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PHYLUM: ROTIFERA
“Wheel bearers”- Rotary animals
Rotifera- “wheel bearers”
Small- most 0.1mm-0.5mm
Aquatic
benthic (living at bottom)
mostly free-living in fresh water, but some
marine.
 The anterior part is modified to a ciliary
organ, the corona or wheel organ.
 Body cavity a pseudocoelom.
 Cuticle- body covering
 Bilateral symmetry
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Body Plan- Pseudocoelom
Pseudocoelom
 space between gut and
mesoderm parts of body
wall
 space filled with fluid
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 for differentiation of systems
 storage of waste products
 used as hydrostatic skeleton
Cuticle

Cuticle- outer covering, over epidermis
◦ for protection against water loss or gain
◦ resistant to environmental chemicals
Body Systems
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Systems they Do NOT have:
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circulatory system
respiratory system
true skeletal system
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Do have:
Excretion: protonephridia
Digestive: complete- mouth anus
Muscular: longitudinal only- whiplike
movements
 Nervous:ladder like with anterior ganglia
 Skeletal: hydrostatic skeleton: for movement
 Reproduction:most separate sexes,
some parthenogenesis- “virgin birth”females produce embryos that grow
and develop without fertilization by
males
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Figure 15.18
Rotifers
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Video-rotifer feeding
Phylum Rotifera
(rotifers)
have a corona with
cilia (like Norelco
shaver head)
 no cilia elsewhere
 Have biforked “foot”
with cement glands
for attachment
 complex digestive
structures
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United streaming Video Clip

http://player.discoveryeducation.com/inde
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