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Superregnum: Eukaryota
Cladus: Unikonta
Cladus: Opisthokonta
Cladus: Holozoa
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Protostomia
Cladus: Ecdysozoa
Cladus: Panarthropoda
Phylum: Arthropoda
Subphylum: Crustacea
Superclassis: Oligostraca
Classis: Ostracoda
Subclasses: MyodocopaPodocopa
Overview of orders

Extant groups (5): HalocypridaMyodocopidaPlatycopidaPodocopida
+ Familia incertae sedis: Eucandonidae
Fossil groups: †Kloedenellocopida – †Palaeocopida


Ostracoda Latreille, 1802

Latreille, P.A. 1802. Histoire naturelle, générale et particulière des crustacés et des insectes. Ouvrage faisant suite à l’histoire naturelle générale et particulière, composée par Leclerc de Buffon, et rédigée par C.S. Sonnini, membre de plusieurs sociétés savantes. Familles naturelles des genres. Tome troisième. F. Dufart, Paris, xii + pp. 13–467 + [1 (errata)]. BHL Reference page.
Antonietto, L.S., Machado, C.P., Do Carmo, D.A. & Rosa, J.W.C. 2012. Recent Ostracoda (Arthropoda, Crustacea) from São Pedro-São Paulo Archipelago, Brazil: a preliminary approach. Zootaxa 3335: 29–53. Preview Reference page.
Chapman, M.A. 1963. A review of the freshwater ostracods of New Zealand. Hydrobiologia 22: 1–40. DOI: 10.1007/BF00039679
Cohen, A.C., Peterson, D.E. & Maddocks, R.F. 2007. Ostracoda. The Light & Smith Manual: Intertidal Invertebrates from Central California to Oregon (Editor: Carlton, J.T.), Fourth Edition: 417–446, 13 plates (184–196). ISBN 9780520239395 and ISBN 0520239393
Kempf, E.K. 1980. Index and Bibliography of Nonmarine Ostracoda. Part 1, Index A. Sonderveröffentlichungen, Geologisches Institut der Universität zu Köln 35: 1–188.
Kempf, E.K. 1980. Index and Bibliography of Nonmarine Ostracoda. Part 4, Bibliography A. Sonderveröffentlichungen, Geologisches Institut der Universität zu Köln 38: 1–186.
Kempf, E.K. 1986. Index and Bibliography of Marine Ostracoda. Part 1, Index A. Sonderveröffentlichungen, Geologisches Institut der Universität zu Köln 50: 1–762.
Kempf, E.K. 1988. Index and Bibliography of Marine Ostracoda. Part 4, Bibliography A. Sonderveröffentlichungen, Geologisches Institut der Universität zu Köln 53: 1–454.
Kempf, E.K. 1995. Index and Bibliography of Marine Ostracoda. Part 6, Index A, Supplement 1. Sonderveröffentlichungen, Geologisches Institut der Universität zu Köln 100: 1–239.
Kempf, E.K. 1997. Index and Bibliography of Nonmarine Ostracoda. Part 6, Index A, Supplement 1. Sonderveröffentlichungen, Geologisches Institut der Universität zu Köln 109: 1–142.
Kempf, E.K. 1997. Index and Bibliography of Nonmarine Ostracoda. Part 9, Bibliography C. Sonderveröffentlichungen, Geologisches Institut der Universität zu Köln 112: 1–144.
Kempf, E.K. 2004. Fossil and Living Ostracoda of the World. Index and Bibliography of Marine Ostracoda. Part 16, Index D: Recent Marine Ostracoda of the World. CD-ROM Edition with 20,686 dataset references (published by the author).
Kempf, E.K. 2006. Fossil and Living Ostracoda of the World. Index and Bibliography of Nonmarine Ostracoda. Part 16, Index D: Recent Nonmarine Ostracoda of the World. CD-ROM Edition with 27,794 dataset references (published by the author).
Martens, K. & Savatenalinton, S. 2011. A subjective checklist of the Recent, free-living, non-marine Ostracoda (Crustacea). Zootaxa 2855: 1–79. PDF
Meisch, C. 2000. Freshwater Ostracoda of Western and Central Europe. In: Süßwasserfauna von Mitteleuropa 8/3. Spektrum Akademischer Verlag, 522 p.
Nogueira, A.A.E., Ramos, M.I.F. & Hunt, G. 2019. Taxonomy of Ostracods from the Pirabas Formation (Upper Oligocene to Lower Miocene), Eastern Amazonia (Pará State, Brazil). Zootaxa 4573(1): 1–111. DOI: 10.11646/zootaxa.4573.1.1 Paywall Reference page.
Pieri, V., Martens, K., Meisch, C. & Rossetti, G. 2015. An annotated checklist of the Recent non-marine ostracods (Ostracoda: Crustacea) from Italy. Zootaxa 3919(2): 271–305. DOI: 10.11646/zootaxa.3919.2.3 Reference page.
Warne, M.T. 2010. Review of Alataleberis McKenzie and Warne, 1986 and description of Alatapacifica gen. nov. (Ostracoda, Crustacea) from the Cenozoic of Australasia. Alcheringa 34(1): 37–60. DOI: 10.1080/03115510903343469
Webber, W.R. et al. 2010. [Chapter] 8 Phylum Arthropoda Subphylum Crustacea shrimps, crabs, lobsters, barnacles, slaters, and kin. pp. 98–232 in Gordon, D.P. (ed.): New Zealand inventory of biodiversity. Volume 2. Kingdom Animalia. Chaetognatha, Ecdysozoa, ichnofossils. Canterbury University Press, Christchurch, New Zealand. ISBN 978-1-87725793-3

