, Nemathelminths
1. How does the parasite survive in the host?
i. Because they are living organisms process metabolic activities.
ii. Depends on host activities .
iii. Lives by fighting or defense host immune systems.
2. What do you know about nemathelminthes?
Nemath means round and helminth means worm. So the phylum nemathelminthes includes
those worms which is elongated, cylindrical and tapering both ends and rounded in cross
section.
3. Distinguish between Platyhelminthes and nemathelminthes
Platehelminthes Nemathelminthes
1. Dorsoventrally flattened 1. elongated, cylindrical, tapering both
end and round in cross section.
2. Size: Milimetres to several 2. millimeters to several centimeter
centimeters sometimes in meters
3. bisexual or monoecious except 3. unisexual sometimes occurs
Schistosoma sp. parthenogenesis
4. digestive system is incomplete or 4. Complete
absent.
5. Intake or Ingest 5. Only ingest
6. body surface : 6. body surface :
Soft , porous , absorbable (tegument) tough or not absorbable (Cuticle)
7. body cavity absent 7. body cavity present
8. life cycle : completely indirect and 8. direct or indirect and highly diversify
simple.
9. Infective stage : metacercaria or meta 9.Larvae stage: L1-L3 or Egg L1- Egg L3
cestode
10. Laying habit / Progeny : Oviparous 10. Oviparous , Ovo-Viviparous ,
Viviparous.
, 4. How to differentiate trematode versus cestode versus nematode?
Feature Trematodes Cestodes Nematodes
1. Common Flukes Tapeworms Roundworms
Name
2. Body Shape Flat, leaf-shaped or Long, flat, ribbon-like, Long, cylindrical,
oval segmented unsegmented
3. Body Bilateral Bilateral Bilateral
Symmetry
4. Digestive Incomplete, usually no Lacks digestive system, Complete digestive
System anus absorbs nutrients tract with mouth and
across body surface anus
5. Life Cycle Complex, often Complex, often involves Variable; can involve
involves multiple intermediate hosts direct or indirect
hosts development
6. Mode of Oral and ventral Scolex with hooks and Lips or teeth around
Attachment suckers suckers the mouth
7. Reproductive Hermaphroditic, Hermaphroditic, each Separate sexes
System complex segment (proglottid) (dioecious)
contains reproductive
organs
8. Common Vertebrates (including Vertebrates (often in Vertebrates, plants, soil
Hosts humans) intestines) organisms
9. Examples Schistosoma, Fasciola Taenia, Ascaris, Enterobius,
Diphyllobothrium Ancylostoma
5. Male is always smaller than female in nematode why?
In nematodes, males are generally smaller than females due to differences in their
reproductive roles and strategies:
Reproductive Efficiency: Female nematodes need more body space to develop and
carry eggs, which requires a larger body size. This helps them produce a high
number of eggs and ensures the survival of the species. In many nematode species,
females produce thousands ( even lakh ) of eggs in their lifetime, so a larger size
supports greater reproductive output.
1. How does the parasite survive in the host?
i. Because they are living organisms process metabolic activities.
ii. Depends on host activities .
iii. Lives by fighting or defense host immune systems.
2. What do you know about nemathelminthes?
Nemath means round and helminth means worm. So the phylum nemathelminthes includes
those worms which is elongated, cylindrical and tapering both ends and rounded in cross
section.
3. Distinguish between Platyhelminthes and nemathelminthes
Platehelminthes Nemathelminthes
1. Dorsoventrally flattened 1. elongated, cylindrical, tapering both
end and round in cross section.
2. Size: Milimetres to several 2. millimeters to several centimeter
centimeters sometimes in meters
3. bisexual or monoecious except 3. unisexual sometimes occurs
Schistosoma sp. parthenogenesis
4. digestive system is incomplete or 4. Complete
absent.
5. Intake or Ingest 5. Only ingest
6. body surface : 6. body surface :
Soft , porous , absorbable (tegument) tough or not absorbable (Cuticle)
7. body cavity absent 7. body cavity present
8. life cycle : completely indirect and 8. direct or indirect and highly diversify
simple.
9. Infective stage : metacercaria or meta 9.Larvae stage: L1-L3 or Egg L1- Egg L3
cestode
10. Laying habit / Progeny : Oviparous 10. Oviparous , Ovo-Viviparous ,
Viviparous.
, 4. How to differentiate trematode versus cestode versus nematode?
Feature Trematodes Cestodes Nematodes
1. Common Flukes Tapeworms Roundworms
Name
2. Body Shape Flat, leaf-shaped or Long, flat, ribbon-like, Long, cylindrical,
oval segmented unsegmented
3. Body Bilateral Bilateral Bilateral
Symmetry
4. Digestive Incomplete, usually no Lacks digestive system, Complete digestive
System anus absorbs nutrients tract with mouth and
across body surface anus
5. Life Cycle Complex, often Complex, often involves Variable; can involve
involves multiple intermediate hosts direct or indirect
hosts development
6. Mode of Oral and ventral Scolex with hooks and Lips or teeth around
Attachment suckers suckers the mouth
7. Reproductive Hermaphroditic, Hermaphroditic, each Separate sexes
System complex segment (proglottid) (dioecious)
contains reproductive
organs
8. Common Vertebrates (including Vertebrates (often in Vertebrates, plants, soil
Hosts humans) intestines) organisms
9. Examples Schistosoma, Fasciola Taenia, Ascaris, Enterobius,
Diphyllobothrium Ancylostoma
5. Male is always smaller than female in nematode why?
In nematodes, males are generally smaller than females due to differences in their
reproductive roles and strategies:
Reproductive Efficiency: Female nematodes need more body space to develop and
carry eggs, which requires a larger body size. This helps them produce a high
number of eggs and ensures the survival of the species. In many nematode species,
females produce thousands ( even lakh ) of eggs in their lifetime, so a larger size
supports greater reproductive output.
