1. FLATWORMS
Belong to the KINDGOM ANIMALIA
PHYLUM PLATYHELMINTHES

2. Flatworm Characteristics
Three germ layers (endoderm, ectoderm, mesoderm)
Bilateral symmetry
Cephalization (has a head)
No Body Cavity

3. Types of Body Cavities (from most primitive to most advanced)
Acoelomates = without coelom
Pseudocoelom = false body cavity
COELOM = fluid filled body cavity

4. FORM AND FUNCTION FEEDING
Free-living - carnivores or scavengers; they have a digestive cavity, mouth and pharynx
Parasites – feed on blood, tissues or pieces of cells from within a HOST
Most do not have a complete digestive system because they absorb material directly from host

5. Respiration, Circulation, and Excretion
Thin bodies allow for materials to diffuse (respiration, excretion, etc)
Flame Cell – specialized cells that remove excess water

6. Response
Ganglia – group of nerve cells that control the body (like a brain)
Eyespot – group of cells that can detect light (like an eye)

7. Movement Flatworms move in 2 ways
Cilia helps them glide through the water
Muscle cells help them twist and turn

8. Reproduction
Sexual Reproduction – most flatworms are hermaphrodites (have both male and female sex organs)
Asexual Reproduction by fission – flatworms can split in two and regenerate

9. Groups of Flatworms CLASS TURBELLARIA - free living flatworms
- live in fresh or marine water
ex. Planarian

10. Dugesia lives in freshwater, mostly a scavenger but can also feed on protists

11. Planarians are hermaphrodites (both sexes)
They can also regenerate body parts and will sometimes split in half to reproduce (FISSION)

12. ANATOMY OF A PLANARIAN

13. Brain (ganglia) - planarian can process information about their environment
Pharynx - used for suckling food in (the mouth is at the end of the pharynx)
Eyespot - simple eye, can detect light
Flame cells - located along the lateral edges, used for excretion
Intestine - digestion (does not have an anus)

14. Class Trematoda = parasitic flatworms
a.k.a “flukes” live in mouth, skin, or gills of host
Primary host = the host in which a parasite reproduces sexually
Intermediate host = the host in which asexual reproduction occurs

15. Schistosoma mansoni - multiple host:
Primary host = human
Intermediate host = snail
Causes Schistosomiasis -in humans; decays lungs liver, spleen, or intestines, occurs in tropical areas with poor sanitation/sewage.

16. Class Cestoda =tapeworms Long, flat, parasitic Live in intestines
Pork Tapeworm Monsters Inside Me:

17. Scolex = a structure that contains suckers and/or hooks
Proglottids = body segments of the tapeworm

18. Each mature proglottid is a hermaphrodite
Testes produce sperm, fertilize the eggs to produce a zygote
Zygotes are passed out through the feces.

19. Sometimes, a dormant, protective cyst is formed in the intermediate host muscles
****This is why you should never eat incompletely cooked meat.