Pentachromacy

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Pentachromacy is the condition of possessing five independent channels for conveying color information. Organisms with pentachromacy are called pentachromats. For these organisms, the perceptual effect of any arbitrarily chosen light from its visible spectrum can be matched by a mixture of no more than five different pure spectral lights.

The normal explanation of pentachromacy is that the organism's retina contains five types of cone cells with different absorption spectra. In practice the number of such receptor types may be greater than five, since different types may be active at different light intensities.

Animals that are pentachromats

Some birds (notably pigeons) and butterflies have five or more kinds of color receptors in their retinae, and are therefore believed to be pentachromats,^[1] though psychophysical evidence of functional pentachromacy is not easy to come by. Lampreys may also be pentachromats.^[2] As with tetrachromacy, it is suggested that women carriers of genes for both mild forms of color blindness, deuteranomaly and protanomaly, are born with five different types of color-sensing cones though the red- and green-deficient cones are later lost.

Pentachromats are capable of seeing 10 billion different colors

According to Jay Neitz, a renowned color vision researcher at the Medical College of Wisconsin, each of the three standard color-detecting cones in the retina – blue, green and red -- can pick up about 100 different gradations of color. But the brain can combine those variations exponentially, multiplying each new variety of cone by 100, so that the average human can distinguish about one million different hues. ^[3] Therefore, a pentachromat would be capable of distinguishing 10 billion different colors. ^[4]

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