Eumalacostraca is a subclass of

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...

s, containing almost all living

malacostraca Malacostraca (from New Latin; ) is the largest of the six classes of crustaceans, containing about 40,000 living species, divided among 16 orders. Its members, the malacostracans, display a great diversity of body forms and include crabs, lobst ...

ns, or about 40,000 described species. The remaining subclasses are the

Phyllocarida Phyllocarida is a subclass of crustaceans, comprising the extant order Leptostraca and the extinct orders Hymenostraca and Archaeostraca. See also *''Ceratiocaris'' *''Cinerocaris'' *''Vladicaris ''Vladicaris'' is an arthropod known from the ...

and possibly the

Hoplocarida Hoplocarida is a subclass of crustaceans. The only extant members are the mantis shrimp (Stomatopoda), but two other orders existed in the Palaeozoic: Aeschronectida Aeschronectida is an extinct order of mantis shrimp-like crustacean Crus ...

. Eumalacostracans have 19 segments (5 cephalic, 8 thoracic and 6 abdominal). This arrangement is known as the "caridoid facies", a term coined by

William Thomas Calman William Thomas Calman (29 December 1871 – 29 September 1952) was a Scottish zoologist, specialising in the Crustacea. From 1927 to 1936 he was Keeper of Zoology at the British Museum (Natural History) (now the Natural History Museum). Life ...

in 1909. The thoracic limbs are jointed and used for swimming or walking. The common ancestor is thought to have had a

carapace A carapace is a Dorsum (biology), dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tor ...

, and most living species possess one, but it has been lost in some subgroups.

Caridoid facies

Calman identified the following features as distinguishing eumalacostracan crustaceans:

"Carapace enveloping the thoracic region; movably stalked eyes; biramous first antenna; scale-like exopod on the second antenna; natatory exopods on the thoracic limbs; elongate, ventrally flexible abdomen; tail fan formed by the lamellar rami of the uropods on either side of the telson."

Classification

Martin and Davis present the following classification of living eumalacostracans into orders, to which extinct orders have been added, indicated by †. The group as originally described by Karl Grobben 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,

. Subclass ''Eumalacostraca'' Grobben, 1892 * Superorder

Syncarida Syncarida is a superorder of crustaceans, comprising the two extant orders Anaspidacea and Bathynellacea, and the extinct order Palaeocaridacea. Fifty-nine living genera are known, in six families: ;Anaspidacea Calman, 1904 *Anaspididae Thomson ...

Packard, 1885 ** †Order Palaeocaridacea ** Order Bathynellacea Chappuis, 1915 ** Order Anaspidacea Calman, 1904 (including Stygocaridacea) * Superorder Peracarida Calman, 1904 ** Order Spelaeogriphacea Gordon, 1957 ** Order

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 t ...

Monod, 1927 ** Order

Lophogastrida Lophogastrida is an order of malacostracan crustaceans in the superorder Peracarida, comprising shrimp-like animals that mostly inhabit the relatively deep pelagic waters of the oceans throughout the world. Most lophogastridan species are l ...

Sars, 1870 ** Order

Mysida Mysida is an order (biology), order of small, shrimp-like crustaceans in the malacostracan superorder Peracarida. Their common name opossum shrimps stems from the presence of a Brood pouch (Peracarida), brood pouch or "marsupium" in females. The ...

Haworth, 1825 ** Order

Mictacea Mictacea is a monotypic order of crustaceans. It was originally erected for three species of small shrimp-like animals of the deep sea and anchialine caves. They were placed in two families, the Mictocarididae and Hirsutiidae, but Hirsutiidae ...

Bowman, Garner, Hessler, Iliffe & Sanders, 1985 ** Order

Amphipoda Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods range in size from and are mostly detritivores or scavengers. There are more than 9,900 amphipod species so far desc ...

Latreille, 1816 ** Order

Isopoda Isopoda is an order of crustaceans that includes woodlice and their relatives. Isopods live in the sea, in fresh water, or on land. All have rigid, segmented exoskeletons, two pairs of antennae, seven pairs of jointed limbs on the thorax, an ...

Latreille, 1817 ** Order

Tanaidacea The crustacean order Tanaidacea (known as tanaids) make up a minor group within the class Malacostraca. There are about 940 species in this order. Description Tanaids are small, shrimp-like creatures ranging from in adult size, with most specie ...

Dana, 1849 ** Order

Cumacea Cumacea is an order of small marine crustaceans of the superorder Peracarida, occasionally called hooded shrimp or comma shrimp. Their unique appearance and uniform body plan makes them easy to distinguish from other crustaceans. They live in so ...

Krøyer, 1846 * Superorder

Eucarida Eucarida is a superorder of the Malacostraca, a class of the crustacean subphylum, comprising the decapods, krill, '' Amphionides'' and Angustidontida. They are characterised by having the carapace fused to all thoracic segments, and by the pos ...

Calman, 1904 ** Order

Euphausiacea Krill are small crustaceans of the order Euphausiacea, and are found in all the world's oceans. The name "krill" comes from the Norwegian word ', meaning "small fry of fish", which is also often attributed to species of fish. Krill are consid ...

Dana, 1852 ** Order

Amphionidacea ''Amphionides reynaudii'' is a species of caridean shrimp, whose identity and position in the crustacean system remained enigmatic for a long time. It is a small (less than one inch long) planktonic crustacean found throughout the world's tropic ...

Williamson, 1973 ** Order

Decapoda The Decapoda or decapods (literally "ten-footed") are an order of crustaceans within the class Malacostraca, including many familiar groups, such as crabs, lobsters, crayfish, shrimp and prawns. Most decapods are scavengers. The order is esti ...

Latreille, 1802 ** †Order

Angustidontida Angustidontidae is an extinct family of eucarid crustaceans and the sole representatives of the order Angustidontida. They were predators ranging in size from about 4 to 9 centimetres in length and lived during the Late Devonian and Early Carb ...

References

{{Taxonbar, from=Q72629 Malacostraca Taxa named by Karl Grobben Arthropod subclasses