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Malacostraca

May 02, 2023

Malacostraca (from New Latin; from Ancient Greek μαλακός (malakós) 'soft', and όστρακον (óstrakon) 'shell') 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, lobsters, crayfish, shrimp, krill, prawns, woodlice, amphipods, mantis shrimp, tongue-eating lice and many other less familiar animals. They are abundant in all marine environments and have colonised freshwater and terrestrial habitats. They are segmented animals, united by a common body plan comprising 20 body segments (rarely 21), and divided into a head, thorax, and abdomen.

Malacostraca
Temporal range: Cambrian–Recent
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Superclass: Multicrustacea
Class: Malacostraca
Latreille, 1802
Subclasses

See text for orders.

Etymology

The name Malacostraca was coined by a French zoologist Pierre André Latreille in 1802. He was curator of the arthropod collection at the National Museum of Natural History in Paris.[1] The name comes from the Greek roots μαλακός (malakós, meaning "soft") and ὄστρακον (óstrakon, meaning "shell").[2] The name is misleading, since the shell is soft only immediately after moulting, and is usually hard.[3] The word was used by Aristotle, who contrasted them with oysters, in comparison with which their shells are pliable. Malacostracans are sometimes contrasted with entomostracans, a name applied to all crustaceans outside the Malacostraca, and named after the obsolete taxon Entomostraca.[4]

Description

 
Leptostraca such as Nebalia bipes retain the primitive condition of having seven abdominal segments.

The class Malacostraca includes about 40,000 species,[5] and "arguably ... contains a greater diversity of body forms than any other class in the animal kingdom".[6] Its members are characterised by the presence of three tagmata (specialized groupings of multiple segments) – a five-segmented head, an eight-segmented thorax and an abdomen with six segments and a telson, except in the Leptostraca, which retain the ancestral condition of seven abdominal segments.[6] Malacostracans have abdominal appendages, a fact that differentiates them from all other major crustacean taxa except Remipedia.[7] Each body segment bears a pair of jointed appendages, although these may be lost secondarily.[8]

Tagmata

The head bears two pairs of antennae, the first of which is often biramous (branching into two parts) and the second pair bear exopods (outer branches) which are often flattened into antennal scales known as scaphocerites.[7] The mouthparts consist of pairs each of mandibles, maxillules (second pair of mouthparts) and maxillae. Except for fairy shrimps, malacostracans are the only extant arthropods with compound eyes placed on moveable stalks,[9][10] although in some taxa the eyes are unstalked, reduced or lost.[11][12]

Up to three thoracic segments may be fused with the head to form a cephalothorax; the associated appendages turn forward and are modified as maxillipeds (accessory mouthparts).[7] A carapace may be absent, present or secondarily lost, and may cover the head, part or all of the thorax and some of the abdomen.[6] It is variable in form and may be fused dorsally with some of the thoracic segments or occasionally be in two parts, hinged dorsally.[11] Typically, each of the thoracic appendages is biramous and the endopods are the better developed of the branches, being used for crawling or grasping. Each endopod consist of seven articulating segments; the coxa, basis, ischium, merus, carpus, propodus and dactylus. In decapods, the claw is formed by the articulation of the dactylus against an outgrowth of the propodus. In some taxa, the exopods are lost and the appendages are uniramous.[7]

There is a clear demarcation between the thorax and the six or seven-segmented abdomen. In most taxa, each abdominal segment except the last carries a pair of biramous pleopods used for swimming, burrowing, gas exchange, creating a current or brooding eggs. The first and second abdominal pleopods may be modified in the male to form gonopods (accessory copulatory appendages).[7] The appendages of the last segment are typically flattened into uropods, which together with the terminal telson, make up the "tail fan".[12] It is the sudden flexion of this tail fan that provides the thrust for the rapid escape response of these crustaceans and the tail fan is also used in steering.[7] In Leptostraca, the appendages on the telson instead form caudal rami (spine-like protrusions).[13]

Internal anatomy

The digestive tract is straight and the foregut consists of a short oesophagus and a two-chambered stomach, the first part of which contains a gizzard-like "gastric mill" for grinding food. The walls of this have chitinous ridges, teeth and calcareous ossicles. The fine particles and soluble material are then moved into the midgut where chemical processing and absorption takes place in one or more pairs of large digestive caeca. The hindgut is concerned with water reclamation and the formation of faeces and the anus is situated at the base of the telson.[14]

Like other crustaceans, malacostracans have an open circulatory system in which the heart pumps blood into the hemocoel (body cavity) where it supplies the needs of the organs for oxygen and nutrients before diffusing back to the heart.[15] The typical respiratory pigment in malacostracans is haemocyanin.[16] Structures that function as kidneys are located near the base of the antennae. A brain exists in the form of ganglia close to the antennae, there are ganglia in each segment and a collection of major ganglia below the oesophagus.[17] Sensory organs include compound eyes (often stalked), ocelli (simple eyes), statocysts and sensory bristles. The naupliar eye is a characteristic of the nauplius larva and consists of four cup-shaped ocelli facing in different directions and able to distinguish between light and darkness.[14]

