Ophiurida

The Ophiurida are an order of echinoderms within the class Ophiuroidea. It includes the vast majority of living brittle stars.

Ophiuridae are a large family of brittle stars of the suborder Ophiurina.

Ophionereididae are a family of brittle stars.

Ophiactidae are a family of brittle stars.

Ophiurina are a suborder of brittle stars containing the majority of living brittle star species.

The Gnathophiurina are a group of Ophiuroidea mostly treated as suborder (but at first as an order Gnathophiurida, and sometimes as infraorder of Ophiurina or not used at all).