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Brief Summary

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The tanaids are a group of around 1,500 known species of mostly small (0.5 to 2 cm long) Peracarida that occur worldwide. They are mainly marine and benthic (bottom-dwelling), but a handful of species live in brackish or nearly fresh water. They often live in burrows or tubes and are known from ocean depths ranging from coastal (1 to 2 m) to around 9000 m. Many are suspension feeders, but some are detritivores or predators. Although most species in this group are free-living or tube-dwelling, Exspina typica have been found in the intestine and body cavity of deep sea holothuroid echinoderms ("sea cucumbers"). The tanaids were found to actively "dig" into the host's skin, grasping tissue with their claws and producing tunnels in the body wall. (Brusca and Brusca 2003; Alvaro et al. 2011; Kakui et al. 2011 and references therein) Kakui et al. (2011) analyzed phylogenetic relationships within Tanaidacea using data from the 18S rRNA gene. An excellent online source on the Tanaidacea is Gary Anderson's Peracarida Taxa and Literature website.
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Tanaidacea

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The crustacean order Tanaidacea (known as tanaids) make up a minor group within the class Malacostraca. There are about 940 species in this order.

Description

Tanaids are small, shrimp-like creatures ranging from 0.5 to 120 millimetres (0.020 to 4.7 in) in adult size, with most species being from 2 to 5 millimetres (0.08 to 0.2 in). Their carapace covers the first two segments of the thorax. There are three pairs of limbs on the thorax; a small pair of maxillipeds, a pair of large clawed gnathopods, and a pair of pereiopods adapted for burrowing into the mud. Unusually among crustaceans, the remaining six thoracic segments have no limbs at all, but each of the first five abdominal segments normally carry pleopods. The final segment is fused with the telson and carries a pair of uropods.[1]

The gills lie on the inner surface of the carapace. The thoracic limbs wash water towards the mouth, filtering out small particles of food with the mouthparts or maxillipeds. Some species actively hunt prey, either as their only food source, or in combination with filter feeding.[1]

Habitat

Most are marine, but some are also found in freshwater coastal habitat or estuaries. The majority of species are bottom-dwellers in shallow water environments, but a few live in very deep water, exceeding for some species 9,000 metres (30,000 ft). In some deep sea environment, they represent the most abundant and diverse fauna to be found.

Life cycle

Tanaids do not undergo a true planktonic stage. The early developmental period is spent while young are within the marsupium of the mother. Subsequently, post-larvae, called mancas, emerge as epibenthic forms. Some species are hermaphroditic.[1]

Taxonomy

The order Tanaidacea is divided into the following sub-orders, superfamilies and families:[2]

See also

References

  1. ^ a b c Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. pp. 768–769. ISBN 0-03-056747-5.
  2. ^ WoRMS (2018). "Tanaidacea". World Register of Marine Species. Retrieved May 7, 2018.

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Tanaidacea: Brief Summary

provided by wikipedia EN

The crustacean order Tanaidacea (known as tanaids) make up a minor group within the class Malacostraca. There are about 940 species in this order.

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cc-by-sa-3.0
copyright
Wikipedia authors and editors
original
visit source
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wikipedia EN