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Eumalacostraca

(Subclass)

Overview

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The Eumalacostraca are a subclass of crustaceans, containing almost all living malacostracans, about 40,000 described species.1] The remaining subclasses are the Phyllocarida and possibly the Hoplocarida or mantis shrimps.[2]

Eumalacostracans have 19 segments (5 cephalic, 8 thoracic, 6 abdominal). The thoracic limbs are jointed and used for swimming or walking. The common ancestor is thought to have had a carapace, and most living species possess one, but it has been lost in some subgroups.

Classification

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Martin and Davis present the following classification of living eumalacostracans into orders, to which extinct orders have been added, indicated by ?.[2]

The group as originally described by Karl Grobben[3] included the Stomatopoda (mantis shrimp), and some modern experts continue to use this definition. This article follows Martin and Davis in excluding them; they are placed in their own subclass, Hoplocarida.

Subclass Eumalacostraca Grobben, 1892

>Superorder Syncarida Packard, 1885
  • Superorder Peracarida Calman, 1904
    • Order Spelaeogriphacea Gordon, 1957
    • Order Thermosbaenacea Monod, 1927
    • Order Lophogastrida Sars, 1870
    • Order Mysida Haworth, 1825
    • Order Mictacea Bowman, Garner, Hessler, Iliffe & Sanders, 1985
    • Order Amphipoda Latreille, 1816
    • Order Isopoda Latreille, 1817 (pillbugs, sowbugs, woodlice)
    • Order Tanaidacea Dana, 1849
    • Order Cumacea Kr?yer, 1846
  • Superorder Eucarida Calman, 1904
    • Order Euphausiacea Dana, 1852
    • Order Amphionidacea Williamson, 1973
    • Order Decapoda Latreille, 1802 (crabs, lobsters, shrimp)

    • References

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    1. ^ Gary C. B. Poore (2002). "Introduction". Crustacea: Malacostraca. Zoological catalogue of Australia. 19.2A. CSIRO Publishing. pp. 1?7. ISBN 9780643069015. http://books.google.co.uk/books?id=ww6RzBz42-4C&pg=PA1. 
    2. ^ a b J. W. Martin & G. E. Davis (2001) (PDF). An Updated Classification of the Recent Crustacea. Natural History Museum of Los Angeles County. pp. 132 pp. http://atiniui.nhm.org/pdfs/3839/3839.pdf. 
    3. ^ C. Grobben (1892). "Zur Kenntnis des Stammbaumes und des Systems der Crustaceen". Sitzungsberichte der Kaiserlichen Akademie der Wissenschaften, Vienna. Mathematisch-naturwissenschaftliche Classe 101: 237?274. 

    Taxonomy

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    The Subclass Eumalacostraca is a member of the Class Crustacea. Here is the complete "parentage" of Eumalacostraca:

    The Subclass Eumalacostraca is further organized into finer groupings including:

    Orders

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    Amphionidacea

    Amphionides reynaudii is the sole representative of the order Amphionidacea, and is a small (less than one inch long) planktonic crustacean found throughout the world's tropical oceans, mostly in shallow waters. [more]

    Amphipoda

    Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. The name amphipoda refers to the different forms of appendages, unlike isopods, where all the thoracic legs are alike. Of the 7,000 species, 5,500 are classified into one suborder, Gammaridea. The remainder are divided into two or three further suborders. Amphipods range in size from 1 to 340 millimetres (0.039 to 13 in) and are mostly detritivores or scavengers. They live in almost all aquatic environments; 750 species live in caves and the order also includes terrestrial animals and sandhoppers such as Talitrus saltator. [more]

    Anaspidacea

    Anaspidacea is an order of crustaceans, comprising eleven genera in four families. Species in the family Anaspididae vary from being strict stygobionts (only living underground) to species living in lakes, streams and moorland pools, and are found only in Tasmania. is found in Tasmania and the south-eastern part of the Australian mainland, where they live in the burrows made by crayfish and in caves. The families Psammaspididae and Stygocarididae are both restricted to caves, but Stygocarididae has a much wider distribution than the other families, with Parastygocaris having species in New Zealand and South America as well as Australia; two other genera in the family are endemic to South America, and one, Stygocarella, is endemic to New Zealand. [more]

