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)
• Water-vascular system
• Complete digestive tract
• Nervous system consisting of nerve net, nerve
  ring, radial nerves

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characteristics

• Tube feet
• deuterostomes
• coelomates whose embryos have
  radial cleavage

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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

• Muscular system
• Swim by undualting
• Body wall muscles contract in
  worm like waves
• Respiratory system
• Respiratory trees
• Water force circulated by rectum contractions

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Class Holothuroidea

• Nervous system
• Additional nerves to tenatacles
• Statocysts
• maintain orientation
• Photoreceptors
• light detectors

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Class Holothuroidea

• Circumoral tentacles
• 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
• Tranverse fission
• 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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• Eleven arm sea star
• Coscinasterias
  muricata