1. Invertebrates – Part 2
Worms and Mollusks

2. Worms

3. Characteristics soft-bodied, long, legless bilateral symmetry
cephalization
three cell layers
epidermis
gastroderm
mesoderm

4. Phylum platyhelminthes

5. Phylum platyhelminthes
The “flatworms”
3 Classes
Turbellaria (free-living)
Cestoda (tapeworms)
Trematoda (flukes)

6. Class turbellaria

7. Planaria

8. Planaria

9. Life processes

10. MOVEMENT
Ciliated cells
Secrete a slime layer
Muscles

11. NUTRITION Absorptive heterotroph Pharynx
Intestine / Gastrovascular cavity
Food: small animals and eggs

12. EXCRETION
Flame cells
Excretory pores

13. RESPONSE Anterior mass of nerve tissue (ganglia that act as a “brain”)
Photoreceptors
Longitudinal nerves
Transverse nerves

14. REPRODUCTION
Asexual – regeneration
Sexual – hermaphroditic

15. Planarian Regeneration

16. Class cestoda

17. Parasitic Flatworms Few sense organs as adults
No external cilia in adults
Thick tegument
Suckers and/or hooks

18. Taenia solium (the pork tapeworm)

19. Taenia solium
Scolex
Proglottid

20. Pork tapeworm lifecycle

21. Symptoms of Parasite Infection

22. Class trematoda

23. Opisthorchis sinensis (the Chinese liver fluke)

24. Chinese liver fluke lifecycle

25. Phylum nematoda