Pristiophorus
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Short-nosed saw shark ( Pristiophorus nudipinnis ) |
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| Pristiophorus | ||||||||||||
| Müller & Henle , 1837 |
The genus Pristiophorus is one of two genera of saw sharks (Pristiophoridae). The species are characterized by a long saw-like snout that sometimes makes up 30 percent of the total length of the animals.
features
The species of the genus Pristiophorus are long, cylindrical and slender. The maximum body lengths range from about 60 cm for the dwarf saw shark to over 130 cm for the long-nosed saw shark . The head is flattened and has a greatly elongated and flattened snout with a typical saw-like rostrum , which, depending on the species, can make up 20 to over 30% of the body length. The rostrum has a distinctive pair of barbels in front of the nostrils as well as pronounced lateral and ventral teeth on the edge of the rostrum . In comparison to the adult animals, young animals usually have one to three small teeth between the large posterior teeth.
The eyes are on the side of the head, behind them the large suction holes . In contrast to the six- gill saw sharks ( Pliotrema ) members of the genus Pristiophorus have five gill slits . All saw sharks have two dorsal fins without thorns and no anal fin. The caudal peduncle has distinct keels and the tail consists only of a large upper lobe, while the lower lobe is absent.
Way of life
The saw sharks of the genus Pristiophorus are ground shark species that can occur from the coastal area in the tidal zone to the deep sea. They predatorily feed on various fish , and they also hunt crustaceans , snails and octopuses . The long rostrum is used to search for food, which is equipped with barbels and other sensory organs and can therefore perceive movements and probably also electrical fields and chemical impressions in the sea floor. The prey is tracked down with a saw, dug up and probably also partly killed. In addition, the saw shark also uses them against attackers and conspecifics.
The sharks are viviparous and do not form a placenta (aplacentally viviparous ).
distribution
All species of saw sharks can only be found in relatively limited distribution areas.
Species of the genus Pristiophorus occur mainly off the coast of Australia, where four of the known species have been described. The Japanese saw shark is another species that lives in the coastal areas off Taiwan and Japan, while the Bahamas saw shark in deep-sea areas of the Caribbean and the dwarf saw shark off the coast of Mozambique , Somalia and Pakistan.
Systematics
The genus Pristiophorus forms together with the monotypical genus Pliotrema , which only contains the six- gill saw shark ( Pliotrema warenni ), the only family in the order of the saw sharks (Pristiophoridae or Pristiophoriformes).
Compagno et al. (2005) distinguish eight Pristiophorus species, four of which are undescribed. Three of these species have now been described : in 2008 the tropical saw shark , in 2011 the dwarf saw shark off the coast of East Africa and most recently in 2013 the Philippine saw shark . In contrast, the "East Australian saw shark", which was formerly known informally by the IUCN under the name " Pristiophorus peroniensis ", is probably identical to the long-nosed saw shark ( Pristiophorus cirratus ).
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Pristiophorus
Müller & Henle , 1837
- Long-nosed saw shark ( Pristiophorus cirratus ( Latham , 1794))
- Tropical sawshark ( Pristiophorus delicatus Yearsley, Last & White , 2008)
- Japanese sawshark ( Pristiophorus japonicus Günther , 1870)
- Philippine sawshark ( Pristiophorus lanae Ebert & Wilms , 2013)
- Dwarf sawshark ( Pristiophorus nancyae Ebert & Cailliet , 2011)
- Short-nosed saw shark ( Pristiophorus nudipinnis Günther , 1870)
- Bahamas saw shark ( Pristiophorus schroederi Springer & Bullis , 1960)
Individual evidence
- ^ Compagno et al .: Sharks of the World. 2005 (see literature )
- ^ A b Gordon K. Yearsley, Peter R. Last, William T. White: A new species of sawshark, Pristiophorus delicatus sp. nov. (Pristiophoriformes: Pristiophoridae), from northeastern Australia. In: PR Last, WT White, JJ Pogonoski: Descriptions of New Australian Chondrichthyans. CSIRO Marine and Atmospheric Research Paper No. 022. 2008, pp. 23–38, PDF (complete volume, 13 MB).
- ↑ DA Ebert, GM Cailliet: Pristiophorus nancyae , a New Species of Sawshark (Chondrichthyes: Pristiophoridae) from Southern Africa. Bulletin of Marine Science. Vol. 87, No. 3, 2011, pp. 501-512, doi : 10.5343 / bms.2010.1108 .
- ↑ David A. Ebert, Hana A. Wilms: Pristiophorus lanae sp. nov., a new sawshark species from the Western North Pacific, with comments on the genus Pristiophorus Müller & Henle, 1837 (Chondrichthyes: Pristiophoridae). Zootaxa . Vol. 3752, No. 1, 2013, pp. 86-100, doi : 10.11646 / zootaxa.3752.1.7 .
literature
- Leonard Compagno, Marc Dando, Sarah Fowler: Sharks of the World. Princeton Field Guides, Princeton University Press, Princeton and Oxford 2005; Pp. 131-136, ISBN 978-0-691-12072-0 .
