Phylum Platyhelminthes

• 1. 20,000 species -most parasitic; only 20 species are free-living.

• I Characteristics• 1. Bilateral symmetry• 2. Triploblastic• 3. Flattened dorsoventrally *• 4. Excretory system of flame cells{protonephridia}

•

Phylum Platyhelminthes contd.

• 5. Many parasitic forms

• 6. Most species hermaphroditic

• 7. Acoelomate

• 8. Animals with definite organs

• 9. Cephalization

• II CLASSIFICATION

• Class- Turbellaria =(free living)