A. mexicanum, also known as the Mexican Axolotl, is a long, cylindrical salamander, reaching lengths of about 30 centimeters (12 inches). A neotenic salamander, its most notable physical feature is its gills, which protrude from the back of its wide head and remain there throughout adulthood. Its legs are short. It has four fingers on each of its front legs and five toes on each of its back legs. In the wild, its coloration is dark, but an albino variety has been bred in captivity (Utah's Hogle Zoo 2003).
- Griffiths, H. I. and Thomas, D. H. (1988). ''What is the status of the Mexican Axolotl?'' British Herpetological Society Bulletin, 88, 3-5.