Phrynophiurida have bursae for gas exchange and excretion.

[1] The integument is leathery, bearing calcareous granules or platelets.

They generally live in deep-sea waters, coiling their arms on branched black coral.

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.