Regalecus glesne
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A belt fish washed up on the Pacific coast of the USA in 1996 |
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| Scientific name | ||||||||||||
| Regalecus glesne | ||||||||||||
| Ascanius , 1772 |
Regalecus glesne is a kind from the family of oarfish (Regalecidae). It is the longest bony fish species in the world. In English, Regalecus glesne is referred to as "King of herrings" and in Swedish synonymously as "Sillkung". In German, however, "Heringskönig" means the Petersfisch ( Zeus faber ).
features
Regalecus glesne is elongated in the shape of a ribbon, strongly flattened on the sides and can reach a length of eight meters and a maximum weight of about 270 kg. Most of the specimens found were less than five meters in length. Reports of specimens 10 or 11 meters long are based on parts of the fore bodies in which the missing rear body has been incorrectly extrapolated by comparison with juvenile specimens . A carcass found on Stronsay Beach in 1808 , which is the basis for reports of 15 or 16 meter long oyster fish, was a badly rotted basking shark ( Cetorhinus maximus ).
Regalecus glesne has 127 to 163 vertebrae, of which 45 to 56 are trunk vertebrae (the closely related Regalecus russelii has 113 to 122 or 34 to 37). The fish is silvery, with blue horizontal stripes and small black dots. The ridges on the head, which are up to one meter high and thickened at the end, are reddish in color. The first ridge is formed by 6 to 8 fin rays connected by a fin membrane (3 to 6 in Regalecus russelii ), the second by 5 to 11 fin rays (a single one in Regalecus russelii ). This is not connected to the anterior ridge or the dorsal fin by a fin membrane. The dorsal fin begins above the back of the head, extends to the tail and thus extends over the entire length of the fish's body. It is supported by 414 to 449 soft rays (333 to 371 in Regalecus russelii ). 90 to 120 of these soft rays are located above the abdomen (less than 82 in the case of Regalecus russelii ). With its undulating movements, the dorsal fin is the main organ for the fish to move. An anal fin is missing, the caudal fin, which is only present in juvenile fish, is small and has four, or more rarely three, long fin rays. The long pectoral fins consist of a single fin ray, the pectoral fins are supported by 11 to 14 fin rays and have a base oriented horizontally to the body axis, so that when placed on the body, they are directed vertically upwards. Large, fully grown fish have 33 to 47 long, bristly gill rakes on the first gill arch (47 to 60 in Regalecus russelii ).
The mouth is toothless and can be pushed forward far (protractile). At the end of the stomach there is a long appendix that extends to the end of the body. The muscle segments of the trunk muscles, in addition to the horizontal, vertical and transversal intermuscular septa of most of the remaining teleostei, are divided by up to three further dorsal horizontal and three further ventral horizontal septa.
Regalecus glesne is capable of self-amputation ( autotomy ). A rear part of the body, e.g. B. the caudal fin, alone or with one or two posterior vertebrae, shed. With increasing age, more and more body sections are shed in the course of a serial autotomy and all specimens that are longer than 1.5 meters have a blunt body end that has been shortened by autotomy. The autotomy does not damage any vital organs and it can only be performed just before the anus. The body parts that are thrown off are never regenerated. There may be a connection between the self-amputation and a lack of food.
Way of life
Regalecus glesne lives in the open ocean at depths of 200 to 20 meters, but can also be found up to a depth of 1000 meters. The species occurs worldwide in all oceans, including the Mediterranean, but has an antitropical distribution, that is, it avoids warm tropical waters between 15 ° north and 15 ° south latitude. Beltfish observations in the tropics are mostly the smaller sister species Regalecus russelii . Underwater photos showed Regalecus glesne with an elongated, stiff body, standing vertically, with the head up and slowly swimming with the undulating dorsal fin. The fish may adopt this posture in order to be able to better make out the silhouette of their prey, which mainly consists of luminous shrimp , other crustaceans and small fish, against the background of the bright water surface. Regalecus glesne is often found in groups of two or three animals, but never in a swarm. It can be observed how the head crests formed by the anterior dorsal fin rays are held vertically upwards and the long pelvic fins are stretched horizontally away from the body. The fish likely spawn between July and December, in the western Atlantic on the coast of North America and the west coast of Florida, in the Mediterranean in the Strait of Messina and in the South Pacific around New Zealand's Chatham Islands, and in southeastern Indic on the west coast of southern Australia. Larvae can be found near the ocean surface.
Systematics
The first scientific description of Regalecus glesne was provided by Peter Ascanius , a pupil of Carl von Linné , in 1772. Together with Regalecus russelii , Regalecus glesne forms the genus Regalecus and together with Agrostichthys parkeri the two species form the belt fish family (Regalecidae), which the largest representatives of the gloss fish-like (Lampriformes) are.
Synonyms of Regalecus glesne are: Regalecus banksii (Valenciennes, 1835) , R. jonesii Newman, 1860 , R. masterii De Vis, 1892 , R. pacificus Haast, 1878 and R. remipes Brünnich, 1788 .
literature
- Tyson R. Roberts : Systematics, Biology, and Distribution of the Species of the Oceanic Oarfish Genus Regalecus (Teleostei, Lampridiformes, Regalecidae). Mémoires du Muséum national d'histoire naturelle , Paris 2012, ISBN 978-2-85653-677-3 .
- MC Benfield, S. Cook, S. Sharuga, MM Valentine: Five in situ observations of live oarfish Regalecus glesne (Regalecidae) by remotely operated vehicles in the oceanic waters of the northern Gulf of Mexico. In: Journal of Fish Biology. 83, 2013, pp. 28-38. (Video on YouTube)
Individual evidence
- ↑ a b Craig R. McClain, Meghan A. Balk, Mark C. Benfield, Trevor A. Branch, Catherine Chen, James Cosgrove, Alistair DM Dove, Lindsay C. Gaskins, Rebecca R. Helm, Frederick G. Hochberg, Frank B. . Lee, Andrea Marshall, Steven E. McMurray, Caroline Schanche, Shane N. Stone, Andrew D. Thaler. Sizing ocean giants: patterns of intraspecific size variation in marine megafauna. In: PeerJ . 2, 2015, p. E715 doi: 10.7717 / peerj.715
Web links
- Regalecus glesne on Fishbase.org (English)