14. Phylum Echinodermata Notes


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14. Phylum Echinodermata Notes

  1. 1. Phylum Echinodermata Kingdom Animalia Phylum Echinodermata Class Asteroidea Class Ophiuroidea Class Echinoidea Class Holothuroidea
  2. 2. Echinoderms: <ul><li>Name means “spiny skin” </li></ul><ul><li>Sea stars, sea cucumbers, sea urchins, etc. </li></ul><ul><li>All marine </li></ul><ul><li>All found on the bottom of the sea </li></ul>
  3. 3. General Characteristics: <ul><li>Lack a head </li></ul><ul><li>Two sides (oral & aboral) </li></ul>
  4. 4. Symmetry - <ul><li>Bilateral Symmetry - </li></ul><ul><li>Common of free moving organisms </li></ul><ul><li>Radial Symmetry - </li></ul><ul><li>Common of sessile (non-moving,/attached </li></ul><ul><li>Free moving and radial symmetry </li></ul><ul><li>Pentaradial Symmetry – body radially symmetrical in 5 parts or multiples of 5 </li></ul>Echinodermata Symmetry -
  5. 5. Endoskeleton: <ul><li>Internal skeleton found within the tissues </li></ul><ul><li>It is always covered by a thin layer of tissue </li></ul><ul><li>Spines and bumps give reference to their name which means “spiny-skinned” </li></ul>
  6. 6. Water Vascular System <ul><li>A network of fluid filled canals </li></ul><ul><li>Used for locomotion, food & waste transport, and respiration </li></ul>
  7. 7. Water Vascular System:
  8. 8. Water vascular system <ul><li>Water enters through the madreporite </li></ul><ul><li>Water is then separated into five radial canals made of double rows of ampullae </li></ul><ul><li>Ampullae are connected to sucker-like podia, the whole thing is called a tube foot </li></ul><ul><li>Contraction of the ampullae causes the podia to move, thus overall locomotion </li></ul>
  9. 9. Dermal Branchiae <ul><li>Soft bumps on the body that absorb oxygen from the water </li></ul>
  10. 10. Digestive System: <ul><li>Sea and brittle stars can evert a portion of their stomach out of there mouth to engulf food </li></ul><ul><li>Digestive enzymes located in glands that extend into the arms </li></ul>
  11. 11. Digestive System: <ul><li>Sea urchins have a longer coiled intestine to allow time for the digestion of plant material </li></ul><ul><li>Sea cucumbers have a similar section to absorb nutrients from the sediment it ingests </li></ul>
  12. 12. Nervous System: <ul><li>Limited knowledge on this aspect except for the presence of a nerve net </li></ul><ul><li>Ocelli – microscopic pigment spots on sea stars that can detect light and dark </li></ul>
  13. 13. Regeneration/Autonomy: <ul><li>The ability to grow lost or damaged body parts </li></ul><ul><li>Some times a severed arm can grow into a new organism if 1/5 of the central disc is present </li></ul>
  14. 14. Class Asteroidea <ul><li>Includes: sea stars or starfish </li></ul><ul><li>Most have 5 arms from a central disk, though can have up to 50 </li></ul><ul><li>Each arm carries an equal share of organ systems </li></ul>
  15. 15. Class Asteroidea <ul><li>Ambulacral grooves contain the tube feet on the arms </li></ul>
  16. 16. Class Asteroidea <ul><li>Pedicellariae </li></ul><ul><li>Tiny pincer-like organs on the aboral side keep the surface clean </li></ul><ul><li>Most sea stars are predators of bivalves, snails, or other attached or slow moving animals </li></ul>
  17. 17. Class Ophiuroidea <ul><li>Includes: Brittle Stars </li></ul><ul><li>Legs proportionally longer and thinner than sea starts </li></ul><ul><li>Allows for better movement </li></ul><ul><li>Organs in central disc </li></ul><ul><li>Tube feet lack suckers </li></ul>
  18. 18. Class Ophiuroidea <ul><li>Eat organic matter and small animals they find on the bottom </li></ul><ul><li>Passed from tube foot to tube foot till it reaches the mouth </li></ul>
  19. 19. Class Echinoidea <ul><li>Includes: Sea Urchins & Sand Dollars </li></ul><ul><li>Body structure forms a round, rigid body with movable spins and pedicellarie </li></ul><ul><li>Locomotion achieved by movable spines </li></ul>
  20. 20. Class Echinoidea <ul><li>Body plan of sea stars repeated by moving arms upward and connecting them at the tips </li></ul><ul><li>Mouth is on the bottom, anus on the top </li></ul><ul><li>Spines: sharp, hollow and sometime contain venom </li></ul>
  21. 21. Plates: <ul><li>10 plates </li></ul><ul><li>Alternating abulacral (have openings for tube feet) and interambulacral (bumps for spines) </li></ul>
  22. 22. Class Echinoidea <ul><li>The mouth has an intricate system of jaws and muscles called Aristotle’s Latern </li></ul><ul><li>Used to bite off algae and other bits of food from the bottom </li></ul>
  23. 23. Class Echinoidea <ul><li>Heart Urchins and Sand Dollars are adapted for the soft bottom of the ocean </li></ul><ul><li>Flat bodies and short spines </li></ul>
  24. 25. Class Holothuroidea <ul><li>Sea Cucumbers </li></ul><ul><li>Similar body plan to a sea urchin, just stretched out from mouth to anus </li></ul><ul><li>Lies on sides, oral and aboral surfaces are at the ends </li></ul>
  25. 26. Class Holothuroidea <ul><li>Most have five rows of tube foot that run mouth to anus </li></ul><ul><li>Some excrete toxic substance as defense mechanism </li></ul><ul><li>Some expulse gut and other internal organs out of the mouth or anus, called evisceration </li></ul><ul><li>Believe that they grow the organs back </li></ul>