AskDefine | Define coelacanth

Dictionary Definition

coelacanth n : fish thought to have been extinct since the Cretaceous Period but found in 1938 off the coast of Africa [syn: Latimeria chalumnae]

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Noun

coelacanth
  1. A species of deep-water fish of the Indian ocean, Latimeria chalumnae, thought until 1938 to have been extinct for 70 million years.

Extensive Definition

Coelacanth (, adaptation of Modern Latin Cœlacanthus > cœl-us + acanth-us from Greek κοῖλ-ος [hollow] + ἄκανθ-α [spine]) is the common name for an order of fish that includes the oldest living lineage of gnathostomata known to date. The coelacanths, which are related to lungfishes and tetrapods, were believed to have been extinct since the end of the Cretaceous period, until the first Latimeria specimen was found off the east coast of South Africa, off the Chalumna River in 1938. (They are, therefore, a Lazarus taxon.) Since 1938, Latimeria chalumnae have been found in the Comoros, Kenya, Tanzania, Mozambique, Madagascar, and in Greater St. Lucia Wetland Park in South Africa. The second species, L. menadoensis, was described from Sulawesi, Indonesia in 1999.

Natural history

They first appear in the fossil record in the Middle Devonian, about 410 million years ago. Prehistoric species of coelacanth lived in many bodies of water in Late Paleozoic and Mesozoic times.
Coelacanths are lobe-finned fish with the pectoral and anal fins on fleshy stalks supported by bones, and the tail or caudal fin diphycercal (divided into three lobes), the middle one of which also includes a continuation of the notochord. Coelacanths have modified cosmoid scales, which are thinner than true cosmoid scales, which can only be found on extinct fish. Coelacanths also have a special electroreceptive device called a rostral organ in the front of the skull, which probably helps in prey detection. The small device also could help the balance of the fish, as echolocation could be a factor in the way this fish moves.

Fossil record

Although now represented by only two known living species, as a group the coelacanths were once very successful with many genera and species that left an abundant fossil record from the Devonian to the end of the Cretaceous period, at which point they apparently suffered a nearly complete extinction. No fossils dated after this point are known to have been found. It is often claimed that the coelacanth has remained unchanged for millions of years but in fact the living species and even genus are unknown from the fossil record. However, some of the extinct species, particularly those of the last known fossil coelacanth, the Cretaceous genus Macropoma, closely resemble the living species. The most likely reason for the gap is the taxon having become extinct in shallow waters. Deep-water fossils are only rarely lifted to levels where paleontologists can recover them, making most deep-water taxa disappear from the fossil record. This situation is still under investigation by scientists.

Latimeria - the modern Coelacanth

Biological characteristics

The average weight of the living West Indian Ocean coelacanth, Latimeria chalumnae, is 80 kg (176 lb), and they can reach up to 2 m (6.5 ft) in length. Adult females are slightly larger than males. Based on growth rings in their ear bones (otoliths), scientists infer that individual coelacanths may live as long as 80 to 100 years. Coelacanths live as deep as 700 m (2300 ft) below sea level, but are more usually found at depths of 90 to 200 m. Living examples of Latimeria chalumnae have a deep blue color which probably camouflages them from prey species; however, the Indonesian species is brown. Latimeria chalumnae is widely but very sparsely distributed around the rim of the western Indian Ocean, from South Africa northward along the east African coast to Kenya, the Comoro Island and Madagascar, seemingly occurring in small colonies. Coelacanth eyes are very sensitive, and have a tapetum lucidum. Coelacanths are almost never caught in the daytime or on nights with full moons, due to the sensitivity of their eyes. Coelacanth eyes also have many rods: receptors in the retina that help animals see in dim light. Together, the rods and tapetum help the fish see better in dark water.
Coelacanths are opportunistic feeders, hunting cuttlefish, squid, snipe eels, small sharks, and other fish found in their deep reef and volcanic slope habitats. Coelacanths are also known to swim head down, backwards and belly up to locate their prey, presumably utilizing its rostral gland. Scientists suspect that one reason this fish has been so successful is that they can slow down their metabolisms at will, sinking into the less-inhabited depths and minimizing their nutritional requirements in a sort of hibernation mode.
The coelacanths which live near Sodwana Bay, South Africa, rest in caves at depths of 90 to 150 m during daylight hours, but disperse and swim to depths as shallow as 55 m when hunting at night. The depth is not as important as their need for very dim light and, more importantly, for water which has a temperature of 14 to 22 °C. They will rise or sink to find these conditions. The amount of oxygen that their blood can absorb from the water through the gills is dependent on water temperature. Scientific research suggests that the coelacanth must stay in cold, well-oxygenated water or else their blood cannot absorb enough oxygen.
In accordance with the Convention on International Trade of Endangered Species treaty, the coelacanth was added to Appendix I (threatened with extinction) in 1989. The treaty forbids international trade for commercial purposes and regulates all trade, including sending specimens to museums, through a system of permits. In 1998, the total coelacanth population was estimated to have been 500 or fewer, a number that would threaten the survival of the species.

