Ophiurida

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Not to be confused with Ophiuroidea, the class that contains Ophiurida.
Ophiuroidea
Temporal range: Devonian - present [1]
Ophiura ophiura.jpg
Ophiura ophiura
Scientific classification
Kingdom: Animalia
Phylum: Echinodermata
Class: Ophiuroidea
Order: Ophiurida
Müller and Troschel, 1840
Suborders

See text.

The Ophiurida are an order of echinoderms within the class Ophiuroidea. It includes the vast majority of living brittle stars.

Characteristics[edit]

They have bursae for respiration and excretion, and dorsal and ventral arm shields are present and usually well developed. Arms are unbranched and incapable of coiling vertically. Most are five-armed, some with 4 or 6 arms as an abnormality, but others properly bear six or seven arms. The madreporite is on the oral surface. The digestive glands are entirely within the central disc.[2] They move their arms side to side by means of ball-and-socket joints. Tropical species tend to contrast color from the environment, but most others prefer to blend in. These biochromes do not include echinochromes.

Systematics and phylogeny[edit]

There is currently no consensus as to the subdivision of the Ophiurida. The order has been divided into the following suborders and infraorders [3]

Another classification scheme divides it into the following suborders:[4]

Another classification scheme divides it as:[5]

Ecology[edit]

Ophiurida have a world-wide distribution range and are found in oceans in different depths. Most of them are herbivores or detritus feeders.

References[edit]

  1. ^ E.Clarkson, E.N.K. Clarkson, Invertebrate Palaeontology and Evolution. Wiley-Blackwell; 4.ed. (1998)
  2. ^ R.C.Brusca, G.J.Brusca. Invertebrates. Sinauer Associates, 2 ed.(2003)
  3. ^ Smith, A.B.; Paterson, G.L.J. . Ophiuroid phylogeny and higher taxonomy: morphological, molecular and palaeontological perspectives. Zool. J. Linn. Soc. 114 (1995)
  4. ^ European Register of Marine Species
  5. ^ Mikko's Phylogeny Archive