The Decapoda or decapods (literally "ten-footed") are an

order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number 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, remipedes, isopoda, isopods, barnacles, copepods, ...

s within the class

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, lobs ...

, including many familiar groups, such as

crab Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all th ...

lobster Lobsters are a family (Nephropidae, synonym Homaridae) of marine crustaceans. They have long bodies with muscular tails and live in crevices or burrows on the sea floor. Three of their five pairs of legs have claws, including the first pair, ...

s, crayfish,

shrimp Shrimp are crustaceans (a form of shellfish) with elongated bodies and a primarily swimming mode of locomotion – most commonly Caridea and Dendrobranchiata of the decapod order, although some crustaceans outside of this order are ref ...

and

prawns Prawn is a common name for small aquatic crustaceans with an exoskeleton and ten legs (which is a member of the order decapoda), some of which can be eaten. The term "prawn"Mortenson, Philip B (2010''This is not a weasel: a close look at nature ...

. Most decapods are

scavenger Scavengers are animals that consume dead organisms that have died from causes other than predation or have been killed by other predators. While scavenging generally refers to carnivores feeding on carrion, it is also a herbivorous feedin ...

s. The order is estimated to contain nearly 15,000 species in around 2,700 genera, with around 3,300 fossil species. Nearly half of these species are crabs, with the shrimp (about 3,000 species) and Anomura including hermit crabs, porcelain crabs, squat lobsters (about 2500 species) making up the bulk of the remainder. The earliest

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

decapod is the

Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, wh ...

'' Palaeopalaemon''.

Anatomy

Decapods can have as many as 38 appendages, arranged in one pair per body segment. As the name Decapoda (from the Greek , ', "ten", and , '' -pod'', "foot") implies, ten of these appendages are considered legs. They are the

pereiopod The decapod ( crustaceans such as a crab, lobster, shrimp or prawn) is made up of 20 body segments grouped into two main body parts: the cephalothorax and the pleon (abdomen). Each segment may possess one pair of appendages, although in variou ...

s, found on the last five thoracic segments. In many decapods, one pair of these "legs" has enlarged pincers, called

chelae A chela ()also called a claw, nipper, or pinceris a pincer-like organ at the end of certain limbs of some arthropods. The name comes from Ancient Greek , through New Latin '. The plural form is chelae. Legs bearing a chela are called chelipeds. ...

, with the legs being called chelipeds. In front of the pereiopods are three pairs of

maxilliped An appendage (or outgrowth) is an external body part, or natural prolongation, that protrudes from an organism's body. In arthropods, an appendage refers to any of the homologous body parts that may extend from a body segment, including ante ...

s that function as feeding appendages. The head has five pairs of appendages, including

mouthparts Mouthparts may refer to: * The parts of a mouth ** Arthropod mouthparts The mouthparts of arthropods have evolved into a number of forms, each adapted to a different style or mode of feeding. Most mouthparts represent modified, paired append ...

, antennae, and antennules. There are five more pairs of appendages on the abdomen. They are called

pleopod The decapod ( crustaceans such as a crab, lobster, shrimp or prawn) is made up of 20 body segments grouped into two main body parts: the cephalothorax and the pleon (abdomen). Each segment may possess one pair of appendages, although in variou ...

s. There is one final pair called

uropod Uropods are posterior appendages found on a wide variety of crustaceans. They typically have functions in locomotion. Definition Uropods are often defined as the appendages of the last body segment of a crustacean. An alternative definition sugge ...

s, which, with the

telson The telson () is the posterior-most division of the body of an arthropod. Depending on the definition, the telson is either considered to be the final segment of the arthropod body, or an additional division that is not a true segment on acco ...

, form the tail fan. Haeckel Decapoda

Evolution

Decapods originated in the Late Ordovician around 455 million years ago, with the Dendrobranchiata (prawns) being the first group to diverge. The remaining group, called Pleocyemata, then diverged between the swimming

groupings and the crawling/walking group called Reptantia, consisting of

lobsters Lobsters are a family (Nephropidae, synonym Homaridae) of marine crustaceans. They have long bodies with muscular tails and live in crevices or burrows on the sea floor. Three of their five pairs of legs have claws, including the first pair, ...

and crabs. High species diversification can be traced to the

Jurassic The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of ...

and

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

periods, which coincides with the rise and spread of modern

coral reefs A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups. ...

