Axolotl

The axolotl (Ambystoma mexicanum) is a neotenic ambystomatid salamander endemic to the Xochimilco and Chalco lake system of the Valley of Mexico near 2,240–2,290 m; Chalco has been drained and the remaining habitat is canal and wetland. Adults reach 15–30 cm, mostly about 23 cm, retaining three pairs of feathery external gills because thyroid output is insufficient for metamorphosis. Wild animals are brownish with gold spotting, and the species regenerates limbs, tail, heart and parts of the brain. The IUCN assessed it as Critically Endangered in 2020; only 50–1,000 wild adults remain.