Genetic Variations of Axolotls (Morphs)

“Morph” is an abbreviation of the term “polymorphism”. This is a word taken from ancient Greek that means “many shapes”.

To a Biologist a polymorphism is a clearly distinguishable genetic variation resulting in the occurrence of two or more different forms or types of individuals among the members of a single species. In other words, a biological polymorphism describes a situation in which there are two or more distinctly different organisms of the same species that occur naturally in significant numbers in a wild population. Each of the different forms is called a morph.

It is possible that the original, wild axolotl population had two different morphs; The melanoid gene that produces solid black axolotls existed in the wild population of Xochimilco and Chaco lagos. Unfortunately there are no records to tell us what percent of the wild axolotls were black. All we have is a few brief descriptions from the 1800s describing axolotls as black or dark brown with spots of yellow, brown, and green.

The white (leucistic) gene also existed in the wild population long ago, as did the Axanthic gene. Technically, though, these are not biological morphs, because neither of these were ever common in the wild population. There were probably several other color-influencing genes hiding in the wild populations, as well. We’ll never know now...

Axolotl breeders use the term “morph” as a replacement for the Genetics term “phenotype”. A phenotype is a description of the effect of genes on the observable traits of an organism. When we say that an axolotl is a “copper”, for example, we are describing an axolotl that has red/orange melanin (pheomelanin) rather than the usual, brown/black melanin (eumelanin). “Albino” describes an axolotl that is missing the gene that produces tyrosinase - an enzyme needed to make melanin of any kind.

In our domestic population of axolotls we recognise several different morphs that are different colors because of differences in the color-producing cells (chromatophores) in their skin, the shape of their bodies, or the number of their gill stalks.

What follows is a list of the currently recognised morphs of axolotls, with pictures at different ages, descriptions, and other information: