1.) Body metamerically segmented; bilateral symmetry
2.) Body wall with outer circular and inner longitudinal muscle layers; outer transparent moist cuticle secreted by epithelium
3.) Chitinous setae, often present on fleshy appendages called parapodia; setae absent in leeches
4.) Coelom well developed and divided by septa, except in leeches; coelomic fluid supplies turgidity and functions as hyrdostatic skeleton
5.) Blood system closed and segmentally arranged; respiratory pigments (hemoglobin, hemerythrin, or chlorocruorin) often present
6.) Digestive system complete and not metamerically arranged
7.) Respiratory gas exchange through skin, gills, or parapodia
8.) Excretory system typically a pair nephridia for each metamere
9.) Nervous system with a double ventral nerve cord and a pair of ganglia with lateral nerves in each metamere; brain, a pair of dorsal cerebral ganglia to connectives to cord
10.) Sensory system of tactile organs, taste buds, photoreceptor cells, and eyes with lenses (in some);
11.) Hermaphroditic or separate sexes; asexual reproduction by building in some
