Lantern sharks

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Lantern sharks
Small black dogfish (Etmopterus spinax), caught near Sardinia.

Small black dogfish ( Etmopterus spinax ), caught near Sardinia .

Systematics
Subclass : Euselachii
Subclass : Plate gill (Elasmobranchii)
without rank: Sharks (selachii)
Superordinate : Squalomorphii
Order : Spiny dogfish (Squaliformes)
Family : Lantern sharks
Scientific name
Etmopteridae
Fowler , 1934

The lantern sharks (Etmopteridae) are a family of small sharks from the order of the dogfish-like (Squaliformes). They occur in parts of the Atlantic , Pacific and Indian Oceans at depths of 50 to 4500 meters and mostly live on continental slopes , less often on the continental shelf or in the open ocean. They prefer tropical to temperate regions, only in the North Atlantic they occur as far as Iceland . With over 50 species described, the lantern sharks are the most species-rich family of dogfish-like species. Very little is known about their way of life. Only the lesser black dogfish ( Etmopterus spinax ), which occurs on the Atlantic coasts of Europe and in the Mediterranean and is also quite common in the deep areas of the northern North Sea, has been relatively well researched.

features

Most species do not even reach a length of 90 centimeters, the largest is Centroscyllium fabricii , which is a maximum of 1.07 meters long. With the dwarf lantern shark ( Etmopterus perryi ) and the cylindrical lantern shark ( E. carteri ), which are only 16 to 20 centimeters long and weigh around 150 grams, the smallest known shark species belong to the lantern sharks. Lantern sharks have two dorsal fins , each preceded by a stinger with a distinct furrow. One anal fin is missing. The tail fin stalk is without lateral keels and without dorsal and / or ventral indentations. The caudal fin has a notch at the bottom. Most species have luminous organs . In addition to the lantern sharks, light organs in sharks are only known to exist in some species of the Dalatiidae . The luminous organs of the lantern sharks are located on the mostly darker belly side and create a greenish sheen that camouflages the fish from below against the bright sea surface. In addition, some species have clearly visible luminous organs on the sides and on the tail. They are probably used for species identification and to keep the swarm together. The skin of the lantern sharks is more or less densely covered with bumpy or conical placoid scales. Like the other species of the dogfish-like order, the lantern sharks are viviparous ( ovoviviparous ).

Centroscyllium fabricii
Centroscyllium granulatum
Dwarf lantern shark ( Etmopterus perryi )

Internal system

There are four genera and over 50 species . The genera are mainly differentiated on the basis of their teeth.

The following cladogram shows the relationship between the genera and the Etmopterus species.

 Etmopteridae 


Centroscyllium


   

Aculeola



   

Trigonognathus


   
 Etmopterus 

Clade II ( E. baxteri, E. granulosus, E. dianthus, E. princeps, E. spinax, E. unicolor )


   

Clade III ( E. gracilispinis, E. polli, E. schultzi, E. virens )



   




E. sheikoi


   

Clade V ( E. brachyurus, E. molleri )



   

Clade VI ( E. dislineatus, E. lucifer )




   

Clade VII ( E. bigelowi, E. fuscus, E. pseudosqualiolus, E. pusillus, E. sentosus )






Tribal history

The fossil record of the lantern sharks is sparse. Only fossil teeth are known and complete fossils are completely absent. The oldest teeth, which can be unequivocally assigned to the lantern sharks, come from the Lutetium , a stage of the Eocene between 48.6 and 40.4 million years ago. They are very similar to the teeth of recent species. Other shark teeth that were assigned to the lantern sharks are known from the chalk . They were described as Eoetmopterus , Proeoetmopterus and Microetmopterus , but show only a slight resemblance to the teeth of today's species and disappear towards the Cretaceous-Tertiary border .

literature

Individual evidence

  1. ^ Alfred Goldschmid: Chondrichthyes. In: W. Westheide, R. Rieger: Special Zoology. Part 2. Vertebrate or skull animals. Spektrum, Munich 2004, ISBN 3-8274-0307-3 , p. 199.
  2. ^ Leonard Compagno, Marc Dando, Sarah Fowler: Sharks of the World. Princeton Field Guides, Princeton University Press, Princeton / Oxford 2005, ISBN 978-0-691-12072-0 , p. 103.
  3. ↑ Nelson, 2006.
  4. ↑ a b c Straube, Iglésias, Sellos, Kriwet, Schliewen: Molecular phylogeny and node time estimation of bioluminescent Lantern Sharks (Elasmobranchii: Etmopteridae). In: Phylogenetics and Evolution. Vol. 56, No. 3, September 2010, pp. 905-917, doi : 10.1016 / j.ympev.2010.04.042 .

Web links

Commons : Lantern Sharks (Etmopteridae)  - Collection of images, videos and audio files