General Annelid Characteristics

  • Coelomate, triploblastic
  • Protosome (lophotrochozoan)
  • Cephalization
  • Bodies are segmented, worm shaped
  • Setae (chaetae)
  • Closed circulatory systems
  • Metanephridia
  • Complete digestive system
  • Marine, freshwater, terrestrial

Phylum Annelida

  • Class Polychaeta (nearly all marine)
  • Class Clitella
    • Subclass Oligochaeta (mostly terrestrial or freshwater)
    • Subclass Hirudinea (mostly freshwater, terrestrial)

Metamerism- Serial repetition of segments


-Earthworms play an essential role in aerating soil and adding nutrients