Additional references

Bergue, C.T., Coimbra, J.C. & Ramos, M.I.F. 2016. Taxonomy and bathymetric distribution of the outer neritic/upper bathyal ostracodes (Crustacea: Ostracoda) from the southernmost Brazilian continental margin. Zootaxa 4079(1): 65–86. DOI: 10.11646/zootaxa.4079.1.5.Reference page.
Cabral, M.C. & Lord, A. 2017. Mesozoic Ostracoda from Portugal (Cabral Type Collection). Zootaxa 4306(1): 140–144. DOI: 10.11646/zootaxa.4306.1.10. Reference page.
Doweld, A.B. 2016. Kuznetsovia, a new generic replacement name for Aenigma Kuznetsova, 1957 (Ostracoda) non Newman, 1836 (Coleoptera). Zootaxa 4114(5): 581–582. DOI: 10.11646/zootaxa.4114.5.4. Reference page.
Doweld, A.B. 2016. New replacement name Kuznetsoviella (Ostracoda): a correction. Zootaxa 4137(2): 276–276. DOI: 10.11646/zootaxa.4137.2.7 Reference page.
Ghaouaci, S., Yavuzatmaca, M., Külköylüoğlu, O. & Amarouayache, M. 2017. An annotated checklist of the non-marine ostracods (Crustacea) of Algeria with some ecological notes. Zootaxa 4290(1): 140–154. DOI: 10.11646/zootaxa.4290.1.8. Reference page.
Ghaouaci, S., Yavuzatmaca, M., Külköylüoğlu, O. & Amarouayache, M. 2017. SOUAD GHAOUACI, MEHMET YAVUZATMACA, OKAN KÜLKÖYLÜOĞLU & MOUNIA AMAROUAYACHE (2017) An annotated checklist of the non-marine ostracods (Crustacea) of Algeria with some ecological notes. Zootaxa, 4290: 140–154. Zootaxa 4365(4): 500–500. DOI: 10.11646/zootaxa.4365.4.10 Full article (PDF) Reference page.
Maillet, S., Milhau, B., Vreulx, M. & Sánchez de Posada, L.C. 2016. Givetian ostracods of the Candás Formation (Asturias, North-western Spain): taxonomy, stratigraphy, palaeoecology, relationship to global events and palaeogeographical implications. Zootaxa 4068(1): 1–78. DOI: 10.11646/zootaxa.4068.1.1. Reference page.
Rasouli, H., Scharf, B.W., Meisch, C. & Aygen, C. 2016. An updated checklist of the Recent non-marine Ostracoda (Crustacea) of Iran, with a redescription of Eucypris mareotica (Fischer, 1855). Zootaxa 4154(3): 273–292. DOI: 10.11646/zootaxa.4154.3.3. Reference page.


