Melanin is a dark pigment responsible for the dark brown to black coloration in animals. Melanism is an overproduction of the pigment melanin, resulting in animals that are entirely, or nearly, all-black. This is often a response to environmental factors.
While this Western Diamondback is unusual, this condition is not so uncommon among many species of reptiles and amphibians.
The opposite of melanistic is often referred to as albino, while the more correct term is amelanistic.
This specimen donated by Bill and Margie Montgomery.