Frilled shark

The frilled shark or frill 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 hexanchiforms, and has been recently proposed to be given its own order Chlamydoselachiformes. Additional extinct types are known from fossil teeth.

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 name. Its dorsal fin[?] is small, anal fin[?] large, and the caudal 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 the 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 to 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[?].

External link

• FishBase entry for Chlamydoselachus anguineus (http://www.fishbase.org/Summary/SpeciesSummary.cfm?id=635)
• More info (http://www.elasmo-research.org/education/shark_profiles/chlamydoselachiformes.htm)