1) Brittle stars 2) Class 3) Subclass ophiurida 
The Ophiurida are an order of echinoderms within the class Ophiuroidea. It includes the vast majority of living brittle stars. ==Characteristics== The upper surface of the disk of Ophiurida is covered with scales. They have bursae for respiration and excretion, and dorsal and ventral arm shields are present and usually well developed. Arms are unb...
• (n. pl.) Same as Ophiurioidea.
O`phi·u'ri·da noun plural [ New Latin ] (Zoology) Same as Ophiurioidea . 
[n] - brittle stars
subclass Ophiurida noun brittle stars