STUDIES OF ANIMAL TYPES 

 VI. A SIMPLE MARINE SPONGE (Grantia) 



Materials. Specimens of Grantia preserved in formalin or 

 alcohol, watch glasses, scalpels or razors, caustic soda, test tubes, 

 glass slides, cover glasses, compound microscope. 



These sponges occur in the sea along the Atlantic and Pacific 

 coasts, and may be obtained from dealers in zoological specimens. 



Directions. (Place the individual sponges in water in watch 

 glasses or small shallow dishes.) 



A. EXTERNAL FEATURES. Note the shape of the body. 

 Note the collar of long, transparent spicules around the 

 free end of the sponge. In nature the other end is attached 

 to some object in the sea. Note the smaller sponges at- 

 tached to the bases of larger ones in some cases. These are 

 produced by the process of budding. 



Note that the collar of long spicules surround an opening, 

 the osculum, or mouth. This osculum is also called the 

 exhalent opening, because the water flows out of the body 

 through it. Observe the small spicules covering the whole 

 body. Can the openings of minute pores be seen on the 

 sides of the body ? 



Make a drawing of the animal. 



B. INTERNAL FEATURES. With a very sharp scalpel 

 or old razor cut a dry specimen in halves, lengthwise. 

 Is" the body solid or hollow ? With the low power objective 

 examine the sides of the body cavity and note the minute 

 openings in them everywhere. These are the openings of 



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