It’s a true “living fossil”: the fish that can live up to 100 years

The coelacanth is a mysterious, giant fish that can live up to 100 years. They were thought to be extinct, but they survived the age of the dinosaurs.

It's huge, survived the age of the dinosaurs and can live up to 100 years. It's the coelacanth, a species of fish thought to be extinct. A study published in Current Biology, has instead discovered that this type of animal reaches even a century of age. Very rare abyssal fish, it seems that for millions of years its morphology has never changed appearing, even today, very similar to its prehistoric ancestors and, for this reason, considered a "living fossil".

The study on the 100 years of the coelacanth

According to French scientists who carried out the study, female coelacanths do not reach sexual maturity until the end of 50 years, while males are sexually mature between 40 and 69 years. The researchers also hypothesized that pregnancy could last about five years. The species has been around for 400 million years and, for a long time, was considered extinct, until coelacanths were found alive off the coast of South Africa in 1938. These animals would also grow very slowly to the size of a human. Until now, it was believed they could live about 20 years, but new research has managed to pinpoint that their lifespan is far longer and can reach a century.

Applying a standard technique for dating commercial fish, scientists have calculated that coelacanths live nearly 100 years. In the past, their hypothetical age had been determined by counting broad lines on a specific type of coelacanth. Instead, the French researchers discovered that smaller lines also had to be calculated, which could only be seen using polarized light. Bruno Ernande, a marine evolutionary ecologist at the French Marine Research Institute and co-author of the study, explained that the polarized light revealed five smaller lines for each of the large ones. The scholars thus concluded that the smaller lines were best correlated with one year of age, which indicated that the oldest specimen they studied was 84 years old.

Analyzing two embryos, however, the team calculated that they were both five years old. Hence the hypothesis that the pregnancy of these fish lasts at least a lustre. Although coelacanths are not genetically similar to other creatures of the deep, such as sharks and rays, their aging would be just as slow. In fact, even sharks can live up to hundreds of years.

The marine fauna continues to offer interesting discoveries between super long-lived and ancient species and others with special and curious features such as mollusks with special teeth and elephant fish that talk to each other.

Stefania Bernardini