The coelacanth Latimeria chalumnae
The museum is fortunate to have in its collections a full size replica of what is arguably the most famous fish in the world, the coelacanth Latimeria chalumnae. The cast was made by Stephen Caine from a recently dead specimen.
Cast of a coelacanth.
Photograph: Martyn L Gorman
The class Osteichthyes (bony fish) is divided into two subclasses: ray-finned (Actinopterygii) and lobe-finned (Sarcopterygii). There are only four living genera of lobe-finned fish, but the group is known from fossils that date back to the very beginning of the class, 400 million years ago in the Devonian period.
The paired fins of the lobe-finned fish are thought to have given rise to the limbs of the land living animals. The living lobe-finned fish include 3 genera of lung-fish, one of each in Australia, Africa and South America. The remaining genus contains just two living species, the coelacanths. Only discovered in 1938, coelacanths represent a group of fishes that had been thought to have been extinct for at least 70 million years.
The original coelacanth was caught a few days before Christmas in 1938, at the mouth of the Chalumna River on the east coast of South Africa. The fish was caught in a shark gill net by Captain Goosen and his crew, who had no idea of the significance of their find. They thought the fish was bizarre enough to alert the local museum in the small South African town of East London.
The Director of the East London Museum at the time was Miss Marjorie Courtney-Latimer. She alerted the prominent south African ichthyologist Dr J.L.B. Smith to this amazing discovery. The Coelacanth was eventually named (scientific name: Latimeria chalumnae) in honour of Miss Courtney-Latimer.
Marjorie Courtney-Latimer's quick sketch of the mystery fish
This coelacanth specimen led to the discovery of the first documented population, off the Comoros Islands, between Africa and Madagascar. For sixty years this was presumed to be the only Coelacanth population in existence.
Marjorie Courtney-Latimer in 2000, aged 93
Photograph: South African Sunday Times
The Sulawesi Coelacanth
On July 30 1998, a coelacanth was caught in a deep-water shark net by local fishers off the volcanic island of Manado Tua in northern Sulawesi, Indonesia. This is about 10 000 km east of the Western Indian Ocean Coelacanth population. The fisher brought the fish to the house of American biologist Mark Erdmann who along with his wife Arnaz had seen a specimen in the outdoor markets the previous September. The local people were familiar with the coelacanth and called it raja laut or 'king of the sea'.
When the coelacanth from Sulawesi was first documented, the only obvious difference between it and the Coelacanth from the Comoros Islands was the colour. The Comoros Coelacanth is renowned for its steel blue colour, whereas fish from the Sulawesi population were reported to be brown. In 1999 the Sulawesi Coelacanth was described as a new species, Latimeria menadoensis by Pouyaud, Wirjoatmodjo, Rachmatika, Tjakrawidjaja, Hadiaty and Hadie.
The discovery of a new species of coelacanth in Sulawesi, opens up the possibility that coelacanths may be more widespread and abundant than was previously assumed.