    Bathynellacea

    Bathynellacea is an order of crustaceans which live interstitially in groundwater. Some species can tolerate low salt concentrations, and at least one African species is a thermophile, living in hot springs and tolerating temperatures up to 55 ?C (131 ?F). Bathynellaceans are minute, blind, worm-like animals with short, weak legs, reaching a maximum size of 3.4 millimetres (0.13 in). They are found on every continent except Antarctica, although they are missing from some islands, including Fiji, New Caledonia and the Caribbean islands. There are two families, and Parabathynellidae; a third family, "Leptobathynellidae", is considered a synonym of Parabathynellidae. [more]

    Cumacea

    Cumacea is an order of small marine crustaceans, occasionally called hooded shrimp. Their unique appearance and uniform body plan makes them easy to distinguish from other crustaceans. [more]

    Decapoda

    The decapods or Decapoda (literally "ten-footed") are an order of crustaceans within the class Malacostraca, including many familiar groups, such as crayfish, crabs, lobsters, prawns and shrimp. Most decapods are scavengers. It is estimated that the order contains nearly 15,000 species in around 2,700 genera, with approximately 3,300 fossil species. Nearly half of these species are crabs, with the shrimp (?3000 species) and Anomura (including hermit crabs, porcelain crabs, squat lobsters: c.?2500 species), making up the bulk of the remainder. The earliest fossil decapod is the Devonian Palaeopalaemon. [more]

    Euphausiacea

    Krill is the common name given to the order Euphausiacea of shrimp-like marine crustaceans. Also known as euphausiids, these small invertebrates are found in all oceans of the world. The common name krill comes from the Norwegian word , meaning "young fry of fish", which is also often attributed to other species of fish. [more]

    Isopoda

    Isopods are an order of peracarid crustaceans, including familiar animals such as woodlice and pill bugs. The name Isopoda derives from the Greek roots (iso-, meaning "same") and p?d?? (podos, meaning "foot"). The fossil record of isopods dates back to the Carboniferous period (in the US Pennsylvanian epoch), at least 300 million years ago. [more]

    Lophogastrida

    Lophogastrida is an order of malacostracan crustaceans in the superorder Peracarida. They are shrimp-like animals that mostly inhabit the relatively deep pelagic waters of the oceans throughout the world. [more]

    Mictacea

    Mictacea is an order of crustaceans, erected for six species of small shrimp-like animals of the deep sea and anchialine caves. [more]

    Mysida

    Mysida is a group of small, shrimp-like crustaceans, an order in the malacostracan superorder Peracarida. Their common name opossum shrimps stems from the presence of a brood pouch, or marsupium, in females. Mysids are mostly found in marine waters throughout the world, but are also important in some fresh- and brackish-water ecosystems of the Northern hemisphere. Some mysids are cultured for experimental purposes and as food source for other cultured marine organisms. [more]

    Spelaeogriphacea

    [more]

    Stygiomysida

    [more]

    Tanaidacea

    [more]

    Thermosbaenacea

    Thermosbaenacea is a group of crustaceans that live in thermal springs in fresh water, brackish water and anchialine habitats. They have occasionally been treated as a distinct superorder (Pancarida), but are generally considered to belong to the Peracarida. Due to their troglobitic lifestyle, thermosbaenaceans lack visual pigments and are therefore blind. [more]

    At least 19 species and subspecies belong to the Order Thermosbaenacea.

    More info about the Order Thermosbaenacea may be found here.

    References

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    1. ^ Gary C. B. Poore (2002). "Introduction". Crustacea: Malacostraca. Zoological catalogue of Australia. 19.2A. CSIRO Publishing. pp. 1?7. ISBN 9780643069015. http://books.google.co.uk/books?id=ww6RzBz42-4C&pg=PA1. 
    2. ^ a b J. W. Martin & G. E. Davis (2001) (PDF). An Updated Classification of the Recent Crustacea. Natural History Museum of Los Angeles County. pp. 132 pp. http://atiniui.nh m.org/pdfs/3839/3839.pdf. 
    3. ^ C. Grobben (1892). "Zur Kenntnis des Stammbaumes und des Systems der Crustaceen". Sitzungsberichte der Kaiserlichen Akademie der Wissenschaften, Vienna. Mathematisch-naturwissenschaftliche Classe 101: 237?274. 

    Sources

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    Last Revised: August 24, 2012
    2012/08/24 13:07:21