Ecology

 
Grapsus grapsus, a terrestrial crab

Malacostracans live in a wide range of marine and freshwater habitats, and three orders have terrestrial members: Amphipoda (Talitridae), Isopoda (Oniscidea, the woodlice) and Decapoda (terrestrial hermit crabs, crabs of the families Ocypodidae, Gecarcinidae, and Grapsidae, and terrestrial crayfish).[18] They are abundant in all marine ecosystems, and most species are scavengers, although some, such as the porcelain crabs, are filter feeders, and some, such as mantis shrimps, are carnivores.[12]

Life cycle

Most species of malacostracans have distinct sexes (a phenomenon known as gonochorism), although a few species exhibit hermaphroditism.[12] The female genital openings or gonopores are located on the sixth thoracic segment or its appendages, while the male gonopores are on the eighth segment or its appendages, or in a small number of species, on the seventh.[11] The naupliar larval stages are often reduced and take place before hatching, but where they occur, a metamorphosis usually occurs between the larval and the adult forms. Primitive malacostracans have a free-swimming naupliar larval stage.[11] Research suggests the common ancestor of Malacostraca had lost the free-living nauplius larval stage, but re-evolved it again through heterochrony in Dendrobranchiata and Euphausiacea, which both has a lecithotrophic (non-feeding) nauplius stage.[19][20]

Mating

Mating behavior has been studied in the freshwater shrimp Caridina ensifera.[21] Multiple paternity, common in the Malacostrica, also occurs in C. ensifera. Reproductive success of sires was found to correlate inversely with their genetic relatedness to the mother.[21] This finding suggests that sperm competition and/or pre- and post-copulatory female choice occurs. Female choice may increase the fitness of progeny by avoiding inbreeding that can lead to expression of homozygous deleterious recessive mutations.[22]

Phylogenetics

Main article: Phylogeny of Malacostraca

The monophyly of Malacostraca is widely accepted. This is supported by several common morphological traits which are present throughout the group and is confirmed by molecular studies.[23] However, a number of problems make it difficult to determine the relationships between the orders of Malacostraca. These include differences in mutation rates in different lineages, different patterns of evolution being apparent in different sources of data, including convergent evolution, and long branch attraction.[24]

There is less agreement on the status of the subclass Phyllocarida with its single extant order, Leptostraca, depending on whether foliaceous (leaf-like) limbs have a single or multiple origin. Some authors advocate placing Phyllocarida in Phyllopoda, a group used in former classification systems, which would then include branchiopods, cephalocarids and leptostracans. A molecular study by American biologists Trisha Spears and Lawrence Abele concluded that phylogenetic evidence did not support the monophyly of this grouping, and that Phyllocarida should be regarded as a subclass of Malacostraca that had diverged from the main lineage at an early date.[11][25]

The following cladogram is based on the 2001 phylogenetic analysis of Richter & Scholtz.[26]

Subclass Phyllocarida

Leptostraca is the only extant order of Phyllocarida, the other two orders, Archaeostraca and Hoplostraca being extinct. Leptostracans are thought to be the most primitive of the malacostracans and date back to the Cambrian period. They range in length from 1 to 4 cm (0.4 to 1.6 in), most being suspension feeders though some are carnivores or scavengers. They have a two part carapace which encloses the head, the whole thorax and part of the abdomen and are the only malacostracans with seven abdominal segments. Three families are known with several genera and about twenty species. They are found worldwide from the intertidal zone to the deep ocean, all but one species being benthic (living on the seabed).[7][11]

Subclass Hoplocarida

 
Squilla empusa,
a mantis shrimp

Stomatopoda is the only extant order of Hoplocarida, the other two orders, Aeschronectida and Archaeostomatopoda being extinct. Stomatopodans, commonly known as mantis shrimps, range in length from 5 to 36 cm (2 to 14 in) and are predators. They have a dorso-ventrally flattened body and a shield-like carapace and are armed with powerful, raptorial claws normally carried in a folded position. There are about 300 species, most living in tropical and subtropical seas although some live in temperate areas. They are benthic, mostly hiding in cracks and crevices or living in burrows, some emerging to forage while others are ambush predators.[7][11]

Subclass Eumalacostraca

The Eumalocostraca contains the vast majority of the approximately 40,000 living species of malacostracans and consists of three superorders, Syncarida, Peracarida and Eucarida. Syncaridans are mostly small and found in freshwater and subterranean habitats. Peracaridans are characterised by having a marsupium in which they brood their young. They are found in marine, freshwater and terrestrial habitats and include Amphipoda, Cumacea, Isopoda and Mysida. Eucarida includes lobsters, crabs, shrimps, prawns and krill.[27]

Fossil record

The first malacostracans appeared sometime in the Cambrian, when animals belonging to the Phyllocarida appeared.[28][29]

Classification

See also: List of prehistoric malacostracans

The following classification of living malacostracans is based on An Updated Classification of the Recent Crustacea (2001) by the American marine biologists Joel W. Martin, curator of crustaceans at the Natural History Museum of Los Angeles County, and George E. Davies.[30] Extinct orders have been added to this[31][32][33] and are indicated by an obelisk (†).

