Critically Endangered
Axolotl
Ambystoma mexicanum
Axolotl is a salamander in the family Ambystomatidae (order Caudata) — Ambystoma mexicanum, recorded as Critically Endangered.
Appearance
Axolotls still show the usual traits of salamander larvae, among them external gills and a caudal fin extending from behind the head to the vent. Three pairs of external gill stalks (rami) originate from behind the head and are used to move oxygenated water. Four gill slits lined with gill rakers are hidden underneath the external gills, that prevent food from entering and allow particles to filter through.
A sexually mature adult Axolotl, at age 18–27 months, measures 15 to 45 cm (6 to 18 in). A size close to 23 cm (9 in) is most common, and any greater than 30 cm (12 in) is rare.
Published measurements include mass about 8 and length about 18.
Range and habitat
Wild axolotls lived in linked highland lakes and wetlands in Mexico. Those lakes were drained — first under the Aztecs, then faster in the twentieth century — and most of that water is now Mexico City.
Pins are Wikidata “endemic to” fields. Orange dots, when present, are GBIF occurrence tiles — survey bias included.
Life history
It stays larval into adulthood — sexually mature without metamorphosis, and adults stay in water and keep their external gills. Axolotls can be hard to tell from the larval stage of other neotenic adult mole salamanders, especially the tiger salamander, or other species such as mudpuppies.
A large captive stock exists; labs keep them because they can regrow limbs, gills, and parts of the eye and brain.
In crisis
Wild axolotls were driven close to extinction after people released tilapia and carp; with a wild population now around 50 to 1,000 adult individuals, IUCN lists it as Critically Endangered; CITES lists it on Appendix II. A population of Ambystoma inhabiting the artificial lake at Chapultepec still holds axolotls. As of 23 October 2019, the extent of occurrence was 467 square kilometres (180 sq mi). Surveys in 1998, 2003, and 2008 counted about 6,000, 1,000, and 100 axolotls per square kilometer, respectively, in Lake Xochimilco.
This can be dangerous for the remaining population, as it causes increased inbreeding and reduced fitness and adaptive potential. The detection of introgressed tiger salamander (A. Tigrinum) DNA in the laboratory Axolotl population raises concerns about the suitability of the captive population as an "ark" for potential reintroduction purposes.
Salamanders disappear when seeps are capped, caves are disturbed, or a pathogen moves through a mountain range.
Axolotl is Critically Endangered on this catalog because that is the IUCN category stored on Wikidata. Confirm the official criteria and any later count on iucnredlist.org.
Sources
Written for this catalog from the English Wikipedia article on Axolotl, Wikidata item Q22718. Family and order context is original field-guide writing about the group, not a copied assessment of this one species. Wikipedia text is CC BY-SA. Not an IUCN assessment. Counts, when quoted, can change — confirm them on the recovery programme and on iucnredlist.org.
