A new record of life expectancy

The Greenland shark turned out to be the main centenarian among vertebrates

Kristina Ulasovich, N+1

An international team of researchers conducted a radiocarbon analysis of the lens of the eye of several Greenland polar sharks and found out that their average life expectancy is about 300 years, while scientists estimated the age of the oldest individual at almost four centuries. Thus, Greenland sharks turned out to be the longest-lived vertebrates. The study is published in the journal Science: Nielsen et al., Eye lens radiocarbon reveals centuries of longevity in the Greenland shark (Somniosus microcephalus).

Greenland polar sharks are widely distributed in the north Atlantic Ocean and are found both at the surface and at a depth of more than two thousand meters. The average body length of an adult individual, as a rule, reaches four to five meters, and the weight can reach up to 400 kilograms, which makes it the largest fish in Arctic waters. Due to the inaccessibility of their habitat, these animals have been little studied, but their slow annual growth (from 0.5 to 1 centimeter in length) suggested that they live exceptionally long.

To determine the life expectancy of Greenland polar sharks, the researchers conducted a radiocarbon analysis of the nucleus of the lens of the eye of 28 female individuals. The fact is that the nucleus of the lens grows throughout the life of the animal, and the older the individual, the more layers of crystalline fibers the nucleus of its lens has. By removing these layers, scientists can get to the embryonic nucleus of the lens, which is formed in a shark before birth, and determine the age of the fish by the content of the carbon-14 isotope in it.

The analysis of scientists showed that the average life expectancy of Greenland polar sharks reaches at least 272 years, which makes them long-lived record holders among vertebrates. The researchers estimated the age of the largest shark (502 centimeters long) at 392 ± 120 years, and individuals whose size was less than 300 centimeters were younger than a hundred years. The authors also claim that sexual maturity in Greenland polar sharks occurs at the age of about 150 years.

Thus, in terms of life expectancy, sharks were second only to the mollusks of Arctica islandica, which live up to 507 years, and became the first among vertebrates, overtaking the previous record holder – the bowhead whale, some individuals of which live up to 211 years. Scientists cannot explain why Greenland polar sharks live so long, but they assume that this is due to the low water temperatures in their habitats and, as a result, the slow metabolism of sharks.

Portal "Eternal youth" http://vechnayamolodost.ru  25.08.2016