Characteristic Features of Coelom

• Sensory system consisting of eyes, photoreceptor cells, statocysts, taste buds and tactile organs.
• Respiration by skin, gills or parapodia.
• Body vermiform, bilaterally symmetrical with metamerism.
• Chitinous setae present
• Schizocoelic coelom - coelom appearing as a split or cavity within mesoderm.
• Blood vascular system closed, often along with retory pigments; plasma contains
• Sexes may be separate, or animals may be hermaphrodites. Cleavage spiral, with mosaic development. When present, larva is trochophores. Some animals show asexual reproduction by budding.
• Presegmental prostomium and post segmental pygidium.
• Nervous system contains a supraesophageal ganglion (cerebral ganglion). Circum oesophageal ring and ventral nerve cord with segmental ganglia.
• Excretory system usually consisting of a pair of nephridia in each segment.
• Different degrees of cephalization are shown.