W orms

1. Worms Flatworms Roundworms Segmented worms

2. Flatworms - Flatworms are the most primitive organisms that have a bilateral symmetrical body structure. Characteristics offlatworms ;

3. habitats - Flat worms live in salt and fresh water, and on the other organisms as parasites.

4. Most planarians live in ponds and streams, often on the bottom of plants or on underwater rocks.

5. Planarians feed on any dead plant or animal matter

6. flatwormshave a nervous system.It is slightly advancedthan that of sponges and coelenterates.

7. There are a few ganglia which form a primitive brain.

8. Nerve net in planaria Nerve cord Ganglia (Brain)

9. Flatworms have one opening which serve as both a mouth and an anus.

10. flatworms don’t have circulatory system.but have a branched digestive tract in contrast to sponges and coelenterates,

11. Their bodies are covered with a mucous like substance. the gas O2 diffuses into the body.

12. They reproduce both sexually and asexually.

13. Reproductive organs of Planaria Ovary testis

15. flatworms have excretory system. It consists of a series of tubules which run along the body and open to the outside.

16. The tubules are branched into cells called flame cells, which collect the excess water from the body and pass it to the duct.

17. Execratory organ of planaria protonephridia Flame cells

18. Nucleus Flame cell

19. The flatworms contain three subclasses. 1-Free living flatworms 2- Parasitic flukes 3- Parasitic tape worms

20. 1-Free living flatworms The best known example is planaria.

21. Planaria

22. 2- Parasitic flukes The best known example is the fluke. It is mostly parasitic.

24. Flukes attach themselves to the organs of their hosts by suckers.

25. Fluke

26. The blood fluke is a common human parasite

27. Adult fluke lives in the blood vessels of human intestines and the bladder. Here it reproduce

28. Life Cycle of the Human Blood Fluke

29. 3- Parasitic tape worms They use human beings as a host. In the human intestine they directly absorb nutrients by diffusion

30. Tapeworm have excretory and nervous systems and a highly developed reproductive system. The lack a mouth and digestive system.

31. Tapeworm

33. Structure of a tapeworm

34. Adult may be form 4 to 9meters in length.

35. Roundworms Phylum Nematoda

36. Roundworms have bilaterally symmetrical body shape.

37. They range in length from less than 1 millimeter to more than a meter

39. Many roundworms are free living, live alone, while others are parasitic.

40. The free living forms are found in fresh water salt water, and in soil.

41. They feed on algae, plant sap, and decaying organic matters.

42. The parasitic forms live on or in most kind of plants and animals.

43. The sexes are separate, and fertilization occurs within the the body of the female.

44. Parasitic roundworms of human Trichina, filaria, pinworm,and hookworm are parasitic roundworms that infect humans.

45. Life cycles of a hookworm

46. Life cycle of Trichina

47. Trichinella Hookworms

48. Ascaris is anther example of a roundworm.

49. Ascaris

50. (Phylum Annelida) The Segmented Worms