Sea Starfish are invertebrates classified in Phylum Echinodermata echino meaning spiny derm means skin. The hard shell wrapped in a skin include thorns sea stars and sea cucumbers, sea urchins, starfish, Pence no structure to the movement. But the move by foot shock (tube feet) and pressure of water. The movement of the sea caused by contraction of the Ampulla then push the tube feet protrude fastened to the floor (like a sucker) and when Ampulla loosen the tube feet, it will shrink and push water back into the Ampulla stretching. contraction of the tube feet many consecutive times cause pressure. Make sea star moves
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