Getting a Tan
Tan mice are mice with the “normal” colors on their backs, and bellies the color of red mice, although there’s a lot of variation in the belly color. There are some genes that will turn the belly white, and then the mouse is called “fox”, because foxes have white bellies.
Based on the rules, you can see what happens to the belly color of a tan mouse based on what other genes it has, by looking at what happens to Red when you add the other genes. See how Red turns to Buff any time the blue gene is there? That’s why a blue tan mouse doesn’t get as red a belly as a black tan one can.
Sable mice come from combining the red gene with the tan gene. Some of these mice are just red, but if they have the right modifiers, (the Umbrous gene) they get shaded from dark on their backs to lighter on their bellies.
The Eraser Gene
We talked about the white paint, and we’ve all seen the big tank in the pet store full of identical looking white mice with pink eyes, called albinos or PEW, for Pink-Eyed-White. What makes them white? Well, there’s a bunch of funny genes that do the same kind of thing to the different paints that the pink eyed gene does. These are the genes that make albinos, chinchillas, siameses, himalayans, and the range of off-white and beige colors.
The albino mice have two albino genes, and these act like an eraser on all the other colors the mouse could have. An albino mouse could have the genes for any of the colors we’ve talked about, but you can’t see them because the albino paints over them with white. It can be hard to tell by looking, but albino mice have less color in their eyes than other mice, even the other pink-eyed ones, so they are more sensitive to light, and more uncomfortable in bright places. Snowball, the albino white mouse, is unhappy when I hold her right underneath the lamp, she likes it darker.
Shades of White
Siamese mice have two of the siamese genes, which are sort of like the albino gene with a thermometer! They look like siamese cats, with creamy light coats shading to dark noses, ears, and feet, which can be any of the normal colors. What happens with the siamese gene is, the warm parts of the mouse get less color, and the colder parts get more. Know how if it’s cold out your fingers, toes, ears and nose get colder first? Same for a mouse.
Himalayan mice have an albino gene and a siamese gene, so their bodies are white like an albino, but their ears, nose, and feet are dark like a siamese. Cool!
Chinchilla is like a special kind of albino gene that only works on the orangy paint. A mouse with the red gene and black eyes and the chinchilla gene will be a black-eyed white, which we sometimes abbreviate as BEW. And a mouse with the red gene and pink eyes will look a lot like an albino!