Coelacanths are quite different from all other living
fishes. They have an extra lobe on their
tail, paired lobed fins, and a vertebral
column that is not fully developed. They are the only living animal to have a fully functional intercranial joint (a division which separates the
ear and
brain from the nasal organs and
eye, and allows the front part of the head to be lifted when the fish is feeding). Perhaps the most interesting feature of the Coelacanth however, is that it has paired fins which move in a similar
fashion to our arms and legs.
On the 30th July 1998, a Coelacanth population was discovered by
American and Indonesian scientists
off Sulawesi,
Indonesia. This is about 10,000 km east of where Coelacanths were previously known to occur in the Western Indian Ocean. The local people from Sulawesi were familiar with the Coelacanth and had a name for it,
raja laut or 'king of the sea'.
The first living Coelacanth was discovered off the east coast of
South Africa, at the mouth of the Chalumna River, a few days before
Christmas in 1938. 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, but still thought the fish
bizarre enough to alert the local museum in the small South African town of East London.
The original
discovery of the Coelacanth in 1938 is still considered to be the zoological find of the
century. This 'living
fossil' comes from a lineage of fishes that was thought to have been extinct since the time of the
dinosaurs.
Coelacanths are known from the
fossil record dating back over 360 million years, with a peak in abundance about 240 million years ago. Before 1938 they were believed to have become extinct approximately 80 million years ago, after mysteriously disappearing from the fossil record. How could the Coelacanth
disappear for over 80 million years and then turn up alive and well in the twentieth
century? The answer seems to lie in the fact that the fossil Coelacanths appear to have lived in
environments conducive to
fossilisation. The modern Coelacanths, both in the Comoros and Sulawesi, however were found inhabiting caves and overhangs in vertical marine
reefs at about 200m depth off newly formed
volcanic islands, an environment that is particularly poor for fossil formation.
When the coelacanth from Sulawesi was first discovered, the only obvious differences between it and the coelacanths from the Comoros Islands was the colour. The Comoros coelacanths,
Latimeria chalumnae, are renowned for their steel blue colour, whereas
specimens from the 'new'
population are reported to be brown. In 1999 the Sulawesi coelacanth was described as a new species,
Latimeria menadoensis
Information taken from the Australian Museum Online and http://www.dinofish.com