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Pristis clavata

(Dwarf Sawfish)

Overview

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Family : Sawfishes ; Inshore and intertidal species found in estuaries and on tidal mudflats [1]. Ascends brackish areas of rivers [1]. Ovoviviparous[2]. Biology little known (Ref. 9859). Flesh may be good to eat[3].

Critically Endangered

Threat status

Common Names

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Click on the language to view common names.

Common Names in Czech:

Piloun Trpaslic

Common Names in Dutch:

Dwergtoonhaai, Dwergzaagrog

Common Names in English:

Dwarf Sawfish, Dwarf Saury, Leichhardt's Sawfish, Queensland Sawfish

Common Names in French:

Poisson-scie

Common Names in Mandarin Chinese:

昆士兰锯鳐, 昆士蘭鋸鰩

Common Names in Spanish:

Pejepeine, Pez-sierra

Description

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Physical Description

Species Pristis clavata

Distinctive Features: All sawfishes are highly modified and elongate rays having a shark-like body and a blade-like snout (termed 'rostrum') that has lateral , tooth-like denticles (termed 'rostral teeth') set into sockets

Dentition: Oral dentition of the dwarf sawfish is similar in both jaws , exhibiting many rows of blunt teeth with rounded cusps and smooth surfaces. The oral teeth of the dwarf sawfish sometimes show wear from use, which may be particularly noticeable towards the symphysis (medial junction of each jaw) along the front series of tooth rows . Dermal Denticles : Dermal denticles of this species cover the body, fins , and rostrum. These denticles have a flat, oval-shaped or rounded crown. Denticles are similar in all development stages, although larger individuals exhibit a more pronounced crown than do young. Denticles along the posterior portion of the body are more elongate and convex . Denticles along the ventral body surface are smaller and are positioned in a pavement-like pattern .

Color:

The dorsal body surface of the dwarf sawfish is olive-brown in color, darker on the head , and fading to a whitish or yellowish ventrally. The fins of this species are often lighter in color than the dorsal body surface.

Size/Age/Growth

No mature male dwarf sawfish have ever been collected, and specimens are required for life history research efforts . The largest specimen recorded measured 4.5 feet (1.4 m ) in total length. This is significantly smaller than the maximum size of any other living sawfish species, lending this species its common name of dwarf sawfish.

Habitat

The habitat preferences of this species is not well known. The dwarf sawfish is known to inhabit coastal and estuarine habitats. This species is known to occur miles up rivers and appears to be common in the Gulf of Carpentaria, particularly over mudflats . The dwarf sawfish has been found in the Pentecost River, Western Australia, as far as 6.2 miles (10 km ) upstream , and in the adjacent estuary .

Biome: Marine [4].

Ecology: Coastal and estuarine habitats in tropical Australia, particularly over mudflats in the Gulf of Carpentaria (Pogonoski et al. 2002). It occurs some distance upriver, almost into freshwater (Last and Stevens 1994).[4].

List of Habitats:

Biology

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Diet

Despite the dwarf sawfish's interesting mode of food gathering, using its rostrum in a side-to-side slashing motion to dislodge invertebrates from substrate and to stun schooling fishes , little is known about the feeding habits of this species. Food items for the dwarf sawfish have not yet been recorded. Probable food items include small fishes and crustaceans, such as crabs and shrimps.

Reproduction

Little is known about the reproduction of the dwarf sawfish. Like sharks , skates , and rays, the dwarf sawfish utilizes internal fertilization. Like all rays, this species utilizes a strategy of embryo nourishment called aplacental yolk sac viviparity . With this strategy, the embryos are nourished only by their yolk sac, which provides energy for them to develop into fully functional young sawfish in utero. The yolk sac is connected to the embryo by a yolk stalk and both of these structures are fully absorbed before the young sawfish are born. The gestation period of the dwarf sawfish is not known, but the largetooth sawfish has a gestation period of about five months. Young dwarf sawfish have not yet been captured and litter sizes of this species have not yet been reported. The young are probably born tail-first. The saw teeth of young sawfish do not fully erupt, and are covered in a sheath of tissue , until after birth so as not to injure the mother. Young dwarf sawfish rostral teeth reach their full size proportionate to the size of the rostrum soon after birth. The reproductive cycle of the dwarf sawfish has not yet been documented, but the largetooth sawfish has been reported to produce litters every other year.

Behavior

Predators:

Predator attacks on dwarf sawfish have not been documented, but likely predators include hammerhead sharks (Sphyrna spp. ), bull sharks (Carcharhinus leucas), copper sharks (Carcharhinus brachyurus), and saltwater crocodiles (Crocodylus porosus).

