WORMS
Nematodes, Cestodes and Flatworms
WORMS
• Nematodes
o Roundworms
o Non-segmented body
• Cestodes
o Tapeworms
o With segmented bodies
• Trematodes
o Flatworms/Flukeworms
Nematodes
• Phylum: Nematoda
• Noted as one of the most
abundant animals on Earth
• Occurs as parasite in animals
and plants
• Considered as free-living
organisms in soil, fresh water,
marine environments and such
• Considered as a great deal in
research especially because of
its parasitic characteristic
involvement in medical,
veterinary and economic
importance
Nematology
- Study of nematodes or roundworms
- Male organ - cloaca
- Female organ - gonopore
Nematodes (Roundworms)
• Bilaterally symmetrical, elongated and usually tapered
on both ends
• Some species contains pseudocoel
• Secretes an external cuticle that is periodically molted
• Known as hermaphroditic organisms – both male and
female reproductive organs in the same individual
• Size ranges from microscopic to 7 meters long (23ft)
• May occur in almost all organs of the body but most
common sites involves alimentary tract, circulatory tract
and respiratory system
Most common Nematodes
•Giant Roundworm – Ascaris lumbricoides
•Hookworm – Ancylostoma duodenale
•Lungworm – Angiosrtonylus cantonensis
•Pinworm – Enterobius vermicularis
•Whipworm – Trichuris trichiura
Ascaris lumbricoides
o Ascaris derived from pigs
(often referred to as Ascaris
suum) may also infect humans
oAlso known
as Giant Roundworm
Anyclostoma duodenale
•Also known as
intestinal hookworm
•Principally infects the
small intestines
o Ancylostoma
caninum
 Small intestine in
dogs
Enterobius vermicularis
o Also known
as "human pinworm", "seat
worm" and "threadworm"
Trichuris trichura
oAlso known as human
whipworm
oRanked as the 3rd most
common roundworm in
humans
Cestodes (Tapeworms)
• Made up of flat and segmented body
• Characterized as ribbonlike
• Has scolex and rostellum – used as an anchoring
organ which helps organism to attach itself to
intestinal mucosa
• Capable of strobilation - . The segments then
develop into separate organisms
Taenia spp.
• Taenia saginata – beef tapeworm
• Taenia solium – pork tapeworm
• Taenia asciatica – asian tapeworm
• Causes taeniasis – parasitic infection
o infection of cyst which develops in the brain is
referred to as neurocysticercosis
Trematodes
• a.k.a flukes/flatworms
• Flat, leaf-like shape with
noted bilateral symmetry
• Has suckers
o Oral sucker – used to aid in
attachment to the host's
tissue for nutrition
o Ventral sucker - (Acetabulum)
- used to aid in attachment
specifically in the internal
organs (e.g. liver and lungs)
Common
Trematodes
• Fasciola hepatica (Liver fluke)
– Fascioliasis
• Schistosoma spp. (Blood
flukes) – Schistosomiasis
• Paragonimus westermani
(Lung fluke) – Paragonimiasis
• Clonorchis sinensis (Chinese
liver fluke) – Clonorchiasis
END