Sphyrna

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Sphyrna
Great hammerhead shark (Sphyrna mokarran)

Great hammerhead shark ( Sphyrna mokarran )

Systematics
Subclass : Plate gill (Elasmobranchii)
without rank: Sharks (selachii)
Superordinate : Galeomorphii
Order : Ground Sharks (Carcharhiniformes)
Family : Hammerhead Sharks (Sphyrnidae)
Genre : Sphyrna
Scientific name
Sphyrna
Rafinesque , 1810

Sphyrna is a genus of hammerhead sharks (Sphyrnidae) that contains all species in the family with the exception of the winged hammerhead shark ( Eusphyra blochii ). It comprises eight species and is found on all subtropical and tropical coasts. Four species of this genus can alsobe foundin the Mediterranean .

Appearance and characteristics

The Sphyrna species are medium to large-sized sharks; the body lengths range from about 90 centimeters in the corona hammerhead shark ( Sphyrna corona ) to over 6 meters in the great hammerhead shark ( Sphyrna mokarran ). Characteristic is the hammer-like widening of the head ( cephalofoil ), at the ends of which are the eyes and at the front edge of which there is another effective sensory organ with the Lozenini ampoules . This head widening is between 17 and 33 percent of the total length of the species of this genus, and 40 to 50 percent of the winghead hammerhead shark ( Eusphyra blochii ). With the exception of the head shape, their habitus corresponds to that of the Requiem sharks (Carcharinidae) and, like them, have 5 gill slits while a spray hole is missing. They also have an anal fin and two dorsal fins , the front of which is larger than the rear.

Way of life

Bow-fronted hammerhead shark ( Sphyrna lewini )

Sphyrna species live mainly as shallow water species, especially above the continental shelf or in other shallow sea areas. The bow-forehead hammerhead shark ( Sphyrna lewini ) and the great hammerhead shark, on the other hand, can also be found in the open ocean in the pelagic region , although they are always close to the coast. All Sphyrna species feed primarily on bony fish , with the great hammerhead shark as an opportunistic hunter also attacking many other marine animals and eating carrion.

The sharks are viviparous and form a yolk sac placenta ( placental viviparous ).

distribution

Distribution areas of the great hammerhead
Distribution areas of the white-fin hammerhead

The hammerheads of the genus Sphyrna can be found in all tropical and subtropical coastal areas. Some species occur in very large areas, such as the great hammerhead shark, which is common in all tropical and subtropical coastal areas. Other species are restricted to regional distribution areas, for example the white-finned hammerhead shark ( Sphyrna couardi ) is only found on the Atlantic coasts of Europe and northwest Africa and the shovel-nosed hammerhead shark ( Sphyrna tiburo ) only on the tropical coasts of North and South America. The smallest area of ​​distribution has the corona hammerhead, which is distributed on the Pacific coast of America from the Gulf of California to Peru .

Systematics

The genus Sphyrna consists of eight recognized species:

The white-finned hammerhead shark ( Sphyrna couardi ), listed in older literature as an independent species , was synonymous with the bow-forehead hammerhead shark in 1986.

Individual evidence

  1. ↑ Alessandro De Maddalena, Harald Bänsch: Sharks in the Mediterranean. Franckh-Kosmos Verlag, Stuttgart 2005; Page 213–223. ISBN 978-3-440-10458-3
  2. ↑ Sphyrna on Fishbase.org (English)
  3. ↑ Sphyrna on Fishbase.org (English)
  4. ^ Leonard Compagno , Marc Dando, Sarah Fowler: Sharks of the World. Princeton Field Guides, Princeton University Press , Princeton / Oxford 2005, pp. 322–326 ISBN 0-691-12072-2
  5. ↑ a b Joseph M. Quattro, William B. III Driggers, James M. Grady, Glenn F. Ulrich, Mark A. Roberts: Sphyrna gilberti sp. nov., a new hammerhead shark (Carcharhiniformes, Sphyrnidae) from the western Atlantic Ocean. Zootaxa, 3702, 2, 2013 doi : 10.11646 / zootaxa.3702.2.5
  6. ^ LJV Compagno: Sharks of the world. An annotated and illustrated catalog of shark species known to date. Part 2. Carcharhiniformes. FAO Species Catalog for Fishery Purposes. Vol. 4. FAO, Rome 1984, pp. 545–547 ISBN 92-5-101383-7 (species portrait  ( page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. ).@1@ 2Template: Dead Link / ftp.fao.org  
  7. ↑ Martin, R. Aidan. (February 24, 1998). Recent Changes in Hammerhead Taxonomy. ReefQuest Center for Shark Research. Retrieved on October 18, 2008.

literature

Web links

Commons : Sphyrna  - collection of images, videos and audio files