Clubnose guitarfish (Glaucostegus thouin)

Synonyms: Rhinobatos thouin
KingdomAnimalia
PhylumChordata
ClassChondrichthyes
OrderRajiformes
FamilyRhinobatidae
GenusGlaucostegus (1)
SizeLength: 2.5 – 3 metres (2)

The clubnose guitarfish is classified as Vulnerable (VU) on the IUCN Red List (1).

The characteristic heart-shaped silhouette of the clubnose guitarfish (Glaucostegus thouin) is the result of a somewhat bizarre feature of its development, where the head is fused on each side to enlarged pectoral fins. Named for its elongated, club-like snout, the clubnose guitarfish has a flattened, slender trunk with rounded pelvic fins and two large dorsal fins, while the long, stout tail bears an imposing, shark-like caudal fin (3) (4). The body is covered in tiny, tooth-like scales which reduce drag in the water and make swimming more efficient. The clubnose guitarfish is generally brownish in colour, sometimes varying from yellow-brown, grey-brown, greenish or black, and is usually white underneath (4) (5).

The clubnose guitarfish is found in inshore waters, spanning from the Red Sea, to Malaysia, Singapore, Thailand, Vietnam, Indonesia, New Guinea and Japan. Unconfirmed reports suggest that the clubnose guitarfish may also inhabit waters in the Mediterranean and Suriname (1) (2) (6).

A bottom-dwelling (benthic) species, the clubnose guitarfish is typically found over soft and sandy substrate at less than 60 metres depth (1).

Relatively little is known about the biology of this species, although it is thought that the clubnose guitarfish feeds on small fish and invertebrates that live on or near the sea bed (1). Most guitarfish in the Rhinobatidae family are suction feeders, where prey is sucked into the mouth and swallowed whole (4) (5) (6). The breeding behaviour of the clubnose guitarfish is not well documented; however, it is likely to be ovoviviparous (5) (6).

The clubnose guitarfish is threatened by both small scale and commercial fisheries where it may be targeted for its valuable fins, or caught accidentally as bycatch. As so little is known about the biology and habitat requirements of the clubnose guitarfish, it is difficult to assess the impact of other potential threats for this species; however, it is likely that human activities, destructive fishing practices, habitat degradation and pollution will all have an increasingly negative impact on survival (1) (6).

Much more research is required on the population structure, biology and ecology of the clubnose guitarfish, in order to determine how fishing practices, habitat destruction and other pressures are threatening the species. In addition, management plans must be developed in order to facilitate the conservation and sustainable management of this species (1). 

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  1. IUCN Red List (September, 2010)
    http://www.iucnredlist.org/
  2. Bonfil, R. and Abdallah, M. (2004) Field identification guide to the sharks and rays of the Red Sea and Gulf of Aden. Food and Agriculture Organisation of the United Nations, Rome. Available at:
    ftp://ftp.fao.org/docrep/fao/009/y5080e/y5080e00.pdf
  3. Campbell, A. and Dawes, J. (2004) Encyclopedia of Underwater Life. Oxford University Press, Oxford.
  4. Carpenter, K.E. and Niem, V.H. (1999) The Living Marine Resources of the Western Central Pacific. Volume 3: Batoid Fishes, Chimaeras and Bony Fishes. Part 1 (Elopidae to Linophyrnidae). Food and Agriculture Organisations of the United Nations, Rome. Available at:
    ftp://ftp.fao.org/docrep/fao/009/x2401e/x2401e00.pdf
  5. Elasmobranch Research Laboratory, Florida Atlantic University (September, 2010)
    http://www.science.fau.edu/sharklab/courses/elasmobiology/families/Rhinobatidae.pdf
  6. Fish Base (September, 2010)
    http://www.fishbase.org/Summary/SpeciesSummary.php?id=12578