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Coelacanth

From Academic Kids

Coelacanth

Conservation status: Secure

Missing image
Coelacanth.png



Latimeria chalumnae
Scientific classification
Kingdom:Animalia
Phylum:Chordata
Class:Sarcopterygii
Order:Coelacanthiformes
Family:Latimeriidae
Genus:Latimeria
Smith, 1939
Species

Latimeria chalumnae
Latimeria menadoensis

Coelacanth (meaning "hollow spine" in Greek; IPA: ) is a species of fish and represents the oldest lineage of living fish known to date. The coelacanth was believed to have been extinct since the end of the Cretaceous period — until a live specimen turned up off the east coast of South Africa in 1938. Today they can be found in the Comoros, Sulawesi (Indonesia), Kenya, Tanzania, Mozambique, Madagascar and the St. Lucia Marine Protected Area in South Africa.

Contents

Biological characteristics

The coelacanth is a lobe-finned fish with the pectoral and anal fins on fleshy stalks supported by bones, and the tail fin divided into three lobes, the middle one of which also has a stalk. The coelacanth has modified cosmoid scales, which are thinner than true cosmoid scales, which can only be found on extinct fish.

The average weight of the coelacanth is 176 pounds (80kg) and they can reach up to 6.5 feet (2m) in length.

They are the only living species known to have a functional intercranial joint, a type of hinge that aids in the consumption of large prey. Coelacanths are also mucilaginous; their scales release mucus and their bodies continually exude oil.

Discovery

First find in South Africa

Marjorie Courtenay-Latimer with the first discovered Coelacanth
Enlarge
Marjorie Courtenay-Latimer with the first discovered Coelacanth

The first hint that a modern, living coelacanth existed was when Marjorie Courtenay-Latimer, who was curator of a museum in East London, South Africa, was inspecting local fish catches for unusual specimens in 1938. She was looking at the catch of a fishing boat that had been fishing for sharks near the Chalumna River and saw an odd blue fish fin in the catch. She pulled the fish out of the pile and brought it to the museum to find out what kind of fish it was. Failing to find it in any of her books, she attempted to contact her friend, Professor James Leonard Brierley Smith, but he was away. Unable to preserve the fish, she sent it to a taxidermist. When Smith returned, he immediately recognized it as a coelacanth, known only from fossils. The species was named Latimeria chalumnae in honour of her and the waters in which it was found. The fish was referred to as a "Living Fossil".

Comoros

A worldwide search was launched for more coelacanths, with a reward of 100 British pounds (a very substantial sum to the average South African fisherman of the time). Fourteen years later, they were found in the Comoros. The Comorians, in the port of Mutsamudu on the Comorian island of Anjouan, were puzzled that someone would pay big money for what the locals called a gombessa or mame, an inferior (nearly inedible) fish that their fishermen occasionally caught by mistake.

They now understand the significance of their endangered species and have a program in place to return any accidentally caught gombessa to deep water so that they can survive.

Smith, who died in 1968, wrote his account of the coelacanth story in the book Old Fourlegs, first published in 1956. His book Sea Fishes of the Indian Ocean, illustrated and co-authored by his wife Margaret, remains the standard ichthyological reference for the region.

Second species in Indonesia

In 1997, Arnaz and Mark Erdmann were traveling on honeymoon in Indonesia and saw a strange fish entering the market at Manado Tua, on the island of Sulawesi. Arnaz Erdmann recognized it as a gombessa, but it was brown, not blue. (The Erdmanns did not realize this was a new species until an expert saw their photo on the Web.) DNA testing revealed that this species, called rajah laut ('King of the Sea') by the Indonesians, is not related to the Comorian population. It was given the scientific name Latimeria menadoensis.

St. Lucia Marine Protected Area in South Africa

In South Africa, the search continued on and off over the years. One diver, 46-year-old, Riaan Bouwer, lost his life exploring for coelacanths in June 1998.

On October 28th, 2000, just south of the Mozambique border, in Sodwana Bay in the St. Lucia Marine Protected Area, three pleasure divers - Pieter Venter, Peter Timm and Etienne le Roux - made a dive to 104 metres and suddenly spotted a coelacanth. Without cameras, the group decided to return.

Calling themselves SA Coelacanth Expedition 2000 the group, with several additional members, returned and on November 26, they performed a first dive without seeing coelacanths. The next day Pieter Venter, Gilbert Gunn, Christo Serfontein and Dennis Harding, went down again. Moving from cavern to cavern, they found three coelacanths. The largest was between 1.5 and 1.8 metres long, the other two 1.2 metres and 1 metre. The fish swam heads down and appeared to be feeding off of ledges. The cameramen took video footage and photos. Then disaster struck. Assisting Christo, who suddenly passed out under water, 34-year-old Dennis Harding rose to the surface with him in an uncontrolled ascent. Harding complained of neck pains and died in the boat. Apparently, he had suffered a cerebral embolism. Christo recovered after being taken underwater for recompression.

However, the find was big news in South Africa. In March-April 2002, the Jago Submersible and Fricke Dive Team descended into the depths off Sodwana and observed 15 coelacanths, one pregnant. Tissue samples were taken using a dart probe.

Taxonomic notes

Coelacanthimorpha or Actinistia are sometimes used to designate the group of Sarcopterygian fishes that contains the Coelacanthiformes.

References

  • "Marjorie Courtenay-Latimer." The Daily Telegraph (London). May 19, 2004.
  • Myrna Oliver. "Marjorie Courtenay-Latimer, 97; Confirmed Rare Fish's Existence." Los Angeles Times. June 13, 2004. pg. B.16
  • Jeremy Pearce. "Marjorie Courtenay-Latimer, Naturalist, Is Dead at 97." New York Times. June 7, 2004. pg. B.6
  • Keith S. Thompson. Living Fossil: The Story of the Coelacanth. New York: W.W. Norton, 1991.

External links

de:Quastenflosser es:Celacanto fi:Latimeria fr:Cœlacanthe ja:シーラカンス jbo:Gombesa nl:Coelacanth pl:Latimeria pt:Celacanto sv:Havstofsstjrt zh:腔棘目

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