WORMS! Ch. 10, 11, 12

Phylum Platyhelminthes ~34,000 Species Symmetry: Bilateral Body Cavity: Acoelomate Body Structures: – Triploblastic – True mesoderm – Unsegmented worms Scolex of a tapeworm

Phylum Platyhelminthes New Advancements (over cnidarians) – Regeneration – Protonepheridia - “First-Kidney” Networks of tubes leading to a nephridiopore, where excretions are released – True mesoderm - triploblastic organisms – Organ Systems

Phylum Platyhelminthes Common Members: – Planaria - free swimming bottom dwellers – Liver Fluke - ectoparasites (attach to aquatic organisms -ex amphibians) – Tapeworm - no digestive tract

Phylum Platyhelminthes Special features: – Muscles – Cilia – Pharynx – used to suck up food – Photoreceptors Parasitic or Free living – Parasitic: Flukes & tapeworms – Free living: Planarians (Tubellarians) Reproduction: – Sexual & Asexual – Most monoecious

Phylum Platyhelminthes Nervous System: pair of anterior ganglion, long longitudinal nerve cords. Digestion: Incomplete gut, pharynx