Phrynophiurida

Phrynophiurida, once known as Euryalae, is an order of brittle stars that includes basket stars. Their leathery skin is covered with calcareous granules or small plates. They have bursae for gas exchange and waste removal.

The ventral arm shields are underdeveloped, and dorsal shields are usually missing. Some arms are branched and can coil vertically. The vertebrae connect via hourglass-shaped joints.

The madreporite sits on the oral surface. Digestive glands stay within the central disc. These animals mostly live in deep-sea waters, where they coil their arms around branched black coral.

Within the order, Asteronychidae have a large disk and slender arms, while Asteroschematidae have a small disk and stout arms. The family Ophiomyxidae stands apart with its soft, unprotected skin, similar to that of Ophiocanops, but lacks the unique gut and gonad features of oegophiurids. Phrynophiurida is split into two suborders: Euryalina (with families Asteronychidae, Asteroschematidae, Gorgonocephalidae, and Euryalidae) and Ophiomyxina (with family Ophiomyxidae). Some modern studies support including Ophiocanopidae, but this is not yet widely accepted.