100 



ECOLOGY 



Part II 



protozoans, roundworms, and flatworms are deeply committed to parasitism. 

 Among parasitic arthropods the insects are best known, such as fleas, lice, bed- 

 bugs. They are transmitters of disease-producing parasites and are themselves 

 in the earlier stages of parashism. 



The life cycles of various parasites are described and figured in Part IV with 

 the groups to which they belong. The accompanying list shows the occurrence 

 of some important animal parasites of man (Table 6.1). 



Table 6.1 

 Some Important Parasites of Man 



Animal Communities 



Organization of Groups. Aggregation is a general term for a group of 

 organisms of the same or different species, associated but not organized into 

 societies. Many of them are examples of natural cooperation and as such were 

 cited at the beginning of this chapter in connection with cooperation. Un- 

 organized groups like these were doubtless the beginnings of complex societies 

 such as those of ants and termites. Animals congregate because their environ- 