 
Cancer pagurus (Eucarida: Decapoda)

Class Malacostraca Latreille, 1802

  • † Archaeostraca Claus 1888
  • † Hoplostraca Schram, 1973
  • Leptostraca Claus, 1880

References

  1. ^ Dupuis, Claude (1974). "Pierre André Latreille (1762–1833): the foremost entomologist of his time". Annual Review of Entomology. 19: 1–14. doi:10.1146/annurev.en.19.010174.000245.
  2. ^ "malacostracan". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
  3. ^ Rich, Patricia Vickers; Fenton, Mildred Adams; Fenton, Caroll Lane; Rich, Thomas Hewitt (1996). "Crustaceans". The Fossil Book: a Record of Prehistoric Life (2nd ed.). Courier Dover Publications. pp. 213–221. ISBN 978-0-486-29371-4.
  4. ^ Clifford, Hugh F. (1991). "Introduction to the Malacostraca". Aquatic Invertebrates of Alberta: an Illustrated Guide. University of Alberta. pp. 173–175. ISBN 978-0-88864-234-9.
  5. ^ Poore, Hugh F. (2002). "Introduction". Crustacea: Malacostraca. Zoological catalogue of Australia. Vol. 19.2A. CSIRO Publishing. pp. 1–7. ISBN 978-0-643-06901-5.
  6. ^ a b c Barnes, R. S. K.; Calow, P.; Olive, P. J. W.; Golding, D. W.; Spicer, J. I. (2001). "Invertebrates with legs: the arthropods and similar groups". The Invertebrates: a Synthesis (3rd ed.). Wiley-Blackwell. pp. 168–206. ISBN 978-0-632-04761-1.
  7. ^ a b c d e f g h Ruppert, Edward E.; Fox, Richard, S.; Barnes, Robert D. (2004). Invertebrate Zoology (7th ed.). Cengage Learning. pp. 625–626. ISBN 978-81-315-0104-7.
  8. ^ Atwater, Dan; Fautin, Daphne G. (2001). "Class Malacostraca: crabs, krill, pill bugs, shrimp, and relatives". Animal Diversity Web. University of Michigan. Retrieved November 23, 2010.
  9. ^ Multicellular Animals: Volume II: The Phylogenetic System of the Metazoa
  10. ^ Optical Design and Evolutionary Adaptation in Crustacean Compound Eyes
  11. ^ a b c d e f g Davie, P. J. F. (2002). "Class Malacostraca. Introduction". Crustacea: Malacostraca. Phyllocarida, Hoplocarida, Eucarida (Part 1). Volume 19.3A of Zoological Catalogue of Australia. CSIRO Publishing. p. 23. ISBN 978-0-643-06791-2.
  12. ^ a b c d Hayward, P. J.; Isaac, M. J.; Makings, P.; Moyse, J.; Naylor, E.; Smaldon, G. (1995). "Crustaceans". In Hayward, P. J.; Ryland, John Stanley (eds.). Handbook of the Marine Fauna of North-West Europe. Oxford University Press. pp. 290–461. ISBN 978-0-19-854055-7.
  13. ^ Ricketts, Edward F.; Calvin, Jack; Phillips, David W.; Hedgpeth, Joel W. (1992). "Rocky shores of bays and estuaries". Between Pacific Tides (5th ed.). Stanford University Press. pp. 269–316. ISBN 978-0-8047-2068-7.
  14. ^ a b Ruppert, Edward E.; Fox, Richard, S.; Barnes, Robert D. (2004). Invertebrate Zoology (7th ed.). Cengage Learning. pp. 610–613. ISBN 978-81-315-0104-7.
  15. ^ Sakurai, Akira. "Closed and open circulatory system". Georgia State University. Retrieved 2014-05-21.
  16. ^ Urich, Klaus (1994). "Respiratory pigments". Comparative Animal Biochemistry. Springer. pp. 249–287. ISBN 978-3-540-57420-0.
  17. ^ Ghiselin, Michael T. (2005). "Crustacean". Encarta. Microsoft.
  18. ^ Little, Colin (1983). "Crustaceans and the evolution of the arthropods". The Colonisation of Land: Origins and Adaptations of Terrestrial Animals. Cambridge University Press. pp. 63–106. ISBN 978-0-521-25218-8.
  19. ^ Evolution of eumalacostracan development—new insights into loss and reacquisition of larval stages revealed by heterochrony analysis
