Phrynophiurida

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Phrynophiurida
Haeckel Ophiodea 70 Astrophyton darwinium.jpg
Gorgonocephalidae sp.
(a basket star)
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Echinodermata
Class: Ophiuroidea
Order: Phrynophiurida
Suborders

Euryalina
Ophiomyxina

The Phrynophiurida (formerly called Euryalae) are an order of brittle stars containing the basket stars.

Contents

Characteristics

Phrynophiurida have bursae for gas exchange and excretion. Their ventral arm shields are rudimentary, and dorsal shields usually absent. Arms sometimes are branched, and can coil vertically. The vertebrae are joined by hourglass-shaped surfaces. The madreporite is on the oral surface. Digestive glands are confined to central disc. [1] The integument is leathery, bearing calcareous granules or platelets. They generally live in deep-sea waters, coiling their arms on branched black coral.

Systematics

The Asteronychidae have a large disk and slender arms, and the Asteroschematidae have a small disk and stout arms.

One remaining family, the Ophiomyxidae, differs in having a soft, unprotected integument, like that of Ophiocanops, but lacks the peculiar features of the gut and gonads in oegophiurids.

Phrynophiurida are divided into the following suborders and families: [2]

The inclusion of Ophiocanopidae is supported by some modern studies, [3] but not yet generally accepted. [4]

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Ophiurida Order of brittle stars

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Zeugophiurina is a suborder of primitive brittle stars with three extinct families. The family Ophiocanopidae with only one living genus and species, Ophiocanops fugiens has been placed here but recent studies have challenged this classification.

Ophiocanops fugiens is a living species in the brittle star family Ophiocanopidae. Though once considered to be the only one living species in this brittle star family, recent research has brought to light three specimens of Ophiocanops that differ substantially from O. fugiens. It has been regarded as the most primitive brittle star, close to Paleozoic forms, though other authors have disagreed with the view. Classification of O. fugiens is highly argued. Ophiocanops is usually placed in the order Oegophiurida or regarded as a genus incertae sedis or even given its own subclass Oegophiuridea. Some recent data suggest its relationship to the extant family Ophiomyxidae.

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References

  1. R.C. Brusca, G.J. Brusca. Invertebrates. Sinauer Associates, 2 ed.(2003)
  2. "Phrynophiurida". Integrated Taxonomic Information System.
  3. Pearse,V.B. et al.,(1998) An accessible population of Ophiocanops off NE Sulawesi,Indonesia. In: Mooi, R. & Telford, M. (Eds.) Echinoderms: San Francisco. Balkema, Rotterdam, pp. 413–418
  4. "Ophiocanopidae". Integrated Taxonomic Information System.