100 ANIMAL LIFE AND SOCIAL GROWTH 



is less confusing to observe. Here, for example, 

 the animals themselves become the principal 

 element in their own immediate environment; 

 this is more truly the case for those individuals in 

 the center of dense aggregations where they are 

 literally surrounded by their fellows. 



There can be no doubt concerning the impor- 

 tance of these animal aggregations in nature; the 

 frequency of their occurrence precludes that. 

 In favorable places along the sea shore every 

 available habitat is crowded with animals as 

 tightly packed as they can penetrate a soft sub- 

 stratum or hold on to a solid one. The surface 

 waters of the ocean may be discolored for miles 

 by starfish eggs or by shoals of tiny mollusks 

 or crustaceans and a pailful of water dipped at 

 random in favorable seasons may contain more 

 jelly-like sea walnuts than water. Fresh waters 

 are notoriously poorer in animal life than is the 

 sea and yet even there suitable ponds are paved 

 with the pebble-like clusters of salamander eggs 

 in the breeding season, in the same way that 

 suitable stream habitats are crowded with fish 

 eggs. In a small stream in the Indiana dunes I 

 once studied for over five months a series of 

 aggregations of water isopods, each animal of 

 which was smaller than a honey bee, but the whole 

 mass can best be pictured by comparing it to full 



