Coelacanths are among the most famous living fossils. They are believed to have undergone almost no changes over the past 400 million years, although not everyone agrees with this view: modern studies show that coelacanths have indeed evolved, meaning they have changed, and even quite rapidly. In any case, only two species of coelacanths from the very ancient order Coelacanthiformes have survived to this day.
Researchers from the French Institute of Marine Research and the National Center for Scientific Research in France report in the journal Current Biology that coelacanths are long-lived not only in terms of evolution but also individually, meaning they live a very long time by fish standards. Previously, the lifespan of coelacanths was estimated, but the results were surprisingly low — only about 20 years.
With the advent of new technologies and samples of scales, more accurate data has been obtained. The age of the fish is determined by special rings on the scales, the number of which increases with each year of life. Previously, some annual rings on coelacanth scales were simply overlooked. Now, for one of the coelacanths whose scales were studied, a total of 84 years was counted. And, as the authors of the study claim, this is not the limit — it can be confidently said that coelacanths live for about a hundred years.
Coelacanths are ovoviviparous: they mature in eggs that the mother carries in her body — this “intrauterine” development lasts for five years; they reach maturity at 55 years.
Among fish, there are also long-lived species in the family Latimeriidae and among sharks. By the way, it is sharks that hold the record for longevity among fish: a few years ago, an article was published in the journal Science stating that Greenland sharks can live up to 500 years.
