Animals in Therapy | Deep Dive

Anyone spare a leg?

Imagine being able to regenerate yourself. Not just an arm or a leg, but your broken heart – even parts of your brain. It’s not a skill that we humans have harnessed yet, but if you were an axolotl, you could. These amazing amphibians, with a genome 10 times bigger than ours, can regrow themselves. Feet, legs, eyes, spinal cord.      

They have even survived head transplants – not something we condone. 

And if it isn’t too much information, this mind-blowing ability comes in handy after someone’s snacked on you, as carnivorous axolotl siblings sometimes do. Ouch!

Stuff of legend

You may already be familiar with the axolotl, whose name is sometimes translated as ‘water dog’; it’s inspired Mexican memes, emojis and characters in video games. Known scientifically as Ambystoma mexicanum, the axolotl once saved the Aztec god of fire and lightning, Xolotl. To avoid being sacrificed, the myth goes, he transformed himself into a salamander.

It’s this idea of transformation, or metamorphosis, that’s especially significant.


Peter Pan of animals

Because while axolotls grow – up to 12 inches – they don’t lose their baby features. Like humans, axolotls are blessed – or cursed – with a condition called neoteny. Although they mature sexually, axolotls don’t physically develop beyond their larval stage. 

Instead, just as humans keep their youthful flat faces into adulthood, axolotls retain their feathery gills, finned tails, and aquatic lifestyles all through their 10-to-15-year lives. In other words, they don’t metamorphose into lung-breathing terrestrials as other salamanders do.

If you haven’t already realized it, this regenerative power and axolotl’s living embodiment of the human fantasy of eternal youth, makes them, well, enormously interesting. To the planet’s dominant species, that is. It means that as well as being strangely exotic, hardy and universally popular pets who never lose their baby-faced cuteness, axolotls have long been objects of scientific fascination and study.

Salamanders everywhere?

In fact, they’re the oldest population of self-sufficient science lab ‘rats’, and probably one of the most inbred. What’s more, like Amur leopards, Chinese giant salamanders and Spix’s macaws, more of them now live, and are bred, in captivity than in the wild. 

Which means that captive axolotls are everywhere. In Japan, confined specimens are so common you can order them deep-fried in restaurants to munch on! But outside of laboratories and restaurants, pet shops and home aquariums, these forever-young salamanders are Critically Endangered.

Numbers nosedive

Native to Xochimilco, today a district in the south of Mexico City, these amphibians with Mona Lisa smiles and permeable skin have had a lot thrown at them. Loss of their one-and-only lake habitat as the city grew; heaps of toxic pollution; and non-native newcomers who turned out to be predators have all wreaked havoc on their numbers. 

Between 1998 and 2015, wild axolotls making their homes in the canals and remaining swampy areas of Xochimilco saw their population drop, drastically. From about 6,000 forever-youngsters per square kilometer (0.4 square miles), to closer to 35. Luis Zambrano, professor at the National Autonomous University of Mexico in Mexico City, who has recorded this decline, thinks there may be fewer than 500 left. 

Save axolotls from extinction

Thankfully, the axolotl is currently protected by the Government of Mexico, and that’s important. So, too, is the work of Zambrano and other biologists who are trying to help wild axolotls by breeding them. The young are released into control ponds and canals in Xochimilco. This way, they hope to preserve at least some of the creature’s genetic diversity.

For the first time in 2022, 12 axolotls were reintroduced to newly restored wild habitats. The aim is to rewild 40 within Xochimilco by the year’s end. But more needs to be done to increase awareness of these exceptional amphibians and act against the threats facing them. We need a better understanding of the population that remains. 

If you feel strongly about this astonishing species, please repost this video or infographic. You can learn more by signing up to our newsletter and checking out organizations that we think are doing a great job:

  • Click here to sign up to our On the Edge newsletter. Once a month we’ll send you remarkable stories about endangered species and the natural world. 

  • Moja  is an environmental organisation which promotes the conservation of the axolotl and its habitat through setting up a conservation centre in Xochimilco.

  • Organizers of the Help Save the Axolotl Care2 petition want the Mexican Government to do more to clean up Lake Xochimilco. 

  • Conservación de Anfibios is a Mexican non-profit dedicated to protecting native and endangered amphibians, including EDGE salamanders related to the axolotl. Its work is supported by On the Edge, via an EDGE Fellowship from the Zoological Society of London.