  20. ^ Naupliar and Metanaupliar Development of Thysanoessa raschii (Malacostraca, Euphausiacea) from Godthåbsfjord, Greenland, with a Reinstatement of the Ancestral Status of the Free-Living Nauplius in Malacostracan Evolution
  21. ^ a b Yue GH, Chang A (2010). "Molecular evidence for high frequency of multiple paternity in a freshwater shrimp species Caridina ensifera". PLOS ONE. 5 (9): e12721. Bibcode:2010PLoSO...512721Y. doi:10.1371/journal.pone.0012721. PMC 2939052. PMID 20856862.
  22. ^ Charlesworth D, Willis JH (2009). "The genetics of inbreeding depression". Nat. Rev. Genet. 10 (11): 783–96. doi:10.1038/nrg2664. PMID 19834483. S2CID 771357.
  23. ^ Hassanin, Alexandre (2006). "Phylogeny of Arthropoda inferred from mitochondrial sequences: Strategies for limiting the misleading effects of multiple changes in pattern and rates of substitution" (PDF). Molecular Phylogenetics and Evolution. 38 (1): 100–116. doi:10.1016/j.ympev.2005.09.012. PMID 16290034.
  24. ^ Jenner, Ronald A.; Ní Dhubhghaill, Ciara; Ferla, Matteo P.; Wills, Matthew A. (2009). "Eumalacostracan phylogeny and total evidence: limitations of the usual suspects". BMC Evolutionary Biology. 9 (1): 21. doi:10.1186/1471-2148-9-21. PMC 2640363. PMID 19173741.
  25. ^ Spears, Trisha; Abele, Lawrence G. (1999). "Phylogenetic Relationships of Crustaceans with Foliaceous Limbs: An 18S rDNA Study of Branchiopoda, Cephalocarida, and Phyllocarida". Journal of Crustacean Biology. 19 (4): 825–843. doi:10.1163/193724099x00538. JSTOR 1549304.
  26. ^ Richter, Scholtz (January 2002). "Phylogenetic analysis of the Malacostraca (Crustacea)". Journal of Zoological Systematics and Evolutionary Research. 39 (3): 113–136. doi:10.1046/j.1439-0469.2001.00164.x.
  27. ^ Davie, P. J. F. (2002). "Class Malacostraca. Introduction". Crustacea: Malacostraca. Phyllocarida, Hoplocarida, Eucarida (Part 1). Volume 19.3A of Zoological Catalogue of Australia. CSIRO Publishing. p. 91. ISBN 978-0-643-06791-2.
  28. ^ Collette, Joseph H.; Hagadorn, James W. (2010). "Three-dimensionally preserved arthropods from Cambrian Lagerstätten of Quebec and Wisconsin". Journal of Paleontology. 84 (4): 646–667. doi:10.1666/09-075.1. S2CID 130064618.
  29. ^ Collette, Joseph H.; Hagadorn, James W. (2010). "Early evolution of phyllocarid arthropods: phylogeny and systematics of Cambrian–Devonian archaeostracans". Journal of Paleontology. 84 (5): 795–820. doi:10.1666/09-092.1. S2CID 85074218.
  30. ^ Martin, Joel W.; Davis, George E. (2001). An Updated Classification of the Recent Crustacea (PDF). Natural History Museum of Los Angeles County. p. 132.
  31. ^ Jenner, Ronald A.; Hof, Cees H. J.; Schram, Frederick R. (1998). "Palaeo- and archaeostomatopods (Hoplocarida: Crustacea) from the Bear Gulch Limestone, Mississippian (Namurian), of central Montana". Contributions to Zoology. 67 (3): 155–186. doi:10.1163/18759866-06703001.
  32. ^ Camacho, A. I.; Valdecasas, A. G. (2008). "Global diversity of syncarids (Syncarida; Crustacea) in freshwater". In Balian, E. V.; Lévêque, C.; Segers, H.; Martens, K. (eds.). Freshwater Animal Diversity Assessment. Developments in Hydrobiology. Vol. 198. Springer. pp. 257–266. doi:10.1007/978-1-4020-8259-7_28. ISBN 978-1-4020-8258-0.
  33. ^ Davie, P. J. F. (2001). "Subclass: Phyllocarida, Introduction". Crustacea: Malacostraca: Phyllocarida, Hoplocarida, Eucarida (Part 1). Zoological catalogue of Australia. Vol. 19.3A. CSIRO Publishing. p. 24. ISBN 978-0-643-06791-2.

