Transcript Ribbonworm and Roundworm

Ribbonworms,
Roundworms, and
Rotifers
Phylum Rhynchocoela
(Ribbon-worm)
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Longest worm
Free living, marine
Long proboscis (muscular thin tube that thrust out to
capture prey)
Acoelomate no body cavity
Digestive tube with opening at both ends
Have circulatory system
Thought to have evolved from flatworms
Nematode (Round-worm)
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Bodies shaped like sharpened pencil
Free living, active hunters
Have a complete gut
Most parasitic
Separate sexes- diecous
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It is thought that eggs could last thousands of years
Nematodes
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May be most important animal group
They are everywhere
 1 apple – 50,000 to 90,000 (no such thing as a
vegetarian)
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Bilateral symmetry
No cilia or flagella – only amebode
Nematodes
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Pseudocoelom body cavity located between
endoderm and mesoderm
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This evolution of a body cavity allows for
Circulation but no heart
 Movement-makes body more rigid
 Organ function-body organs can function without being
distorted
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Ascaris
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Ascaris can infect humans-eggs in soil for years-eggs
get into blood and is carried to the lungs where the
larva cause respiratory distress and can also get in your
intestines
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Most common human worm infection
 Common in tropical and subtropical areas where
sanitation and hygiene are poor.
 Past by human or pig fecal material
Necator
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Necator Hookworm-moist soils of the tropics-bores
into soles of the feet-causes anemia
 Infects host when an infective larva penetrates the
host's skin. The juvenile worm migrates through the
host's body and finally ends up in the host's small
intestine where it grows to sexual maturity.
 A hookworm’s mouthparts are modified into cutting
plates. Attachment of hookworms to the host's
small intestine causes on form of hemorrhages, and
the hookworms feed on the host's blood.
Trichinella
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Trichinella found in pigs-can infect humans if eat pork that
isn’t cooked well-infects muscles in humans
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Worse than eating raw chicken
 Mealy grainy pork – DON’T EAT!!!!!!!!!!!!!
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Higher in prevalence in people living in parts of Europe,
Asia, and Southeast Asia than in the United States.
The life cycle is completed with the larvae encysting in
striated muscle, hence why you can get it by eating uncooked
meat.
Causes fever, edema, muscle weakness and tenderness
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Pinworm
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Pinworm females crawl out of anus and lay eggs50% of college students have pinworm at sometime.
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Intestinal infection
Biggest symptom is an itchy butt
Filarial
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Filarial worms cause elephantitis- enlargement of
body parts due to blocked ducts.
 Mosquitoes are reservoir host
 Infects 120 million people a year, infects mostly in
India, Africa and Asia.
 These worms lodge in the lymphatic system, the
network of nodes and vessels.
Rotifers
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Free swimming hunters (mostly freshwater that is still)
Swim with cilia- crown head called Corona
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Feed on bacteria and protist
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Makes them appear to whirl like a wheel
Some species have been known to be cannibalistic
One way gut
Pseudocoelom
99% female
Homework
1.
2.
Why might it be accurate to describe
ribbonworms as a transitional group between
flatworms and roundworms?
Compare and contrast ascaris and necator.