86 GENERAL BIOLOGY 



Are they symmetrically arranged? Do they join the gastric 

 cavity? The canals extend to the periphery of the bell and 

 open into a marginal canal which extends completely around 

 the medusa and communicates with the hollow tentacles. 

 Why is there such a system of canals in the medusa and not 

 in the polyp? 



Hanging from the under surface of the canals are large, 

 convoluted, ribbon-like organs, brownish in color. These 

 are the reproductive organs. The medusae are males or 

 females, but the reproductive organs look alike. 



Draw the entire medusa from the side; also from the 

 oral aspect. Draw a portion of a tentacle showing the 

 arrangement of the nematocysts, and the adhesive organ. 



