Polychaeta is the largest class within Phylum Annelida. This class is primarily composed of Marine worms.


  • Metameric Body Segmentation
    • The body is arranged in metameres, small body segments.
    • Allows compartmentalization in case of injury.
    • Allows specialization for certain bodily functions.
  • Parapodium
    • Extensions of the body that allow for locomotion.
    • Have Setae sticking out of the ends, bristles which aid in locomotion.
  • Prostomium
    • “Mouth” of the annelid.
  • Cuticle
  • Move by “Undulating
  • Digestive system fitting their food source.
    • Some predatory members have jaws with poison glands for subduing their prey
    • Others are herbivorous or filter feeders.
  • Closed circulatory system
    • Dorsal and Ventral Aorta
    • Parapodia increase surface area for gas exchange.
  • Nervous System
    • Suprapharyngeal ganglion
    • Sensory Fuctions
    • Motor Functions
    • Regulate contraction of muscles
  • Excretion Systems
  • Reproduction
    • Mostly Sexual, Dioecious
    • Can reproduce by Budding


Campbell & Reece. "Biology" Benjamin Cummings. 6th Edition, 661
Miller & Harley. "Zoology" McGraw Hill. 7th Edition, 212-217

Pol`y*chae"ta (?), n. pl. [NL., from Gr. many + hair.] Zool.

One of the two principal groups of Chaetopoda. It includes those that have prominent parapodia and fascicles of setae. See Illust. under Parapodia.


© Webster 1913.

Log in or register to write something here or to contact authors.