GENERAL CHARACTERS 1. Annelida are mostly aquatic marine or freshwater, some terrestrial, burrowing or living in tubes, sedentary or free-living. Some are commensal and parasitic also. 2. Body triploblastic, bilaterally symmetrical, elongated and vermiform. 3. Body metamerically segmented externally by transverse grooves and internally by septa into a number of divisions each division is called a segment, metamere or somite. 4. Organ-system grade of body organization. underlying epidermis. 5. outer covering of the body iscuticle secreted by the circular and longitudinal muscles. 6. Body wall is contractile, consisting ofan outer epidermis, 7. Appendages when present are unjointed. most of the cases archaetae in