THE PHYLA ASCHELMINTHES AND NEMERTEA 



223 



jaws. The jaws of Philodlna are stout and ridged for grinding the food 

 particles into a soft pulp. They chew constantly while feeding. The 

 pharynx leads to a large stomach by way of a short esophagus sur- 

 rounded by digestive glands. These glands have been observed to se- 

 crete into the stomach material that is assumed to be enzymatic. Di- 

 gestion takes place rapidly in the stomach cavity and the nutrients are 

 quickly absorbed into the gastrodermis cells. The stomach opens into 

 a short intestine, which leads to the bladder. 



A pair of nephridial tubules opening into the bladder drain a series 

 of flame cells that extend forward in the body. The bladder fills and 



^^-^^ Brain 



Moulh 



Whzcl 

 or^an 



Flame cell 



Pharynx 

 Jaws 



Digestive 

 ■'' and 



Stomach 



Ovary 



Nephridial 

 tubule 



Intestine 



Bladder 

 Anas 



Pedal 

 lands 



Figure 12.2. Ventral view of a rotifer, Philodina roseola, showing many of the 

 internal structures. Redrawn from Hyman. 



