CHAPTER 



PHYLUM ROTIFERA 



THE Rotifera are minute animals mostly confined to fresh water, 

 a few only being found in the sea. Many of them swim about by 

 means of a loop of cilia which encircles the front end of the body, 

 but some are sessile. The motion of these cilia induced the early 

 observers to think that the animal had wheels in front, whence the 

 name (Lat. rota, a wheel; fero, to carry). There is a complete 

 transparent alimentary tube, ending in an anus situated on the 

 dorsal side in front of the hind end of the body, the latter forming 

 a ventral projection called the foot. The first part of the tube is 

 a stomodaeum, and lined like the rest of the skin with cuticle. 

 This cuticle is thickened to form teeth which work on one another, 

 the whole organ being called a mas tax. The activity of the 

 mastax enables one at once to distinguish a Rotifer from other 

 minute animals. 



Floscularia cornuta, often termed F. appendiculata, is a widely 

 distributed species. It lives in ponds, ditches and pools, usually 

 attached by its posterior end to some water-weed or other body 

 and surrounded by a gelatinous tube into which the animal can 

 retire. The length of the animal when extended is 0*2 to 0'3 mm. 

 The body is covered by a thin cuticle, and may be divided into 

 three regions, the head, the trunk and the foot. When the animal 

 is extended the last-named is stretched out and smooth, but it is 

 wrinkled when the animal withdraws into its tube. It terminates 

 in a disc, on which opens the duct of two large glands which 

 secrete an adhesive substance, by means of which the foot is 

 anchored. 



The anterior end of a Rotifer, on which the mouth opens, is 

 called the disc. In Floscularia this is produced into five long 

 tentacle-like processes fringed with stiff bristles which serve -as a. 

 net to entangle small animals and plants. The cilia which produce 



