1. Unsegmented Worms Phylum Platyhelminthes

2. I. Unsegmented worms A. = Worms that are not divided into sections externally & internally B. E.g. 1. Phylum Platyhelminthes aka flatworms 2. Phylum Nematoda aka Roundworms

3. C. What is a coelom? = fluid-filled body cavity between body wall & digestive tract

4. Kinds of coelom 1. Acoelomate= no coelom i.e. body cavity is NOT fluid filled

5. Kinds of coelom 2. Pseudocoelomate = Fluid filled body cavity BUT No mesentary or peritoneum

6. Kinds of coelom 3. Eucoelomate = True coelom w/ mesentary (holds gut in place) & peritoneum (mesodermal lining of body cavity

7. D. Phylum Platyhelminthes 1.Class : Turbellaria – planarians 2. Class : Trematoda – flukes 3. Class : Cestoda – tapeworms

8. D. Phylum Platyhelminthes Also Acoelomate: Phylum Nemertea – ribbon worms Phylum Gnathostomulida- jaw worms

9. E. General Info re: Flatworms 1. = “platy” = flat “helminth” = worm 2. Body structure a. Size range 1 mm ------► many meters (Cestoda) b. Shape – flattened dorso-ventrally c. Only several cell layers thick

10. E. General Info re: Flatworms  Cells fill body cavity (not fluid)

11. F. Level of Organization = organ system

12. G. Symmetry bilateral (has forward movement & cephalization) I ‘m a little bilateral animal too!

13. H. Habitat aquatic (freshwater or marine) moist soil endoparasites of vertebrates

14. I. Feeding - Class Turbellaria Planarians- mostly free-living carnivore or scavengers

15. –Incomplete digestive tract – one opening (no anus) –Mouth on ventral side –Protrusible pharynx –Gastrovascular cavity (GVC) – “Intestine” very branched –Enzymes digest food I. Feeding - Class Turbellaria

16. I. Feeding - Class Trematoda Parasitic flukes endoparasites of vertebrates need only minimal digestive tract E.g. Human Liver fluke

17. I. Feeding – Class Cestoda tapeworms –Endo-parasites –Scolex w/ hooks & suckers –NO need for dig. tract – absorbs nutrients from gut of host suckers scolex

18. J. Respiration - via diffusion (only a few cell layers thick)

19. K. Internal transport via diffusion Marine flatworm

20. L. Excretion – via diffusion EXCEPTION: planarians have flame cells ( w/ flagella that help move waste to excretory pores, then out of the body

21. M. Response – (Nervous system) 1.Primitive brain – anterior ganglia ganglion = cluster of nerve cells 2. Two Longitudinal nerves (the length of the body) 3. Ladder-like cross-bridges of nerves

22. M. Response – (Nervous system)

23. 4. Sense organs: (flatworms) a. Ocelli – eyespots / photodetectors b. Auricles - contain chemoreceptors (chemicals) & thigmoreceptors (touch) c. Statocysts – balance d. Rheoreceptors – sense direction of water current

24. N. Locomotion - Planaria – use cilia, slime, circular and longitudinal muscles to GLIDE –Trematoda, Cestoda – little motion cilia

25. O. Reproduction 1. Asexual – Regeneration (Planaria only) 2. Sexual – a. pattern = monoecious (hermaphrodites) b. cross- fertilization (swap sperm)

26. P. Ecological Roles 1. Scavengers/ predators – recycle nutrients to ecosystem (Class Turbellaria) 2. Prey for fish & birds (Class Turbellaria) 3. Endo-parasites (cause disease) (Class Trematoda & Class Cestoda)