Japanese saw shark
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Japanese saw shark ( Pristiophorus japonicus ) |
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| Pristiophorus japonicus | ||||||||||||
| Günther , 1870 |
The Japanese saw shark ( Pristiophorus japonicus ) is a shark from the family of saw sharks (Pristiophoridae). Like its relatives, the shark is characterized by a long saw-like snout, which makes up up to 30 percent of the body length of this species. He lives in the northwestern Pacific off the coasts of Korea, northern China, Japan and Taiwan.
features
The Japanese saw shark reaches a length of 136 to 153 cm. The body is long, cylindrical and slim. The head is flattened and has a very elongated and flattened snout with a saw-like rostrum typical of saw sharks , which makes up between 26 and 30 percent of the body length of this species. The rostrum has a distinctive pair of barbels in front of the nostrils as well as 23 to 43 pronounced posterior teeth and up to 21 ventral teeth on the side edge of the "saw". The barbels in this species are close to the nostrils and thus closer to the mouth than to the tip of the saw; In front of the barbels there are 15 to 26 lateral and 9 to 14 ventral teeth and behind them 8 to 17 lateral and 8 to 9 ventral teeth. Young animals also have one or two small teeth between the larger side teeth, and they also have light-colored edges on the pectoral and dorsal fins.
The color of the top of its body ranges from solid brown to red-brown, the underside is white. There is a dark center line on the rostrum, at the same time the sides are colored darker.
The eyes are on the side of the head, behind them the large suction holes . Like other species of the genus, the sawshark has five gill slits . Like all saw sharks, it has two dorsal fins without a thorn and no anal fin . The tail stalk has clear keels, the tail consists only of a large upper lobe while the lower lobe is absent in all sawsharks.
Way of life
The Japanese saw shark is a type of ground shark. It feeds predatory on various fish and other soil organisms ( crustaceans , snails and squids ). 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 ). The females get up to 12 young animals in one litter. With a body length of about 98 to 100 cm, the animals are sexually mature.
distribution
The Japanese saw shark can be found in the northwestern Pacific off the coasts of Korea , northern China, Japan and Taiwan . Its habitat is in the area of the continental shelf near the sea floor over muddy and sandy bottom.
literature
- Leonard Compagno , Marc Dando, Sarah Fowler: Sharks of the World. Princeton Field Guides, Princeton University Press, Princeton and Oxford 2005; Pp. 132-133, ISBN 978-0-691-12072-0 .
- Albert Günther: Catalog of the Fishes in the British Museum. Volume Eighth, London 1870, p. 433 ( BHL ).
Web links
- Japanese saw shark on Fishbase.org (English)
- Pristiophorus japonicus inthe IUCN Red List of Threatened Species 2013.1. Posted by: Wang, Y., Tanaka, S. & Nakaya, K., 2008. Retrieved November 6, 2013.