Phylum Platyhelminthes

1. Phylum Platyhelminthes Flatworms Monogenian Flukes Tapeworms

2. Phylum Platyhelminthes The phylum consists of four classes • Turbellaria (flatworm) • Trematoda (fluke) • Cestoda (tapeworm) • Monogenian

3. Reproduction • Almost all are simultaneous hermaphrodites • Parasitic species (flukes and tapeworms) have complex lifecycles, with various hosts and several different larval stages • Incredible powers of regeneration Phylum Platyhelminthes

4. Nervous System • Free-living species usually have a well-developed sensory system • Parasites generally have less elaborate systems. WHY? Phylum Platyhelminthes

5. Taxonomic Summary • Phylum Platyhelminthes (Flatworms) • Class Turbellaria • Class Cestoda • Class Trematoda • Class Monogeneans Phylum Platyhelminthes

6. Class Turbellaria Most are free–living, benthic, tiny and inconspicuous • Primarily marine and freshwater, many interstitial • 4,500 species Free-living Flatworm Phylum Platyhelminthes

7. Flatworm Body Plans • bilateral symmetry • Acoelomate • triploblastic

8. Digestion • Mouth is usually located at the anterior end or mid-body on ventral surface • Some species also have a protrusible pharynx that captures food and transfers it into the mouth • Can be carnivores or scavenge on dead animals and detritus

9. Digestion Mouth is usually located at the anterior end or mid-body on ventral surface 9

10. Some species also have a protrusible pharynx that captures food and transfers it into the mouth Can be carnivores or scavenge on dead animals and detritus Feeding Habits

11. Feeding Habits

12. Excretion Excretory system Contains flame bulbs 12

13. Nervous System • Posses several nerve cords with a centralized ganglia(brain)

14. Reproduction • Reproduction occurs with the reciprocal exchange of sperm • Fertilized eggs are released and usually develop directly into flatworms • Muller's larva Phylum Platyhelminthes

15. Mating & Reproduction • Chemosensory to find mate • Hermaphroditic

16. Regeneration • Many species posses remarkable powers of regeneration and repair wounds Phylum Platyhelminthes

17. Camouflage flatworm nudibranch

18. Toxins • Staurosporine • Tetrodoxin

19. HawaiianFlatworms Class Turbellaria

20. Hawaiian Flatworms Pseudoceros cf. rubroanus Pseudoceros ferrugineus Planocera cf. oligoglena Pseudoceros dimidiatus Pseudobiceros sp. Class Turbellaria

21. Defining characteristics Scolex Proglottids Class Cestoda (Tapeworms) Phylum Platyhelminthes

22. Proglottids • Proglottids • Each animal can be 3,000 – 4,000 per animal • Amazing reproductive output • Each may contain several ovaries and 1,000 distinct testes Phylum Platyhelminthes

23. Problems of a parasitic existence • Reproduce within the definitive host • Get fertilized eggs out of the host • Contact a new and appropriate host • Obtain entrance into the host • Locate the appropriate environment within the host • Maintain position within the host • Withstand an often anaerobic environment • Avoid digestion or attack by the hosts immune system • Avoid killing the host, at least until reproduction is completed Phylum Platyhelminthes

24. Class Trematoda (Flukes) • All are external and internal parasites of other animals • Leech-like bodies with a sucker at each end • Have a gut and well-developed reproductive system, never segmented

25. Trematoda Lifecycles • The lifecycle is complex with up to 4 different hosts and several larval types Phylum Platyhelminthes

26. Trematodes of Concern