Eumalacostraca is a subclass of

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

s, containing almost all living

malacostraca Malacostraca is the second largest of the six classes of pancrustaceans behind insects, containing about 40,000 living species, divided among 16 orders. Its members, the malacostracans, display a great diversity of body forms and include crab ...

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. This clade of marine crustaceans diversified extensively during the Ordovician. See also *'' Ceratiocari ...

and possibly the Hoplocarida. 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 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 tortoises, the unde ...

, 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 a number of modern experts and databases (ex.

NCBI The National Center for Biotechnology Information (NCBI) is part of the National Library of Medicine (NLM), a branch of the National Institutes of Health (NIH). It is approved and funded by the government of the United States. The NCBI is loca ...

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

Packard, 1885 ** †Order Palaeocaridacea ** Order Bathynellacea Chappuis, 1915 ** Order

Anaspidacea Anaspidacea is an Order (biology), order of crustaceans, comprising eleven genera in four families. Species in the family Anaspididae, Anaspidesidae vary from being strict stygobite, stygobionts (only living underground) to species living in lake ...

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 Habitat (ecology), habitats. They have occasionally been treated as a distinct superorder (Pancarida), but are generally consider ...

Monod, 1927 ** Order

Lophogastrida Lophogastrida is an Order (biology), 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 s ...

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

Amphipoda Amphipoda () is an order (biology), 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 10,700 amphip ...

Latreille, 1816 ** Order

Isopoda Isopoda is an order of crustaceans. Members of this group are called isopods and include both aquatic species and terrestrial species such as woodlice. All have rigid, segmented exoskeletons, two pairs of antennae, seven pairs of jointed l ...

Latreille, 1817 ** Order

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

Dana, 1849 ** Order

Cumacea Cumacea is an order (biology), 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. ...

Krøyer, 1846 * Superorder Eucarida Calman, 1904 ** Order Euphausiacea Dana, 1852 ** Order

Decapoda The Decapoda or decapods, from Ancient Greek δεκάς (''dekás''), meaning "ten", and πούς (''poús''), meaning "foot", is a large order of crustaceans within the class Malacostraca, and includes crabs, lobsters, crayfish, shrimp, a ...

Latreille, 1802 ** †Order Angustidontida Gueriau, Charbonnier & Clément, 2014

References

Malacostraca Taxa named by Karl Grobben Arthropod subclasses {{Malacostraca-stub