12th August 2016
New record for longest-lived vertebrate
New research has found that the Greenland shark (Somniosus microcephalus) is the longest-lived vertebrate ever known, able to reach a lifespan of nearly 400 years.
Greenland sharks can live as long as 400 years, and reach sexual maturity at the age of about 150, according to a new study published today in the peer-reviewed journal Science. This makes these animals the longest-lived vertebrates on Earth.
The Greenland shark (Somniosus microcephalus) is widely distributed across the North Atlantic, with adults reaching lengths of four to five metres (13 to 16 feet). The biology of the Greenland shark is poorly understood, yet their extremely slow growth rates, at about 1 cm per year, hint that these fish benefit from exceptional longevity.
Traditional methods for determining the age of a species involve analysing calcified tissue, a feature that is sparse in Greenland sharks. To determine the average age of this species, Julius Nielsen et al. therefore applied radiocarbon dating techniques to the eye lenses of 28 females, caught as by-catch. Their analysis suggests an average lifespan of at least 272 years. The two largest sharks in this study, at 493 cm and 502 cm in length, were estimated to be 335 and 392 years old, respectively.
Furthermore, since previous reports suggest that females of this species reach sexual maturity at lengths greater than 400 cm, the corresponding age would be at least 156 years old, the authors say. Based on these results, the Greenland shark is now the oldest-known vertebrate to roam the Earth. The previous record holders were tortoises, which often live for 150+ years, with one specimen in March 2006 dying at the age of 250.
The biology of Greenland sharks may provide clues that help to extend human longevity. In 2015, scientists mapped the genome of the bowhead whale in the hope of understanding the cause of its 200-year lifespan.
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