River shark

Taxobox
name = River sharks
regnum = Animalia
phylum = Chordata
classis = Chondrichthyes
subclassis = Elasmobranchii
ordo = Carcharhiniformes
familia = Carcharhinidae
genus = "Glyphis"
genus_authority = Agassiz, 1843
subdivision_ranks = Species
subdivision = See textThe river sharks are six (three to be formally described) rare species of shark in the genus "Glyphis", although, due to their secretive habits, other species could easily remain undiscovered. The river sharks are members of the family Carcharhinidae, and thus share the basic characteristics of the group. The bull shark is sometimes called both the river shark and the Ganges shark; it should not be confused with the true river sharks of "Glyphis".

Characteristics

In general, all river sharks feature the following field characteristics:
* a short, broadly rounded snout (its length less than the mouth width);
* small, widely spaced nostrils;
* small, dark eyes;
* broad, serrated upper teeth;
* very short labial furrows (lip grooves), restricted to the jaw corners;
* a broad dorsal fin with the mid-base closer to the base of the pectoral fins than those of the pelvic fins; and
* an anal fin with a deeply excised posterior margin.

Morphology

River sharks are very similar in overall morphology to requiem sharks of the genus Carcharhinus, but can be distinguished from them by the following characteristics:
* cusps of lower teeth protrude prominently when mouth is closed;
* the second dorsal fin is 1/2 to 3/5 the height of the first dorsal fin;
* the origin of the second dorsal fin is slightly anterior to the origin of the anal fin;
* precaudal pit is longitudinal rather than crescent-shaped.

pecies

* Ganges shark, "Glyphis gangeticus" (Müller & Henle, 1839)
* Speartooth shark, "Glyphis glyphis" (Müller & Henle, 1839)
* Irrawaddy River shark, "Glyphis siamensis" (Steindachner, 1896)
* Bizant river shark, "Glyphis sp. A", not yet described.
* Borneo river shark, "Glyphis sp. B", not yet described.
* New Guinea river shark, "Glyphis garricki", one of 113 new species.

ee also

* List of sharks
* Camden Riversharks

References

*
* [http://www.asfb.org.au/research/tsp/tfp_nsshark.htm Northern Speartooth Shark - Glyphis sp. C]
* Compagno, Dando, & Fowler, "Sharks of the World", Princeton University Press, New Jersey 2005 ISBN 0-691-12072-2

External links

* [http://www.elasmo-research.org/conservation/river_sharks.htm The Mysterious, Endangered River Sharks. (Accessed 11/26/06)]