Megamouth shark

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Megamouth shark

Data deficient (IUCN)

Scientific classification

Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Subclass:	Elasmobranchii
Order:	Lamniformes
Family:	Megachasmidae
Genus:	Megachasma
Species:	M. pelagios

Binomial name

Megachasma pelagios
Taylor, Compagno and Struhsaker, 1983

Sharks Portal

The megamouth shark, Megachasma pelagios, is an extremely rare and unusual species of shark, discovered in 1976, with 38 specimens known to be caught or sighted as of 2006 and three recordings on film. Like the basking shark and whale shark, it is a filter feeder, consuming plankton and jellyfish, and is distinctive for its large head with rubbery lips. It is so unlike any other type of shark that it is classified in its own family Megachasmidae, though it has been suggested that it may belong in the family Cetorhinidae of which the basking shark is currently the sole member.

1 Physical characteristics
2 Capture
- 2.1 Hoax
3 Known specimens
4 References
5 External links

[edit] Physical characteristics

The appearance of the megamouth is distinctive. It has a large mouth with small teeth, a broad rounded snout (observers have mistaken it for a young orca), a generally brownish-blackish color on top and white underneath, and an asymmetrical tail with a long upper lobe, similar to the thresher shark. The interior of its gill slits are lined with finger-like gill rakers that capture its food. A relatively poor swimmer, the megamouth has a soft, flabby body and lacks keels. These are very large sharks, with the largest specimen to date reaching 4.8 m (16 ft) and 1 tonne (2,205 lb). Reproduction is ovoviviparous.

[edit] Capture

The first megamouth was captured on November 15, 1976 about 25 miles off the coast from Kaneohe, Hawaii when it became entangled in the sea anchor of a United States Navy ship. Examination of the 4.5 m (14.6 ft), 750 kg (1,650 lb) specimen by Leighton Taylor showed it to be an entirely unknown type of shark, rivaling the coelacanth as the most sensational discovery in ichthyology during the 20th century.

[edit] Hoax

The long delay between initial discovery (1976) and the scientific description (1983) became the focus of an elaborate practical joke by two friends of Leighton Taylor, Richard Ellis of the American Museum of Natural History and John McCosker, director of San Francisco's Steinhart Aquarium. Ellis and McCosker photocopied random articles from Japanese scientific journals and inserted photographs of the megamouth shark and a map of the type location and an English abstract, making it appear as if a Japanese team under guidance of John E. Randall of the Bishop Museum was to snatch the scientific merits of the description right from under Taylor's nose. An accomplice in Japan then mailed the "preprints" to Taylor, who was naturally dumbstruck. He then had his Japanese-American secretary translate the "paper", only to be told that it contained things like musings about the cat in Japanese art, and rhinoceroses in Ueno Zoo, but nothing about the megamouth shark. Hidden on the last page were the names of Ellis and McCosker, put there deliberately for Taylor to find them. Realizing he had been had, Taylor finally wrote up the description. The remark on its last page, "Particular thanks go to Richard Ellis and John McCosker for preparation of a preliminary manuscript which was of great help in the production of this final paper," is in reference to this incident.

[edit] Known specimens

In the 30 years since its discovery, as of May 2006 only 38 megamouth specimens have been caught or sighted. They have been found in the Pacific, Atlantic and Indian oceans. At least ten specimens have been found in the vicinity of Japan, more than any other single area. Specimens have also been pulled from the waters near Hawaii, California, Taiwan, the Philippines, Indonesia, Australia, South Africa, Brazil, Senegal and Ecuador.

Caught 25 miles off Kaneohe, Hawaii on November 15, 1976. Displayed at the Bernice Pauahai Bishop Museum in Honolulu.
Caught off Catalina Island, California, November 29, 1984. Displayed at the Los Angeles County Museum, Los Angeles.
Caught off Mandurah, Australia, August 18, 1988. Displayed at the Western Australian Museum.
Washed ashore off Hamamatsu, Japan, January 23, 1989 and discarded.
Washed ashore off Suruga Bay, Japan in June, 1989, and released.
Found on October 21, 1990, entangled in a drift gillnet off Dana Point, California. Specimen was taken alive, then released with tracking devices. The shark was observed to move close to the surface at night and deeper during the day.
Carcass washed up in Hakata Bay, Japan on November 29, 1994. Displayed at Marine World Umino-Nakamichi.
Caught off Dakar, Senegal on May 4, 1995. Discarded.
Caught in Brazilian waters. Now on display at the Instituto de Pesca, São Paulo, Brazil.
Caught off Toba, Japan on May 1, 1997. Displayed at the Toba Aquarium.
Megamouth # 11 found dead on the shores of Macajalar Bay, Cagayan de Oro Philippines on the night of February 20, 1998. Fish was later hacked into pieces and consumed that day.

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28. Megamouth found dead on the shores of in Macajalar Bay, Cagayan de Oro Philippines, around 3 am on January 30, 2005.

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37. Caught off Atami, Shizuoka, Japan on May 4, 2006.

38. Caught off Mexico, on November 16, 2006

A complete list of specimens is available here.

[edit] References

Compagno (2000). Megachasma pelagios. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 10 May 2006. Database entry includes a brief justification of why this species is listed as data deficient
Megachasma pelagios (TSN 159983). Integrated Taxonomic Information System. Accessed on 23 January 2006.
Berra, Tim M. (1997): "Some 20th century fish discoveries". Environmental Biology of Fishes 50: 1–12.
Taylor, L.R. et al. (1983): "Megamouth - a new species, genus, and family of lamnoid shark (Megachasma pelagios, family Megachasmidae) from the Hawaiian Islands". Proc. Cal. Acad. Sci. 43A: 87–110.
Elizaga, Elson "Megamouth Shark in Cagayan de Oro"
Sun Star Cagayan de Oro "Megamouth shark found dead in Oro"
Florida Museum of Natural History Megamouth Shark # 38: The First Megamouth Shark, Megachasma pelagios, Found in Mexican Waters
List of all megamouth sharks found