Swordfish
| Swordfish | ||||||||||||
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Saw-sword fish ( Assurger angac ), note the tail fin, which is only millimeter-sized! |
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| Systematics | ||||||||||||
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| Scientific name of the genus | ||||||||||||
| Assurger | ||||||||||||
| Whitley , 1933 | ||||||||||||
| Scientific name of the species | ||||||||||||
| Assurger angac | ||||||||||||
| ( Alexander , 1917) |
The saw-sword fish ( Assurger angac ) is a rather rare representative of the hairtail (Trichiuridae). It belongs to the subfamily Lepidopodinae (that is, that their "ventral fins are scale-shaped"), in which the caudal fin is either very tiny or completely reduced. The fish is longer, but more elongated and narrower than the black scabbard fish (which is in the subfamily Aphanopodinae). Assurger is monotypical .
features
The fish becomes 2.5 m long; it is light silver with a blue sheen. There may be a black spot on the front end of the dorsal fin membrane. The body is 25 to 28 times longer than high, but very narrow and band-shaped. The head takes up 7–8% of the total length. The spine consists of 125–130 elements. The dorsal fin is very low, consists of several free rays at the front and extends from the back of the head to the tapering rear end, on which there is still a millimeter-sized but bilobed caudal fin. The anal fin is even lower in the front section. All rays are undivided, but quite soft. The dorsal keel marked by the dorsal fin continues on the head to the muzzle. The mouth is quite small, the lower jaw protrudes a little; Both jaws have small connective tissue extensions at the front end and are covered with smaller fangs (those at the front end of the premaxillary are larger). The sideline shows a normal course.
Fin formula : D 116-123, A 76-90. P 10-12. V: Rudiment present as a small thorn.
distribution
Assurger has so far been proven in the area of continental and island slopes: in the Atlantic Ocean along the whale ridge , off Puerto Rico and off Uruguay ; in the Indian Ocean off Western Australia ; in the Pacific off New Guinea , southern Japan , the Midway Islands , near Hawaii , off California , in the area of the Nazca Ridge and the Salas-y-Gómez Ridge .
Behavior and meaning
The light coloring and the (smaller) eyes show that Assurger lives meso-, mostly bathypelagic (up to about 400 m depth), the young, however, epipelagic, i.e. near the surface. In the larvae and juvenile fish, as is common with the Trichiuridae and the closely related Gempylidae , the V-spines are still long and the D are high (Richards 2006). There are still no relevant live observations for the sawfish. The very tiny caudal fin naturally raises the question of whether it is “already completely inoperable” or not still serving a particularly “devious” propulsion (cf. Aphanopus carbo ). In food tests, the fish had small fish (e.g. anchovies) and squids in the stomach. It is only caught randomly on fishing rods or in trawls and is then considered edible. Due to the general devastation of marine biotopes, it could also be endangered.
literature
- Izumi Nakamura, Nikolaj V. Parin: Snake mackerels and cutlassfishes of the world. An annotated and illustrated catalog of the Snake Mackerels, Snoeks, Escolars, Gemfishes, Sackfishes, Domine, Oilfish, Cutlassfishes, Scabbardfishes, Hairtails, and Frostfishes known to date (= FAO Species Catalog. Vol. 15 = FAO Fisheries Synopsis. No. 125 , Vol. 15). Food and Agriculture Organization of the United Nations, Rome 1993, ISBN 92-5-103124-X .
- Francisco J. Neira, Anthony G. Miskiewicz, Thomas Trnski: Larvae of Temperate Australian Fishes. Laboratory Guide for Larval Fish Identification. University of Western Australia Press, Nedlands 1998, ISBN 1-876268-17-4 .
- William J. Richards (Ed.): Early Stages of Atlantic Fishes. An Identification Guide for the Western Central North Atlantic. 2 volumes. CRC Taylor & Francis, Boca Raton FL et al. 2006, ISBN 0-8493-1916-1 .
Web links
- Saw sword fish on Fishbase.org (English)
Single receipts
- ↑ To the names: (English) razorback scabbardfish, also "Razor-back-Degenscheiden-Fisch"; (Spanish) sable aserrado, "saw-sword" (always meant is a warrior [but of course there is no sawn sword ], no stabbing sword); " Anzac " is probably an anagram of Nazca , where the fish was apparently discovered, which the British-Australian ornithologist and zoologist Wilfred Backhouse Alexander, 1885–1965, first described at the museum in Perth in 1917 as Evoxymetopon anzac ; " Assurger " (coined in 1933 by the British-Australian ichthyologist Gilbert Percy Whitley, 1903–1975, at the Museum in Sydney) is, so to speak, "American (here: Australian) Latin": assurgere = adsubrigere "to rise", (here, for example :) to swim up ; the associated (classic) action noun would be “ assurrector ”, float.