External links

May 02, 2023
malacostraca, from, latin, from, ancient, greek, μαλακός, malakós, soft, όστρακον, óstrakon, shell, largest, classes, crustaceans, containing, about, living, species, divided, among, orders, members, malacostracans, display, great, diversity, body, forms, incl. Malacostraca from New Latin from Ancient Greek malakos malakos soft and ostrakon ostrakon shell 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 lobsters crayfish shrimp krill prawns woodlice amphipods mantis shrimp tongue eating lice and many other less familiar animals They are abundant in all marine environments and have colonised freshwater and terrestrial habitats They are segmented animals united by a common body plan comprising 20 body segments rarely 21 and divided into a head thorax and abdomen MalacostracaTemporal range Cambrian Recent PreꞒ Ꞓ O S D C P T J K Pg NScientific classificationKingdom AnimaliaPhylum ArthropodaSubphylum CrustaceaSuperclass MulticrustaceaClass MalacostracaLatreille 1802SubclassesEumalacostraca Hoplocarida PhyllocaridaSee text for orders Contents 1 Etymology 2 Description 2 1 Tagmata 2 2 Internal anatomy 3 Ecology 4 Life cycle 5 Mating 6 Phylogenetics 6 1 Subclass Phyllocarida 6 2 Subclass Hoplocarida 6 3 Subclass Eumalacostraca 6 4 Fossil record 7 Classification 8 References 9 External linksEtymology EditThe name Malacostraca was coined by a French zoologist Pierre Andre Latreille in 1802 He was curator of the arthropod collection at the National Museum of Natural History in Paris 1 The name comes from the Greek roots malakos malakos meaning soft and ὄstrakon ostrakon meaning shell 2 The name is misleading since the shell is soft only immediately after moulting and is usually hard 3 The word was used by Aristotle who contrasted them with oysters in comparison with which their shells are pliable Malacostracans are sometimes contrasted with entomostracans a name applied to all crustaceans outside the Malacostraca and named after the obsolete taxon Entomostraca 4 Description Edit Leptostraca such as Nebalia bipes retain the primitive condition of having seven abdominal segments The class Malacostraca includes about 40 000 species 5 and arguably contains a greater diversity of body forms than any other class in the animal kingdom 6 Its members are characterised by the presence of three tagmata specialized groupings of multiple segments a five segmented head an eight segmented thorax and an abdomen with six segments and a telson except in the Leptostraca which retain the ancestral condition of seven abdominal segments 6 Malacostracans have abdominal appendages a fact that differentiates them from all other major crustacean taxa except Remipedia 7 Each body segment bears a pair of jointed appendages although these may be lost secondarily 8 Tagmata Edit The head bears two pairs of antennae the first of which is often biramous branching into two parts and the second pair bear exopods outer branches which are often flattened into antennal scales known as scaphocerites 7 The mouthparts consist of pairs each of mandibles maxillules second pair of mouthparts and maxillae Except for fairy shrimps malacostracans are the only extant arthropods with compound eyes placed on moveable stalks 9 10 although in some taxa the eyes are unstalked reduced or lost 11 12 Up to three thoracic segments may be fused with the head to form a cephalothorax the associated appendages turn forward and are modified as maxillipeds accessory mouthparts 7 A carapace may be absent present or secondarily lost and may cover the head part or all of the thorax and some of the abdomen 6 It is variable in form and may be fused dorsally with some of the thoracic segments or occasionally be in two parts hinged dorsally 11 Typically each of the thoracic appendages is biramous and the endopods are the better developed of the branches being used for crawling or grasping Each endopod consist of seven articulating segments the coxa basis ischium merus carpus propodus and dactylus In decapods the claw is formed by the articulation of the dactylus against an outgrowth of the propodus In some taxa the exopods are lost and the appendages are uniramous 7 There is a clear demarcation between the thorax and the six or seven segmented abdomen In most taxa each abdominal segment except the last carries a pair of biramous pleopods used for swimming burrowing gas exchange creating a current or brooding eggs The first and second abdominal pleopods may be modified in the male to form gonopods accessory copulatory appendages 7 The appendages of the last segment are typically flattened into uropods which together with the terminal telson make up the tail fan 12 It is the sudden flexion of this tail fan that provides the thrust for the rapid escape response of these crustaceans and the tail fan is also used in steering 7 In Leptostraca the appendages on the telson instead form caudal rami spine like