1. Unsegmented Worms

2. PHYLUM NEMATODA
….the roundworms
Roundworms

3. Taxonomy
Kingdom: Animalia Phylum: Nematoda Class: Secernentea Adenophorea

4. Phylum Nematoda Vocab Hookworm * 4. trichinosis
1. parthenogenesis cuticle
Hookworm * trichinosis
Pinworm* filarial worm*
7. Elephantiasis vermiform
9. cloaca Microfilaria

5. 1. PARTHENOGENESIS- modified form of sexual reproduction by the development of a gamete without fertilization
2. CUTICLE- noncellular, protective organic layer secreted by the external epithelium (hypodermis) of many invertebrates
3. HOOKWORM- (New World or American Hookworm) Necator americanus; found in southern US; adults live in small intestine
4. TRICHINOSIS- caused by (the porkworm) Trichinella spiralis larvae; get from eating undercooked meat; characterized by muscular pain, fever, edema (swelling), & other symptoms
5. PINWORM- Enterobius vermicularis; most common roundworm parasites in the US
6. FILARIAL WORM- Wuchereria spp.; elongate, threadlike nematodes that live in the lymphatic system, where they block the vessels
7. ELEPHANTIASIS- a chronic filarial disease most commonly occurring in the tropics due to the infection of lymphatic vessels with the nematode Wuchereria spp.
8. VERMIFORM- resembling a worm in shape; long and slender
9 . CLOACA- a common opening for excretory, digestive, & reproductive systems
10. MICROFILARIA- the prelarval stage of filarial worms; found in the blood of humans and the tissues of the vector (carrier)

6. Characteristics
Pseudocoelomates- big advancement… why?

7. Characteristics cont
Most small, many are microscopic, but a few are over 3 feet
Bilateral symmetry, cylindrical body tapered at both ends, no segmentation

8. Characteristics cont No cilia or flagella
Mostly dioecious, (male and female reproductive organs in separate organisms of the species)
female larger

9. What system takes up most of the organism’s body?

10. Characteristics cont
Most nematodes are free-living and are found in virtually all habitats, but mostly in soil and fruits.
Some are parasitic
Plant Nematode

11. Characteristics cont
Have a complete digestive system consisting of a mouth, muscular pharynx, non-muscular intestine (only one cell layer thick), and an anus.
4 parts of a complete digestive system

12. Quick Review Questions
What type of body cavity do nematodes have?
What type of symmetry do they have?
What does the term “dioecious” mean?
Where can you find nematodes?
Do they have a digestive system?
Explain.

13. Feeding
Many free-living roundworms use grasping mouthparts and spines to catch and eat other small animals.

14. Respiration, Circulation and Excretion
Roundworms exchange gases and excrete metabolic waste through their body walls.
They depend on diffusion to carry nutrients and waste through their bodies.

15. Movement
Fluid in the pseudocoelom and muscles extending the length of their bodies function as a hydrostatic skeleton.
Aquatic roundworms contract muscles to move like snakes through the water.
Soil-dwelling roundworms push their way through the soil by thrashing around.

16. Reproduction Roundworms reproduce sexually.
Most species have separate sexes.
Parasitic roundworms often have life cycles that involve two or three different hosts or several organs within a single host.

17. Questions What do nematodes use their mouthparts for?
How do nematodes breathe?
How do nematodes move?
How do nematodes reproduce?

18. Discussion
1. Explain why being a pseudocoelomate is a big advancement for nematodes. (Make reference to a previous phylum we have studied and connect the reference to nematodes.)
2. Explain the difference between being a hermaphrodite and being dioecious. Discuss these differences.

19. Nematode hatching

20. A Marine Nematode

21. Parasitic Nematodes Foldable *3 sheets of paper *several markers
Wuchereria spp.
Parasitic Nematodes Foldable *3 sheets of paper *several markers
Ascaris lumbricoides
Enterobius vermicularis
Necator americanus
Trichinella spiralis
PARASITIC NEMATODES

22. Roundworms and Human Disease

23. Ascaris
Ascaris lumbricoides is a serious parasite of humans and many other vertebrate animals.
It absorbs digested food from the host’s small intestine.

