Tanaidacea

Taxobox | name = Tanaids

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image_width = 250px
image_caption = "Tanaisus lilljeborgi" (a tanaid from the North Sea)
regnum = Animalia
phylum = Arthropoda
subphylum = Crustacea
classis = Malacostraca
superordo = Peracarida
ordo = Tanaidacea
ordo_authority = Dana, 1849
subdivision_ranks = Families
subdivision = *Suborder Anthracocaridomorpha
Family Anthracocarididae
*Suborder Apseudomorpha
Superfamily Apseudoidea
Family Apseudellidae
Family Apseudidae
Family Gigantapseudidae
Family Kalliapseudidae
Family Metapseudidae
Family Numbakullidae
Family Pagurapseudidae
Family Parapseudidae
Family Sphyrapidae
Family Tanzanapseudidae
Family Whiteleggiidae
Superfamily Jurapseudoidea
Family Jurapseudidae
*Suborder Neotanaidomorpha
Family Neotanaidae
*Suborder Tanaidomorpha
Superfamily Cretitanaoidea
Family Cretitanaidae
Superfamily Tanaoidea
Family Tanaidae
Superfamily Paratanaoidea
Family Agathotanaidae
Family Anarthruridae
Family Colletteidae
Family Leptocheliidae
Family Leptognathiidae
Family Nototanaidae
Family Paratanaidae
Family Pseudotanaidae
Family Pseudozeuxidae
Family Tanaellidae

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

Morphological characteristics

Most tanaids are small (2 to 5 mm long), but adult size reaches 0.5 to 120 mm. They have a carapace formed via fusion of the first 2 thoracic somites. They also have chelate first pereiopods, 6 free thoracic somites, 5 abdominal somites bearing pleopods and a pleotelson with a pair of terminal or subterminal uropods.

Habitat

Most are marine, but some are also found in freshwater coastal habitat or estuaries. They can live in very deep water environment, exceeding for some species 9,000 m. 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.