, a key habitat for the decapods. The cladogram below results from analysis by Wolfe ''et al.'' (2019).

Classification

Classification within the order Decapoda depends on the structure of the

gill A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they ar ...

s and legs, and the way in which the

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...

e develop, giving rise to two suborders: Dendrobranchiata and Pleocyemata. The Dendrobranchiata consist of prawns, including many species colloquially referred to as "shrimp", such as the "white shrimp", '' Litopenaeus setiferus''. The Pleocyemata include the remaining groups, including "true shrimp". Those groups that usually walk rather than swim (Pleocyemata, excluding Stenopodidea and Caridea) form a clade called Reptantia. This classification to the level of superfamilies follows De Grave ''et al.'' Penaeus vannamei 01

Blue crab on market in Piraeus - Callinectes sapidus Rathbun 20020819-317

Order Decapoda Latreille, 1802 *Suborder Dendrobranchiata Bate, 1888 ** Penaeoidea Rafinesque, 1815 **

Sergestoidea Sergestoidea is a superfamily of prawns, divided into two families – the Luciferidae Luciferidae is a family of prawns. These prawns are small, characterised by bioluminescence and the loss or reduction of some appendages. They are predator ...

Dana, 1852 *Suborder Pleocyemata Burkenroad, 1963 **Infraorder Stenopodidea Bate, 1888 **Infraorder Caridea Dana, 1852 *** Procaridoidea Chace & Manning, 1972 *** Galatheacaridoidea Vereshchaka, 1997 *** Pasiphaeoidea Dana, 1852 *** Oplophoroidea Dana, 1852 *** Atyoidea De Haan, 1849 *** Bresilioidea Calman, 1896 *** Nematocarcinoidea Smith, 1884 *** Psalidopodoidea Wood-....., 1874 *** Stylodactyloidea Bate, 1888 *** Campylonotoidea Sollaud, 1913 *** Palaemonoidea Rafinesque, 1815 *** Alpheoidea Rafinesque, 1815 *** Processoidea Ortmann, 1896 *** Pandaloidea Haworth, 1825 *** Physetocaridoidea Chace, 1940 ***

Crangonoidea Crangonoidea is a superfamily of shrimp containing the two families Crangonidae Crangonidae is a family of shrimp, of the superfamily Crangonoidea, including the commercially important species ''Crangon crangon''. Its type genus In biolog ...

Haworth, 1825 **Infraorder Astacidea Latreille, 1802 *** Enoplometopoidea de Saint Laurent, 1988 *** Nephropoidea Dana, 1852 *** Astacoidea Latreille, 1802 *** Parastacoidea Huxley, 1879 **Infraorder Glypheidea Winckler, 1882 *** Glypheoidea Winckler, 1882 **Infraorder Axiidea de Saint Laurent, 1979b **Infraorder Gebiidea de Saint Laurent, 1979 **Infraorder Achelata Scholtz & Richter, 1995 **Infraorder Polychelida Scholtz & Richter, 1995 **Infraorder Anomura MacLeay, 1838 *** Aegloidea Dana, 1852 *** Galatheoidea Samouelle, 1819 *** Hippoidea Latreille, 1825a *** Chirostyloidea Ortmann, 1892 *** Lithodoidea Samouelle, 1819 *** Lomisoidea Bouvier, 1895 *** Paguroidea Latreille, 1802 **Infraorder Brachyura Linnaeus, 1758 ***Section Dromiacea De Haan, 1833 ****

Dromioidea Dromioidea is a superfamily of crabs mostly found in Madagascar. Dromioidea belongs the group Dromiacea, taxonomically ranked as a section, which is the most basal grouping of Brachyura crabs. Dromiacea likely diverged from the rest of Brac ...