protrusions 13 Internal anatomy Edit The digestive tract is straight and the foregut consists of a short oesophagus and a two chambered stomach the first part of which contains a gizzard like gastric mill for grinding food The walls of this have chitinous ridges teeth and calcareous ossicles The fine particles and soluble material are then moved into the midgut where chemical processing and absorption takes place in one or more pairs of large digestive caeca The hindgut is concerned with water reclamation and the formation of faeces and the anus is situated at the base of the telson 14 Like other crustaceans malacostracans have an open circulatory system in which the heart pumps blood into the hemocoel body cavity where it supplies the needs of the organs for oxygen and nutrients before diffusing back to the heart 15 The typical respiratory pigment in malacostracans is haemocyanin 16 Structures that function as kidneys are located near the base of the antennae A brain exists in the form of ganglia close to the antennae there are ganglia in each segment and a collection of major ganglia below the oesophagus 17 Sensory organs include compound eyes often stalked ocelli simple eyes statocysts and sensory bristles The naupliar eye is a characteristic of the nauplius larva and consists of four cup shaped ocelli facing in different directions and able to distinguish between light and darkness 14 Ecology Edit Grapsus grapsus a terrestrial crab Malacostracans live in a wide range of marine and freshwater habitats and three orders have terrestrial members Amphipoda Talitridae Isopoda Oniscidea the woodlice and Decapoda terrestrial hermit crabs crabs of the families Ocypodidae Gecarcinidae and Grapsidae and terrestrial crayfish 18 They are abundant in all marine ecosystems and most species are scavengers although some such as the porcelain crabs are filter feeders and some such as mantis shrimps are carnivores 12 Life cycle EditMost species of malacostracans have distinct sexes a phenomenon known as gonochorism although a few species exhibit hermaphroditism 12 The female genital openings or gonopores are located on the sixth thoracic segment or its appendages while the male gonopores are on the eighth segment or its appendages or in a small number of species on the seventh 11 The naupliar larval stages are often reduced and take place before hatching but where they occur a metamorphosis usually occurs between the larval and the adult forms Primitive malacostracans have a free swimming naupliar larval stage 11 Research suggests the common ancestor of Malacostraca had lost the free living nauplius larval stage but re evolved it again through heterochrony in Dendrobranchiata and Euphausiacea which both has a lecithotrophic non feeding nauplius stage 19 20 Mating EditMating behavior has been studied in the freshwater shrimp Caridina ensifera 21 Multiple paternity common in the Malacostrica also occurs in C ensifera Reproductive success of sires was found to correlate inversely with their genetic relatedness to the mother 21 This finding suggests that sperm competition and or pre and post copulatory female choice occurs Female choice may increase the fitness of progeny by avoiding inbreeding that can lead to expression of homozygous deleterious recessive mutations 22 Phylogenetics EditMain article Phylogeny of Malacostraca The monophyly of Malacostraca is widely accepted This is supported by several common morphological traits which are present throughout the group and is confirmed by molecular studies 23 However a number of problems make it difficult to determine the relationships between the orders of Malacostraca These include differences in mutation rates in different lineages different patterns of evolution being apparent in different sources of data including convergent evolution and long branch attraction 24 There is less agreement on the status of the subclass Phyllocarida with its single extant order Leptostraca depending on whether foliaceous leaf like limbs have a single or multiple origin Some authors advocate placing Phyllocarida in Phyllopoda a group used in former classification systems which would then include branchiopods cephalocarids and leptostracans A molecular study by American biologists Trisha Spears and Lawrence Abele concluded that phylogenetic evidence did not support the monophyly of this grouping and that Phyllocarida should be regarded as a subclass of Malacostraca that had diverged from the main lineage at an early date 11 25 The following cladogram is based on the 2001 phylogenetic analysis of Richter amp Scholtz 26 Malacostraca PhyllocaridaHoplocaridaEumalacostraca DecapodaAmphionidaceaEuphausiaceaPeracarida ThermosbaenaceaMysidaLophogastridaSpelaeogriphaceaMictaceaCumaceaTanaidaceaIsopodaSyncarida AnaspidaceaBathynellaceaSubclass Phyllocarida Edit Leptostraca is the only extant order of Phyllocarida the other two orders Archaeostraca and