STUDY II. PORIFERA. Sponges. 



Central ideas : Transition to many-celled animals. 

 Beginnings of division of labor among cells. 



1. A SIMPLE SPONGE. Grantia ciliata. 



A. Habitat. (Dem.) 



1. What is the source of this material? 



2. In what kind of places on the sea-coast are these 



sponges to be found? 



3. Why cannot living sponges of this kind be secured 



for your study ? 



B. General Observations. 



Answer questions 1, 5 and 6 by a drawing. 



1. What is the shape of this sponge ? 



2. Is this shape typical for all Grantiee ? Examine 



several specimens before deciding what the typical 

 shape is. 



3. What is the exact length in millimeters ? 



4. What is the average length ? Make a definite line 



at one side of the drawing showing the exact 

 average length of all the sponges measured by 

 the class. (Dem.} 



5. Observe the needle or bristle-like structures (spicules) 



projecting from the body. 



6. How do the two ends of the sponge differ? One 



end of the living sponge (proximal end) is always 

 attached to some pier, rock or such support while 

 the other end (distal end) is free. 

 13 