Tree of Life Web Project. 2002. Ostracoda. Version 1 January 2002 (temporary). Ostracoda in The Tree of Life Web Project.
World Ostracoda Database

Vernacular names
беларуская: Ракушкавыя
Deutsch: Muschelkrebse
English: ostracods
euskara: Ostrakodo
français: Ostracode
עברית: צדפונאים
magyar: Kagylósrákok
lietuvių: Kiautavėžiai
Nederlands: Mosselkreeftjes
polski: Małżoraczki
русский: Ракушковые
svenska: Musselkräftor
中文: 介形纲

stracods, or ostracodes, are a class of the Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 70,000 species (only 13,000 of which are extant) have been identified,[1] grouped into several orders. They are small crustaceans, typically around 1 mm (0.04 in) in size, but varying from 0.2 to 30 mm (0.008 to 1 in) in the case of Gigantocypris. Their bodies are flattened from side to side and protected by a bivalve-like valve or "shell" made of chitin, calcium carbonate and protein. The hinge of the two valves is in the upper (dorsal) region of the body. Ostracods are grouped together based on gross morphology. While early work indicated the group may not be monophyletic[2] and early molecular phylogeny was ambiguous on this front,[3] recent combined analyses of molecular and morphological data found support for monophyly in analyses with broadest taxon sampling.[4]

Ecologically, marine ostracods can be part of the zooplankton or (most commonly) are part of the benthos, living on or inside the upper layer of the sea floor. Ostracods has been found as deep as 9,307 km (genus Krithe).[5] While Myodocopa is restricted to marine environments,[6] the Podocopida are also common in fresh water, and terrestrial species of Mesocypris are known from humid forest soils of South Africa, Australia and New Zealand.[7] But all three major podocopid lineages, Cypridocopina, Darwinulocopina and Cytherocopina, have several representatives living in terrestrial habitats.[8] They have a wide range of diets, and the group includes carnivores, herbivores, scavengers and filter feeders.

As of 2008, around 2000 species and 200 genera of non-marine ostracods are found.[9] However, a large portion of diversity is still undescribed, indicated by undocumented diversity hotspots of temporary habitats in Africa and Australia.[10] Non-marine species have been found to live in sulfidic cave ecosystems, deep groundwaters, hypersaline waters, acidic waters with pH as low as 3.4, phytotelmata in plants like bromeliads, and in temperatures varying from almost freezing to more than 50 °C in hot springs.[11][12] Of the known specific and generic diversity of non-marine ostracods, half (1000 species, 100 genera) belongs to one family (of 13 families), Cyprididae.[10] Many Cyprididae occur in temporary water bodies and have drought-resistant eggs, mixed/parthenogenetic reproduction, and the ability to swim. These biological attributes preadapt them to form successful radiations in these habitats.[13]

Ostracod comes from the Greek óstrakon meaning shell or tile.
The large ostracod Herrmannina from the Silurian (Ludlow) Soeginina Beds (Paadla Formation) on eastern Saaremaa Island, Estonia

Ostracods are "by far the most common arthropods in the fossil record"[14] with fossils being found from the early Ordovician to the present. An outline microfaunal zonal scheme based on both Foraminifera and Ostracoda was compiled by M. B. Hart.[15] Freshwater ostracods have even been found in Baltic amber of Eocene age, having presumably been washed onto trees during floods.[16]

Ostracods have been particularly useful for the biozonation of marine strata on a local or regional scale, and they are invaluable indicators of paleoenvironments because of their widespread occurrence, small size, easily preservable, generally moulted, calcified bivalve carapaces; the valves are a commonly found microfossil.

A find in Queensland, Australia in 2013, announced in May 2014, at the Bicentennary Site in the Riversleigh World Heritage area, revealed both male and female specimens with very well preserved soft tissue. This set the Guinness World Record for the oldest penis.[17] Males had observable sperm that is the oldest yet seen and, when analysed, showed internal structures and has been assessed as being the largest sperm (per body size) of any animal recorded. It was assessed that the fossilisation was achieved within several days, due to phosphorus in the bat droppings of the cave where the ostracods were living.[18]
Anatomy of Cypridina mediterranea

The body of an ostracod is encased by a carapace originating from the head region, and consists of two valves superficially resembling the shell of a clam. A distinction is made between the valve (hard parts) and the body with its appendages (soft parts).
Body parts
Ostracod swimming motions (in real time)

The body consists of a head and thorax, separated by a slight constriction. Unlike many other crustaceans, the body is not clearly divided into segments. The abdomen is regressed or absent, whereas the adult gonads are relatively large.

