Arm stout and tapered, usually five but occasionally varying from four to seven. Numerous small white spines on arms arranged in a reticular pattern, generally forming a star-shaped pattern on the center of body. Color from yellow-orange to dark brown or purple. Average arm radius 14 cm.

The subject of many past field experiments dealing with its role as an intertidal predator.

Middle and low intertidal and subtidal to 88 m; Alaska to Baja California. Rare below Santa Barbara.