IMG Boa Constrictors
A boa constrictor IMG looks like a normal boa at birth. It darkens into a near-solid black animal over several years. Every snake settles into a shade between true black and deep charcoal. Because it keeps changing for years, the adult you end up with is not the same as the hatchling you buy.
About the IMG gene
The IMG boa constrictor gene produces more black pigment as the animal gets older. In 2007, Peter Kahl proved it was genetic after seeing a Colombian boa. This anerythristic snake was strikingly dark and stood out from her litter. You are buying a colour project when you buy one because the colour it shows in its first year is not its final look.
Appearance
A normal boa looks similar to an IMG hatchling, which only has a bit more black pigment. This pigment builds with every shed. By the time it is an adult, the animal is close to solid black with a tail as dark as the body. The speed and how dark an individual gets varies from snake to snake.
Genetics
The IMG gene is dominant. Because one copy produces the darkening, a boa with IMG paired to a normal boa will still produce darkened offspring. The homozygous Super IMG results from two copies. There are no known related traits and no known allelic complex for IMG. Breeders have put it into designer combinations with other boa genes, including Hypo. Kahl first produced it in 2007 from a litter of anerythristic Colombian boas.