axolotl

The axolotl, Ambystoma mexicanum, is a paedomorphic salamander related to the tiger salamander. The species was originally found in several lakes, such as Lake Xochimilco underlying Mexico City. Axolotls are unusual among amphibians in that they reach adulthood without undergoing metamorphosis. Instead of taking to the land, adults remain aquatic and gilled. Axolotls should not be confused with the larval stage of closely related tiger salamander species, which are widespread in much of North America and occasionally become paedomorphic. Neither should they be confused with mudpuppies, fully aquatic salamanders from a different family that are not closely related to the axolotl but bear a superficial resemblance. As of 2020, wild axolotls were near extinction due to urbanization in Mexico City and consequent water pollution, as well as the introduction of invasive species such as tilapia and perch.