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Coelacanth
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Coelacanth (adaptation of Modern Latin Cœlacanthus > cœl-us + acanth-us from Greek ????-?? [hollow] + ??a??-a [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.
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Encyclopedia
Coelacanth (adaptation of Modern Latin Cœlacanthus > cœl-us + acanth-us from Greek ????-?? [hollow] + ??a??-a [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 iSimangaliso Wetland Park, Kwazulu-Natal in South Africa. The second extant species, L. menadoensis, was described from Sulawesi, Indonesia in 1999. The coelacanth has no real commercial value, apart from being coveted by museums and private collectors for obvious reasons. As a food fish the coelacanth is almost worthless as its tissues exude oils even when dead, imparting the flesh with a foul flavour.
Natural history
They first appeared in the fossil record in the Middle Devonian. 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. 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. 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 Coelacanths
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 commonly 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 Comoros 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 or belly up to locate their prey, presumably utilizing their rostral gland. Scientists suspect that one reason this fish has been so successful is that specimens are able to 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 population of the West Indian Ocean coelacanth was estimated to have been 500 or fewer, a number that would threaten the survival of the species. L. chalumniae is listed as critically endangered and L. menadoensis is listed as vulnerable by IUCN.
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 -15 months.
Discoveries
Timeline of discoveries| Date | Description | | 1938 | (December 23) First discovery of a modern coelacanth 30 kilometers SW of East London, South Africa. | | 1952 | (December 21) Second specimen identified in the Comoros. Since then more than 200 have been caught around the islands. | | 1988 | First photographs of coelacanths in their natural habitat, by Hans Fricke off Grande Comore. | | 1991 | First coelacanth identified near Mozambique, 24 kilometers offshore NE of Quelimane. | | 1995 | First recorded coelacanth on Madagascar, 30 kilometers S of Tuléar. | | 1997 | (September 18) New species of coelacanth found in Indonesia. | | 2000 | A group found by divers off Sodwana Bay, iSimangaliso Wetland Park, South Africa. | | 2001 | A group found off the coast of Kenya. | | 2003 | First coelacanth caught by fisherman in Tanzania. Within the year, 22 were caught in total. | | 2004 | Canadian researcher William Sommers captured the largest recorded specimen of coelacanth off the coast of Madagascar. | | 2007 | (May 19) Indonesian fisherman Justinus Lahama caught a 1.31 meter (4.30 ft) long, 51 kilogram (112 lb) coelacanth off Sulawesi Island, near Bunaken National Marine Park, that survived for 17 hours in a quarantined pool. | | 2007 | (July 15) Two fishermen from Zanzibar caught a coelacanth measuring 1.34 meters (4.40 ft), and weighing 27 kilograms (60 lb). The fish was caught off the north tip of the island, off the coast of Tanzania. | |
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 Domoni 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. Mark thought it was a gombessa (Comoros coelacanth), although it was brown, not blue. An expert noticed their pictures on the Internet and realized its significance. Subsequently, the Erdmanns contacted local fishermen and asked for any future catches of the fish to be brought to them. A second Indonesian specimen, 1.2 m in length and weighing 29 kg., was captured alive on July 30, 1998. It lived for six hours, allowing scientists to photographically document its coloration, fin movements and general behavior. The specimen was preserved and donated to the Museum Zoologicum Bogoriense (MZB), part of the Indonesian Institute of Sciences (LIPI).
DNA testing revealed that this specimen differed genetically from the Comorian population. Superficially, the Indonesian coelacanth, locally called raja laut ("King of the Sea"), appears to be the same as those found in the Comoros except that the background coloration of the skin is brownish-gray rather than bluish. This fish was described in a 1999 issue of Environmental Biology of Fishes by Pouyaud et al. It was given the scientific name Latimeria menadoensis. A molecular study estimated the divergence time between the two coelacanth species to be 40–30 mya.
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.
iSimangaliso Wetland Park in South Africa
In South Africa, the search continued on and off over the years. 46-year-old diver Riaan Bouwer lost his life searching for coelacanths in June 1998.
On the 28th of October 2000, just south of the Mozambique border in Sodwana Bay in the St. Lucia Marine Protected Area, three deep-water divers, Pieter Venter, Peter Timm, and Etienne le Roux, made a dive to 104 metres and unexpectedly spotted a coelacanth.
