Aug 10, 2009
Most humans and many animals with albinism appear white or very pale; the multiple types of melanin pigment are responsible for brown, black, gray, and some yellow colorations. In some animals, especially albinistic birds and reptiles, ruddy and yellow hues or other colors may be present on the entire body or in patches (as is common among pigeons), due to the presence of other pigments unaffected by albinism such as porphyrins, pteridines and psittacins, as well as carotenoid pigments derived from the diet. Some animals are white or pale due to chromatophore (pigment cell) defects, do not lack melanin production, and have normal eyes; they are referred to as leucistic.
The eyes of an animal with albinism occasionally appear red due to the underlying retinal blood vessels showing through where there is not enough pigment to cover them. In humans this is rarely the case, as a human eye is quite large and thus produces enough pigment to lend opacity to the eye, often colouring the iris pale blue. However, there are cases in which the eyes of an albinistic person appear red or purple, depending on the amount of pigment present.
The albinistic are generally (but see related disorders below) as healthy as the rest of their species, with growth and development occurring as normal, and albinism by itself does not cause mortality (though the lack of pigment is an elevated risk for skin cancer and other problems.) Many animals with albinism lack their protective camouflage and are unable to conceal themselves from their predators or prey; the survival rate of animals with albinism in the wild is usually quite low. However the novelty of albino animals has occasionally led to their protection by groups such as the Albino Squirrel Preservation Society.