FIELD BOOK OF PONDS AND STREAMS 



There are distinct societies of rotifers; in the open surface 

 water there is a host of minute transparent ones, the plankton 

 rotifers, in the plant-filled shallows near shore is another great 

 company of them which live in the ooze and on the stems and 

 leaves of plants. The agile, swift-moving rotifers feed upon 

 microscopic animals; the largely slower ones are vegetarians. 

 Many of them eat out the cells of filamentous algse, and green 

 Spirogyra mats are usually full of them. 



One of the few rotifers visible to the naked eye is Melicerta 

 (Fig. 102) which builds itself a case by cementing together 

 little brown pellets which can be clearly seen through a good 

 hand-lens. Melicerta lives on the under sides of lily-pads 

 (Fig. 18) and dozens of them can be found upon almost any 

 branch of horn wort or water milfoil (PI. IV). 



130 



