1. Phylum Platyhelminthes
Flatworms
Flukes
Tapeworms
Phylum Platyhelminthes

2. Phylum Platyhelminthes
The phylum consists of four classes
Turbellaria
Trematoda
Cestoda
Triclad Flatworm
Phylum Platyhelminthes

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

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

6. Phylum Platyhelminthes
Class Turbellaria
Most are free–living, tiny and inconspicuous
Primarily marine and freshwater
Free-living
Flatworm
Phylum Platyhelminthes

7. Phylum Platyhelminthes
Flatworm Body Plans
Exhibit bilateral symmetry, acoelomate, and are triploblastic
Parenchyma tissue
Phylum Platyhelminthes

8. Digestion and Excretion
Mouth is usually located at the anterior end or mid-body on ventral surface
Excretory system
Contains flame bulbs
Phylum Platyhelminthes

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

10. Turbellarian Lifestyles
Most are benthic
Posses several nerve cords with a centralized ganglia (brain)
Phylum Platyhelminthes

11. Phylum Platyhelminthes
Turbellarian Habits
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
Phylum Platyhelminthes

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

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

14. Phylum Platyhelminthes
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

15. Phylum Platyhelminthes
Beef tapeworm
Phylum Platyhelminthes

16. 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

17. 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
Phylum Platyhelminthes

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

19. Phylum Platyhelminthes
Trematodes of Concern
Schistosomiasis
Deadly prominent disease in many regions of the world
Bores into the skin of the definitive host and travels in the circulatory system to the heart the lungs and the kidneys where it feeds and grows
Inflammation is caused by eggs becoming trapped in the hosts tissues
Chinese liver fluke
Lives in the bile duct of humans, cats, and dogs (1-2 cm.)
Goes through two intermediate hosts
Infection occurs from ingestion of raw fish
Phylum Platyhelminthes