowhead whale (Balaena mysticetus, estimated longevity of 211 years)," said the study led by PhD student Julius Nielsen of the University of Copenhagen.
"The life expectancy of the Greenland shark is exceeded only by that of the ocean quahog (Arctica islandica, 507 years)."
Jack Musick, a Virginia Institute of Marine Science professor and shark expert who was not involved in the current study, said in a statement that he was not surprised by the team's results.
"Four hundred is extreme, but believable," Musick said, "because the species lives in such cold water, has an extremely slow metabolism, and reaches such an enormous size."
