# Axolotl — Facts, Threats & Conservation

*Ambystoma mexicanum*

> An axolotl (Ambystoma mexicanum) is a neotenic salamander from the Xochimilco canals near Mexico City that stays aquatic and larval-looking for life, keeping external gills. Famous for regenerating limbs, organs and brain tissue, it is Critically Endangered in the wild yet common in captivity.

**IUCN status:** Critically Endangered (IUCN, 2020) in the wild  ·  **WARN range:** Mexico

## Quick facts
| Fact | Value |
| --- | --- |
| Scientific name | Ambystoma mexicanum |
| Common name | Axolotl (Mexican walking fish, though it is not a fish) |
| Size | Typically ~23 cm; range about 15-45 cm |
| Lifespan | Around 10-15 years |
| Diet | Carnivore: worms, insects, crustaceans, molluscs, small fish |
| Habitat | Freshwater canals and wetlands |
| Range | Xochimilco, Mexico City (historically also Lake Chalco) |
| Reproduction | Egg-laying; females can lay hundreds of eggs per clutch |
| Notable trait | Neoteny; regenerates limbs, organs and brain tissue |
| CITES | Appendix II |

## Scientific classification
- **Kingdom:** Animalia
- **Phylum:** Chordata
- **Class:** Amphibia
- **Order:** Urodela (Caudata)
- **Family:** Ambystomatidae
- **Genus:** Ambystoma
- **Species:** Ambystoma mexicanum

## Conservation status
- **Status:** Critically Endangered in the wild (IUCN Red List). Abundant in captivity, but its only natural population, in the Xochimilco canals near Mexico City, has collapsed to perhaps a few hundred or fewer individuals, with some surveys finding almost none.
- **Population:** Fewer than ~1,000 mature individuals in the wild (estimates vary; some surveys find very few)
- **Trend:** Decreasing
- **Assessed:** 2020
- **CITES:** Appendix II
- Threatened by urbanisation, water pollution, drainage of wetlands and invasive fish such as tilapia and carp. Conservation focuses on water-quality improvement, invasive-fish-free refuges and traditional chinampa farming in Xochimilco.

## Key facts: Axolotl
- The axolotl is a salamander that stays aquatic and larval-looking for life, a trait called neoteny.
- It is native only to the Xochimilco canal system near Mexico City, historically also Lake Chalco.
- It can regenerate limbs, parts of the heart, spinal cord and even brain tissue, making it a key research animal.
- It is Critically Endangered in the wild yet abundant in captivity, a stark conservation paradox.
- Its main threats are urbanisation, water pollution and invasive fish such as tilapia and carp.
- It is listed on CITES Appendix II, regulating international trade.

## What makes the axolotl unique
The axolotl's defining feature is neoteny: it reaches sexual maturity and reproduces while retaining the body of a larva. Where most salamanders absorb their gills, climb onto land and breathe air as adults, the axolotl keeps its three pairs of feathery external gills, its broad tail fin and its fully aquatic lifestyle throughout its roughly 10-to-15-year life. Most individuals stop developing because their bodies produce very little thyroid hormone, the chemical signal that normally triggers metamorphosis. Wild axolotls are usually dark and mottled, providing camouflage among canal sediment and plants. The pale pink and white animals familiar from aquariums and photographs are largely the result of captive breeding for leucistic and albino colour forms, which are rare or absent in the wild. Adults most commonly measure around 23 cm long, though sizes from roughly 15 to 45 cm are recorded. Their permanently upturned mouths give them a distinctive smiling appearance that has made them a global internet and pop-culture icon.

## Regeneration and scientific importance
The axolotl is one of the most studied animals in regenerative biology. It can regrow entire amputated limbs, complete with bone, muscle, nerves and skin, in a matter of weeks, and it can repair its heart, spinal cord, retina and parts of its brain rather than forming scar tissue. After injury, cells near the wound form a structure called a blastema, which rebuilds the missing part in the correct shape and orientation. Researchers study this process to understand why mammals, including humans, cannot regenerate in the same way. The axolotl has also become important in developmental biology, cancer resistance research and tissue-engineering studies. Its genome is enormous, around 32 billion base pairs, roughly ten times the size of the human genome and one of the largest animal genomes ever sequenced. Because the species breeds readily in captivity and tolerates laboratory conditions well, hundreds of thousands of axolotls now live in research facilities and homes worldwide, descended largely from a small number of founder animals.

