Indriya in Hinduism are the sense organs in the human body and are of two types – those of mind and those of action, each consisting of five sub-types. The five buddhi-indriyas or jnanendriyas (mental or sense organs) are the eye (for sight), nose (for smell), tongue (for taste), ear (for hearing) and skin (for touch). The five karma indriyas (sense organs that are related to bodily actions) are the larynx (for speech), hands (for grasping), legs (for walking), the anus (for excretion) and genitals (for procreation).
All living beings are to be grouped according to the number of sense organs they possess. Thus micro-organisms and plants possess only the sense of touch, and worms the sense of touch and taste. Bugs have, in addition, the sense of smell. Flies and moths have also the sense of sight. Mammals, reptiles, fish and human beings have all five organs, besides mental capacity.
The five mental senses are connected also with the five basic physical elements, namely, bhumi (earth), agni (fire), jala (water), vayu (air) and akasha (space). Thus the eye group is related to the different colors of the earth and visual forms, due to the light of fire. The other mental senses are also connected in different ways with the said five elements of nature, vis., earth to smell, water to taste, air to touch, and ether to hearing.
The indriya maka a person feel a sensation and reach accordingly. It is explained that the karm indriyas are twofold, namely that of chetana-karma (thought) and that of acetana-karma (activity). Both are again of two kinds, one due to kayika karma (bodily motion) and the other due to vacika-karma (speech), leading respectively to kayika-avijnapti-karma (subconscious activity) and kayika vijnapati karma (conscious activity). The process involved here is that, corresponding to every sensation, first a latent energy is impressed in our person, termed avijnapti rupa (sub conscious state), which immediately transforms itself into its vijnapti rupa (conscious state). It is in this manner that a person actually experiences the result of the actions of sense organs.