Worm Phyla: Platyhelminthes (flatworms - acoelomates) Nematoda (roundworms - pseudocoelomates)

1. Worm Phyla: Platyhelminthes (flatworms - acoelomates) Nematoda (roundworms - pseudocoelomates) Annelida (segmented worms – coelomates)

2. Phylum #1 Platyhelminthes(flatworms) Classes: 1. Turbellaria (free-living) 2. Trematoda (parasitic) 3. Cestoda (parasitic)

3. Phylum Platyhelminthes ("flatworms") Evolved from Cnidarians, gained bilateral symmetry and developed excretory, nervous and reproductive systems. Bilateral, acoelomates. Digestion = single opening (mouth and pharnyx) and digestive cavity. Excretory = flame cells excrete wastes. No circulatory or respiratory systems; diffusion only for O2 / CO2 exchange. Sexual (hermaphrodites) and asexual reproduction regeneration.

4. Class #1Turbellaria(Phylum Platyhelminthes) • free-living scavengers • branched intestines with pharynx tube • eyespots, can learn (chopped up & fed to others...) • hermaphroditic; sexually reproduce

6. A variety of marine turbellarians

7. Eurylepta Thisturbellarianflatwormmimics a (very unsavory) sea slug

8. Marine Flatworms mating

9. Class #2Trematoda - flukes(Still Phylum Platyhelminthes) • Parasitic (species-specific) • Thick, protective "tegument" resists acids/enzymes • No digestive system (diffusion only for gases / food) no eyespots; very little cephalization • Ex: Swimmer's itch, Schistosoma, Liver flukes

10. Sheep liver fluke

11. Sheep livers with trematode fluke

12. Schistosoma male/female

13. Schistosoma male / female blood flukes

14. Typical Schistosoma egg Schistosome eggs, which may become lodged within the hosts intestinal wall or in liver, are the major cause of pathology in schistosomiasis.

15. Class # 3Cestoda(tapeworms)(still Phylum Platyhelminthes) • parasites (mostly mild symptoms in well- nourished people) • scolex (head with hooks) • proglottids (egg cases) • Ex: Diplydium (cat intestines  feces  larval fleas  adult fleas  another cat  ingested by licking fur)

16. Scolex of tapeworm

17. Nereis closeup

18. Methane hydrate deposits on the ocean floor teem with life. Residents include ferocious polychaete ice worms that burrow into the formations and defend their lairs against intruders.

19. Tapeworm (Class Cestoda) • Scolex and proglottids

20. PhylumNematodes (roundworms)Evolution- gained body cavity (pseudocoelom), separate sexes, and complete digestive system (2 openings). Bilateral symmetry. Dioeciuos– not hermaphrodites. Complete digestive system (two openings). Circulation and respiration through diffusion.

21. Nematodes are pseudocoelomates

23. DISEASES • Pinworm (Enterobius sp.): eggs swallowed (dust/food)  lg. intestine (lay eggs)  anus (itching) • Lungworm (Ascaris sp.): eggs swallowed  penetrate to lungs  throat  swallowed  intestine (lay eggs) • Trichinosis: cysts ingested (pork, bear)  intestine (pain, diarrhea, fever)  blood  muscles (lumps, pain) • Hookworm (Huck Finn disease): bloodstream  push abdomen through intestine  eggs outside • Brainworms, heartworms, Guinea worms (“the fiery serpent” makes great tattoos!), Filaria (clog lymph: elephantiasis), Loa loa (eyeworms)

24. The Fiery Serpent- Guinea Worm

26. Trichina-- a roundworm (nematode) common in pork • picture shows capsule embedded in muscle tissue. • enters host via raw or poorly cooked meat • eggs shed in the gastrointestinal tract--> feces • eggs eaten by herbivores --> encyst in muscle • encysted worm is resistant to antihelmithic drugs.

27. Heartworm-- a parasitic nematode

28. Pinworms-- infections of kids (itchy eggs!) Reminder: Kingdom Animalia; Phylum Nematoda

30. Phylum Annelida The Segmented Worms

31. Evolution-development of coelom. • Cephalization! Well-developed nervous system: nerve cord with ganglion in each segment and anterior brain • Bilaterally symmetrical • Organs within a true coelom (cavity within mesoderm) • Compartmentalization of organs / movement of parts of body • Closed circulatory system with five pairs of “aortic arches” • Most have red hemoglobin in blood (efficient) Sophisticated digestive system: • mouth  pharynx esophagus  crop gizzard  intestine  anus • Appendages: Setae &/or parapodia • Excretion- Nephridia remove nitrogenous wastes; wets skin • Respiration—use diffusion • Most hermaphroditic, some dioecious.

32. Classes of Annelids • Oligochaeta: earthworms, nightcrawlers, (aquatic) tubifex worms • 20-45 tons of soil/year/acre processed by worms on organic farms • each worm processes its own weight each day • Polychaeta: bristleworms, tube worms, featherdusters • marine worms with parapodia and (most) jaws! • Hirudinea: terrestrial / aquatic leeches • some parasitic, some free-living • medicinal anticoagulant “hirudin”

34. Fanworm

36. A filter-feeding polychaete: feather-duster

37. Bristle-worm (nereis)

38. The medicinal leech is best known as the organism used for blood letting (people used to believe many health problems caused by "bad" blood). They are being used once again to remove blood from hematomas (areas of blood leakage) resulting from surgery (like re-attaching severed limbs, etc.).

40. http://www.sp.uconn.edu/~mcbstaff/graf/AvHm/MedUsemain.htm