Explain predation with a suitable example.

(N/A) Predation can be thought of as nature's way of transferring energy fixed by plants to higher trophic levels. When we think of predator and prey,the tiger and the deer are quite obvious examples,but the sparrow eating any seed is no less a predator.
Although animals eating plants are categorized separately as herbivores,they are not very different from predators in a broad ecological context.
Besides acting as conduits for energy transfer across trophic levels,predators play other important roles. They keep prey populations under control. In the absence of predators,prey species could achieve very high population densities and cause ecosystem instability. When certain exotic species are introduced into a geographical area,they become invasive and spread fast because the invaded land does not have its natural predators. The prickly pear cactus introduced into Australia in the early $1920$s caused havoc by spreading rapidly into millions of hectares of rangeland. Finally,the invasive cactus could be brought under control only after a cactus-feeding predator (a moth) from its natural habitat was introduced. Biological control methods adopted in agricultural pest control are based on the ability of the predator to regulate prey population.
Predators also help in maintaining species diversity in a community by reducing the intensity of competition among competing prey species. In the rocky intertidal communities of the American Pacific Coast,the starfish $Pisaster$ is an important predator. In a field experiment,when all the starfish were removed from an enclosed intertidal area,more than $10$ species of invertebrates became extinct within a year because of interspecific competition.
If a predator is too efficient and overexploits its prey,then the prey might become extinct and,following it,the predator will also become extinct for lack of food. This is the reason why predators in nature are 'prudent'.
Prey species have evolved various defenses to lessen the impact of predation. Some species of insects and frogs are cryptically coloured (camouflaged) to avoid being detected easily by the predator. Some are poisonous and therefore avoid being eaten by the predator.