Nature holds great many secrets, which we make use of and it can lead us for greater understanding of our place in the scheme of things. Growth rings of trees help us reconstruct climate conditions of a bygone age; marine animals like nautilus are marked similarly and shall we say we are custodians of time? So much so we can say with the Preacher emphatically: Yes He has set eternity in our hearts! (Eccl.3:11). Our heatbeats are one way of counting it in terms of eternity. Who but a fool shall assume such a service that Nature does is to enable some fill their coffers with silver by exploiting the natural resources, and in the process make the world far less fortunate for future?
In our uniqueness we carry our condemnation that we neglected while we have had time to improve the lot of those who merited our support. Conservation is one way we point our kinship with our Maker.
Researchers used radiocarbon dating to determine the ages of 28 of the sharks, and estimated that one female was about 400 years old. The results are published in the journal Science (science.sciencemag.org).
Lead author Julius Nielsen, a marine biologist from the University of Copenhagen, said: “We had our expectations that we were dealing with an unusual animal, but I think everyone doing this research was very surprised to learn the sharks were as old as they were.”
The team found that the sharks grow at just 1cm a year, and reach sexual maturity at about the age of 150. Greenland sharks are huge beasts, that can grow up to 5m in length.
For some fish, scientists are able to examine ear bones called otoliths, which when sectioned, show a pattern of concentric rings that scientists can count as they would the rings in a tree.
Sharks are harder, but some species, such as the Great White, have calcified tissue that grows in layers on their back bones, that can also be used to age the animals.
“But the Greenland shark is a very, very soft shark – it has no hard body parts where growth layers are deposited. So it was believed that the age could not be investigated,” Mr Nielsen told the BBC
However the team found a clever way of working out the age.
“The Greenland shark’s eye lens is composed of a specialised material – and it contains proteins that are metabolically inert,” explained Mr Neilson.
“Which means after the proteins have been synthesised in the body, they are not renewed any more. So we can isolate the tissue that formed when the shark was a pup, and do radiocarbon dating.”
The team looked at 28 sharks, most of which had died after being caught in fishing nets as by-catch.
Using this technique, they established that the largest shark – a 5m-long female – was extremely ancient.
Because radiocarbon dating does not produce exact dates, they believe that she could have been as “young” as 272 or as old as 512. But she was most likely somewhere in the middle, so about 400 years old.
It means she was born between the years of 1501 and 1744, but her most likely date of birth was in the 17th century.
“Even with the lowest part of this uncertainty, 272 years, even if that is the maximum age, it should still be considered the longest-living vertebrate,” said Mr Nielsen.
The former vertebrate record-holder was a bowhead whale estimated to be 211 years old.
But if invertebrates are brought into the longevity competition, a 507-year-old clam called Ming holds the title of most aged animal.( ack: By Rebecca Morelle
Science Correspondent, BBC News/Aug.11, 2016)