Lined Thuridilla

The family Plakobranchidae (listed as Elysiidae in some sources) includes shell-less species with flap-like parapodia extending over the sides of their bodies. The parapodia contain branches of the digestive gland and also function in respiration. Many species retain chloroplasts as kleptoplastids and some may show substantial variation in morphology based on differences in diet or associated chloroplasts.