CLASS ASTEROIDEA

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CLASS ASTEROIDEA

• SEA STARS

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CLASS ASTEROIDEA

• Brightly colored
• Five arms
• Oral opening oriented downward
• Pedicellariae
• surround each spine
• keep body clean of algae and
  small animals

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OSSICLES

• Calcium carbonate plates
• Held in place by connective tissue
• Covered by epidermal layer

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Water-Vascular system

• Provide movement
• H2O enters madreporite on aboral surface
• Passes through stone canal
• Connects to ring canal circling mouth
• Passes to radial canal extends in each arm
• Enters tube feet

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Water-Vascular system

• Ampulla fills with H2O
• Contraction force H2O into tube foot
• Causes extension
• Tube feet muscles contract
• Pushes H2O back into ampulla

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