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Body Plan
Transport within the Body
Closed (blood, not hemolymph, transported with tiny blood vessels)
  • Closed circulatory system transports food too all parts of the body
  • Longitudinal vessels run through the entire length and branch to reach all tissues of the body; Many have more than one pair of hearts
  • Gas Exchange
    Method of Waste Disposal
    Nervous System
    Important Distinguishing Feature
  • No special respiratory organs, but simple diffusion through body surface; the epithelia needed to be moisturized to ensure diffusion
  • Tiny blood vessels help to transport oxygen
  • Polychaeta: parapodia, or pairs of ridge like structures, function as gills with an extended area of skin for gas exchange
  • Metanephridia with ciliated funnels removes wastes from the blood, which are discharged with external pores
  • Digestive system is one long tube, with an anus to release food waste
  • Centralized nervous system and a number of special sensory cells, including touch, taste, light, and moisture
  • Sensors available for touch, light-detection, moisture, taste,
  • Each segment is kept in control by a pair of ganglia
  • Hermaphrodites, but could also cross-fertilize to vary genes
  • Polychaeta: external fertilization, with separate sexes
  • Mostly worms with closed circulatory systems and metanephridia to remove wastes