ostracods
Information about ostracods
| Ostracoda Fossil range: Cambrian to recent | ||||||||
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| Scientific classification | ||||||||
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| Subclasses and Orders | ||||||||
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Myodocopa Sars, 1866
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Ostracoda is a class of the Crustacea, sometimes known as the seed shrimp because of their appearance. Some 50,000 extinct and extant species have been identified, grouped into several orders. This group may not be monophyletic (exhibiting monophyly)[1]. Ostracod taxa are grouped into a Class based on gross morphology. Their molecular phylogeny remains ambiguous[2].
Ostracods are small crustaceans, typically around one mm in size, but varying between 0.2 to 30 mm, laterally compressed and protected by a bivalve-like, chitinous or calcareous valve or "shell". The hinge of the two valves is in the upper, dorsal region of the body.
Ecologically, marine ostracods can be part of the zooplankton or (most commonly) they are part of the benthos, living on or inside the upper layer of the sea floor. Many ostracods, especially the Podocopida, are also found in fresh water and some are known from humid continental forest soils.
Fossils
Ostracods have a long and well-documented fossil record from the Cambrian to the present day. An outline microfaunal zonal scheme based on both foraminifera and ostracoda was compiled by M. B. Hart (1972)[3].Ostracods have been particularly useful for the biozonation of marine strata on a local or regional scale, and they are invaluable indicators of paleo-environments because of their widespread occurrence, small size, easily-preservable generally-moulted calcified bivalve carapaces, the valves are a commonly found microfossil.
Morphology
The body of an ostracod is encased by two valves, which together form the duplicature. A distinction is made between the valve (hard parts) and the body with its appendages (soft parts).Soft parts and ontogeny
)
Anatomy of Cypridina mediterranea
During the ontogeny the epidermis (containing mesodermal tissue) invaginates ventrolaterally near the cephalon/thorax area. This invagination proceeds upwards and tailwards, until the whole animal is enveloped by a double tissue layer on both sides: this forms the duplicature. The dorsal region never becomes invaginated, and is called the isthmus. The mesodermal tissue in the duplicature develops into the vestibulum. The vestibulum makes contact with the body near the isthmus. It plays a role in oxygenation. In paleo-ecology, the size of the vestibulum can be cautiously interpreted as an environmental indicator. The two double tissue layers surrounding the animal each have an inner and an outer lamella, which surrounds the vestibulum. These lamellae are surrounded by a chitinous cuticle, that is secreted by the epidermal cells.
Like all arthropods, ostracods develop discontinually. Before reaching maturity 8 larval stages (instars) are passed.
Hard parts
The epidermal cells may also secrete calcium carbonate after the chitinous layer is formed, resulting in a chalk layer enveloped by chitin. This calcification is not equally pronounced in all orders. During every instar transition, the old carapace (chitinous and calcified) is rejected and a new, larger is formed and calcified. The outer lamella calcifies completely, while the inner lamella calcifies partially, with the rest remaining chitinous. The partial inner lamella calcification occurs when the ostracod becomes adult. The partial inner lamella calcification is most strongly developed frontally (see electron micrograph). The marginal zone is the area where inner and outer lamella meet, and includes part of the vestibulum. The edge of the marginal zone is called the fused zone, and in this area inner and outer lamella join. The fused zone can contain marginal pore canals. These, along with non-marginal pore canals (that are dispersed evenly along the ostracod's valve) connect the vestibulum to the outer world. The line of concrescence is the visible line between the vestibulum and the fused zone. In many cases, this line is wavering and follows the marginal pore canals. On the inner lamella, a selvage may be present.)
Inside of a right cytherocopid ostracod valve. Cyamocytheridea sp. from the Eocene (Lower Lutetian, ±49 Mya) of Nederokkerzeel, Belgium
External links
Key to the two subclasses: [1]International Research Group on Ostracoda: [2]
References
1. ^ Fortney, R. and Thomas, R. "Arthropod Relationships" (1998)
2. ^ Yamaguchi, S. and Endo, K. "Molecular phylogeny of Ostracoda (Crustacea) inferred from 18S ribosomal DNA sequences: implication for its origin and diversification" Marine Biology Volume 143, Number 1 (2003)
3. ^ Hart, M. B.; 1972. A correlation of the macrofaunal and microfaunal zonations of the Gault Clay in southeast England; The Boreal Lower Cretaceous; Geological Journal Special Issue No. 5
2. ^ Yamaguchi, S. and Endo, K. "Molecular phylogeny of Ostracoda (Crustacea) inferred from 18S ribosomal DNA sequences: implication for its origin and diversification" Marine Biology Volume 143, Number 1 (2003)
3. ^ Hart, M. B.; 1972. A correlation of the macrofaunal and microfaunal zonations of the Gault Clay in southeast England; The Boreal Lower Cretaceous; Geological Journal Special Issue No. 5
The Cambrian is a major division of the geologic timescale that begins about 542 ± 1.0 Ma (million years ago) at the end of the Proterozoic eon and ended about 488.3 ± 1.7 Ma with the beginning of the Ordovician period (ICS, 2004).
