To appreciate the possibilities and limitations of exchange of chemical information, the chemical ecologist needs to understand how the chemical senses work. There are a number of outstanding reviews and books on chemoreception per se. In addition to the general principles of chemoreception, the chemical ecologist is particularly interested in adaptations of anatomy and performance to specific abiotic and biotic conditions that optimize signal detection and maximize information gain. Here odor reception will be treated from an ecological viewpoint and only to the extent that it is an essential step in the behavior of an animal moving about in its environment and attending to vital cues. While sensory studies in the laboratory employ simple and clean stimuli, noise and the need for filtering are important factors in sensory ecology (Ali, 1978).

Encounter and exposure: orientation, sniffing, licking, tasting

The ecologist is interested in behaviors that animals employ before odor molecules even reach their chemical sense organs. Animals can manipulate the amount of odorants reaching the chemoreceptors by manipulating airflow toward the receptors, body movements, or locomotion. In its natural environment, an animal may seek or avoid stimulation by odors. Such behaviors cannot be satisfactorily addressed in the confines of laboratory studies. A foraging carnivore or herbivore exposes itself continuously to new chemical signals. Alerted by a sound or visual stimulus, an antelope or deer may turn into the wind and sniff.