Phrynophiurida is an order of brittle star

Brittle star

Brittle stars or ophiuroids are echinoderms in the class Ophiuroidea closely related to starfish. They crawl across the seafloor using their flexible arms for locomotion. The ophiuroids generally have five long slender, whip-like arms which may reach up to in length on the largest specimens...

s containing Basket star

Basket star

Basket stars are a group of brittle stars. They are treated as a suborder Euryalina or order Euryalida. Many of them have characteristic many-branched arms. They generally live in deep sea habitats.The life span in the wild is up to 35 years. They weigh around 11 lbs, or 5 kg...

s.

Characteristics

Phrynophiurida have bursae for as exchange and excretion. Their ventral arm shields are rudimentary, dorsal shields usually absent. Arms sometimes branched, can coil vertically. The vertebrae are joined by hourglass-shaped surfaces. Madreporite

Madreporite

The madreporite is a lightcolored calcerous opening used to filter water into the water vascular system of echinoderms. It acts like a pressure-equalizing valve. It is visible as a small red or yellow button-like structure, looking like a small wart, on the aboral surface of the central disk of a...

 is on oral

Mouth

The mouth is the first portion of the alimentary canal that receives food andsaliva. The oral mucosa is the mucous membrane epithelium lining the inside of the mouth....

 surface. Digestive glands are confined to central disc. The integument is leathery, bearing
calcereous granules or platelets. They generally live in deep-sea waters, coiling its 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:

• Euryalina
  • Asteronychidae
  • Asteroschematidae
  • Gorgonocephalidae
    Gorgonocephalidae
    Gorgonocephalidae are a family of Basket stars.They have characteristic many-branched arms.Gorgonocephalidae are the largest ophiuroids ....
    
    
  • Euryalidae
• Ophiomyxina
  • Ophiomyxidae
  • ?Ophiocanopidae

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