Human can distinguish colors when incoming light reacts with the cone cells in the retina of eye.
There are three types of cone cells. Based on how they respond to light of wavelengths you will perceive the three basic colors; red, green and blue. The rest of the colors are perceived as a result of your brain combining the different cone cells.
Often it is claimed that women distinguish colors better than men. This is partly true since 2-3 % of women have also fourth type of cone cells instead of the normal three.
This is called tetrachromacy. A person like this can distuinguish up to 100 million different color tones.
Some people have color blindness. It is notably more common amongst the men: in research it's been found that 8 % of men are color blind as opposed to only 0,4 % of women.
color blindness is caused by lack or defectiveness of cone cells in the retina of eye.
For a color blind person some colors look misleadingly similar. The most common form of color blindness is deuteranomaly, a difficulty to distinguish red and green.
Please notice that on this page you can't test color blindness, but your ability to differiate color tones.
Birds are famous for their excellent eyesight. Their eyes can see even five basic colors and the number of different color combinations is vast.
Bees and many other insects can see ultraviolet light. That helps them to notice which plants are full of nectar and need pollination.
In most mammals' eyes there are less cone cells than in human's eyes which makes them see a smaller-scale color spectrum. Many mammals hunt at night when it's more important to distinguish shapes than colors.
Marine fish register only blue and green light. In turn, fish living in lakes and rivers see shades of red.
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