Calling themselves "SA Coelacanth Expedition 2000", the group returned with photographic equipment and several additional members. On the 27th of November, after an unsuccessful initial dive the previous day, four members of the group, Pieter Venter, Gilbert Gunn, Christo Serfontein, and Dennis Harding, found three coelacanths. The largest was between 1.5 and 1.8 metres in length; the other two were from 1 to 1.2 metres. The fish swam head-down and appeared to be feeding from the cavern ledges. The group returned with video footage and photographs of the coelacanths.
During the dive, however, Serfontein lost consciousness, and 34-year-old Dennis Harding rose to the surface with him in an uncontrolled ascent. Harding complained of neck pains and died from a cerebral embolism while on the boat. Serfontein recovered after being taken underwater for decompression sickness treatment.
In March–April 2002, the Jago Submersible and Fricke Dive Team descended into the depths off Sodwana and observed fifteen coelacanths. A dart probe was used to collect tissue samples.
Tanzania
Coelacanths have been caught off the coast of Tanzania since 2004. Two coelacanths were initially reported captured in Kigombe, a small village off the edge of the Indian Ocean in August 2004. A spate of 19 more specimens of these extremely rare fishes weighing between 25 kg. to 80 kg. were reported netted in the space of the next 5 months, with another specimen captured in January 2005. A coelacanth weighing as much as 110 kg. was reported by the Observer newspaper in 2006. Officials of the Tanga Coastal Zone Conservation and Development Programme, which has a long-term strategy for protecting the species, see a connection with the timing of the captures with trawling - especially by Japanese vessels - near the coelacanth's habitat, as within a couple of days of trawlers casting their nets coelacanths have turned up in shallow-water fishing nets intended for sharks. The sudden appearance of the coelacanth off Tanzania that has raised real worries about its future due to damage done to the coelacanth population by the effects of indiscriminate trawling methods and habitat damage.
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."
In a March 2008 report the Tanzania Natural Resource Forum, a local environmental NGO, warned that a proposed port project at Mwambani Bay could threaten a coastal population of coelacanth .
Taxonomy
Subclass Coelacanthimorpha (Actinistia) are sometimes used to designate the group of Sarcopterygian fish that contains the Coelacanthiformes. The following is a classification of known coelacanth genera and families:
Class Sarcopterygii
Subclass Coelacanthimorpha
The coelacanth in popular culture
The coelacanths' widely-published status as a "living fossil" earned it a place in music, video games, literature, and television. "Coelacanth" is the title of songs and albums by bands including John Fahey, Shriekback, Mr. Children and Polysics.
Coelacanths are also heavily featured in video games. The coelacanth appears in games such as Animal Crossing,, Mega Man X2, SEGA Marine Fishing, E.V.O.: Search for Eden (dubbed "Coelafish"), We Love Katamari, Me and My Katamari, Endless Ocean, Animal Crossing, and Aquanaut's Holiday: Hidden Memories. A giant, mutated coelacanth with a humanoid face appears as the boss of the fourth level in Contra: Shattered Soldier. The Coelacanth was also the inspiration for the Pokémon Relicanth, the Digimon Coelamon, (a flying Coelacanth), and bosses in the Darius series.
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.
In Ryu Murakami's 69 (novel), Ken's band is named Coelacanth.
Interröbang Cartel's works include the album (in progess) Bad Coelacanth and the song Prelude to the Afternoon of a Coelacanth.
The Transformers character Skalor, one of the Seacons, has an alternate mode based on the coelacanth.
Coelocanths have featured in film and TV series such as Atlantis: The Lost Empire, Monster on the Campus and Futurama.
The sculptress Jeanne Grut produced two faience figures of coelacanths for the Royal Copenhagen porcelain manufactory in a series known as 'Blue Fish'. Originally made in 1963, these are still produced today.
A 2001 Volkswagen commercial has a mechanic comparing their discovery of a full-sized spare tire in the trunk of a Volkswagen Jetta to the discovery of a coelacanth off the coast of Madagascar.
In Sayonara Zetsubou Sensei, Nozomu complains about how everything no longer resembles the original as they continue to change. Kafuka explains that everything has to evolve then Abiru refutes him by saying that when the Coelacanth was rediscovered, it remained true to its original form and they set off to find more species that may have not evolved after their supposed extinction.
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.
In a scene in the Tintin book The Calculus Affair, Tintin and Captain Haddock stop a car that they believe is carrying their friend Professor Calculus. The car's passenger opens his trunk, showing that Calculus is not there, and asks "Now where's your coelacanth?", a mispronunciation of Calculus's name.
See also
External links
- (ACEP), as the South African Coelacanth Conservation and Genome Resource Programme
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- Coelacanth: the fish out of time
- at MarineBio.org
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- of the two coelacanths species based on the whole mitochondrial genome sequences.
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