Axolotl

The axolotl (Ambystoma mexicanum) is a fully aquatic salamander native exclusively to the ancient lake complex of Xochimilco, on the southern edge of Mexico City. Unlike most amphibians, it retains its larval features throughout its adult life, a trait called neoteny, keeping its external gills, flat tail, and wide head indefinitely rather than undergoing metamorphosis. It is a top predator in its shallow, canal-based habitat, feeding on small fish, worms, crustaceans, and mollusks, and plays a stabilizing role in the food web of what remains of the Xochimilco wetland system.

The axolotl is listed as Critically Endangered on the IUCN Red List, with wild populations having declined sharply due to habitat loss, water pollution, and the introduction of non-native species, particularly tilapia and carp, which compete with and predate upon axolotls. The urban expansion of Mexico City has reduced and fragmented the network of chinampas, the traditional raised-bed agricultural islands that once supported clean, slow-moving water across a far wider area. Although the species is held in very large numbers in laboratory and captive settings worldwide, wild individuals have become genuinely scarce, with surveys conducted in the early 2020s recording densities far lower than those documented a decade prior.