## The wild axolotl in peril
The contrast between the captive and wild axolotl is dramatic. In its only natural home, the canals and wetlands of Xochimilco on the southern edge of Mexico City, the species has collapsed. Surveys over recent decades have recorded sharp declines, and some find almost no animals at all; estimates suggest only a few hundred or fewer remain in the wild, leading the IUCN to list it as Critically Endangered. The causes are tied to the growth of one of the world's largest urban areas. Wetlands have been drained and built over, and remaining waterways suffer from sewage, agricultural run-off and pollution. Invasive fish introduced for food and the aquarium trade, particularly tilapia and carp, eat axolotl eggs and young and compete for food. Restoration efforts in Xochimilco focus on improving water quality, creating refuges free of invasive fish and working with local chinampa farmers who maintain the area's traditional floating gardens, on which the canals depend.

## Axolotl vs typical salamander
| Feature | Axolotl | Typical salamander (e.g. tiger salamander) |
| --- | --- | --- |
| Adult form | Stays larval and aquatic (neoteny) | Metamorphoses into land-dwelling adult |
| Gills | Keeps external feathery gills for life | Loses gills, breathes with lungs/skin |
| Habitat as adult | Fully aquatic | Often terrestrial or semi-aquatic |
| Regeneration | Exceptional: limbs, heart, spinal cord, brain | Limited |
| Conservation | Critically Endangered in the wild | Varies; many species Least Concern |

## What WARN does
WARN does not currently run a dedicated field project for the axolotl, which lives only in a small area of central Mexico, outside WARN's five partner countries. This guide is part of WARN's free educational and awareness work, helping people understand a species whose wild survival hangs in the balance. The same pressures that threaten the axolotl, habitat loss, water pollution and invasive species, also harm the wetland and freshwater animals WARN does protect elsewhere.

If you value clear, science-based wildlife guides like this one, a small gift helps fund WARN's habitat and freshwater conservation work for animals facing the very same threats.

## Frequently asked questions: Axolotl
### Are axolotls endangered?
Yes. The IUCN lists the axolotl as Critically Endangered in the wild, where it survives only in the Xochimilco canal system near Mexico City. Estimates suggest just a few hundred or fewer remain, and some surveys find almost none. This is despite the species being extremely common in captivity, where hundreds of thousands live in labs, classrooms and home aquariums.

### Can axolotls really regrow their limbs?
Yes. Axolotls can regenerate entire amputated limbs, complete with bone, muscle, nerves and skin, usually within weeks. They can also repair the heart, spinal cord, retina and even parts of the brain without scarring. After injury, cells gather into a structure called a blastema that rebuilds the missing tissue. This rare ability makes the axolotl a key animal in regenerative medicine research.

### Why do axolotls stay babies their whole lives?
Axolotls show neoteny, meaning they keep larval features and stay aquatic for life instead of metamorphosing into land-dwelling adults like most salamanders. This happens because their bodies produce very little thyroid hormone, the signal that normally triggers metamorphosis. They keep their feathery external gills and tail fin yet still become sexually mature and breed in this larval-looking form.

### Where do axolotls live in the wild?
Axolotls are native only to the canal and wetland system of Xochimilco on the southern edge of Mexico City, and historically to the now largely drained Lake Chalco. This single, shrinking habitat is the reason the species is so vulnerable: as Mexico City has expanded, the wetlands have been polluted, drained and invaded by non-native fish, leaving very little suitable habitat.

### What do axolotls eat?
Axolotls are carnivores. In the wild they eat small prey such as worms, insects, insect larvae, small crustaceans, molluscs and tiny fish, sucking them in with a rapid gulp. In captivity they are commonly fed earthworms, bloodworms and specially formulated pellets. Their permanently larval anatomy means they hunt entirely underwater, detecting prey by movement and smell.

### What is the difference between an axolotl and a salamander?
An axolotl is a salamander, specifically a species in the mole salamander family. The key difference is that most salamanders metamorphose into terrestrial adults, losing their gills and living partly on land. The axolotl does not: through neoteny it keeps its gills, tail fin and aquatic lifestyle for life. Its close relative, the tiger salamander, does undergo full metamorphosis.

## Sources
- [Axolotl - Wikipedia](https://en.wikipedia.org/wiki/Axolotl)
- [IUCN Red List: Ambystoma mexicanum](https://www.iucnredlist.org/species/1095/53947343)
- [CITES Appendix II listing](https://cites.org/eng/app/appendices.php)
- [Encyclopaedia Britannica — Axolotl](https://www.britannica.com/animal/axolotl)
- [National Geographic: Axolotl](https://www.nationalgeographic.com/animals/amphibians/facts/axolotl)

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Full guide: https://worldanimalrescuenetwork.org/wildlife-guides/axolotl