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Scientific classification or biological classification is a method by which biologists group and categorize species of organisms. Scientific classification also can be called scientific taxonomy, but should be distinguished from folk taxonomy, which lacks scientific basis.
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Arthropoda
Latreille, 1829
Subphyla and Classes
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Latreille, 1829
Subphyla and Classes
- Subphylum Trilobitomorpha
- Trilobita - trilobites (extinct)
- Subphylum Chelicerata
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crustaceans (Crustacea) are a large group of arthropods, comprising approximately 52,000 described species [1], and are usually treated as a subphylum [2].
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Pierre André Latreille (November 20, 1762 - February 6, 1833) was a French entomologist. His works describing insects assigned many of the insect taxa still in use today.
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class is the rank in the scientific classification of organisms in biology below Phylum and above Order.
For example, Mammalia is the class used in the classification of dogs, whose phylum is Chordata (animals with notochords) and order is Carnivora (mammals that eat meat).
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For example, Mammalia is the class used in the classification of dogs, whose phylum is Chordata (animals with notochords) and order is Carnivora (mammals that eat meat).
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order (Latin: ordo, plural ordines) is a rank between class and family (termed a taxon at that rank). The superorder is a rank between class and order. Exact details of formal nomenclature depend on the Nomenclature Code which applies.
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Myodocopa
Sars, 1866
Orders
Traditionally, the Myodocopa and Podocopa have been classified as subclasses within the class Ostracoda, although there is some question about how closely related the two
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Sars, 1866
Orders
- Halocyprida
- Myodocopida
Traditionally, the Myodocopa and Podocopa have been classified as subclasses within the class Ostracoda, although there is some question about how closely related the two
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Georg Ossian Sars (April 20 1837 - April 9 1927) was a Norwegian marine biologist.
Like his father, Michael, Georg Sars was a marine taxonomist, and is credited with the discovery of a number of new species, particularly mysids and ostracods.
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Like his father, Michael, Georg Sars was a marine taxonomist, and is credited with the discovery of a number of new species, particularly mysids and ostracods.
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Myodocopida
Sars, 1866
Superfamilies
Cypridinoidea
Sarsielloidea
Cylindroleberidoidea
The Myodocopida is one of the two orders within the Myodocopa, in turn a subclass of the Ostracods.
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Sars, 1866
Superfamilies
Cypridinoidea
Sarsielloidea
Cylindroleberidoidea
The Myodocopida is one of the two orders within the Myodocopa, in turn a subclass of the Ostracods.
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Halocyprida
Dana, 1853
Suborders
Cladocopina
Halocypridina
The Halocyprida is one of the two orders within the Myodocopa, in turn a subclass of the ostracods.
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Dana, 1853
Suborders
Cladocopina
Halocypridina
The Halocyprida is one of the two orders within the Myodocopa, in turn a subclass of the ostracods.
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James Dwight Dana (February 12 1813–April 14 1895) was an American geologist, mineralogist and zoologist. He made important studies of mountain-building, volcanic activity, and the origin and structure of continents and oceans.
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Podocopa
Müller, 1894
Families
See text
The Podocopa are a subclass of ostracods. This subclass can be differentiated from the other subclass (Myodocopa) by the morphology of the second antenna: the Podocopa have a relatively long endopod,
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Müller, 1894
Families
See text
The Podocopa are a subclass of ostracods. This subclass can be differentiated from the other subclass (Myodocopa) by the morphology of the second antenna: the Podocopa have a relatively long endopod,
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Fritz Müller
Here in Brazil
Born March 31 1821
Died May 21 1897 (aged 76)
Brazil
Nationality German
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Here in Brazil
Born March 31 1821
Died May 21 1897 (aged 76)
Brazil
Nationality German
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Podocopida
Sars, 1866
Suborders
See text
The Podocopida is an order within the Podocopa. It includes the following taxa: Bairdiocopina, Cytherocopina, Darwinulocopina, Cypridocopina and Sigilliocopina.
