1. Phylum Platyhelminthes ( flatworms ) Prepared by : Nada H. Lubbad

2. General characteristic:
Metazoa.
Triploblastic :
Acoelomate.
Bilaterally symmetrical, and dorsoventrally flattened (flat worms ) , cephalization was established.
Free-living or parasites ( both ecto-and endoparasites).
Usually hermaphrodite, The individual produces the male as well as the female gamete, Sexes are present together.
Platyhelminthes
Ectoderm
Mesoderm
Endoderm
Turbellaria
Trematoda
Cestoda

3. Class Turbellaria:
Free-living , mostly marine organisms and freshwater.
Ciliated glandular epidermis.
Mouth ventral and posterior in position.
Most move by means of cilia and mucous.
Muscle contractions also permit turning, twisting and folding of the body.
Turbellarians are carnivores and prey on other animals or eat dead animal remains (scavenge).
They have well developed sensory structures, including eyespots, mechanoreceptors, and chemoreceptors

4. Planaria
External features

5. Internal features

8. T.S of Planarian

9. Class Trematoda Flukes are parasites.
Leaf like body without ciliated epidermis in the adult, but covered by a thick tegument.
They have a suckers, which they cling to the body of the host.
They have 2-branched alimentary canal with an anterior mouth.
They are divided into two subclasses:
- Monogenea, ectoparasites and develop directly on a single type of host.
- Digenea, endoparasites and develop in more than one host.

10. Fasciola: liver fluke Fasciola hepatica , Digenea.
Have to suckers : oral and ventral
They live in the bile ducts of cattle , feeding on the bile and causing the disease known as “ liver rot “ as a result of the irritation caused by their surface spines.

15. Schistosoma (Bilharzia): Blood flukes
Digenea.
It causes schistosomiasis or bilharziasis.
The life history is similar to Fasciola, but lacks the redia stage.
Schistosoma haematobium, lives in venous vesical plexus and drops its egg in the venules of urinary bladder to pass out with urine.
- sexes are separate.
- the intermediate hot is a freshwater snail called Bulinus truncatus

18. Schist. Haematobium egg

19. Class Cestoda Tapeworms, endoparasites and lack alimentary canal.
They have a great power of reproduction, both asexual and sexual.
Taenia, posses defining characteristics: proglottides , suckers with hooks.
T.saginata (beef tapworm) , T.solium (pork tapeworm) both infect man.
Hermaphrodite , each proglottis develop both sets of genital organs.
Self fertilization , occurs within the same proglottis or cross fertilization between different proglottides of the same or other worms.