Ophiurida

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Ophiurida Fossil range: Devonian - present [1]
Ophiura ophiura
Scientific classification
Kingdom: Animalia Phylum: Echinodermata Subphylum: Eleutherozoa Superclass: Cryptosyringida 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.

Contents 1 Characteristics 2 Systematics and phylogeny 3 Ecology 4 References

[edit] Characteristics

The upper surface of the disk of Ophiurida is covered with scales^[2]. They have bursae for respiration and excretion, dorsal and ventral arm shields are present and usually well developed. Arms are unbranched and incapable of coiling vertically. Madreporite is on oral surface. Digestive glands are entirely within central disc^[3].

[edit] Systematics and phylogeny

There is currently no consensus as to the subdivision of the Ophiurida. The order has been divided into the following suborders and infraorders ^[4]:

• Ophiomyxina
• Ophiurina
  • Hemieuryalina
  • Chilophiurina
  • Gnathophiurina
  • Ophiodermatina
  • Ophiolepidina

Another classification scheme divides it into the following suborders^[5]:

• Chilophiurina Matsumoto, 1915
• Laemophiurina Matsumoto, 1915
• Ophiotrichidae Ljungman, 1867
• Ophiurina Müller & Troschel, 1840

Another classification scheme divides it as^[6]:

• Chilophiurina
• Laemophiurina
• Gnathophiurina

[edit] Ecology

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

[edit] References