Eucarids ( lat. Eucarida ) - superorder of crustaceans from the class of higher crayfish (Malacostraca). Eucarides include decapods , euphausiaids and amphionidacs . They are characterized by carapace , covering all the thoracic segments, and the peculiarities of the movement of the stalked eyes .
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 Meganyctiphanes norvegica, north krill | |||||||||||||||||||||||||
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Eucarida Calman , 1904 | |||||||||||||||||||||||||
Units
Eucarids are extremely diverse and rich in species. Three units are distinguished among them:
Euphausiaids
Representatives of the euphausiae group are collectively called krill . These are marine shrimp-like organisms whose abdominal limbs ( pleopods ) function as swimming limbs. They live in large schools and feed mainly on plankton . This group includes only about 90 species, but some of these species are among the most numerous on the planet. Indeed, it is estimated that the total biomass of Antarctic krill Euphausia superba is 500 million tons.
Decapods
Detachment decapods has 15 thousand species. Representatives of this detachment have 5 pairs of chest limbs and a well-developed carapace , covering the gills . The decapods include crabs , lobsters and shrimp . The structure of the gills of decapods is divided into suborders Dendrobranchiata and Pleocyemata , and these taxa, in turn, are divided into several infraorders: real shrimp ( Caridea ), spear shrimp ( Stenopodidea ), half-tailed crayfish ( Anomura ), and other crabs ( Brachychy .
Amphionidacea
In addition, there is one mysterious species of eucarids, Amphionides reynaudii , which is the only representative of the order Amphionidacea ; due to the loss of some characteristic features caused by small sizes, for a long time its systematic position remained unclear.
Phylogeny
The phylogeny of eucarids remains largely controversial. In particular, the monophilia of this taxon is in question:
- Monophyletic : many scientists hold the view that eucarids are a treasure, sister Peracarida or generally higher cancers or mysids (paraphyletic group Schizopoda).
- Paraphyletic : some argue that the paraphyletic group of the eucaris formed as a treasure with Peracarida .
- Polyphyletic : some combined the euphausiae with mysids , forming Schizopoda , or the euphausiae with hoplocarids and decapods , forming Peracarida .
Links
- WoRMS. Eucarida (Inaccessible link) . World Register of Marine Species (2010). Date of treatment February 7, 2011. Archived on April 28, 2011.
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