Note
Ophiuroids are stellate echinoderms with a central flattened disc sharply set off from the arms (Fig. IA, B). The arms of most ophiuroids are long sinuous structures, and this accounts for their common name, serpent stars. Due to the ease by which many species autotomize and subsequently regenerate their arms, ophiuroids are also called brittle stars (Fig. IC). Living ophiuroids are divided into two orders, the Phrynophiurida and the Ophiurida, with the majority of ophiuroids being members of the Ophiurida (Table I). The microanatomy of these two orders differs in many respects, and their differences are highlighted in this chapter.