We humans have an unnerving tendency to rashly believe that we are at the pinnacle of all natural things. We also like to believe that we're a long-lived species, but the truth of the matter is, there are tubeworms out there that live longer than us. Now scientists believe they may have found the longest-living vertebrate on Earth: Greenland sharks which could live to be as ancient as 512 years old.
In a study published in Science, an international team of researchers detail how they developed a technique to determine the age of these sharks (also known as gurry sharks, or grey sharks), who live in the cold waters of the North Atlantic and Arctic Ocean. Surprisingly, scientists haven't had a reliable way to find out how old these creatures were, until recently.
Small Greenland sharks are rare for me to encounter. Today we caught the smallest shark on long line in the #greenlandsharkproject measuring only 1.6 m and after samples for genetics were taken it was released with an identification tag 🦈✌🏻 #greenlandshark #northernorway #science #sharkscience #norway #arctic #marinebiology #shark #extrmemfishing #deepsea #andørja #marinescience #biology #ocean
That's because Greenland sharks (Somniosus microcephalus) -- which can grow up to 24 feet (7 meters) long -- are considered "soft sharks," and have none of the biological markers that scientists might use to find out the age in other shark species, such as calcified vertebrae.
Instead, the team used radiocarbon dating to measure carbon isotopes absorbed by the eye tissue of a group of 28 Greenland sharks, in addition to making estimates based on their size. Greenland sharks are a slow-growing species, increasing in size by 1 centimetre (0.39 inches) a year. So with the largest shark of the study group, measuring 5.4 metres (18 feet) long, the team estimates that it could be anywhere between 272 and 512 years old -- with an error margin of about 120 years. Says Julius Nielsen, a marine biologist and Ph.D. student who was part of the research team:
It's important to keep in mind there's some uncertainty with this estimate. But even the lowest part of the age range—at least 272 years—still makes Greenland sharks the longest-living vertebrate known to science.
It's not totally clear why Greenland sharks live for so long. Other scientists postulate that it may be in their genes, or it could be the fact that they live in relatively cold temperatures and have a slow metabolism. While we might not know yet why these mysterious marine creatures are blessed with such long lives, these scientists are hoping that its newfound fame as one of Earth's longest-living vertebrates will boost conservation efforts to protect it and its habitat. More over at International Business Times and Science.