Square tails
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| Systematics | ||||||||||||
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| Tetragonuridae | ||||||||||||
| Risso , 1810 | ||||||||||||
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| Tetragonurus | ||||||||||||
| Risso, 1810 |
The square tails ( Tetragonurus ), also called corner tails or square tails , are fish from the order of the Scombriformes . They live in all tropical and temperate parts of the world's oceans .
features
They are very slender, torpedo-shaped elongated fish. Their bodies are covered with diamond-shaped comb scales that are keeled. The tail stalk is long and has a keel on each side. Square tails have two dorsal fins , the hard rays of the first are shorter than the soft rays of the second. The second dorsal fin is directly opposite the anal fin . Adult animals still have their pelvic fins , which sit far in front, slightly behind the pectoral fins . Square tails are 50 to 70 centimeters long.
Fin formula : dorsal X – XX / 10–17, anal I / 10–16
Square tails eat rib jellyfish , jellyfish and salps . Because of the nettle poisons ingested, their meat is said to be toxic. Young fish live in the protection of jellyfish or salps.
species
- Tetragonurus atlanticus Lowe, 1839 .
- Tetragonurus cuvieri Risso , 1810 .
- Tetragonurus pacificus Abe, 1953 .
Fossil record
A fossil corner tail ( Tetragonurus sp.) Is known from the Pliocene of the Marecchia (northern Italy).
Individual evidence
- ^ Karl Albert Frickhinger: Fossil Atlas of Fishes. Mergus - Verlag für Natur- und Heimtierkunde Baensch, Melle 1991, ISBN 3-88244-018-X .
literature
- Joseph S. Nelson : Fishes of the World. 4th edition. John Wiley & Sons, Hoboken NJ et al. 2006, ISBN 0-471-25031-7 .
- Kurt Fiedler: Fish (= textbook of special zoology. Vol. 2: Vertebrates. Part. 2). Gustav Fischer, Jena 1991, ISBN 3-334-00338-8 .
Web links
- Square tails on Fishbase.org (English)