Bigeye Sixgill Shark ( Hexanchus nakamurai )

/ / Fish

Description

This deep water shark can reach lengths of up to 180cm and a weight of 22kg. It is named for its large fluorescent green eyes that are located in its narrow pointed head with six gill slits rather than the usual five gill slits found in most shark species (1). Its narrow body is a brownish grey colour, fading on the underside (1).

Behaviour

Due to the bottom dwelling nature of this shark little is known of its behaviour. They are thought to be solitary, only coming together in order to mate (2).

Life cycle

There is little information available on the lifecycle of the Bigeye Sixgill shark. It is suggested that their lifespan could be anything between 20 and 80 years and sexual maturation could be between 11 and 35 years (3). As with most shark species, they are ovoviviparous but the litter size is uncertain. The young are thought to measure approximately 43cm when born (1).

Habitat

Bigeye Sixgill sharks are a deep water species that spend the day at the seabed down to depths of approximately 2000m. They come closer to the surface at night in order to feed (2).

Distribution

Temperate and Tropical regions worldwide

Migration

There is no information on large scale migrations by the Bigeye Sixgill shark, however studies have shown that they undertake extensive vertical migration on a diurnal scale in order to feed at the surface at night (4).

Food

Their diet is thought to consist of fish and crustaceans (4).

Conservation Status

IUCN Red List Status: Data Deficient

Due to deep nature this species is difficult to study and therefore not enough data has been collected in order to correctly classify its conservation status.

References

Description written by Jo Pollett (2009)

(1)   Bester, C., 2006. Florida Museum of Natural History: Ichthyology Department. Biological Profiles – Bigeye Sixgill. [Online] Available at: http://www.flmnh.ufl.edu/fish/gallery/descript/BigeyeSGill/BigeyeSGill.html [Accessed 19 August 2009].

(2)   ARKive, 2009. Bigeyed Six-Gill Shark – Hexanchus nakamurai – Information – ARKive – facts and status. [Online] Available at: http://www.arkive.org/bigeyed-six-gill-shark/hexanchus-nakamurai/info.html [Accessed 19 August 2009].

(3)   IUCN SSC, 2005. IUCN / SSC Shark Specialist Group. [Online] Available at: http://www.flmnh.ufl.edu/fish/organizations/ssg/ssg.htm [Accessed 19 August 2009].

(4)   Compagno, L.J.V. 1984 FAO species catalogue. Vol. 4. Sharks of the world. An annotated and illustrated catalogue of shark species known to date. Part 1 – Hexanchiformes to Lamniformes. FAO Fish. Synop. 125(4/1):1-249.