Cape town – The coelacanth, a wondrous fish that was thought to have become extinct with the dinosaurs 66 million years ago before it was unexpectedly found alive and well in 1938 off the east coast of South Africa, still surprises scientists with more surprises.
Scientists said that a new study of these fish, which live in the great depths of the sea and are active at night and are closely related to their incubating environment, live five times longer than previously thought – that is, they live for nearly a century – and that females carry their young for five years, which is the longest known pregnancy period. for any animal.
Harold Walker of the Scripps Institution of Oceanography, who was not part of the research, said the five-year gestation period is “quite strange” for fish or any animal.
After focusing on two living species of coelacanth, scientists concluded that they develop and grow at a slower rate than any other fish, and females of them do not reach sexual maturity until about 55 years of age, while males sexually mature between 40 and 69 years, a feature that exposes these fish to danger. Hunt before you can reproduce and perpetuate the species.
Females are somewhat larger than males, reaching about seven feet (two meters) in length and weighing 240 pounds (110 kg).
Coelacanths are so endangered that scientists can only study specimens that have already been caught and dead.
The researchers used annual growth rings on fish scales to determine the age of the coelacanth, said marine biologist Kélég Mahé of the French Oceanographic Institution, lead author of the study published this week in the journal Current Biology.
Coelacanths, a type of “prehistoric” fish, first appeared in the Devonian period about 400 million years ago, about 170 million years before the emergence of dinosaurs. Based on the fossil record, it is believed to have disappeared during the mass extinction that wiped out three-quarters of all living species following an asteroid impact at the end of the Cretaceous period.
When the coelacanth was found alive, it was called a “living fossil”, a description that scientists are now avoiding.
Study co-author Bruno Ernandi, a marine evolutionary ecologist at the French Marine Research Institute, noted that although coelacanths are not genetically related and show wide evolutionary differences, they age slowly like other sharks and rays.
“They may have developed similar life histories because they share the same type of habitat,” he added.
Slow-growing nocturnal coelacanths live in the ocean depths of up to half a mile (800 metres), and during daylight hours they reside in volcanic caves alone or in small groups.
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