Prey detection is the process by which predators are able to detect and locate their prey via sensory signals. This article treats predation in its broadest sense, i.e. where one organism eats another.Predators are in an evolutionary arms race with their prey, for which advantageous mutations are constantly preserved by natural selection. In turn, predators too are subject to such selective pressure, those most successful in locating prey passing on their genes in greater number to the next generation's gene pool. Adaptations of prey that allow them to avoid predators are widespread, those that make them hard to find being collectively known as crypsis. Crypsis may involve temporal evasion such as nocturnality, behavioral methods such as hiding, and non-behavioral adaptations such as camouflage. Antipredator adaptations include methods other than crypsis, such as aposematism and the ability to fight.There are a variety of methods used to detect prey. Sensory systems used include the visual system, olfactory system (smell), auditory system (hearing) and the somatosensory system (such as touch). Some predators may use all of these senses in pinpointing their prey, while others may depend mainly or entirely on a single one. Detection methods may also be divided into direct detection of the prey organism itself, and indirect clues, such as the smell of its urine.Once a predator has found its prey it will not always attempt to chase or eat it. Prey have other ways of deterring predators from eating them besides avoiding detection. Aposematic plants and animals may have conspicuous coloration such that potential consumer such as a herbivore will avoid eating them based on unpleasant past experiences. Even if a predator may wish to eat its prey, locomotive animals may be extremely difficult to catch.