Giant guitarfish

The giant guitarfish (Rhynchobatus djiddensis), also known as the whitespotted wedgefish is a large species of guitarfish in the family Rhinidae. It is restricted to the Red Sea, Persian Gulf, and western Indian Ocean,[1] but was formerly considered more widespread due to confusion with its relatives.[2]

For the giant guitarfish in the genus Glaucostegus, see common shovelnose ray.

Giant guitarfish
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Chondrichthyes
Subclass:
Elasmobranchii
Order:
Rhinopristiformes
Family:
Rhinidae
Genus:
Rhynchobatus
Species:
R. djiddensis
Binomial name
Rhynchobatus djiddensis
Forsskål, 1775

Taxonomy and range

The giant guitarfish was previously believed to range throughout a large part of the Indo-Pacific, but recent evidence has shown that it, as traditionally defined, actually was a species complex consisting of four different species.[2] In addition to the giant guitarfish, this complex includes the white-spotted guitarfish, the broadnose wedgefish and possibly the smoothnose wedgefish. With these as separate species, the giant guitarfish has a relatively restricted range: It is found only in the Red Sea and Persian Gulf, and the western Indian Ocean as far south as South Africa.[1][3]

Description

A large fish reaching up to 3.1 m (10 ft) long and weighing as much as 227 kg (500 lb).[3] It is brownish or greyish above with a variable pattern of white spots. Juveniles have a black spot above each pectoral fin, but in adults it is a dusky ring or absent. There is a dark, bar-like pattern between the eyes (on top of the head), which separates it from the other Rhynchobatus species in its range.[1]

Behavior

Breeding

It is ovoviviparous, and a female can give birth to litters of up to 10 young.[3][4]

Diet

The giant guitarfish feeds on bivalves, crabs, lobsters, squid and small fish.[3][4]

Ventral view.

Habitat

It is a shy fish, found from 2–50 m (6.6–164.0 ft) depth, inhabiting areas with sandy sea floor. These are generally around coastal reefs or reef flats, but they will sometimes venture into the brackish waters of estuaries.[3][4]

Interaction with man

The giant guitarfish is harmless to humans. It is listed as critically endangered on the IUCN red list as its population are believed to have declined significantly due to unregulated high levels of exploitation for its flesh and fins;[2] the latter for shark fin soup. Its low fecundity and presumed slow growth rate make it highly vulnerable to unsustainable exploitation.[2]

References
  1. Last; White; de Carvalho; Séret; Stehmann; Naylor, eds. (2016). Rays of the World. CSIRO. pp. 68–75. ISBN 9780643109148.
  2. Kyne, P.M., Gledhill, K. & Jabado, R.W. 2019. Rhynchobatus djiddensis. The IUCN Red List of Threatened Species 2019: e.T39394A121035795. https://doi.org/10.2305/IUCN.UK.2019-2.RLTS.T39394A121035795.en. Downloaded on 26 July 2019.
  3. Froese, Rainer and Pauly, Daniel, eds. (2007). "Rhynchobatus djiddensis" in FishBase. 7 2007 version.
  4. Lieske, E. and Myers, R.F. (2004) Coral reef guide; Red Sea London, HarperCollins ISBN 0-00-715986-2
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