Hoplostraca being extinct Leptostracans are thought to be the most primitive of the malacostracans and date back to the Cambrian period They range in length from 1 to 4 cm 0 4 to 1 6 in most being suspension feeders though some are carnivores or scavengers They have a two part carapace which encloses the head the whole thorax and part of the abdomen and are the only malacostracans with seven abdominal segments Three families are known with several genera and about twenty species They are found worldwide from the intertidal zone to the deep ocean all but one species being benthic living on the seabed 7 11 Subclass Hoplocarida Edit Squilla empusa a mantis shrimp Stomatopoda is the only extant order of Hoplocarida the other two orders Aeschronectida and Archaeostomatopoda being extinct Stomatopodans commonly known as mantis shrimps range in length from 5 to 36 cm 2 to 14 in and are predators They have a dorso ventrally flattened body and a shield like carapace and are armed with powerful raptorial claws normally carried in a folded position There are about 300 species most living in tropical and subtropical seas although some live in temperate areas They are benthic mostly hiding in cracks and crevices or living in burrows some emerging to forage while others are ambush predators 7 11 Subclass Eumalacostraca Edit The Eumalocostraca contains the vast majority of the approximately 40 000 living species of malacostracans and consists of three superorders Syncarida Peracarida and Eucarida Syncaridans are mostly small and found in freshwater and subterranean habitats Peracaridans are characterised by having a marsupium in which they brood their young They are found in marine freshwater and terrestrial habitats and include Amphipoda Cumacea Isopoda and Mysida Eucarida includes lobsters crabs shrimps prawns and krill 27 Fossil record Edit The first malacostracans appeared sometime in the Cambrian when animals belonging to the Phyllocarida appeared 28 29 Classification EditSee also List of prehistoric malacostracans The following classification of living malacostracans is based on An Updated Classification of the Recent Crustacea 2001 by the American marine biologists Joel W Martin curator of crustaceans at the Natural History Museum of Los Angeles County and George E Davies 30 Extinct orders have been added to this 31 32 33 and are indicated by an obelisk Odontodactylus scyllarus Hoplocarida Stomatopoda Porcellio scaber and Oniscus asellus Peracarida Isopoda Cancer pagurus Eucarida Decapoda Class Malacostraca Latreille 1802 Subclass Phyllocarida Packard 1879 Archaeostraca Claus 1888 Hoplostraca Schram 1973 Leptostraca Claus 1880Subclass Hoplocarida Calman 1904 Aeschronectida Schram 1969 Archaeostomatopoda Schram 1969 Stomatopoda Latreille 1817Subclass Eumalacostraca Grobben 1892 Superorder Syncarida Packard 1885 Palaeocaridacea Brooks 1979 Bathynellacea Chappuis 1915 Anaspidacea Calman 1904 Superorder Peracarida Calman 1904 Spelaeogriphacea Gordon 1957 Thermosbaenacea Monod 1927 Lophogastrida Sars 1870 Mysida Haworth 1825 Mictacea Bowman et al 1985 Amphipoda Latreille 1816 Isopoda Latreille 1817 Tanaidacea Dana 1849 Cumacea Kroyer 1846 Superorder Eucarida Calman 1904 Euphausiacea Dana 1852 Amphionidacea Williamson 1973 Decapoda Latreille 1802References Edit Dupuis Claude 1974 Pierre Andre Latreille 1762 1833 the foremost entomologist of his time Annual Review of Entomology 19 1 14 doi 10 1146 annurev en 19 010174 000245 malacostracan Oxford English Dictionary Online ed Oxford University Press Subscription or participating institution membership required Rich Patricia Vickers Fenton Mildred Adams Fenton Caroll Lane Rich Thomas Hewitt 1996 Crustaceans The Fossil Book a Record of Prehistoric Life 2nd ed Courier Dover Publications pp 213 221 ISBN 978 0 486 29371 4 Clifford Hugh F 1991 Introduction to the Malacostraca Aquatic Invertebrates of Alberta an Illustrated Guide University of Alberta pp 173 175 ISBN 978 0 88864 234 9 Poore Hugh F 2002 Introduction Crustacea Malacostraca Zoological catalogue of Australia Vol 19 2A CSIRO Publishing pp 1 7 ISBN 978 0 643 06901 5 a b c Barnes R S K Calow P Olive P J W Golding D W Spicer J I 2001 Invertebrates with legs the arthropods and similar groups The Invertebrates a Synthesis 3rd ed Wiley Blackwell pp 168 206 ISBN 978 0 632 04761 1 a b c d e f g h Ruppert Edward E Fox Richard S Barnes Robert D 2004 Invertebrate Zoology 7th ed Cengage Learning pp 625 626 ISBN 978 81 315 0104 7 Atwater Dan Fautin Daphne G 2001 Class Malacostraca crabs krill pill bugs shrimp and relatives Animal Diversity Web University of Michigan Retrieved November 23 2010 Multicellular Animals Volume II The Phylogenetic System of the Metazoa Optical Design and Evolutionary Adaptation in Crustacean Compound Eyes a b c d e f g Davie P J F 2002 Class Malacostraca Introduction Crustacea Malacostraca Phyllocarida Hoplocarida Eucarida Part 1 Volume 19 3A of Zoological