De Haan, 1833 ****

Homolodromioidea Homolodromiidae is a family of crabs, the only family in the superfamily Homolodromioidea. In contrast to other crabs, including the closely related Homolidae, there is no strong ''linea homolica'' along which the exoskeleton breaks open during ...

Alcock, 1900 ****

Homoloidea Homoloidea is a superfamily of dromiacean crabs. Homoloidea belongs the group Dromiacea, taxonomically ranked as a section, and is the sister group to Dromioidea. Dromiacea is the most basal grouping of Brachyura crabs, and likely diverged ...

De Haan, 1839 ***Section Raninoida De Haan, 1839 ***Section Cyclodorippoida Ortmann, 1892 ***Section Eubrachyura de Saint Laurent, 1980 ****Subsection Heterotremata Guinot, 1977 *****

Aethroidea The Aethridae are a family of crabs in their own superfamily, Aethroidea. It contains these genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the h ...

Dana, 1851 *****

Bellioidea Belliidae is a family of crabs of the 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 ...

Dana, 1852 *****

Bythograeoidea The Bythograeidae are a small family of blind crabs which live around hydrothermal vents. The family contains 16 species in six genera. Their relationships to other crabs are unclear. They are believed to eat bacteria and other vent organisms. B ...

Williams, 1980 *****

Calappoidea Calappoidea is a superfamily of crabs comprising the two families Calappidae and Matutidae. The earliest fossils attributable to the Calappoidea date from the Aptian The Aptian is an age in the geologic timescale or a stage in the stratig ...

De Haan, 1833 *****

Cancroidea Cancroidea is a superfamily of crabs, comprising the families Atelecyclidae and Cancridae. http://boletinsgm.igeolcu.unam.mx/bsgm/vols/epoca04/6502/%2810%29Osso.pdf Four other families have been separated into new superfamilies: Cheiragonidae ...

Latreille, 1802 *****

Carpilioidea Carpilioidea is a superfamily of crabs containing a single extant family, Carpiliidae and three extinct families. The modern range of the family includes the Indo-Pacific, Western Atlantic and Caribbean Sea. The fossil record of the group exten ...

Ortmann, 1893 *****

Cheiragonoidea Cheiragonidae is a small family of crab Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden enti ...

Ortmann, 1893 *****

Corystoidea Corystidae is a family of crabs, in its own superfamily, Corystoidea. It includes what was once thought to be the oldest Eubrachyuran fossil, '' Hebertides jurassica'', thought to be dating from the Bathonian (Middle Jurassic); the species was s ...

Samouelle, 1819 *****

Dairoidea Dairoidea is a superfamily of crabs, comprising two families which each contain a single genus: Dairidae (the living fossil A living fossil is an extant taxon that cosmetically resembles related species known only from the fossil record. ...

Serène, 1965 *****

Dorippoidea Dorippoidea is a superfamily of crabs. The earliest fossils attributable to the Dorippoidea date from the Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geo ...

MacLeay, 1838 *****

Eriphioidea Eriphioidea is a superfamily of crabs, containing the six families Dairoididae, Eriphiidae, Hypothalassiidae, Menippidae, Oziidae and Platyxanthidae. They are united by a number of characters, including a marked difference in size between ...

MacLeay, 1838 *****

Gecarcinucoidea Gecarcinucoidea is a superfamily of freshwater crabs. Its members have been grouped into families in various ways, with some authors recognizing families such as "Deckeniidae", "Sundathelphusidae", and "Parathelphusidae", but now only the family ...

Rathbun, 1904 *****

Goneplacoidea Goneplacoidea is a superfamily of crabs containing 11 extant families, and two families known only from fossils (marked "†"). * Acidopsidae * † Carinocarcinoididae * Chasmocarcinidae * Conleyidae * Euryplacidae * Goneplacidae * Litoch ...

MacLeay, 1838 *****

Hexapodoidea Hexapodidae is a family of crabs, the only family in the superfamily Hexapodoidea. It has traditionally been treated as a subfamily of the family Goneplacidae, and was originally described as a subfamily of Pinnotheridae. Its members can be dis ...

Miers, 1886 *****

Leucosioidea Leucosioidea is a superfamily of crab Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entir ...

