Axolots
Image Courtesy of Dr. Steven Scadding, <http://www.uoguelph.ca/zoology/devobio/210labs/regen1.html>
The axolotl (Ambystoma mexicanum) is a salamander that is indigenous to a lake beneath Mexico City. Axolotls are neotenous and retain juvenile traits throughout adulthood (such as external gills). They can be induced into adulthood in the lab if treated with thyroxine (2).
The axolotl is a very useful tool for studying regeneration. Many argue that it fulfills the August Krogh principle for research animals. The August Krogh principle states that for every research question there is a perfect species with which to test the question. The axolotl is able to regenerate from just about any non-fatel wound. While other species of salamander may have comparable regenerative capabilities, none are as easy to breed in captivity and house as axolotls. Also, axolotls have different color mutations (2,3).
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The Wild Type
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The White Mutant
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Images Courtesy of Dr. Steven Scadding, <http://www.uoguelph.ca/zoology/devobio/210labs/regen1.html>
Today 99% percent of axolotls are found in research labs. The wild populations are endangered due to the lost habitat caused by the expansion of Mexico City (3).