White-edge freshwater whipray (Himantura signifer)

loading
White-edge freshwater whipray
loading
Loading more images and videos...

White-edge freshwater whipray fact file

White-edge freshwater whipray description

KingdomAnimalia
PhylumChordata
ClassChondrichthyes
OrderRajiformes
FamilyDasyatidae
GenusHimantura (1)

Very little is known about this mysterious ray, as just ten specimens have been identified and studied in museums (1). Named for the pale margin of its disc-shaped body (2), the white-edge freshwater whipray is light grey in colour on the upper surface (3), and the underside is very pale, which aids camouflage amongst the river bed and water surface respectively. Two pale spots are visible on the ray's upper surface, each one positioned between an eye and a spiracle (2), a small opening which allows water to pass over the gills whilst the ray is still. Characteristic of the Himantura genus, this whipray also has a long, slender tail. Male white-edge freshwater whiprays differ from females by the possession of a pair of claspers, which are used to transfer sperm to the female during mating (2) (3).

Size
Total length: 200 cm (2)
Maximum weight: 8000 g (2)
Top

White-edge freshwater whipray biology

Little is known about the life history and ecology of the white-edge freshwater whipray, as few individuals have been studied. Its diet consists of crustaceans and shellfish dwelling on the river bed (2). Reproduction is ovoviviparous, a method of reproduction in which the young, known as pups, develop within eggs that remain inside the female’s body until they hatch; the female then gives birth to live young (2).

As with many ray species, a sharp spine on the tail is used for defence and can cause painful and potentially fatal injuries for enemies, including humans (2).

Top

White-edge freshwater whipray range

The white-edge freshwater whipray is thought to have a limited range in four tropical river systems within South East Asia. The few specimens identified have come from Thailand, Malaysia and Indonesia (1) (2).

Top

White-edge freshwater whipray habitat

Primarily occurring in tropical freshwater habitats, the white-edge freshwater whipray glides across sandy river and estuary bottoms (1) (2). However, studies have revealed that this species also enters brackish water at some time in its life (4).

Top

White-edge freshwater whipray status

Classified as Endangered (EN) on the IUCN Red List (1).

IUCN Red List species status – Endangered

Top

White-edge freshwater whipray threats

Like a number of other freshwater ray species, the white-edge freshwater whipray is under threat, primarily by habitat loss and degradation, as habitat is cleared to make way for new residential and industrial sites. Where this building occurs in river catchment areas, alteration to the water supply and flow can negatively affect the freshwater habitat of this species (5).

The clearance of forests can also have enormous impacts on the surrounding freshwater habitats and their inhabitants. Without the protective layer of the forest canopy, more rain reaches the ground and quickly runs into the rivers, resulting in floods downstream during monsoon periods. Conversely, without the forest to soak up rainfall and slowly release it into nearby streams, drought can occur in the upper reaches of streams during dry periods (6). Dams are constructed to try and prevent flooding downstream; however, these barriers have a negative impact on the white-edge freshwater whipray by splitting and isolating populations (1) (5).

Development can also cause pollution, which drastically impacts the nearby rivers. This includes industrial waste, sewage and agricultural chemical build up, as well as silt run-off from mining (1) (5). In addition, the white-edge freshwater whipray is known to be eaten in Thailand (3), and the intense fishery industry in much of this species’ range threatens populations through bycatch. It is also captured to satisfy demand for the aquarium market (7).

Top

White-edge freshwater whipray conservation

A conservation project was initiated by the Thai government in the 1990s, consisting of a breeding programme to boost populations upstream of dams (1). However, this was unfortunately put on hold in 1996 and no definite conservation measures for this species have been in place since (1).

Hope for this little-known ray is likely to come from successful management and conservation of tropical freshwater ecosystems as biodiversity hotspots, rather than species-specific measures. However, this is a tough challenge, involving national policy change and continued research (8).

View information on this species at the UNEP World Conservation Monitoring Centre.
Top

Authentication

Information authenticated (30/11/09) by Dr Jim Ballantyne, Department of Integrative Biology, University of Guelph.

This species information was authored as part of the ARKive and Universities Scheme.
Top

Glossary

Brackish
Slightly salty water, usually a mixture of salt and freshwater, such as that found in estuaries.
Bycatch
In the fishing industry, the part of the catch made up of non-target species.
Crustaceans
Diverse group of arthropods (a phylum of animals with jointed limbs and a hard chitinous exoskeleton) characterised by the possession of two pairs of antennae, one pair of mandibles (parts of the mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, slaters, woodlice and barnacles.
Genus
A category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.
Top

References

  1. IUCN Red List (March, 2010)
    http://www.iucnredlist.org/
  2. FishBase (November, 2009)
    http://www.fishbase.org/
  3. Ballantyne, J. (2009) Pers. comm.
  4. Otake, T., Ishii, T. and Tanaka, S. (2005) Otolith strontium: calcium ratios in a freshwater stingray, Himantura signifer Compagne and Roberts, 1982, from Chao Phraya River, Thailand. Coastal Marine Science, 29, 147-153.
  5. Fowler, S.L., Cavanagh, R.D., Camhi, M., Burgess, G.H., Cailliet, G.M., Fordham, S.V., Simpfendorfer, C.A. and Musick, J.A. (2005) Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes. Status Survey. IUCN/SSC Shark Specialist Group, IUCN, Gland.
  6. Park, C.C. (1992) Tropical Rainforests. Routledge, London.
  7. Vidthayanon, C. (1997) Elasmobranch Diversity and Status in Thailand. In: Fowler, S. L., Reed, T. M. and Dipper, F. A. (Ed). Elasmobranch Biodiversity, Conservation and Management,Proceedings of the International Seminar and Workshop, Sabah, Malaysia, July 1997. IUCN, Cambridge.
  8. Gopal, B. (2005) Does inland aquatic biodiversity have a future in Asian developing countries? Hydrobiologia, 542: 69-75.
X
Close

Image credit

White-edge freshwater whipray  
White-edge freshwater whipray

© Johnny Jensen / imagequestmarine.com

Image Quest Marine
The Moos
Poffley End
Witney
Oxfordshire
OX29 9UW
United Kingdom
Tel: +44 (0) 1993 704050
Fax: +44 (0) 1993 779203
info@imagequestmarine.com
http://www.imagequestmarine.com/stock

X
Close

Link to this photo

ARKive species - White-edge freshwater whipray (Himantura signifer) Embed this ARKive thumbnail link ("portlet") by copying and pasting the code below.

Terms of Use - The displayed portlet may be used as a link from your website to ARKive's online content for private, scientific, conservation or educational purposes only. It may NOT be used within Apps.

Read more about

X
Close

MyARKive

MyARKive offers the scrapbook feature to signed-up members, allowing you to organize your favourite ARKive images and videos and share them with friends.

Play the Team WILD game:

Team WILD, an elite squadron of science superheroes, needs your help! Your mission: protect and conserve the planet’s species and habitats from destruction.

Conservation in Action

Which species are on the road to recovery? Find out now »

Help us share the wonders of the natural world. Donate today!

Blog