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Echinoderms
Sea Star
Sea Cucumber
Brittle Star
Urchin
Sand Dollar (Keyhole Urchin)
Video Clip from Blue Planet
https://www.youtube.com/watch?v=r4cX2EPt2zE
Finger of Death
Phylum Echinodermata
“Spiny skin”Radial symmetry – 5 parts or multiples of 5Water vascular system – hydraulic pressure system for movement
Water Vascular System
WVS Operation
Water enters through madreporiteThrough tube system to ampullae of feetMuscle contracts - water ejected onto foot – suctionMuscle relaxes – water back into ampullae – no suction
Skeletons
Plates under skin (some fused) or spicules (endoskeleton)Ca(CO3) – like mollusks
Projections
Sea Stars
Flexible – plates of skeleton with musclesAmbulacral groove with tube feetMouth and anusEyespots sense light
Sea Star Feeding
Diet – mollusks, coralOpens shells with tube feetExtrudes stomachLiquefies mollusk
Brittle Stars
Distinct central diskTube feet have no suction – send food to mouthArms for locomotionMouths with teethNo anus
Regeneration
Need 1/5 of central disk and 1 arm to regenerate
Sea Urchins
TestMouth and anusBall and socket spinesSpines and tube feet for movement
Sea Urchins
Algae-eaters and scavengersMouth with teeth (Aristotle’s Lantern)
Sand Dollars
Flat sea urchinsShort spines
Sea Cucumber
Elongated bodySmall skeletal fragmentsModified tube feet for tentacles on oral end