Creature Feature: Frilled Shark - "The Living Fossil"

In 2007, a fisherman near Tokyo, Japan, told Awashiwa Marine Park officials that he’d just seen a very unusual eel-like creature with needle-sharp teeth. Staff at the park followed the fisherman, who directed them to the 5-foot-long oddity. They caught the creature, which was later identified as a frilled shark. 

Unfortunately, this poor girl died (no need to speculate on the cause of death here - in poor condition when found, she only lasted a few hours in captivity), but this unusual species still lives on. First scientifically recognized in 1881, the species was further studied and described in a manuscript by American zoologist Samuel Garman entitled "An Extraordinary Shark" in 1884. He named it Chlamydoselachus anguineus from the chlamy ("frill") and selachus ("shark"), and the Latin anguineus for "snake-like". [1] Commonly known as "frilled" (or "frill") shark, this species is also known as "lizard shark", "scaffold shark" or "silk shark". Because of its ancient ancestry and "primitive" characteristics, it has been described as a "living fossil". [2] 

As you can see by its odd appearance, this creature has been held possibly responsible for "sea-serpent" sightings over the years. It has many unusual features, including six pairs of collar-like gills with a frilly appearance (hence its name). Its skin is generally a uniform dark brown or gray. Unique among sharks, its first gill continues completely across the throat, and its jaw is actually located at the back of the head rather than underneath.  Armed with 300 trident-shaped teeth arranged in 25 rows and a extremely flexible jaw, it is believed to swallow its prey whole while using its teeth to prevent escape. 

Rarely observed by man, it is believed the frilled shark hovers effortlessly in the water column at depth due to the production of low-density oils and hydrocarbons in its extremely large liver. Using its posterior fins for propulsion, it strikes at its prey like a snake. Recent studies show that it eats primarily squid and other cephalopods, but may also consume bony fish and other sharks.

Seldom encountered alive, the frilled shark is believed to pose no danger to humans. Each year small numbers of frill sharks are unintentionally caught by deepwater commercial fisheries around the world, using trawls, gillnets, and longlines. This shark is sometimes sold for meat or processed into fishmeal, but is not economically significant. Because of its very low reproductive rate and the continuing expansion of commercial fisheries into its habitat, the International Union for Conservation of Nature (IUCN) has listed it as Near Threatened. [4]

[1] Ebert, D.A. (2003). Sharks, Rays, and Chimaeras of California. University of California Press. pp. 50–52. ISBN 0-520-23484-7. http://books.google.com/?id=1SjtuAs702kC&pg=PA149.


[2] Bright, M. (2000). The Private Life of Sharks: The Truth Behind the Myth. Stackpole Books. pp. 210–213. ISBN 0-8117-2875-7.


[3] ReefQuest Centre for Shark Research. http://www.elasmo-research.org/education/ecology/deepsea-frilled_shark.htm


[4] Paul, L. and Fowler, S. (2003). "Chlamydoselachus anguineus". IUCN Red List of Threatened Species. Version 2010.1. International Union for Conservation of Nature. http://www.iucnredlist.org/apps/redlist/details/41794. Retrieved April 25, 2010.

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