24. Ascarids taken from children of one village.

25. Ascaris Dissection Round Worm Dissection
Sexual dimorphism: physical characteristics that are used to differentiate males from females
2 ways to tell males from females:
Males are smaller
Males have a coiled hook at posterior end for copulation

26. Dissected Female

27. Monsters Inside Me…Ascaris

28. Coughing up worms Ascaris
Monsters Inside Me
Ascaris

29. Ascaris lumbricoides Giant intestinal roundworm
Ascariasis is the disease you get from the worm
Aka Hand to mouth disease
Largest roundworm a human can get (up to 16 inches)
Begins life as free living eggs in soil
800 million throughout the world are infected
Live in small intestine of humans
Produce large # of eggs that exit with feces
Internal anatomy is mainly reproductive organs & digestive tract
2nd stage larvae is the infective stage
Human ingests embryonated eggsthey hatch in the intestinelarvae penetrate intestinal wall & are carried via circulation to lungsmolt 2x in lungsmigrate up trachea & are swallowed

30. Worms attain sexual maturity in the intestine, mate & begin egg production
Infection in US is rare – worm is brought over by people returning from vacation
Adult worms can live in intestinal tract for years undetected
Can grow up to 16 inches long
In undeveloped/unsanitary African countries 95% of the population is infected

31. Life cycle

32. Trichinella
Adult Trichinella worms live and mate in the intestines of their hosts.
Larvae travel through the bloodstream and burrow into organs and tissues.
50 µm
Encysted juveniles
Muscle tissue

33. Trichinella cont
Trichinella completes its life cycle only when another animal eats muscle tissue containing these cysts.
Humans can get trichinosis by eating raw or incompletely cooked pork.

34. Cysts in Contaminated Pork Trichinella spiralis

36. Trichinella

37. Trichinella spiralis Porkworm
Live in mucosa of small intestine of humans & other carnivores & omnivores (the pig)
In intestine, adult females give birth to young larvae that enter the circulatory system & are carried to skeletal (striated) muscle of same host young larvae encyst in skeletal muscles & remain
Another host must ingest infective meat (muscle) to continue the life cycle
Humans get it by eating improperly cooked pork
Once ingested, larvae excyst in stomach & make their way to the small intestine where they molt 4x & develop into adults

39. Hookworms Necator americanus..American hookworm
Hookworm eggs hatch and develop in the soil.
They use sharp toothlike plates and hooks to burrow into the skin and enter the bloodstream.

40. Hookworms cont
Hookworms travel through the blood of their host to the lungs and down to the intestines.
There, they suck the host’s blood, causing weakness and poor growth.
Small hookworms

41. Monsters…Flesh-eating Hookworms

42. Hookworm.. healthbyte http://www.youtube.com/watch?v=IMIDIAUBF8Y
Hookworm relationships:)

43. HOOKWORM
*Filariaform=threadlike
*this is NOT a filarial worm

44. Necator americanus New World Hookworm/American Hookworm
Found in Southern US
Adults live in small intestine where they hold onto the intestinal wall w/teeth & feed on blood and tissue fluid
Females can produce 10,000 & eggs daily, which can pass out of the body in feces
Egg hatches on warm, moist soil
Humans can became infected with a filaria-form larva penetrates the skin & usually between toes
Outside defecation & subsequent walking barefoot are methods of becoming infected

45. Hookworms Mild symptoms: rash, mild diarrhea
Severe symptoms: anemia, weight loss
Common in areas with warm temp & decent amount of rainfall
Tx: 1-3 days of meds to eliminate worms
Recheck stool to make sure worms are gone

46. Filiarial Worms
Filarial worms are threadlike worms that live in the blood and lymph vessels of birds and mammals.
They are transmitted by mosquitoes.
Causes Elephantiasis

