Myodocopida

(invertebrate zoology) An order of the subclass Ostracoda.

An order of marine organisms that forms an important part of the class Ostracoda (subphylum Crustacea) and comprises three suborders. It has a long geological history that extends back at least to the Early Silurian. However, the lightly calcified carapaces of the species in this order are a factor in their having a sparse fossil record. Indeed, of the sixteen families of myodocopids, three are known only from modern marine environments. Species of those families that have a fossil record are quite rare and discontinuous in their stratigraphical distribution. Myodocopids are only abundant as fossils from organically rich shale that was deposited in deep, anoxic environments, especially those of the Devonian seas. Such environments were devoid of benthic (bottom-dwelling) life, but the valves and carapaces of the nektonic (free-swimming) myodocopids, both immature forms (termed instars) and adults, sank into such environments and were preserved. See also Crustacea; Ostracoda.

The myodocopids are typically much larger than other ostracodes and may be more than a centimeter long, although adults of most species are unlikely to be longer than 3 mm. As is characteristic of ostracodes, the carapace of the myodocopids comprises two valves that are joined along the animal's dorsum by a hinge and ligament. Among the myodocopids, the anterior portions of both valves are marked by a characteristic notch through which the setaceous antennae or antennules protrude. The appendages of all ostracodes are homologous with those of other crustaceans and, as is characteristic of arthropods in general, have been highly modified during their evolution. The appendages of the myodocopids are especially well adapted for swimming. Sexual dimorphism is not as pronounced among the myodocopids as it is among most smaller, more heavily calcified ostracodes.

Myodocopids are not exclusively planktonic as is often assumed. They are typically strong swimmers, but many are nektobenthic, swimming in proximity to the substrate. Others, however, live near the surface of the open ocean and are not associated with the environments of deposition that lie far beneath them on the ocean floor, where their valves and carapaces will ultimately be deposited. A fascinating characteristic of the myodocopids is the ability of many species to secrete bioluminescent material into the water. This bioluminescence functions as highly elaborate courtship displays that are species-specific and facilitate recognition of potential mates. See also Bioluminescence; Crustacea; Ostracoda.

Myodocopida
A myodocopid ostracod from southern Australia
Scientific classification
Kingdom: Animalia Phylum: Arthropoda Subphylum: Crustacea Class: Ostracoda Order: Myodocopida Sars, 1866 [1] Suborder: Myodocopina Sars, 1866 [2]
Superfamilies and families
Cylindroleberidoidea Cylindroleberididae Cypridinoidea Cypridinidae Sarsielloidea Philomedidae Rutidermatidae Sarsiellidae

Wikispecies has information related to: Myodocopida

The Myodocopida is one of the two orders within the Myodocopa, in turn a subclass of the Ostracoda. The Myodocopida are distinguished by a worm-like seventh limb, and, usually, a rostrum above an incisur (notch) from which the antennae can protrude ^[3]. Unlike other ostracods, many species of the Myodocopida have lateral compound eyes ^[4]. Over the last thirty years there has been much research into the morphology, behaviour and distribution of myodocopids. More recently, DNA sequences have been used to investigate the phylogeny of various groups.

References

1. ^ Myodocopina (TSN 609937). Integrated Taxonomic Information System.
2. ^ Myodocopina (TSN 84196). Integrated Taxonomic Information System.
3. ^ Louis S. Kornicker (1993). Antarctic and Subantarctic Myodocopina (Ostracoda). Koeltz Scientific Books. ISBN 187876246X. 
4. ^ Louis S. Kornicker (1975). "Antarctic Ostracoda (Myodocopina)". Smithsonian Contributions to Zoology 163: 1–720. 

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