Transcript Nematoda: Roundworms

Nematoda: Roundworms
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First phylum to have the Complete digestive tract:
mouth and anus
 Pseudocoelomate: fluid filled between endoderm
and mesoderm
 Hydrostatic skeleton under pressure which means
only one shape is possible (tapered hotdog)
Phylum Nematoda
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Reproduction is usually
sexual—females are
generally larger than
males.
Fertilization is internal,
and a female can deposit
100,000 or more fertilized
eggs per day.
The zygotes of most
species are resistant cells
capable of living in harsh
conditions.
Hookworm
Roundworms
Pinworm
Ascaris: intestinal
roundworm
1,000,000 cases in
USA: 1.2 billion
worldwide
Heartworm
Ascaris life cycle
Removal of Guinea Worm
http://www.youtube.com/watch?v=mUz9gqLmyQ0
nematodes
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http://www.youtube.com/watch?v=JBLem
M3tzRM soil nematodes
http://www.youtube.com/watch?v=gmFHn
QKbSM8 lymphatic filariasis
(elephantiasis) 1 billion worldwide
Annelida: segmented worms
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Polychaetes, earthworms, leeches
 Eucoelomate
 Segmented body plan
 Closed circulatory system
 Protostome: opening in gastrula becomes the mouth
Annelida: key structures
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Bristles on
side
Aortic arches
leeches
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Fused
segments to
allow for
blood
storage
Blood
thinner
released to
help sucking
http://www.youtube.com/watch?v=
DZig6EL5B6A&feature=PlayList
&p=F648EFCC1BE6AAA3&playn
ext=1&index=10
Earthworms in Australia
Earthworms are
hermaphroditic. They
fertilize each other with the
clitellum secreting a mucus
sack to collect the eggs
and sperm. This sack is
then placed into the ground
until babies are developed.
annelids
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Polychaete: clamworm
http://www.youtube.com/watch?v=LdHzR
Ndz2HU