PHYLUM ECHINODERMATA spiny skin

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PHYLUM ECHINODERMATA(spiny skin)

• Sea star
• Sea urchin
• Sand dollar
• Sea cucumber

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ECHINODERM CHARACTERISTICS

• Calcareous endoskeleton
• ossicles
• 
  Biscuit sea star
  
  Tosia australis
• Adults with pentaradial symmetry
• (No cephalization oral / aboral)
• Tube feet

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classes

• 7 000 species
• 80 species are sessile (non-motile)
• 6 existing classes

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Class Holothuroidea

• Sea cucumbers
• 1 500 species
• Sluggish burrowers / creepers
• No rays
• Elongate
• Permanent ventral
• Bilateral symmetry

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Class Holothuroidea

• tube feet surround mouth
• Digestive system
• stomach
• Long, looped intestines
• Rectum
• anus
• Snot sea cucumberLeptosynapta dolabrifera

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Class Holothuroidea

• Eviseration for defense
• regeneration
• Dioecious single gonad
• External fertilization
• trepang

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predator

• About the only thing that eats orange sea
  cucumbers are sea stars. It took an 18 cm
  sunflower star 22 hours to eat an 8 cm sea
  cucumber.   Other sea star predators include the
  orange sun star and the leather star.  

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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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Sea star feeding
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• Eleven arm sea star
• Coscinasterias
  muricata

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• http//www.photovault.com/Link/Animals/Aquatic/oEc
  hinoderms/AAOVolume01.html