Valvatida

Taxobox
name = Valvatida

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image_width = 200px
image_caption = "Mediaster aequalis"
regnum = Animalia
subregnum = Eumetazoa
phylum = Echinodermata
classis = Asteroidea
ordo = Valvatida
ordo_authority = Perrier, 1884
subdivision_ranks = Families
subdivision = See text.

Valvatida is an order of starfish in the class Asteroidea, which contains 695 species in 165 genera in 14 families. The order encompasses both tiny species, which are only a few milimetres in diameter, like those in the genus "Asterina", and sea stars, which can reach up to 75 cm like species in the genus "Thromidia". Almost all species in this order have five arms with tube feet. This order is primarily identified by the presence of conspicuous marginal ossicles, which characterizes most of the species. Clamp-type pedicellaria are the main type of pedicellaria in this group.

Families

* Sub-order Granulosina
** Archasteridae
** Chaetasteridae
** Goniasteridae
** Odontasteridae
** Ophidiasteridae
** Oreasteridae
* Sub-order Tumulosina
** Podosphaerasteridae
** Sphaerasteridae

References

*de
* Burchett M, Dando M, Waller G; "SeaLife: A Complete Guide to the Marine Environment"; Smithsonian Institute Press, USA; ISBN 1-56098-633-6, 1996.
* [http://tolweb.org/Asteroidea]