3 Unifying Characteristics Spiny SkinInternal Skeleton – “endoskeleton”Water vascular systemMuscular tube feet (suction cup feet)Pentaradia Symmetry5 rays of symmetry
4 Water Vascular SystemMadreporite - sieve-like opening to the water vascular system
5 Water Vascular System Functions: Respiration Circulation Movement Ring & Radial CanalsTube FeetCirculationMovement
6 Tube FeetEach tube foot is basically a suction cup, muscles pull up the centre of the cup causing suctionMany feet working together can exert huge force, allowing “walking” and attacking
7 Groups of Echinoderms Sea Urchins and Sand Dollars Brittle Stars Grazers and DetrivoresSolid plates protect internal organsBrittle StarsFilter feeders and DetrivoresSlender/Flexible arms – detach and distractSea CucumbersDetrivoresEviscerate themselves as defence!Sea StarsPredatoryRegenerative if dismembered!Sea Lilies and Feather StarsFilter FeedersFeather dusters of the sea
8 Sea Urchins and Sand Dollars Grazers and DetrivoresSolid plates protect internal organs
9 Brittle Stars Filter feeders and Detrivores Slender/Flexible arms – detach and distract
10 Sea CucumbersDetrivoresEviscerate themselves as defence!