Reproduction

Female coelacanths give birth to live young, called "pups", in groups of between 5 and 25 fry at a time; the pups are capable of surviving on their own immediately after birth. Their reproductive behaviors are not well known, but it is believed that they are not sexually mature until after 20 years of age. Gestation time is 13 months.

Discoveries

First find in South Africa

On December 23, 1938, Hendrik Goosen, the captain of the trawler Nerine, returned to the harbour at East London, South Africa, after a trawl around the mouth of the Chalumna River. As he frequently did, he telephoned his friend, Marjorie Courtenay-Latimer, curator at East London's small museum, to see if she wanted to look over the contents of the catch for anything interesting. At the harbour, Latimer noticed a blue fin and took a closer look. There she found what she later described as "the most beautiful fish I had ever seen, five feet long, and a pale mauve blue with iridescent silver markings."
Failing to find a description of the creature in any of her books, she attempted to contact her friend, Professor James Leonard Brierley Smith, but he was away for Christmas. Unable to preserve the fish, she reluctantly sent it to a taxidermist. When Smith returned, he immediately recognized it as a coelacanth, known only from fossils. Smith named the fish Latimeria chalumnae in honor of Marjorie Courtenay-Latimer and the waters in which it was found. The two discoverers received immediate recognition, and the fish became known as a "living fossil." The 1938 coelacanth is still on display in the East London, South Africa, museum.
However, as the specimen had been stuffed, the gills and skeleton were not available for examination, and some doubt therefore remained as to whether it was truly the same species. Smith began a hunt for a second specimen that would take more than a decade.

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, one specimen was found in the Comoros, but the fish was no stranger to the locals — in the port of Mutsamudu on the Comorian island of Anjouan, the Comorians were puzzled to be so rewarded for a "gombessa" or "mame", their names for the nearly inedible fish that their fishermen occasionally caught by mistake.
The second specimen, found in 1952 by Comorian fisherman Ahamadi Abdallah, was described as a different species, first as 'Malania hunti' and later as Malania anjounae, after Daniel François Malan, the South African Prime Minister who had dispatched an SAAF Dakota at the behest of Professor Smith to fetch the specimen. It was later discovered that the lack of a first dorsal fin, at first thought to be significant, was caused by an injury early in the specimen's life. Ironically, Malan was a staunch creationist; when he was first shown the primitive creature, he exclaimed, with a twinkle, "My, it is ugly. Do you mean to say we once looked like that?" The specimen retrieved by Smith is on display at the SAIAB in Grahamstown, South Africa where he worked.
The Comorians are now aware of the significance of the endangered species, and have established a program to return accidentally-caught coelacanth to deep water.
As for Smith, who died in 1968, his account of the coelacanth story appeared 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.
In 1988, National Geographic photographer Hans Fricke was the first to photograph the species in its natural habitat, off Grande Comore's west coast.