Parasites:

The newly described parasite species Neoheterocotyle darwinensis n. sp. lives within the gills of the dwarf sawfish, and is known to occur near Darwin , Australia. Other species likely to use the dwarf sawfish as a host include Nonacotyle pristis, a species known to inhabit the gills of the freshwater sawfish, monogenean helminths such as Erpocotyle caribbensis and Pristonchocotyle intermedia, both inhabiting the gills of largetooth sawfish in Central America, and the cestode helminths Phyllobothrium pristis and Anthobothrium pristis, both inhabiting the spiral valve of largetooth sawfish in Central America. Other potential parasites include copepods , nematodes , protozoans , and trematodes . Areas of parasite inhabitation may include the skin , gills, and digestive tract.

Taxonomy

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Synonyms

Pristis pectinata Latham

Notes

Name Status: Accepted Name .

Last scrutiny: Data last modified by FishBase 18-Oct-2000

The genus Pristis is taxonomically chaotic with uncertainty regarding the true number of valid species (Compagno and Cook 1995a). The practical difficulties associated with resolving these taxonomic issues are acute, since it is extremely difficult to obtain specimens or tissue samples from these increasingly rare species for taxonomic research. This species may possibly have been misidentified as Pristis pectinata, whose distribution in the Indo-Pacific is uncertain. [4].

Similar Species

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The presence of a rostrum having laterally protruding teeth separates sawfishes from all other batoids (skates and rays).

The dwarf sawfish can be distinguished from sawsharks (Pristiophorus spp.) by its lack of barbels, ventrally located gills (versus laterally), and its similar-sized rostral teeth.

The dwarf sawfish is distinguished from the knifetooth sawfish (Anoxypristis cuspidata) by its sharply pointed rostral teeth (versus blade-like), the location of the first pair of rostral teeth near the rostral base, its unicuspidate dermal denticles along the body (versus tricuspidate or lack of denticles), its tapering and broad rostrum, and the lack of a well-developed lower caudal fin lobe.

The dwarf sawfish is distinguished from the freshwater sawfish (Pristis microdon) by the more posterior first dorsal fin position, the lack of a lower caudal fin lobe, and the spacing of the rostral teeth being slightly closer to each other towards the rostral tip (versus evenly spaced).

The dwarf sawfish is distinguished from the largetooth sawfish (Pristis perotteti) by its geographic range, and by the same characteristics that separate it from the freshwater sawfish (see above).

The dwarf sawfish is distinguished from the smalltooth sawfish (Pristis pectinata) by the fewer average number of rostral teeth per side (18-23, versus 20-34 per side), and the position of the first dorsal fin origin posterior to the pelvic fins.

The dwarf sawfish is distinguished from the green sawfish (Pristis zijsron) by the fewer number of rostral teeth per side (typically 18-23, versus 23-37 per side), the forward location of the first dorsal fin, and the second dorsal fin being smaller than the first dorsal fin. The dwarf sawfish also has a tapered rostrum and its inter-tooth space between the last two teeth is less than two times the inter-tooth space of the first two teeth.

In addition to the above characteristics, the dwarf sawfish is significantly smaller, on average, than any other sawfish species.

Members of the genus Pristis

ZipcodeZoo has pages for 12 species and subspecies in this genus:

P. cirratus (Longnose Saw Shark) · P. clavata (Dwarf Sawfish) · P. cuspidatus (Knifetooth Sawfish) · P. microdon (Largetooth Sawfish) · P. pectinata (Atlantic Prickly Skate) · P. pectinatus (Small-Tooth Common Sawfish) · P. peroteti (Large-Tooth Sawfish) · P. perotteti (Large-Tooth Sawfish) · P. perrotteti (Large-Tooth Sawfish) · P. pristis (Small-Toothed Sawfish) · P. pristis perotteti (Large-Tooth Sawfish) · P. zijsron (Narrowsnout Sawfish)

More Info

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Further Reading

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Notes

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Contributors

Data Sources

Accessed through GBIF Data Portal March 01, 2008:

Identifiers

Footnotes

  1. Compagno, L.J.V. and P.R. Last (1999). Pristidae. Sawfishes. p. 1410-1417. In K.E. Carpenter and V. Niem (eds.) FAO identification guide for fishery purposes. The Living Marine Resources of the Western Central Pacific. FAO, Rome. [back]
  2. Dulvy, N.K. and J.D. Reynolds (1997). Evolutionary transitions among egg-laying, live-bearing and maternal inputs in sharks and rays. Proc. R. Soc. Lond. B 264:1309-1315. [back]
  3. Last, P.R. and J.D. Stevens (1994). Sharks and rays of Australia. CSIRO, Australia. 513 p. [back]
  4. Cook, S.F., Compagno, L.J.V. & Last, P.R. 2006. Pristis clavata. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. <www.iucnredlist.org>. Downloaded on 04 February 2012. [back]
Last Revised: 2013-10-29