1. Phylum: Nematoda
“thread-like”, commonly called roundworms, found just about everywhere
Examples: ascaris, pinworms, hookworms, trichina worms

2. Traits
Round bodies

3. Traits
Non-segmented

4. Traits
Bilateral symmetry

5. Traits
cephalized

6. Traits
Tube-in-a-tube (complete) digestive system – 2 openings

7. Traits
Longitudinal muscles only

8. Traits
Flame cells

9. Advantages of a complete digestive system
Can eat continuously
Can eliminate wastes without losing good food

10. Why are worms so long?
Since they have a straight G.I. tract, they must be long in order to have a tract long enough to digest and absorb food before it reaches the anus

11. Excretory system
Flame cells collect waste and force them out through a series of tubes with one common exit

12. Reproduction
Most are dioecious

13. Two categories:
Free living
Parasitic

14. Freeliving More abundant than the parasitic nematodes
Live in soil and water (fresh and salt)

15. Freeliving Nematodes Bacterial feeders Fungal feeders
Many are beneficial in helping to control disease and cycle nutrients in the soils

16. Size = average 1 mm in length
Larger one consuming smaller parasitic ones

17. Plant parasitic nematodes
Form cysts on the roots

18. Parasites
Live in another organism

19. A few main types… Ascaris Pinworms Hookworms Trichina worms
Filarial worms

20. Ascaris

21. Ascaris
Studied a lot because they are big and cheap

22. Ascaris life cycle
Adults live in pig intestines, mate, eggs leave with feces
Pigs ingest contaminated food or water, start over
Since the cycle is simple, it’s hard to break

23. Ascaris larvae

24. Ascaris
Mouth

25. Ascaris in Pig Intestines

26. Pinworms

27. Pin worms
Most common nematode parasite in humans

28. Pin worm life cycle
Adults live in human intestines, mate, females crawl out the anus and lay eggs on the surrounding skin
Kid scratches self, then eats without washing hands, starts over

29. Pinworm in Colon

30. Cure
Easy, oral medicine goes directly to them and are flushed out with feces

31. Prevention
Wash hands, especially after using the bathroom

32. Hookworms

33. Hook worms
Intestinal parasites of humans, suck blood

34. Hook worm life cycle
Adults live in intestines, mate, eggs leave with feces
Hatch into larvae which bore through bare feet and eventually enter the lungs
Crawl up trachea, are swallowed, start over

36. Hookworm larvae tracks

37. Symptoms
Abdominal pain, severe diarrhea, anemia

38. Prevention
Wear shoes
good sewage system

39. Trichina worms

40. Trichina worms Cause trichinosis, can be fatal Red swollen eyes
Fatigue and diarrhea
Brain swelling
Heart failure

41. Trichina worm life cycle
Adults live in pigs intestines, mate, eggs immediately hatch into larvae which bore through intestines into blood stream
Eventually lodge and form cysts in the muscles, another animal eats it, start over

42. Meat infested with Trichina worm

43. Prevention
Cook meat well
Inspect meat
Don’t feed pigs raw meat

44. Filarial worms

45. Filarial worms
Cause elephantitis by clogging lymph nodes so they can’t drain fluids from the limb

46. Filarial worm life cycle
Live and mate in fluids of body tissues, larvae are sucked out by mosquitoes and injected into another animal

48. Prevention
Kill mosquitoes