Second species in Indonesia

On September 18, 1997, Arnaz and Mark Erdmann, traveling in Indonesia on their honeymoon, saw a strange fish enter the market at Manado Tua, on the island of Sulawesi.
On May 19, 2007, Justinus Lahama, an Indonesian fisherman, caught a 1.3-metre-long, 50kg/110 pound coelacanth off the coast near Manado, on northern Sulawesi Island near Bunaken National Marine Park. After spending 30 minutes out of water, the fish, still alive, was placed in a netted pool in front of a restaurant at the edge of the sea. It survived for 17 hours. Coelacanths, closely related to lungfish, usually live at depths of 200-1,000 metres. The fish was filmed by local authorities swimming in the metre-deep pool, then frozen after it died. AFP claim French, Japanese and Indonesian scientists working with the French Institute for Development and Research carried out a necropsy on the coelacanth with genetic analysis to follow. The local university is now studying the carcass.
Hassan Kolombo, a programme co-ordinator, said. "Once we do not have trawlers, we don't get the coelacanths, it's as simple as that." His colleague, Solomon Makoloweka, said they had been pressuring the Tanzanian government to limit trawlers' activities. He said: "I suppose we should be grateful to these trawlers, because they have revealed this amazing and unique fish population. But we are concerned they could destroy these precious things. We want the government to limit their activity and to help fund a proper research program so that we can learn more about the coelacanths and protect them." SEGA Marine Fishing, E.V.O.: Search for Eden (where the coelacanth is dubbed "Coelafish"), We Love Katamari, Me and My Katamari, and Endless Ocean. The Coelacanth was also the inspiration for the Pokémon Relicanth, the Digimon Coelamon, the Ancient Fish discovery in Skies of Arcadia (which is simply a flying Coelacanth), and bosses in the Darius series .
The coelacanth is also featured in books. In Margaret Atwood's novel Oryx and Crake, the coelacanth is used as a symbol for the underground scientific association Extinctathon. In Dirk Gently's Holistic Detective Agency, Professor Chronotis admits to causing the extinction of the dodos by trying to save the Coelacanth. In Lee Battersby's Father Muerte and the Rain, coelacanths rain from the sky when an ancient butterfly is stolen from its home time. The reference to the Latimeria Chalumnae is also a recurring one in Anne Landsman's novel, The Rowing Lesson, which is set, in part, in pre-World War II South Africa. Specific reference is made to the coelacanth's discovery as part of the narrative and as an allegorical reference to one's connection with the past.
A textbook on the C programming language by Peter van der Linden entitled Expert C Programming - Deep C Secrets (1994) features a Coelecanth on its cover. Coelacanths have also been featured in television shows, such as Futurama, and in movies, such as Monster on the Campus
Shriekback performed a primitive woodwind and synthesizer instrumental, "Coelacanth", for their 1985 album, Oil & Gold.
Coelocanths can be seen in the Disney animated film Atlantis- the Lost Empire.
In the 2008 film, Cloverfield, one of the characters mentions a "...fish that was found off the coast of Madagascar that was thought to have been extinct for centuries" as an example of where the monster came from.
The Collectible Card Game Yu-Gi-Oh! has a card from the set Phantom Darkness named Superancient Deepsea King Coelacanth, and its effect reflects its opportunistic hunting.
A Pokemon named Relicanth is based on the Coelocanth. It is described as "a fish-like Pokémon with features that seem ancient and primitive".
In the online MUD named Achaea, Dreams of Divine Lands, this fish is located in the deepest depths of the ocean, only reachable by the new and fantastic introduction of ships to the fantasy world.
The reference to the Latimeria Chalumnae is a recurring one in Anne Landsman's novel, "The Rowing Lesson", which is set, in part, in pre-World War II South Africa.
Finally, coelacanths have been used as symbols in objects and as nicknames. "Les Coelecantes" (meaning "the Coelacanths") is a nickname for the Comoros national football team. Coelacanths have been shown on coins, phone cards, and beer bottles.

References

External links

portal Fish
coelacanth in Bulgarian: Латимерия
coelacanth in Catalan: Cel·lacant
coelacanth in Czech: Latimérie podivná
coelacanth in Danish: Coelacanth
coelacanth in German: Quastenflosser
coelacanth in Spanish: Coelacanthimorpha
coelacanth in Esperanto: Celakantoformaj
coelacanth in French: Cœlacanthe
coelacanth in Korean: 실러캔스
coelacanth in Indonesian: Coelacanth
coelacanth in Italian: Latimeria
coelacanth in Lojban: gombesa
coelacanth in Dutch: Coelacanten
coelacanth in Japanese: シーラカンス
coelacanth in Norwegian: Kvastfinnefisker
coelacanth in Polish: Latimeria
coelacanth in Portuguese: Celacanto
coelacanth in Russian: Целакант
coelacanth in Simple English: Coelacanth
coelacanth in Slovak: Latiméria divná
coelacanth in Finnish: Latimeria
coelacanth in Swedish: Tofsstjärtfiskar
coelacanth in Thai: ปลาซีลาแคนท์
coelacanth in Vietnamese: Bộ Cá vây tay
coelacanth in Ukrainian: Целакант
coelacanth in Chinese: 腔棘魚
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