7. Response and Movement Nerve ring and Radial Nerves Sensory Cells Movement is through the tube feet Sand dollars and sea urchins Sea and brittle stars Sea cucumbers
9. Sea Urchins and Sand Dollars Class Echinoidea Have a large, solid plate that forms a box around their internal organs Detritivores or grazers that eat algae Some have large sharp spines
10. Brittle Stars Class Ophiuroidea Slender, flexible arms and can scuttle around quite rapidly Can shed one or more arms when attacked. The arms will keep moving to distract the predator Filter feeders and detritivores that hide by day
12. Sea Stars Class Asteroidea Carnivorous As long as it contains a portion of the central part of the body, pieces of sea stars can repair itself into a new animal
13. Sea Lilies and Feather Stars Class Crinoidea Filter feeders Sessile