All About Albinism
Animals that are white instead of their normal color quickly capture our attention and imagination. Albinos are rare, but common enough that almost everyone has seen one, or knows someone that has.
Albinos have the characteristics of other members of their species, except that their cells are unable to produce melanin, a dark pigment that results in normal coloration in the skin, scales, eyes or hair. A lack of melanin usually causes an animal—or parts of an animal—to appear white or pink, or to have a bleached look.
Animals can be pure or partial albinos. Pure albinos usually have pink eyes, nails, scales and skin. They're pink because, without coloration, the blood vessels show through. In humans and some other animals, the eyes of an albino are light blue or green because of the way light passes through the iris.
Partial albinos have some of the coloration typical of their species, but parts of their body appear white. Piebald deer, which have splotches of white on their fur as adults, are a good example. Many red-winged blackbirds have a partially white wing, and partial albino raccoons will have a white patch on their fur.
Being white doesn't make an animal an albino. The true test is whether it has pink or light blue eyes.
Leucistic animals have mostly white skin, hair or scales, but will have some dark pigmentation in their eyes and nails. Though leucistic animals are not as rare as true albino animals, many are displayed at zoos.
An Inherited Trait
Albinism is passed genetically from parents to offspring. Each cell contains numerous pairs of genes, one from each parent. These genes transmit traits through generations. An albino offspring results from a specific combination of genes.
Albinos are infrequent because the genes for that trait are recessive, while the genes for normal pigmentation are dominant. If both are present, normal pigmentation occurs. If only recessive genes occur, albinism may result. Only a small percentage of animals carry the recessive gene, so the chance of the pairing of recessive genes in an individual animal is slight.
In humans, for example, about one in 70 people carry a recessive gene for albinism, and about one in 20,000 humans are albinos.
At least 300 species of animals in North America have albino individuals. In Missouri, people have photographed or witnessed albinism in turtles, catfish, salamanders, deer, frogs, snakes, bluebirds and raccoons.
The degree of albinism varies among animal groups. Some researchers working with