154 



SOME REACTIONS AMONG ANIMALS 



Observations. 1. By means of specimens or chart, note the different 

 kinds of individuals in a colony of bees. Are they all alike ? If not, how 

 do they differ ? 



2. Examine a paper wasp's nest or study Figure 47. Also examine a 



termite's nest, or at least 

 a Figure of one as in Thomp- 

 son's Animal Life, page 86. 

 Do these nests show evi- 

 dences of skilled work ? 

 Show if there is division of 

 labor in these communities. 



Conclusions. 1. Do the 

 individuals of these groups 

 work for the benefit of them- 

 selves solely, or mainly for 

 the good of the commu- 

 nity ? 



2. Sum up the benefits of 

 communal life to animals. 



3. Which is the most ef- 

 fective relationship of the 

 two just studied ? 



FIG. 47. Hornets' nest, opened to show 

 cells of the comb. A result of animals 

 working for the welfare of the commu- 

 nity. (After Overton.) 



c. Commensalism or 

 Symbiosis (Optional) 



Note. Many animals of 

 different kinds cooperate and 

 mutually help one another 

 and in this way are more successful in the struggle for existence. This is 

 known as commensalism or symbiosis. 



Observations. 1. Examine specimens of hermit crabs with sea anem- 

 ones on their shells. If no specimens are available, study Figures 105 

 and 106, Jordan and Kellogg, Animal Life. 



2. Many sponges are said never to be found except on the backs and 

 legs of certain crabs. Where do sponges ordinarily grow ? 



Conclusions. 1. Show how sea anemones with thousands of sting- 

 ing cells might be of advantage to crabs. 



2. Might the sea anemones be helped in any way ? 



3. Show how sponges and crabs might be mutually helpful. 



