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Weighing in at 9 tons 20, pounds and typically growing to around 10 meters 32 feet long, the whale shark is the largest living species of fish. Despite the name, it is not a whale, though it is the size of one. Like many kinds of whales, it filter feeds on plankton. Many things about the whale shark have remained unknown to science; how long they can live, their mortality rate, and how exactly to determine the age of a specimen from its remains was chief among them. However, these questions are now a little closer to being settled. In a study recently published in Frontiers in Marine Science, scientists explain how they were able to date the bones of two whale sharks who met their fate earlier than they may have expected. Like trees, whale sharks' bones have growth rings.
Whale sharks Rhincodon typus are the largest living fish in the world, averaging about 32 feet 10 meters long and weighing tens of thousands of pounds each.
Despite their massive profiles and impressive ranges whale sharks inhabit all tropical waters on Earth and are thought to migrate enormous distances during mating seasonthe animals are endangered and have proven very hard to study in the wild. Scientists still don't know some very basic facts about whale sharks - for example, how they mate or how long they live.
Now, marine biologists are much closer to answering that second question thanks to an unusual biological clock - radioactive carbon left over from Cold War-era nukes. In a study published today April 6 in the journal Frontiers in Marine Scienceresearchers dated carbon - a naturally-occurring type of radioactive carbon that was released into the sky en masse during nuclear weapons tests in the s and s - embedded in the vertebrae of two whale sharks who died long ago in fishing nets in Taiwan and Pakistan.
Carbon dating sharks
Much like trees, whale shark vertebrae produce growth rings that increase in number throughout the shark's lifespan; however, until now, scientists had no idea how often those rings actually form, and so have been unable to use them to confirm a given shark's age.
Related: Attempted whale shark mating caught on camera for the first time in history.
Enter carbon a type of carbon that occurs naturally all over the world, but became extra-prevalent in the air and ocean after several industrialized nations conducted hundreds of atmospheric nuclear bomb tests last century.
Because carbon decays at a steady rate, the study authors were able to look at the subtle differences in the ratio of carbon to other isotopes, or forms, of carbon in each shark's vertebral growth rings, and therefore figure out exactly how much time had past between the formation of one ring and the next.
Aug 12, Radiocarbon dating of eye lens nuclei from 28 female Greenland sharks (81 to cm in total length) revealed a life span of at least years. Only the smallest sharks ( cm or less) showed signs of the radiocarbon bomb pulse, a time marker of the early countryconnectionsqatar.com by:
With this knowledge, Meekan and his colleagues were able to confirm the ages of the two dead sharks at 35 and 50 years old, respectively. Because neither of the two sharks died of old age, those numbers fit in with prior estimates that whale sharks can live incredibly long lives - likely upwards of years, according to one study of 44 live whale sharks.
Atomic bomb tests help scientists finally date sharks
Not long after the study was published, Heinemeier received a request from police in Germany. They needed his help cracking an unusual case.
Why Carbon Dating Might Be in Danger
Two, he found, had been born in the second half of the nineteen-eighties, the third between and The mother was ultimately sentenced to four years in prison. InHeinemeier received another request, this time from Steffensen, who had recently travelled to Greenland and confronted the longevity puzzle.
Heinemeier told him about his recent breakthrough in the murder case and suggested that Steffensen return to Greenland and bring back some lenses.
But there was a problem. Though sharks do possess crystallines in their eyes, acquiring enough samples for a rigorous study was an expensive and logistically tricky proposition; at first, Steffensen managed to get just two.
Nielsen and his collaborators published their results in August of last year.
Nov 25, Using carbon dating and a new method involving proteins in the lens of the eye, Danish scientists have unravelled the mystery of how long Greenland sharks live. Apr 07, This isn't the first time carbon dating has been used to calculate the age of sharks, but the application to whale sharks is seen as a big deal because the animals are endangered. Aug 12, The eyes have it - Radiocarbon dating finds a Greenland shark that could be years old Proteins in the lens of the eye have been around for countryconnectionsqatar.com: Shalini Saxena.
With the help of a mathematical model that linked size with age, they estimated that one sixteen-foot female was at least two hundred and seventy-two years old, and possibly as much as five hundred and twelve years old. Still, it firmly established Greenland sharks as the longest-living vertebrates on Earth. In theory, the biggest ones could be nearly six centuries old.
Because carbon decays at a steady rate, the study authors were able to look at the subtle differences in the ratio of carbon to other isotopes, or forms, of carbon in each shark's vertebral. One seemingly simple thing was resolved this week, as scientists finally put an age range on whale sharks by dating the slightly radioactive carbon isotope their bones collected after Cold War. Radiocarbon dating (also referred to as carbon dating or carbon dating) is a method for determining the age of an object containing organic material by using the properties of radiocarbon, a radioactive isotope of carbon. The method was developed in the late s at the University of Chicago by Willard Libby, who received the Nobel Prize in Chemistry for his work in
The question now is how the sharks do it. Increasingly, scientists are searching the natural world for the genetic and behavioral mechanisms that endow creatures with their special abilities-that make elephants virtually immune to cancer, say, or axolotls capable of regenerating a lost limb. There may be Greenland sharks alive today that were born before Christopher Columbus; the species is not even thought to reach sexual maturity until around a hundred and fifty years of age.
Inthe flash of the first-ever nuclear explosion illuminated the skies over the New Mexico desert. By Alex Wellerstei n.
By Ceridwen Dove y. By Carolyn Korman n.
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