Functional Response in Relation to Predator-Prey Interaction

Predation refers to the consumption of one organism known as the prey by another known as the predator in which the prey is alive when the predator first attacks it. Predation is beneficial to the predator and harmful to the prey. This is a broad group which covers a wide variety of interactions and numerous types of predators. For the purpose of this essay we will concentrate on classifying predators according to their individual taxonomic and functional responses.

When the predator and the prey meet they will interact with each other. Natural predators appear to regulate the numbers of prey. This brings us to a key question which this essay sets out to answer, if the number of prey increases, can the predator quickly adjust its rate of prey capture to take advantage of the situation?

Predators called prudent predators select prey of the highest quality and will switch prey when other foods become more profitable. Prudent predators show preference for the prey they consume, in order to maximise net energy gain per unit time. An important factor in predation-prey interactions is the rate at which individual predators can capture individual prey items. The response of the predator consumption rate to increases in prey density is called the functional response

Probably the simplest method of classifying predators is the taxonomic classification system. Carnivores are predators which consume animals. True predators kill their prey straight away after attacking them. During their lifetime they kill many prey. This is an takes in carnivores for example lions, snakes, seagulls and carnivorous plants. Even plankton eating large mammals, seed eating rodents and ants are included in this classification.

Grazers attack huge n...

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...w prey density. Examples include slugs feeding on grass. Handling time is the time taken to catch, kill, process, eat and digest the prey. Handling time varies with different prey types. As prey density increases finding prey becomes easy however handling the prey still takes up the same amount of time. Consumption rate reaches a maximum determined by the maximum number of handling times that can be fitted in to the total time.

Type three functional response occurs in predators which increase their search activity with increasing prey density. Initially there is a slow rise in predation rate at low prey densities then mortality increases with prey increasing density, and then declines. Examples include a fly feeding on sugar.

The graph shows the changes in the number of prey attacked per unit time by a single predator as the initial prey density is varied.