![]() They also used new methods, including polarized light microscopy and scale interpretation technology mastered at IFREMER’s Sclerochronology Centre, Boulogne-sur-mer, France, to estimate individuals’ age and body growth more precisely than before. They were able to examine 27 specimens in all. In the new study, Mahé, along with co-authors Bruno Ernande and Marc Herbin, took advantage of the fact that the French National Museum of Natural History (Muséum National d’Histoire Naturelle de Paris, MNHN) has one of the largest collections of coelacanths in the world, ranging from embryos in utero to individuals of almost two meters. That seemed surprising considering that the coelacanth’s other known biological and ecological features, including slow metabolism and low fecundity, were more typical of fish with slow life histories and slow growth like most other deep-water species. If that were the case, it would make coelacanths among the fastest-growing fish given their large size. Those studies led to the notion that the fish didn’t live more than 20 years. Credit: MNHNĮarlier studies attempted to age coelacanths by directly observing growth rings on the scales of a small sample of 12 specimens. This image shows a coelacanth embryo with yolk sac from the MNHN collection. “Our new age estimation allowed us to re-appraise the coelacanth’s body growth, which happens to be one of the slowest among marine fish of similar size, as well as other life-history traits, showing that the coelacanth’s life history is actually one of the slowest of all fish.” “Our most important finding is that the coelacanth’s age was underestimated by a factor of five,” says Kélig Mahé of IFREMER Channel and North Sea Fisheries Research Unit in Boulogne-sur-mer, France. They also report that coelacanths live life extremely slowly in other ways, reaching maturity around the age of 55 and gestating their offspring for five years. The researchers found that their oldest specimen was 84 years old. Now, researchers reporting in the journal Current Biology on June 17 have evidence that, in addition to their impressive size, coelacanths also can live for an impressively long time - perhaps nearly a century. Once thought to be extinct, lobe-finned coelacanths are enormous fish that live deep in the ocean. Credit: Laurent Ballesta Coelacanths may live five times longer than researchers expected. This image shows adult coelacanth scales.
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