Reproduction 



63 



justed more or less to life in fresh water or on land. Many species 

 of animals tend to segregate most sharply into particular habitats 

 while breeding. Certain species of salamanders may often live to- 

 gether but when mating and spawning segregate into diiferent 

 situations (Noble, 1927). 



Fig. 9. In a Colombian swamp a snail deposits its group of eggs 

 above the surface of the water where there is an abundance of oxy- 

 gen and more or less freedom from aquatic predators. 



Animals continually seek suitable breeding sites. This leads such 

 animals as wasps and birds to resort to craggy cliffs; certain birds 

 and seals seek out barren ocean islands; and other birds fly far to 

 the Arctic barren lands. To attain proper conditions animals also 

 leave the ocean for fresh water and aquatic habitats on land. Thus 

 they secure safety, aeration, and other desiderata. The seeking of 



