Frilled shark
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[Photo] Frilled shark (Chlamydoselachus anguineus), from plate VI of Ocean Ichthyology by Goode and Bean. Enhanced image from the NOAA Photo Library: Image ID: figb0582, Historic NMFS Collection

The frilled shark, Chlamydoselachus anguineus, is a primitive shark species, of the family Chlamydoselachidae in the order Hexanchiformes. The Southern African frilled shark is a proposed new species from the Southern African range. These two species are very different from the other hexanchiform sharks, and it has been recently proposed that the two frilled sharks should be given their 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 protrudes 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 m 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 1,400 m. They typically eat other sharks, squid, and bony fish.

Reproduction is not well understood, but like many other sharks they bear live young (ovoviviparous), with litter sizes of 2 to 12 pups. Compagno states "They are pregnant for a long time, probably one to two years". This would give the frilled shark the possibility of having the longest gestation of any vertebrate, even 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.

On January 23, 2007, staff at Awashima Marine Park in Shizuoka, south of Tokyo, were alerted by fishermen to a 'strange eel like fish with razor sharp teeth'. The fish was identified as a female 1.6m frilled shark and was captured by park staff who were concerned that the shark appeared to be unhealthy. The shark died a few hours after capture. This rare surface appearance of a frilled shark has been attributed to the animal being unwell and possibly disoriented.

http://en.wikipedia.org/wiki/Frilled_shark

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