Wednesday, July 29, 2020

Animal Kingdom - Notes | Class 11 | Part 5: Platyhelminthes

4. ANIMAL KINGDOM

PHYLUM PLATYHELMINTHES (FLATWORMS): GENERAL CHARACTERS

  1. Grades of organization:
    • Organ & Organ system.
  2. Symmetry:
    • Bilateral symmetry.
  3. Germ layers:
    • Triploblastic.
  4. Coelom:
    • Acoelomate
  5. Habit and habitat:       
    • Mainly aquatic. Endoparasites.
    • Some are free-living.
  6. Digestive system:          
    • Incomplete.
  7. Respiratory system:
    • Absent
  8. Circulatory system:
    • Absent
  9. Reproduction:
    • Asexual (fragmentation) and Sexual.
    • Hermaphrodite.
    • Internal Fertilization.
    • Development is indirect.
    • Many larval stages.
  10. Unique features:
    • Unsegmented, dorso-ventrally flattened body (except tape worms).
    • Excretion and osmo-regulation by Flame cells.
    • Parasites have Hooks & suckers.
    • Some absorb nutrients from the host through their body surface.
  11. Examples:
    • Taenia solium (Tape worm) 
    • Fasciola (Liver fluke)
    • Planaria (shows high regeneration capacity).

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