Consider, for instance, the complex social hunting behavior of lions and wolves the long sticky tongues and accurate aim of some fish, toads, and certain lizards the folding fangs and venom-injection apparatus of viperine snakes spiders and their webs the deep-sea angler fish and snakes such as boas that suffocate their prey by constriction. Long-term evolutionary escalations of this sort have resulted in some rather intricate and often exceedingly complex adaptations. Hence, in the evolution of a prey-predator relationship, the prey evolves so as to dissociate itself from the interaction while the predator continually maintains the relationship. Obviously, these two selective forces oppose one another as the prey become more adept at escaping from their predators, the predators in turn evolve more efficient mechanisms for capturing them. Thus, selection on the prey population favors new adaptations that allow prey individuals to avoid being found, caught, and eaten. However, members of the prey population that are better able to escape predators should normally be at a selective advantage within the prey population. Hence, natural selection acting on the predator population tends to increase the predator's efficiency at finding, capturing, and eating its prey. Individual predators that are better able to capture prey should have more resources at their disposal and should therefore normally be more fit than those that are less proficient at capturing prey.

In contrast, competition is a symmetric process in that both species are affected adversely and, where possible, each tends to evolve mechanisms whereby the relationship with the other is avoided. It is directional in the sense that one member of the pair (the predator) benefits from the association while the other (the prey) is affected adversely. Predation is often readily observed and easily studied, and neither its existence nor its importance in nature is doubted.

Predator vs prey animal pairs