Crayfish

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Crayfish
Noble crayfish (Astacus astacus)

Noble crayfish ( Astacus astacus )

Systematics
Sub-stem : Crustaceans (Crustacea)
Class : Higher crabs (Malacostraca)
Order : Decapods (decapoda)
Subordination : Pleocyemata
Partial order : Large crayfish (Astacidea)
Superfamily : Crayfish
Scientific name
Astacoidea
Latreille , 1802
Jackdaw Shrimp ( Austropotamobius pallipes )
Eryma mandelslohi , Upper Brown Jura

The crayfish superfamily is a taxon of the higher crayfish (Malacostraca). This family includes the noble crayfish , also known as the European crayfish.

All species that belong to this superfamily are characterized by a similar structure of the body in the head-chest area (front body) and the structured abdomen. Both are covered by a thick carapace . There are five pairs of legs on the front body, the front of which has been transformed into large scissors. The rest of the legs serve as walking legs with gills hanging on them, with which the crayfish breathes.

Way of life

Crayfish are crepuscular and nocturnal . Most species are solitary. As they are sensitive to pollution in their habitat, crayfish are, within certain limits, an indicator of the biological water quality of a site.

nutrition

Crayfish grab prey with their large claws. The smaller claws of the second and third pair of legs cut the prey and lead it to the mouth.

Crayfish are omnivores : They catch aquatic insects, worms , newts , mussels and fish if they can be captured. Sick fish and carrion are easier to get than healthy animals, which is why they are more often on the menu of crayfish. Crayfish do not shy away from eating conspecifics that have temporarily become defenseless due to molting . But they also like to eat water plants, autumn leaves, algae and moldy wood.

Systematics

The crayfish as a whole are divided into four families: the species of the northern hemisphere into the families Astacidae, Cambaridae and Cambaroididae and those of the southern hemisphere into the family Parastacidae . Astacidae are found in Europe, Canada and the USA. Cambaridae live in North America and have also been introduced in Europe. Cambaroididae occur in northern East Asia. Parastacidae are common in Australia, New Zealand, New Guinea, Madagascar, and South America.

The large crabs of the Astacidea living in fresh water form a monophyletic group; this indicates that the transition to fresh water occurred only once. The southern group of Parastacidae was separated from the northern groups after the disintegration of the supercontinent Pangea . The Parastacidae are therefore placed in their own superfamily, the Parastacoidea. Astacidae, Cambaridae and Cambaroididae then form the superfamily Astacoidea.

The position of the East Asian genus Cambaroides was problematic and puzzling for a long time . In various studies, this was either the closest related to the Cambaridae or the Astacidae, and then included in one of these families, or it was a sister group to both. According to recent genetic studies, it is probably the sister group of the Astacidae. Because of this problematic history, it is now, as the only genus, placed in its own family Cambaroididae.

The families are listed in the following list with some of the species listed as examples:

Fossil is also known to the family of the Cricoidoscelosidae. The only species is Cricoidoscelosus aethus Taylor, Schram & Shen 1999. This was found in the Chinese Jehol group , which is placed either in the Upper Jurassic or in the Cretaceous period.

literature

  • Christoph Chucholl, Peter Dehus: Crayfish in Baden-Württemberg. Biology, distribution, endangerment, protection . Fisheries Research Center Baden-Württemberg (FFS), Langenargen 2011, 92 pages.

Individual evidence

  1. ↑ Sammy De Grave, N. Dean Pentcheff, Shane T. Ahyong et al .: A classification of living and fossil genera of decapod crustaceans . In: Raffles Bulletin of Zoology . Supplement No. 21. 2009, p. 1–109 ( pdf 7.73 MB [accessed February 18, 2012]).
  2. ↑ Keith A. Crandall & Sammy De Grave (2017): An updated classification of the freshwater crayfishes (Decapoda: Astacidea) of the world, with a complete species list. Journal of Crustacean Biology 37 (5): 615-653. doi: 10.1093 / jcbiol / rux070

Web links

Commons : Astacidea  - collection of images, videos and audio files