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.