All organisms need energy to survive. Gazelles, for example, are herbivores that feed on vegetation, while cheetahs are carnivores that consume gazelles. This type of interaction is called predation, where one organism, the predator, gains energy by consuming another organism, the prey.

A predator's acute senses, such as sight, smell, and hearing, enable them to detect prey. Specialized physical features, such as teeth or claws, facilitate the capture and consumption of prey.

Routine predator-prey interactions cause prey to evolve traits that allow them to escape detection or capture.

For example, most birds evolved exceptional eyesight, including color vision, to hunt prey. A defense known as crypsis allows prey to avoid visual detection by blending in with their environment. Larva and adult peppered moths, for instance, evolved body and wing colorings that closely match their host trees' branches and bark.

Rather than hide, monarch butterflies advertise their toxicity with ornate, brightly-colored wings. Such warning coloration, or aposematism, acts as a prey's visual cue to predators that it is hazardous or inedible. Monarch caterpillars ingest milkweed, which makes them toxic as adults. Birds that ignore the monarch's warning experience its bad taste or become nauseous and avoid future contact.

When a species' aposematism is effective, other species that share the same predators may evolve to copy, or mimic, that coloration.

Mullerian mimicry occurs when harmful species with similar aposematic appearances share the costs of predator education. Viceroy butterflies, for example, are toxic and closely mimic the monarch's appearance. Predators that try one species learn to avoid the other, rather than risk another unpleasant feeding experience.

Alternatively, Batesian mimicry occurs when a harmless species mimics a harmful species. Predators typically steer clear of the bright, tricolor, banded pattern observed on venomous coral snakes. Non-venomous king snakes exploit this by mimicking the coral snake's appearance.

Predator-prey interactions resemble an arms race. As prey evolve to avoid predation, predators evolve in response, like the cheetah's enhanced speed to better capture prey. Such reciprocal natural selection between interacting species is known as coevolution.