1. Flatworms
Platyhelminthes

2. Flatworms Simplest animals with organ systems
Three primary tissue layer
Ectoderm, endoderm, mesoderm
Bilateral
Cephalization
No coelom

3. Turbellarians Digestive system – pharynx, branching gut Ex: Planarian
enzymes secreted first
Ex: Planarian
Nervous system – ganglia, nerve cords, eye spots
Respond in cordinated fashion

4. Excretory – flame cells remove unwanted liquids, passed thru ducts to pores on surface
Circulation – diffusion
Respiration - diffusion

5. Reproduce sexually (hermaphrodites)
Asexually - regeneration

6. Cestoda and Trematoda Tapeworms and fluke, respectively Parasitic
Lost gut in mouth, habitat rich in predigested food
Complex life cycle – sexual and asexual with multiple hosts