47. Filarial worm in cow eye

48. Elephantiasis

49. Elephantiasis cont

50. Monsters Inside Me .. Filarial worms

51. Filaria- causes, symptoms, etc.

52. Elephantiasis

53. Filariasis Treatment.. India

54. Wuchereria spp. Filarial worms In tropical countries
250+ million humans infected
Wuchereria bancrofti & Wuchereria malayi
Fluid in connective tissue accumulates in peripheral (outer) tissuesenlargement of various appendages = elephantiasis
Transmitted by mosquitoes
Prevalent filarial worm in the US is Dirofilaria immitis
Since these adult worms live in the heart and large arteries of the lungs, the infection is called heartworm disease
Hard to eliminate
Condition can be fatal
Prevention – heartworm meds

55. Wuchereria spp. Filariasis – info & treatment
Lymphatic system blockage causes excessive swelling
120 million ~ Africa, India, South Asia, Pacifica
25 million Indian people alone
Noninvasive treatment
14 days inpatient
1. wash w/ medicated soap
2. submerge in solution
3. antibiotic cream
4. yoga
5. massage
6. wrap in compression
Continue treatment at home for 6 months
50% reduction in swelling
Strict vegetarian diet

56. Enterobius vermicularis…PINWORMS
colonoscopy
Meducational
case study

57. Enterobius vermicularis
Human pinworm aka threadworm (UK)
Most common roundworm parasite
Adults become established in lower part of large intestine
@ night, females migrate out to opening of anus
& deposit eggs containing 1st stage larva & die
Females & eggs produce an itching sensation
Easily spread because scratching an itch contaminates the hands & bed clothes/sheets
When hands touch mouth & eggs are swallowed, the eggs hatch
Larvae molt 4x in the small intestine & migrate to large intestine
Adults mate & females soon begin egg production

58. Small – thin- white – roundworm
Can affect all people
Common among children, institutionalized persons & household members of persons w/pinworm infection
Treatable with OTC (over the counter) or rx (prescription) meds
Reinfection, which occurs easily, should be prevented
Can do scotch tape test to check for infestation
Pinworms are not usually a serious situation

59. Lifecycle of a Pinworm

60. NEMATODES & INSECTS

61. BENEFICIAL NEMATODES?!! Isn’t than an oxy moron?

64. Ascaris Dissection and Nematodes Slideshow

65. Nematoda
Quiz

66. In roundworms, the body cavity that forms between the endoderm and mesoderm is the
ganglion.
hydrostatic skeleton.
pseudocoelom.
coelom.

67. All of the following are parasitic roundworms EXCEPT
Tapeworms
filarial worms
Hookworms
ascarid worms

68. Characteristics of roundworms include a digestive system with
one opening and a pseudocoelom.
one opening but no pseudocoelom.
two openings and a pseudocoelom.
two openings but no pseudocoelom.

69. Gas exchange and excretion of metabolic wastes in roundworms occurs
via a complex system of alveoli.
through their body walls by diffusion.
through excretory tubules.
by flame cells.

70. The roundworms called ascarids cause harm by
causing serious body swelling.
burrowing into body tissues and causing pain.
causing malnutrition.
causing internal bleeding.

71. In roundworms, the body cavity that forms between the endoderm and mesoderm is the
ganglion.
hydrostatic skeleton.
pseudocoelom.
coelom.

72. All of the following are parasitic roundworms EXCEPT
Tapeworms
filarial worms
Hookworms
ascarid worms

73. Characteristics of roundworms include a digestive system with
one opening and a pseudocoelom.
one opening but no pseudocoelom.
two openings and a pseudocoelom.
two openings but no pseudocoelom.

74. Gas exchange and excretion of metabolic wastes in roundworms occurs
via a complex system of alveoli.
through their body walls by diffusion.
through excretory tubules.
by flame cells.

75. The roundworms called ascarids cause harm by
causing serious body swelling.
burrowing into body tissues and causing pain.
causing malnutrition.
causing internal bleeding.