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Sars, 1866
Suborders
See text
The Podocopida is an order within the Podocopa. It includes the following taxa: Bairdiocopina, Cytherocopina, Darwinulocopina, Cypridocopina and Sigilliocopina.
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class is the rank in the scientific classification of organisms in biology below Phylum and above Order.
For example, Mammalia is the class used in the classification of dogs, whose phylum is Chordata (animals with notochords) and order is Carnivora (mammals that eat meat).
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For example, Mammalia is the class used in the classification of dogs, whose phylum is Chordata (animals with notochords) and order is Carnivora (mammals that eat meat).
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crustaceans (Crustacea) are a large group of arthropods, comprising approximately 52,000 described species [1], and are usually treated as a subphylum [2].
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In phylogenetics, a group is monophyletic (Greek: "of one race") if it consists of an inferred common ancestor and all its descendants. A taxonomic group that contains organisms but not their common ancestor is called polyphyletic, and a group that contains some but not all
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Molecular phylogeny is the use of the structure of molecules to gain information on an organism's evolutionary relationships. The result of a molecular phylogenetic analysis is expressed in a so-called phylogenetic tree.
Every living organism contains DNA, RNA, and proteins.
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Every living organism contains DNA, RNA, and proteins.
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Bivalvia
Linnaeus, 1758
Subclasses
Anomalosdesmata
Cryptodonta
Heterodonta
Paleoheterodonta
Palaeotaxodonta
Pteriomorphia
and see text
Bivalves are mollusks belonging to the class Bivalvia.
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Linnaeus, 1758
Subclasses
Anomalosdesmata
Cryptodonta
Heterodonta
Paleoheterodonta
Palaeotaxodonta
Pteriomorphia
and see text
Bivalves are mollusks belonging to the class Bivalvia.
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Chitin (C8H13O5N)n (IPA: [ˈkaɪtn̩]) is a long-chain polymer of beta-glucose that forms a hard, semitransparent material found throughout the natural world.
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Zooplankton are the heterotrophic (or detritivorous) component of the plankton that drift in the water column of oceans, seas, and bodies of fresh water. The name is derived from the Greek terms, ζῴον
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Benthos are the organisms which live on, in, or near the seabed, also known as the benthic zone.[1] Although the term derived from the Greek for "depths of the sea"<ref name="caml" />, the term is also used in freshwater biology to refer to organisms at
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Podocopida
Sars, 1866
Suborders
See text
The Podocopida is an order within the Podocopa. It includes the following taxa: Bairdiocopina, Cytherocopina, Darwinulocopina, Cypridocopina and Sigilliocopina.
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Sars, 1866
Suborders
See text
The Podocopida is an order within the Podocopa. It includes the following taxa: Bairdiocopina, Cytherocopina, Darwinulocopina, Cypridocopina and Sigilliocopina.
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- For other uses of the term, see Fossil (disambiguation)
FOSSIL is a standard for allowing serial communication for telecommunications programs under the DOS operating system.
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The Cambrian is a major division of the geologic timescale that begins about 542 ± 1.0 Ma (million years ago) at the end of the Proterozoic eon and ended about 488.3 ± 1.7 Ma with the beginning of the Ordovician period (ICS, 2004).
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Foraminifera
d'Orbigny, 1826
Orders
Allogromiida
Carterinida
Fusulinida - extinct
Globigerinida
Involutinida - extinct
Lagenida
Miliolida
Robertinida
Rotaliida
Silicoloculinida
Spirillinida
Textulariida
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d'Orbigny, 1826
Orders
Allogromiida
Carterinida
Fusulinida - extinct
Globigerinida
Involutinida - extinct
Lagenida
Miliolida
Robertinida
Rotaliida
Silicoloculinida
Spirillinida
Textulariida
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thorax is a division of an animal's body that lies between the head and the abdomen.
In mammals, the thorax is the region of the body formed by the sternum, the thoracic vertebrae and the ribs. It extends from the neck to the diaphragm, not including the upper limbs.
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In mammals, the thorax is the region of the body formed by the sternum, the thoracic vertebrae and the ribs. It extends from the neck to the diaphragm, not including the upper limbs.
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Segmentation in biology refers to the division of some metazoan bodies and plant body plans into a series of semi-repetitive segments, and the question of the benefits and costs of doing so. As such, segmentation is related to the more general concept of modularity.
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