The genus Ophiura is part of the lager family Ophiuridae, which is a diverse group containing more than 2000 species, most found at depth (Stöhr et al. 2012). They range in size from 2 to 10 cm, prefer living on muddy substrates, and have a worldwide distribution (Guille et al., 1986). They feed mostly on detritus and phytoplankton, but some are predatory and feed on epibenthic or infaunal organisms (Woodley, 1975; Boos et al., 2010; Stöhr et al. 2012). The geneal ophiuroid body plan consists of a central disc, which is usually pentagonal to round in shape, and generally five arms that are offset from the disc (Stöhr et al. 2012). Many members of the genus Ophiura have pairs of scales where the disc meets the arms (Forbes, 1843). However, several species deverge from this body plan.
Unlike their closely related relatives, the seastars, they do not rely on tube feet for locomotion. Instead, they use their arms to push or pull sediment in order to propel themselves forward (Stöhr et al. 2012). Also unlike seastars, they have jaws closing their mouth area. The number of jaw plates corresponds to the number of legs, and have been hypothesized to have evolved from abulacral plates (Hendler, 1988; Stöhr et al. 2012).
Ophiura get their name from the greek work ophis meaning serpent and oura meaning tail. This is in reference to their snake-like arms. Their common name, brittle star, comes from their fragile nature, and can easily fragment when they are stressed (Stöhr & O'Hara, personal observation).
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