Pentachromat
Encyclopedia
Pentachromacy describes the capability and capacity for capturing, transmitting, processing, and perceiving five independent channels of color
information through the primary visual system. Organisms with pentachromacy are termed pentachromats. For these organisms, it would take at least five differing ranges of wavelengths along the electromagnetic spectrum to reproduce their full visual spectrum. In comparison, a combination of red, green, and blue wavelengths of light are all that is necessary to simulate most of the common human trichromat
visual spectrum.
One proposed explanation for pentachromacy is a retina
containing five diverse types of cone cell
s with differing absorption spectra. In actuality the number of cone cell types may be greater than five as different types may be active at a specific intensity or range of intensities for a given wavelength of electromagnetic radiation.
s (notably pigeons) and butterflies
have five or more kinds of color receptors in their retinae, and are therefore believed to be pentachromats, though psychophysical
evidence of functional pentachromacy is lacking. Research also indicates that some lamprey
s, members of the Petromyzontidae family, may be pentachromats. It is suspected that a human female could inherit multiple alleles for color blindness
as protanomaly, deuteranomaly, and/or tritanomaly leading to the phenotypic expression of at at least four and possibly as many as six different types of color-sensing cones, although the red-, green-, and blue-deficient cones would have degenerative spectral sensitivity.
, a renowned visual spectrum researcher at the University of Washington
, the three common types of cones in the human retina — long, medium, and short — can each distinguish approximately 100 intensities of light throughout their continuum of sensitivity within the visual spectrum. The visual cortex in the occipital lobe
of the cerebrum can multiplex these varying intensities which allows a typical human to distinguish approximately one million discrete hues. Theoretically, a pentachromat, assuming the same spectral resolution of 100 intensities for each of five cone cell types, may be capable of distinguishing up to 10 billion colors.
Color
Color or colour is the visual perceptual property corresponding in humans to the categories called red, green, blue and others. Color derives from the spectrum of light interacting in the eye with the spectral sensitivities of the light receptors...
information through the primary visual system. Organisms with pentachromacy are termed pentachromats. For these organisms, it would take at least five differing ranges of wavelengths along the electromagnetic spectrum to reproduce their full visual spectrum. In comparison, a combination of red, green, and blue wavelengths of light are all that is necessary to simulate most of the common human trichromat
Trichromat
Trichromacy or trichromaticism is the condition of possessing three independent channels for conveying color information, derived from the three different cone types...
visual spectrum.
One proposed explanation for pentachromacy is a retina
Retina
The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...
containing five diverse types of cone cell
Cone cell
Cone cells, or cones, are photoreceptor cells in the retina of the eye that are responsible for color vision; they function best in relatively bright light, as opposed to rod cells that work better in dim light. If the retina is exposed to an intense visual stimulus, a negative afterimage will be...
s with differing absorption spectra. In actuality the number of cone cell types may be greater than five as different types may be active at a specific intensity or range of intensities for a given wavelength of electromagnetic radiation.
Animals that are potentially pentachromats
Some birdBird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s (notably pigeons) and butterflies
Butterfly
A butterfly is a mainly day-flying insect of the order Lepidoptera, which includes the butterflies and moths. Like other holometabolous insects, the butterfly's life cycle consists of four parts: egg, larva, pupa and adult. Most species are diurnal. Butterflies have large, often brightly coloured...
have five or more kinds of color receptors in their retinae, and are therefore believed to be pentachromats, though psychophysical
Psychophysics
Psychophysics quantitatively investigates the relationship between physical stimuli and the sensations and perceptions they effect. Psychophysics has been described as "the scientific study of the relation between stimulus and sensation" or, more completely, as "the analysis of perceptual...
evidence of functional pentachromacy is lacking. Research also indicates that some lamprey
Lamprey
Lampreys are a family of jawless fish, whose adults are characterized by a toothed, funnel-like sucking mouth. Translated from an admixture of Latin and Greek, lamprey means stone lickers...
s, members of the Petromyzontidae family, may be pentachromats. It is suspected that a human female could inherit multiple alleles for color blindness
Color blindness
Color blindness or color vision deficiency is the inability or decreased ability to see color, or perceive color differences, under lighting conditions when color vision is not normally impaired...
as protanomaly, deuteranomaly, and/or tritanomaly leading to the phenotypic expression of at at least four and possibly as many as six different types of color-sensing cones, although the red-, green-, and blue-deficient cones would have degenerative spectral sensitivity.
Pentachromats may see up to 10 billion different colors
According to Jay NeitzJay Neitz
Jay Neitz is professor of ophthalmology and a color vision researcher at the University of Washington in Seattle, Washington in the United States.- Cone cells and the numbers of colors an organism can see :...
, a renowned visual spectrum researcher at the University of Washington
University of Washington
University of Washington is a public research university, founded in 1861 in Seattle, Washington, United States. The UW is the largest university in the Northwest and the oldest public university on the West Coast. The university has three campuses, with its largest campus in the University...
, the three common types of cones in the human retina — long, medium, and short — can each distinguish approximately 100 intensities of light throughout their continuum of sensitivity within the visual spectrum. The visual cortex in the occipital lobe
Occipital lobe
The occipital lobe is the visual processing center of the mammalian brain containing most of the anatomical region of the visual cortex. The primary visual cortex is Brodmann area 17, commonly called V1...
of the cerebrum can multiplex these varying intensities which allows a typical human to distinguish approximately one million discrete hues. Theoretically, a pentachromat, assuming the same spectral resolution of 100 intensities for each of five cone cell types, may be capable of distinguishing up to 10 billion colors.