Latreille, 1806
Ostracoda are small crustaceans with a bivalved carapace or shell, resembling a clam shell, enclosing an unsegmented body with five to seven paired appendages. See also pages Os. 1 Introduction and Os. 4 Morphology.
Description
Shell shape is highly variable and its surface is smooth to ornate. As the animal grows, the shell is shed, growing again after each moult. Valves of the shell connected dorsally by a ligament. Shell penetrated by pores, bearing setae of various kinds. The shell is closed by muscles which leave attachment scars on the inner surface of the valves.
Head and body: first antenna (or antennule) and second antenna (or antenna) well developed. The maxilla (or fourth limb, maxillula, or first maxilla) is a variable feeding limb. Fifth limb (or maxilla, or first thoracic leg) generally with a large epipodial plate. Furca either anterior or posterior to the anus. Digestive system consisting of mouth and gut. Most species have an anterodorsal median eye, which sometimes receives light through a translucent spot in the shell. Other species have paired compound lateral eyes.
Circulatory system and respiration: there is an open circulatory system; a heart may be present or absent. Respiration is by diffusion through the thin cuticle that covers the entire body.
Reproduction
Sexes usually separate; fertilization internal, accomplished by a complicated copulatory apparatus. Embryos are brooded in the posterodorsal section of the shell, or the eggs released into the water. There are four to nine instar larvae with bivalve shells, thus resembling the adults.
Habitats
Most ostracods live burrowed in the substrate or are epibenthic crawlers, others are planktonic. Fresh, brackish and marine waters. Lakes, streams, ponds, ditches, oceans.
Classification
According to Maddock's classification (1982) six orders are distinguished:
Class Maxillopoda
Subclass Ostracoda
Order Podocopida
Order Platycopida
Order Myodocopida Sars, 1866
Order Bradoriida
Order Leperditicopida
Order Palaeocopida
The first three orders are extant, the others are extinct. Planktonic ostracods belong to the Order Myodocopida. Below an outline of the Myodocopida; bold text denotes the taxa treated here. The classification by Athersuch et al. (1989) has been adopted.
Order Myodocopida Sars, 1866
Suborder Halocypridina Dana, 1849
Family Thaumatocyprididae Mueller, 1906
Family Entomoconchidae Brady, 1868
Family Halocyprididae Claus, 1891
Subfamily Deeveyinae Kornicker and Iliffe, 1987
Subfamily Halocyprinae Dana, 1849
Genus Fellia
Genus Halocypria
Genus Halocypris
Subfamily Conchoecinae Müller, 1912
Genus Alacia
Genus Boroecia
Genus Conchoecetta
Genus Conchoecilla
Genus Conchoecia
Genus Conchoecissa
Genus Discoconchoecia
Genus Gaussicia
Genus Loricoecia
Genus Macroconchoecia
Genus Metaconchoecia
Genus Mikroconchoecia
Genus Mollicia
Genus Obtusoecia
Genus Orthoconchoecia
Genus Paraconchoecia
Genus Paramollicia
Genus Porroecia
Genus Proceroecia
Genus Pseudoconchoecia
Subfamily Archiconchoecinae Poulsen, 1969
Genus Archiconchoecia
Subfamily Euconchoecinae Poulsen, 1969
Genus Bathyconchoecia
Genus Euconchoecia
Suborder Cladocopina Sars, 1866
Family Polycopidae Sars, 1866
Suborder Myodocopina Sars, 1866
Family Cypridinidae Baird, 1850
Subfamily Cypridininae Brady and Norman, 1896
Genus Macrocypridina
Genus Gigantocypris
Subfamily Azygocypridinae Kornicker, 1970
Family Philomedidae Müller, 1912
Subfamily Philomedinae Müller, 1912
Subfamily Pseudophilomedinae Kornicker, 1967
Family Cylindroleberidae Müller, 1906
Subfamily Cylindroleberidinae Müller, 1906
Subfamily Cyclasteropinae Poulsen, 1965
Family Sarsiellidae Brady and Norman, 1896
Family Rutidermatidae Brady and Norman, 1896