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WORMS
Roundworms
Phylum: Nematoda
• Characteristics
– Long
– Smooth
– Pseudocoelomates
• Body cavity b/t the body wall and digestive tube;
however, it is not completely lined with mesoderm.
Ascaris
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Long, smooth
Parasitic
Tapered at the end
Length: 12 inches
Infects animals by
attaching to the intestine
and causing blockage
• Can cause illness in lungs
similar to pneumonia
(Example: Roundworm)
Hookworm (Example: Roundworm)
• Parasitic
• Larva are found in
contaminated soil
• Sticks to feet of animals
and bores thru skin of foot
• Travels to lungs 
windpipe back of
throat digestive system
and attaches its jaws to the
intestine.
• Victim = anemia and
sluggishness
• Reproduction  eggs
pass out with the feces
into the soil
• Cycle continues
• Size = small as
eyelash
Ex. Hookworm
Trichina Work or Porkworm
• Parasite
• Found infecting pigs
and meat
– Ingest encysted
trichina worm
– Worm grows in
intestines
– Burrows into muscle
– Infects humans who
don’t cook properly
Flatworm
Phylum: Platyhelminthes
• Example: Planaria
– Scavenger
– Transparent
– 3 layers  ectoderm – protection; 
mesoderm – nerves and muscle;  endoderm –
internal organs
– Acoelomate –no body cavity b/t body wall and
digestive tube
– Mouth – round opening at end of pharynx
• Located half way down on ventral (underside) side
Planaria (Flatworm cont.)
• Vacuums up microscopic organisms pass into
intestine  packaged and digested in vacuoles.
• Vacuoles take place of circulatory system
– Distribute nutrients and oxygen and pick up wastes and
CO2.
– Expelled through mouth
• AKA cross-eyed worm b/c has 2 eyespots
– Sensitive to light and send signals to nerve tissue with
form a brain
• Sense taste, touch and smell
Planaria (Flatworm cont.)
• Movement  shortening and elongating
and twisting body
• Reproduction = asexually by fission
– Fission  dividing into 2
– Hermaphroditic
Tapeworm (Flatworm cont.)
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Phylum: Platyhelminthes
Parasitic
Long and ribbon-like grayish-white body
2 parts
– Scolex – knob shaped head – ring of hook and
several suckers
– Proglottids – repeating square sections each
contain a set of reproductive organs
Tapeworm (Flatworm cont.)
• Attaches to intestine and robs of nutrients
• Proglottids are added near the head as
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tapeworm grows.
Older proglottids break away and leave
body with feces
Animals feed on feces and take in eggs in
proglottids – cycle continues.
Infect humans from uncooked meat
Cause: weight loss, energy loss, muscular
aches, breathing difficulty