A fish thought extinct for millions of years keeps turning up alive off Africa

In December 1938, a museum curator in a South African port city sifted through a fishing trawler’s catch and pulled out a heavy, steel-blue fish more than a metre long, with thick, limb-like fins unlike anything she had seen. She could not identify it, but she sensed it mattered. It turned out to be a coelacanth, a creature science had known only from fossils and had assumed vanished from the oceans tens of millions of years ago. The discovery is still described as one of the most important natural-history finds of the twentieth century.

A fish known only from fossils

Coelacanths appear in the fossil record reaching back roughly 400 million years, then seem to disappear around 66 million years ago, at the same boundary that marks the end of the dinosaurs. For that reason, scientists had long treated them as an extinct branch of ancient fishes, familiar only from impressions in stone. As the Smithsonian’s Ocean portal explains, the fish belongs to a lineage of lobe-finned fishes whose fleshy, muscular fins are of special interest because they sit near the evolutionary origins of the four-limbed animals that eventually moved onto land.

The 1938 catch that upended the record

The curator was Marjorie Courtenay-Latimer of the East London Museum, who had asked local fishermen to set aside anything unusual from their nets. When a trawler working near the mouth of the Chalumna River brought in the strange blue fish, she preserved what she could and alerted a chemist and fish expert, J.L.B. Smith, who recognized it as a living coelacanth and gave the species the name Latimeria chalumnae in her honor. The find, recounted by Smithsonian magazine, overturned the assumption that the group had died out with the dinosaurs and set off a decades-long hunt for more specimens.

Living populations off Africa and beyond

It took years to locate where the fish actually lived. Later specimens were traced primarily to the deep waters around the Comoro Islands in the western Indian Ocean, off the East African coast, where coelacanths shelter by day in underwater caves along steep volcanic slopes and hunt at night. The fish typically live at depths of around 150 to 250 metres, in cool water far below where most diving or fishing reaches, which helped them stay hidden for so long. Then, in 1997 and 1998, biologists were astonished to find coelacanths thousands of kilometres away in Indonesia, near Sulawesi, which proved to represent a second, distinct species. The animals turn up in fishermen’s nets from time to time rather than being easily sought out, which is why each confirmed catch still draws scientific attention.

Why living fossil is only half right

The coelacanth is often called a living fossil, a phrase suggesting it has remained unchanged since prehistory, but biologists treat that label with caution. As the Natural History Museum in London points out, the modern coelacanth is not identical to its ancient relatives and has continued to evolve; it simply belongs to a very old and slow-changing lineage. Its biology is genuinely unusual: it can grow to around two metres, gives birth to live young after a long gestation, and has a distinctive hinged skull. Rather than a frozen relic, it is better understood as a rare survivor of a group that once thrived and now clings on in a few deep-sea refuges.

An enduring reminder that the record is incomplete

The coelacanth endures as a cautionary tale about declaring anything gone for good. A fish presumed extinct for tens of millions of years was living quietly in the deep the entire time, unnoticed until a trawler and an alert curator brought it to light. Both known species are now considered threatened, caught only accidentally and dependent on hard-to-study deep-water habitats. Their continued appearances off Africa and in Indonesia keep alive a simple, humbling lesson: the fossil record marks where evidence runs out, not necessarily where life does.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

More from Morning Overview