Big humpback shrimp
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Great humpback shrimp ( Dikerogammarus villosus ) |
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| ( Sowinsky , 1894) |
The great humpback shrimp ( Dikerogammarus villosus ), originally described as Gammarus marinus var. Villosa , but later placed in the family of the Pontogammaridae , is a predatory flea shrimp up to 20 mm long . It only got its German name after it immigrated as a neozoon into almost all German water systems.
description
The great humpback shrimp grows up to 2 cm in length and is one of the larger representatives of the shrimp found in Central Europe. Its color is variable, white-yellowish to greenish and often provided with clear, dark bands. The antennae are reddish brown, the eyes red. Two conspicuous, conical bumps on the segments of the end of the back (urosome) were decisive for the German-language name. The hair on the flagellum of the second antennae is considerably longer than the individual limbs of the flagellum; the hair on the antenna base is loose. These features distinguish the great humpback shrimp from its relatives Dikerogammarus haemobaphes and Dikerogammarus bispinosus .
distribution
Originally distributed in the lower reaches of the rivers that flow into the Black Sea , for a long time it only populated the Danube up to the middle reaches. The cancer first appeared in 1992 in the German Danube, in 1993 in the Main-Danube Canal , in 1994 in the Main and in 1995 in the Rhine , via which it reached Lake Constance in 2002 . In 2007 he had already conquered the Upper Rhine to Stein am Rhein . In 1998 the species was detected in the Weser near Minden , in the Mittelland Canal , Elbe Lateral Canal , in the Elbe and in the Elbe-Havel Canal , already dominating in many canal sections. Today it is also widespread in the Elbe, with further occurrences in the Havel and Spree . The animal has now reached the Oder , has already penetrated into the Rhone system in the west and has been detected in Lake Garda in the south . In the meantime, the humpback shrimp is also widespread in some lakes in the foothills of the Alps, such as Lake Zurich. It was only discovered here in February 2006 and has apparently settled the whole lake unnoticed in a few years. In 2010 the species was also detected in Great Britain .
habitat
Large individuals are often found under stones or in cracks, where they wedge themselves with their splayed Peraeopods (sternum) III-V. It is common in colonies of the migrating mussel . Smaller individuals also colonize the near-surface algae felt of stones and sheet piling .
Way of life
The great humpback shrimp is omnivorous. It feeds predatory as a predator of Gammarus tigrinus (like itself a shrimp of the suborder Gammaridea ) and probably important predator of Chelicorophium curvispinum . Its rapid expansion is due to its great aggressiveness in the biotope , which has already led to a reduction in biodiversity and the local extinction of certain species. In addition to the predatory food, the great humpback shrimp can also live on dead plant remains.
Reproduction
The female carries the male, which is always larger, with her on her back before laying eggs (precopula). The female then lays the eggs in a brood chamber on the front side of the abdomen. After fertilization by the male, the eggs remain in this brood chamber until the finished crabs hatch. Like all flea shrimp, the great humpback shrimp care for the brood.
Individual evidence
- ↑ Uta Mürle, Andreas Becker and Peter Rey: A new flea shrimp in Lake Constance. Dikerogammarus villosus (Great humpback shrimp). 2003 PDF
- ↑ Vorarlberg: Cancers have to take the paternity test
- ↑ Large humpback shrimp: Distribution in Switzerland and the Rhone region
See also
Web links
- New flea cancer in northern German canals
- Dikerogammarus villosus - Killer Shrimp (PDF; 215 kB)
- Neozoa (macrozoobenthos) in German waters
- The great humpback shrimp. In: Fauna Europaea Database. European Commission under the Fifth Framework Program, accessed on February 27, 2010 .