Rotifers  are smaller than many protists,
   but are multicellular and have specialized organ systems.
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   The   crown   of   cilia   is   a  lophophore,  placing  them  in  the
   Lophotrochozoa.
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   Rotifers  reproduce  by  parthenogenesis,  in  which  females  produce
   offspring from unfertilized eggs; some species lack males entirely.