Introducing the elusive ‘Christmas fish’- living fossil
Tuesday 24th December 2013
Few animal discoveries of the 20th century created as much of a stir as the coelacanth – a creature which sheds light on how fish made the transition onto land, says PENNY HAWORTH
Much like the dinosaurs of Jurassic Park, the coelacanth captured the imagination of people across the world.
It has been given all manner of nicknames – “living fossil,” “fossil fish,” “dinofish,” “the fish that time forgot,” “the Christmas fish,” “the £100-reward fish” and “Old Fourlegs.”
Seventy-five years ago, on December 22 1938, Marjorie Courtenay-Latimer, the curator of the East London Museum in Eastern Cape, South Africa, was at the harbour to see if there were any specimens of interest in the trawl nets.
Her friend Hendrik Goosen, skipper of the fishing boat Nerine, had set aside some fish from his catch for her.
Most of them were sharks that she was already familiar with – but a strange shape lying beneath the other fish attracted her attention.
It was an unusual blue colour, but all the more strange was the shape of its fins – they didn’t resemble anything she had seen before.
Wrapping the fish in a sack, Courtenay-Latimer needed to get it back to the museum and from there into storage.
The best way to preserve the fish until an expert could look at it would be to freeze it, but this was not possible – neither the hospital nor a nearby butchery, the only places in East London with fridges large enough to hold it, were prepared to store the large, smelly creature.
Not having sufficient formalin to preserve the specimen intact, Courtenay-Latimer had no choice but to have the organs removed and the animal stuffed.
She made a sketch and, together with a short description, sent it to Professor JLB Smith, a fish specialist at Rhodes University in Grahamstown.
On holiday in Knysna in the Western Cape province, Smith found the letter among his Christmas mail.
He described his reaction when he saw the sketch – “a bomb seemed to burst in my brain.”
Smith immediately recognised the fish in the sketch. But at the same time could hardly believe that this could be true.
However, the strange, fleshy fins were indeed typical of coelacanths, a group of fish that – according to scientific knowledge at the time – had died out millions of years previously.
It was a full two months before Smith finally got to East London to see the specimen.
“The first sight hit like a white hot blast!”
After having seen the stuffed fish for himself, he could confirm that it was indeed a coelacanth.
In naming the fish for science, he called it Latimeria chalumnae to pay tribute to Courtenay-Latimer for pursuing her hunch and to note that the fish had been found off the Chalumna river near East London.
Scientists had been studying coelacanths since 1839, but only through the fossil remains.
The first person to describe a fossil fish was a Swiss naturalist called Louis Agassiz.
He had named a fossil fish found in Durham, northern England, Coelacanthus granulatus.
The genus name “Coelacanthus” comes from two Greek words meaning “hollow” and “spine,” referring to the hollow spines of the vertebrae that connect to the bones which support the tail fin rays. “Granulatus” describes the rough texture of the fish’s spiny scales.
During the century that followed scientists found fossils of many species of coelacanth.
The earliest coelacanth species first appeared about 400 million years ago – the most recent appeared to have lived about 70m years ago and that was where, to all intents and purposes, it seemed that the record ended – coelacanths seemed to have completely disappeared.
Smith wrote an article for the well-known science journal Nature in which he described Latimeria chalumnae.
Popular and scientific interest in the find was fuelled by intense media coverage of the discovery.
For Smith, however, the more he studied the specimen, the more questions cropped up – he knew he needed another specimen to find the answers.
However, it was to take another 14 years before a second coelacanth was found.
In his determination to find more evidence of the existence of coelacanths, Smith posted a reward of £100 in three languages – English, Portuguese and French – for the first two specimens found.
A trader called Captain Eric Hunt distributed leaflets throughout the Comores archipelago in the Indian Ocean on Smith’s behalf.
Fishermen in the Comores had seen coelacanths in their catches from time to time and called it “gombessa,” but the flesh was oily and no good to eat, so they didn’t value it and usually threw the remains back into the ocean.
On December 20 Hunt was notified that a local fisherman had captured a coelacanth in the Comores.
On December 23 1952 Smith received a telegram from Hunt – HAVE FIVE FEET SPECIMEN COELACANTH TREATED FORMALIN HERE KILLED TWENTIETH ADVISE OR SEND PLANE REPLY HUNT DZAOUDZI COMORES.
Smith realised that he had no way to bring the fish to South Africa and made a desperate plea to the then prime minister Dr DF Malan, who agreed that an air force Dakota aeroplane be made available.
Smith later told the story of the rediscovery of the coelacanth in his famous book, Old Fourlegs.
What did the fossil record tell scientists?
Although fossils of Latimeria chalumnae have not been found, the species has not evolved far from the coelacanths that existed millions of years ago. In many ways this makes it a “living fossil” able to shed light on the much earlier stages in the evolutionary record.
Before the discovery of live coelacanths, no-one knew how they swam, whether they lived in groups, how they hunted or, as Smith had theorised, whether they used their lobed fins to “walk” on the seabed?
Scientists needed to see the animals, alive in their natural habitat. No fossil could provide this kind of evidence.
Now, with new technology available, for the first time scientists have been able to study these remarkable creatures close up.
We’ve come a long way since Marjorie Courtenay-Latimer’s first sighting of a strange blue fish.
This article is reproduced with kind permission of Penny Haworth. She is the manager of communications and governance at the South African Institute for Aquatic Biodiversity in Grahamstown.