Frill shark
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The frill shark or frilled shark (Chlamydoselachus anguineus) is a primitive shark, the sole living member of the Chlamydoselachidae in the order Hexanchiformes. It is very different from the other hexanchiform sharks, and it has been recently proposed that the frilled shark should be given its own order: Chlamydoselachiformes. Additional extinct types are known from fossil teeth; thought to be extinct itself, it was only discovered in Japanese waters in the 19th century.(Allen, 48)
Superficially the frilled shark resembles a dark brown or gray eel, but the six gill slits identify it as a shark. The tissue of the gill slits protudes somewhat, thus inspiring the common name. Its dorsal fin is small, anal fin large, and the caudal fin(tail fin) is highly asymmetric, the ventral part almost unnoticeable. Its teeth are small, tricuspid, and very sharp. It has been recorded at up to 2 meters in length.
Distribution is worldwide, but they seem to be uncommon across this range. The sharks are usually found at depths of 120 m to 1,300 m. They typically eat other sharks, squid, and bony fish.
Reproduction is not well understood, but like many other sharks they bear live young, with litter sizes of 2–12. It has been suggested that the gestation period is about 3.5 years, which would give the frilled shark the longest gestation of any vertebrate, considerably exceeding the elephant's period of 22 months.
Frilled sharks appear regularly in the catches from bottom trawling, and when caught are used as food or for fishmeal.
See also
References
- Paul & Fowler (2003). [Chlamydoselachus anguineus]. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 11 May 2006. Database entry includes justification for why this species is near threatened
- [Chlamydoselachus anguineus (TSN 159813)]. Integrated Taxonomic Information System. Accessed on 23 January 2006.
- Allen, Thomas B. The Shark Almanac. New York: The Lyons Press, 1999. ISBN 1558215824
External links
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