Invertebrate Zoology Lecture Notes Ppt New [extra Quality] -

Secondary radial symmetry (pentaradial) as adults, but bilateral as larvae.

Free-living forms use ventral ciliated epidermis and mucous pathways to glide. Parasitic classes utilize a syncytial neodermis (tegument) that resists host digestive enzymes and immune systems. Organ System Integration:

Primarily marine worms featuring lateral, fleshy outgrowths on each segment called parapodia . These serve dual functions in locomotion and gas exchange.