the Mexican axolotl salamander has the rare trait of retaining its larval features throughout its adult life. This condition means it keeps its tadpole-like dorsal fin, which runs almost the length of its body, and its feathery external gills, which protrude from the back of its wide head.
Found exclusively in the lake complex of Xochimilco near Mexico City, axolotls differ from most other salamanders in that they live permanently in water. In extremely rare cases, an axolotl will progress to maturity and emerge from the water, but by and large, they are content to stay on the bottom of Xochimilco’s lakes and canals.
Close relatives of the tiger salamander, axolotls can be quite large, reaching up to a foot (30 centimeters) in length, although the average size is closer to half that. They are typically black or mottled brown, but albino and white varieties are somewhat common, particularly among captive specimens.