Samouelle, 1819 *****

Majoidea The Majoidea are a superfamily of crabs which includes the various spider crabs. Taxonomy In "''A classification of living and fossil genera of decapod crustaceans''" De Grave and colleagues divided Majoidea into six families: * Family Epial ...

Samouelle, 1819 *****

Orithyioidea ''Orithyia sinica'', sometimes called tiger crab or the tiger face crab, is a "singularly unusual" species of crab, whose characteristics warrant its separation into a separate genus, family and even superfamily, having previously been included ...

Dana, 1852c *****

Palicoidea Palicoidea is a superfamily (zoology), superfamily of crabs, comprising the two families Crossotonotidae and Palicidae. Together, they contain 13 genera, including two genera in the Palicidae known only from fossils. The two families were previou ...

Bouvier, 1898 *****

Parthenopoidea Parthenopidae is a family of crabs, placed in its own Superfamily (taxonomy), superfamily, Parthenopoidea. It comprises nearly 40 genera, divided into two subfamilies, with three genera ''incertae sedis'': ;Daldorfiinae Ng & Rodríguez, 1986 * ...

MacLeay, *****

Pilumnoidea Pilumnoidea is a superfamily of crabs, whose members were previously included in the Xanthoidea. The three families are unified by the free articulation of all the segments of the male crab's abdomen and by the form of the gonopods. The earlie ...

Samouelle, 1819 ***** Portunoidea Rafinesque, 1815 ***** Potamoidea Ortmann, 1896 *****

Pseudothelphusoidea Pseudothelphusidae is a family of freshwater crabs found chiefly in mountain streams in the Neotropics. They are believed to have originated in the Greater Antilles and then crossed to Central America via a Pliocene land bridge. Parasitology Pse ...

Ortmann, 1893 *****

Pseudozioidea Pseudozioidea is a superfamily (zoology), superfamily of crabs, formerly treated in the Eriphioidea, Carpilioidea, Xanthoidea, Pilumnoidea and Goneplacoidea. A number of fossils from the Eocene onwards are known from the family Pseudoziidae. Elev ...

Alcock, 1898 *****

Retroplumoidea Retroplumidae is a family of heterotrematan crabs, placed in their own (monotypic) superfamily, Retroplumoidea. Classification Eight genera are recognised, of which all but two are only known from fossils: *'' Archaeopus'' † Rathbun, 1908 *'' ...

Gill, 1894 *****

Trapezioidea Trapezioidea is a superfamily of crabs. Its members live symbiotically with corals, and have a fossil record stretching back to the Eocene. Families The World Register of Marine Species The World Register of Marine Species (WoRMS) is a tax ...

Miers, 1886 *****

Trichodactyloidea Trichodactylidae is a family of crabs, in its own superfamily, Trichodactyloidea. They are all freshwater animals from Central and South America, including some offshore islands, such as Ilhabela, São Paulo. Only one of the 50 species is known ...

H. Milne-Edwards, 1853 ***** Xanthoidea MacLeay, 1838 ****Subsection Thoracotremata Guinot, 1977 *****

Cryptochiroidea Cryptochiridae is a family of crabs known commonly as gall crabs or coral gall crabs. They live inside dwellings in corals and cause the formation of galls in the coral structure.Johnsson, R., et al. (2006)The association of two gall crabs (Brac ...

Paul'son, 1875 *****

Grapsoidea The Grapsoidea are a superfamily of crabs; they are well known and contain many taxa which are terrestrial (land-living), semiterrestrial (taking to the sea only for reproduction), or limnic (living in fresh water). Another well-known member wit ...

MacLeay, 1838 *****

Ocypodoidea The Ocypodoidea, or ocypoid crabs, are a superfamily of crab Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail ...

Rafinesque, 1815 ***** Pinnotheroidea De Haan, 1833

References

External links

*
Decapod Crustacea
"Tree of Life" page at the Natural History Museum of Los Angeles County * {{Authority control Crustacean orders Malacostraca Extant Devonian first appearances Taxa named by Pierre André Latreille

Anatomy

Evolution

Classification

See also

References

External links