Annelids are triploblastic, bilaterally syimmetrical metamerically segmented, coelomate worms with a thin flexible cuticle around GENERAL CHARACTERS 1. Annelida are mostly aquatic marine or freshwater, some terrestrial, burrowing or living tubes, sedentary or free-living. Some are commensal and parasitic also 2. Body triploblastic, bilaterally symmetrical, elongated and vermiform.