Two days before Christmas in 1938, a young museum curator in the small South African port of East London went down to the docks, as she often did, to look over the local trawler's catch for anything unusual. Marjorie Courtenay-Latimer noticed a blue fin poking out from beneath a pile of sharks and rays. When she pulled the fish free she saw something she did not recognise and could not forget: a heavy, steel-blue creature nearly two metres long, with strange limb-like fins and thick armoured scales. She had, without knowing it, just found a living fossil that science had confidently declared extinct for tens of millions of years.
A fish out of deep time
The fish was a coelacanth, and its significance is hard to overstate. Coelacanths were known only from fossils — an ancient lineage that appeared in the fossil record hundreds of millions of years ago and then seemed to vanish from it entirely around the time of the great extinction that killed the dinosaurs, roughly sixty-six million years ago. As far as science was concerned, coelacanths had died out with the ammonites and the great reptiles. To find one alive was, in the words often used since, like discovering a living dinosaur.
Courtenay-Latimer, unable to identify her prize and unable to preserve the whole animal in the summer heat, saved what she could and wrote to the one person she thought might help: a chemistry lecturer and amateur ichthyologist named J.L.B. Smith. By the time Smith saw the specimen much of it had spoiled, but he recognised it instantly and was, by his own account, thunderstruck. In 1939 he formally described the species and, in a gracious tribute, named it Latimeria chalumnae after its discoverer and the Chalumna River near where it was caught.
One problem gnawed at Smith: he had a single specimen, largely gutted, and no idea where such fish actually lived. He spent years searching, distributing reward posters across the western Indian Ocean, before a second coelacanth was finally caught in 1952 near the Comoro Islands, between Mozambique and Madagascar. The Comoros, it turned out, were the population's stronghold, and the fish was well known to local fishermen there, who occasionally hauled them up from deep water and regarded them as barely worth eating.
Not our ancestor, but our cousin
The coelacanth is often loosely called "the missing link" or the ancestor of land animals, and that overstates it in a way quizzes like to catch out. Coelacanths belong to the lobe-finned fishes, a group whose fleshy, limb-like fins sit on bony stalks quite unlike the thin rayed fins of most fish. It was from lobe-finned ancestors that the first four-legged land vertebrates — and thus all amphibians, reptiles, birds and mammals, including us — eventually evolved. So the coelacanth is a close cousin of our distant fishy forebears, a surviving branch of that ancient group, but it is not itself our direct ancestor. It has been quietly evolving on its own line all this time.
And it is a genuinely strange animal. Coelacanths live in deep, dark water, often sheltering in caves by day; they can grow to around two metres and live for many decades. They move their paired fins in an alternating pattern reminiscent of a four-legged walk, and they possess an odd hinge in the skull found in no other living creature. Then, in 1997, came a second surprise: a marine biologist honeymooning in Indonesia, Mark Erdmann, spotted a coelacanth in a local market, thousands of kilometres from the Comoros. It proved to be a distinct second species, Latimeria menadoensis, brownish rather than blue — a second living fossil found, once again, by sheer chance in a fish market.
The coelacanth's story is a standing rebuke to scientific overconfidence. We had written this creature off completely, filed it firmly under "extinct, sixty-six million years," and it was swimming in the Indian Ocean the whole time, familiar to fishermen who had no idea it was supposed to be a miracle. It took a curious young woman on a dockside, refusing to ignore an odd blue fin, to bring it back from the dead — a reminder that the ocean is deep, our knowledge shallow, and the word "extinct" should always be spoken with a little humility. Biologists now use the term "Lazarus taxon" for a species that vanishes from the fossil record only to turn up alive, and the coelacanth is its patron saint.
Quiz nuggets
- The living coelacanth was discovered in 1938 by museum curator Marjorie Courtenay-Latimer in East London, South Africa.
- Coelacanths were thought extinct for about 66 million years, known only from fossils until that catch.
- Ichthyologist J.L.B. Smith identified and named the species Latimeria chalumnae in 1939, after Courtenay-Latimer.
- A second population was found near the Comoro Islands in 1952; a distinct second species, Latimeria menadoensis, was found in Indonesia in 1997.
- Coelacanths are lobe-finned fish, close relatives of the ancestors of land vertebrates — but not our direct ancestors.