Reduced but real coelom lined with mesoderm. Usually indirect with bipinnaria larvae, other larvae in some spp. Larvae are generally more motile than adults, then they metamorphose and settle, developing a new mouth and anus and new arms. Capable of regeneration from an arm and a small portion of the central disc. Body Support hydrostatic support by water vascular system .
Sensory organs are few and primitive.
Simple visual, touch, and chemoreceptive senses. Pedicellariae on the integument keep the body surface clean of encrusting organisms and function in food gathering. Tube feet are controlled by hydrostatic pressure in water vascular system and allow creeping and slow predation. Crinoids are sessile. Water enters through the madreporite and travels through the stone canal, to the ring canal, and thence to the radial canals.