FLATWORM PHYLUM : PLATYHELMINTHES GROUP 2. • Phylum Platyhelminthes includes the flatworms. Platy means “flat,” like a plate; helminth “worm”. 3. Characteristics feature • Invertebrate organism • Flatworm have soft and unsegmented body • No body cavity (no specialized respiratory and circulatory system) also called acoelomate • Other species have digestive system (incomplete or absent) • Most flatworm have gastro-vascular cavity. • Diffuse CO2 and O2 through the body wall 4. Characteristics feature • Primitive nervous system is present (can sense stimuli and coordinate movement) • Have excretory organ called nephridium formed by channels with terminal flame cell which control excretion and osmoregulation. (Excretetion of nitrogenous wastes through protonephridial pores or their mouth) • Can reproduce Sexually and Asexually • Most species are hermaphrodites