The head is the largest part of the body, and bears four pairs of appendages. Two pairs of well-developed antennae are used to swim through the water. In addition, there are a pair of mandibles and a pair of maxillae. The thorax has three primary pairs of appendages. The first of these has different functions in different groups. It can be used for feeding (Cypridoidea) or for walking (Cytheroidea), and in some species it has evolved into a male clasping organ. The second pair is mainly used for locomotion, and the third is used for walking or cleaning, but can also be reduced or absent. In the Myodocopina it is a multisegmented cleaning organ that resembles a worm. Their external genitals seem to originate from the fusion of three to five appendages. The two "rami", or projections, from the tip of the tail point downward and slightly forward from the rear of the shell.[19][20][21]: 40 

Podocopa, the largest subclass, have no gills, heart or circulatory system, and blood simply circulates between the valves of the shell. The other subclass of ostracods, the Myodocopa, do have a heart, and the family Cylindroleberididae also have 6-8 lamellar gills. Nitrogenous waste is excreted through glands on the maxillae, antennae, or both.[19][22]

The primary sense of ostracods is likely touch, as they have several sensitive hairs on their bodies and appendages. Compound eyes are only found in Myodocopina within the Myodocopa.[23] The order Halocyprida in the same subclass is eyeless.[24] Podocopid ostracods have just a naupliar eye, although Platycopida don't have eyes at all,[25] consisting of two lateral ocelli and a single ventral ocellus, but the ventral one is absent in some species.[19][26][27]
Palaeoclimatic reconstruction
Articulated ostracod valves in cross-section from the Permian of central Texas; typical thin section view of an ostracod fossil

A new method is in development called mutual ostracod temperature range (MOTR), similar to the mutual climatic range (MCR) used for beetles, which can be used to infer palaeotemperatures.[28] The ratio of oxygen-18 to oxygen-16 (δ18O) and the ratio of magnesium to calcium (Mg/Ca) in the calcite of ostracod valves can be used to infer information about past hydrological regimes, global ice volume and water temperatures.

Male ostracods have two penises, corresponding to two genital openings (gonopores) on the female. The individual sperm are often large, and are coiled up within the testis prior to mating; in some cases, the uncoiled sperm can be up to six times the length of the male ostracod itself. Mating typically occurs during swarming, with large numbers of females swimming to join the males. Some species are partially or wholly parthenogenetic.[19]

In the subclass Myodocopa, all members of the order Myodocopida have brood care, releasing their offspring as first instars, allowing a pelagic lifestyle. In the order Halocyprida the eggs are released directly into the sea, except for a single genus with brood care. In the subclass Podocopa, brood care is only found in Darwinulocopina and some Cytherocopina in the order Podocopida. In the remaining Podocopa it is common to glue the eggs to a firm surface, like vegetation or the substratum. These eggs are often resting eggs, and remain dormant during desiccation and extreme temperatures, only hatching when exposed to more favorable conditions.[29][30] The eggs hatch into nauplius larvae, which already have a hard shell.[19]

A variety of fauna prey upon ostracods in both aquatic and terrestrial environments. An example of predation in the marine environment is the action of certain Cytherocopina in the cuspidariid clams in detecting ostracods with cilia protruding from inhalant structures, thence drawing the ostracod prey in by a violent suction action.[31] Predation from higher animals also occurs; for example, amphibians such as the rough-skinned newt prey upon certain ostracods.[32]

Some ostracods, such as Vargula hilgendorfii, have a light organ in which they produce luminescent chemicals.[33] Most use the light as predation defense, while some, in the Caribbean, use the light for mating. These ostracods are called "blue sand" or "blue tears" and glow blue in the dark. Their bioluminescent properties made them valuable to the Japanese during World War II, when the Japanese army collected large amounts from the ocean to use as a convenient light for reading maps and other papers at night. The light from these ostracods, called umihotaru in Japanese, was sufficient to read by but not bright enough to give away troops' position to enemies.[34]
See also

iconCrustaceans portal

Mari Mari Group, fossil formation in the state of Amazonas of northwestern Brazil


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Review of Ostracoda (Crustacea) living below the Carbonate Compensation Depth and the deepest record of a calcified ostracod
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Oldest penis:
The oldest fossilised penis discovered to date dates back around 100 million years. It belongs to a crustacean called an ostracod, discovered in Brazil and measuring just 1mm across.
World's oldest sperm 'preserved in bat poo', Anna Salleh, ABC Online Science, 14 May 2014, accessed 15 May 2014
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