PHYLUM ROTIFERA Wheel bearers Rotary animals Rotifera wheel

PHYLUM: ROTIFERA “Wheel bearers”- Rotary animals

Rotifera- “wheel bearers” �Small- most 0. 1 mm-0. 5 mm �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

Body Plan- Pseudocoelom �space between gut and mesoderm parts of body wall �space filled with fluid � 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 � Systems they Do NOT have: � circulatory system � respiratory system � true skeletal system � 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

Figure 15. 18

Rotifers �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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