The Phenomenon of Predation^ 



By THE LATE PaUL L. ErRINGTON 



"Nature's way is ant way that works." My students know I like 

 that expression. As a generalization relating to the opportunism 

 and adjustment of Life, relating to the eaters and the eaten, it covers 

 the field. 



Predators kill and eat the animals they know as prey, however they 

 are able to do so. They prey according to their opportunities, their 

 adaptations, and — sometimes — their psychological preferences. Their 

 predation may be rather indiscriminate, that is, within common sense 

 limitations. It may be highly specific, highly selective. It may grade 

 into the related phenomenon that we refer to as parasitism. When the 

 prey consists of eggs or sessile animals, it may not differ fundamentally 

 in its operation from grazing by herbivores. 



For that matter, certain peculiarly adapted plants may prey upon 

 animals. Bladderworts capture and digest small crustaceans in their 

 traplike organs. Pitcher plants and sundews take insect victims as a 

 regular way of life. And, whether one thinks of bacteria or viruses as 

 being predatory or parasitic or saprophytic, the basic natural laws to 

 which they conform in their exploitation of the exploitable are still 

 those applying to the phylogenetically higher organisms. 



The common denominator throughout is exploitation of the exploit- 

 able ; but, if we think of just that in considering the phenomenon of 

 predation, we may easily oversimplify. For there has been a lot of 

 evolution shaping the patterns of interrelationships of living things 

 with each other and with their physical environments. Diversity and 

 complexity in these interrelationships are wholly consistent with 

 diversity and complexity in the forms of living things. 



I do not advocate straining to distinguish between borderline cases of 

 predation and parasitism, or trying to judge precisely where predation 

 and parasitism leave off and exploitation of dead or dying organic 

 material begins. Preoccupation with definitions in relationships that 

 by their nature have much leeway in them can, I think, defeat under- 



* Reprinted by permission from American Scientistj June 1963. 



766-746—65 41 507 