Catalogue of Australia CSIRO Publishing p 23 ISBN 978 0 643 06791 2 a b c d Hayward P J Isaac M J Makings P Moyse J Naylor E Smaldon G 1995 Crustaceans In Hayward P J Ryland John Stanley eds Handbook of the Marine Fauna of North West Europe Oxford University Press pp 290 461 ISBN 978 0 19 854055 7 Ricketts Edward F Calvin Jack Phillips David W Hedgpeth Joel W 1992 Rocky shores of bays and estuaries Between Pacific Tides 5th ed Stanford University Press pp 269 316 ISBN 978 0 8047 2068 7 a b Ruppert Edward E Fox Richard S Barnes Robert D 2004 Invertebrate Zoology 7th ed Cengage Learning pp 610 613 ISBN 978 81 315 0104 7 Sakurai Akira Closed and open circulatory system Georgia State University Retrieved 2014 05 21 Urich Klaus 1994 Respiratory pigments Comparative Animal Biochemistry Springer pp 249 287 ISBN 978 3 540 57420 0 Ghiselin Michael T 2005 Crustacean Encarta Microsoft Little Colin 1983 Crustaceans and the evolution of the arthropods The Colonisation of Land Origins and Adaptations of Terrestrial Animals Cambridge University Press pp 63 106 ISBN 978 0 521 25218 8 Evolution of eumalacostracan development new insights into loss and reacquisition of larval stages revealed by heterochrony analysis Naupliar and Metanaupliar Development of Thysanoessa raschii Malacostraca Euphausiacea from Godthabsfjord Greenland with a Reinstatement of the Ancestral Status of the Free Living Nauplius in Malacostracan Evolution a b Yue GH Chang A 2010 Molecular evidence for high frequency of multiple paternity in a freshwater shrimp species Caridina ensifera PLOS ONE 5 9 e12721 Bibcode 2010PLoSO 512721Y doi 10 1371 journal pone 0012721 PMC 2939052 PMID 20856862 Charlesworth D Willis JH 2009 The genetics of inbreeding depression Nat Rev Genet 10 11 783 96 doi 10 1038 nrg2664 PMID 19834483 S2CID 771357 Hassanin Alexandre 2006 Phylogeny of Arthropoda inferred from mitochondrial sequences Strategies for limiting the misleading effects of multiple changes in pattern and rates of substitution PDF Molecular Phylogenetics and Evolution 38 1 100 116 doi 10 1016 j ympev 2005 09 012 PMID 16290034 Jenner Ronald A Ni Dhubhghaill Ciara Ferla Matteo P Wills Matthew A 2009 Eumalacostracan phylogeny and total evidence limitations of the usual suspects BMC Evolutionary Biology 9 1 21 doi 10 1186 1471 2148 9 21 PMC 2640363 PMID 19173741 Spears Trisha Abele Lawrence G 1999 Phylogenetic Relationships of Crustaceans with Foliaceous Limbs An 18S rDNA Study of Branchiopoda Cephalocarida and Phyllocarida Journal of Crustacean Biology 19 4 825 843 doi 10 1163 193724099x00538 JSTOR 1549304 Richter Scholtz January 2002 Phylogenetic analysis of the Malacostraca Crustacea Journal of Zoological Systematics and Evolutionary Research 39 3 113 136 doi 10 1046 j 1439 0469 2001 00164 x Davie P J F 2002 Class Malacostraca Introduction Crustacea Malacostraca Phyllocarida Hoplocarida Eucarida Part 1 Volume 19 3A of Zoological Catalogue of Australia CSIRO Publishing p 91 ISBN 978 0 643 06791 2 Collette Joseph H Hagadorn James W 2010 Three dimensionally preserved arthropods from Cambrian Lagerstatten of Quebec and Wisconsin Journal of Paleontology 84 4 646 667 doi 10 1666 09 075 1 S2CID 130064618 Collette Joseph H Hagadorn James W 2010 Early evolution of phyllocarid arthropods phylogeny and systematics of Cambrian Devonian archaeostracans Journal of Paleontology 84 5 795 820 doi 10 1666 09 092 1 S2CID 85074218 Martin Joel W Davis George E 2001 An Updated Classification of the Recent Crustacea PDF Natural History Museum of Los Angeles County p 132 Jenner Ronald A Hof Cees H J Schram Frederick R 1998 Palaeo and archaeostomatopods Hoplocarida Crustacea from the Bear Gulch Limestone Mississippian Namurian of central Montana Contributions to Zoology 67 3 155 186 doi 10 1163 18759866 06703001 Camacho A I Valdecasas A G 2008 Global diversity of syncarids Syncarida Crustacea in freshwater In Balian E V Leveque C Segers H Martens K eds Freshwater Animal Diversity Assessment Developments in Hydrobiology Vol 198 Springer pp 257 266 doi 10 1007 978 1 4020 8259 7 28 ISBN 978 1 4020 8258 0 Davie P J F 2001 Subclass Phyllocarida Introduction Crustacea Malacostraca Phyllocarida Hoplocarida Eucarida Part 1 Zoological catalogue of Australia Vol 19 3A CSIRO Publishing p 24 ISBN 978 0 643 06791 2 External links Edit Crustaceans portal Media related to Malacostraca at Wikimedia Commons Stebbing Thomas Roscoe Rede 1911 Malacostraca Encyclopaedia Britannica Vol 17 11th ed pp 457 459 Malacostraca Tree of Life Web Project Introduction to the Malacostraca University of California Berkeley Malacostraca The Paleobiology Database Malacostraca image key Guide to the marine zooplankton of south eastern Australia Tasmanian Aquaculture and Fisheries Institute Retrieved from https en wikipedia org w index php title Malacostraca amp oldid 1144495524, wikipedia, wiki, book, books, library,

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