Sawshark
Japanese saw shark ( Pristiophorus japonicus )
The Sägehaie ( Pristiophoridae ) family is a family of sharks, which in turn consists of two genera, Pliotrema and Pristiophorus, there. Without further relatives they form at the same time one of the eight orders of sharks, the Sägehaiartigen ( Pristiophoriformes ).
Dissemination
The previously known species live mainly in the western Atlantic, in Cuba, Florida and the Bahamas, in the southwest Indian Ocean in South Africa and the Western Pacific from Australia to Japan.
Features
Sägehaie form one of the most original groups of sharks and their external shape with the elongated, blade type Rostrum can easily lead to confusion with the sawfish, but which are counted among the rays and different from those of the Sägehaie by the two barbels on each side of the saw and that the gill slits are not due to the fact on the underside of the body. The flat saw is alternately filled with large and small teeth, which are replaced regularly. Most species are not more than one and a half meters, the largest up to 140 centimeters in length, the Sechskiemer - saw shark. As the angel sharks also have the Sägehaie two stingless dorsal fins, no anal fin, and large spray holes.
Way of life
Sägehaie feed on small fish, crustaceans and squid and multiply ovoviviparous. Much of their behavior and their circumstances is not explored until now.
Search for food, the long rostrum is used, which is equipped with barbels and other sense organs and thereby moves and probably can perceive electric fields and chemical impressions in the seabed. The prey is tracked with the saw, dug and probably partly also killed. In addition, it is used by some Sägehaien against an attacker and against conspecifics.
Genera and species
There are two species, one of which is typically mono-, and eight types described. The genera differ in the number of gill openings as well as in the construction of the teeth. Pliotrema has six gill slits, the larger Rostralzähne are sawed, the teeth reinforced by transverse surveys. In Pristiophorus the teeth are smooth, the large Rostralzähne remain small, there are only five gill slits.
Compagno et al. 2004 mention nine species in two genera, the genus Pliotrema only one species ( monotypic genus ) and the genus Pristiophorus eight species, of which four undescribed contains. Three of these species have since been described. The first, the Tropical saw shark was described in 2008 by Yearsley, load, and White, another, the dwarf saw shark off the coast of East Africa. was described in 2011 by Ebert and Cailliet, and the third, the Philippine saw shark, was described in 2013, while the Australian Eastern saw shark is still undescribed and is currently conducted according to Compagno as Pristiophorus species A.
- Pliotrema ( Regan, 1906) Sechskiemer - saw shark ( Pliotrema warenni ( Regan, 1906) )
- Longnose saw shark ( Pristiophorus cirratus ( Latham, 1794) )
- Tropical saw shark ( Pristiophorus delicatus Yearsley, load & White, 2008)
- Japanese saw shark ( Pristiophorus japonicus ( Günther, 1870) )
- Philippine saw shark ( Pristiophorus lanae Ebert & Wilms, 2013)
- Dwarf saw shark ( Pristiophorus nancyae ) Ebert & Cailliet, 2011
- Short nose saw shark ( Pristiophorus nudipinnis ( Günther, 1870) )
- Bahamas saw shark ( Pristiophorus schroederi ( Springer & Bullis, 1960) )
- Australian Eastern saw shark ( Pristiophorus species A; unwritten)