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 can ...

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, l ...

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

Phyllocarida Phyllocarida is a subclass of crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapoda, decapods, ostracoda, seed shrimp, branchiopoda, branchiopods, argulidae, fish lice, krill, remipe ...

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, 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 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 ** 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 Krøyer, 1846 * Superorder Eucarida 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 Williamson, 1973 ** Order Decapoda Latreille, 1802 ** †Order Angustidontida

References

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