If you’ve spent any time on the internet or spoken to a child in the last decade, you’ve probably heard of Minecraft.

It’s literally the best-selling video game, ever. Back in October of 2020, the team at Minecraft announced  that as part of a new update, they’d be adding an obscure salamander  to the game called an axolotl.

Now if you’re the kind of  nerd who watches scishow, you may have known about these  critters before they were cool.. But at the time, not many  people had heard of them. So adding axolotls to the game  was what introduced them to, probably, millions of people.

Especially that all-important youth market. By 2021, the axolotl was an internet icon. And you can see why, right?  I mean, look at that face.

Not only that, but axolotls  can do some really cool things. Like, regenerating their arms, and legs, and even parts of their brains. These extraordinary abilities have made  axolotls popular with researchers, too.

Western science has had its eyes  on axolotls since the 1700s, waaay before it was cool. And in that time, they’ve helped us understand everything from spinal injuries to embryonic development. Today, some scientists hope that these  little pink weirdos, complimentary, could also help us explore new medical frontiers.

Like, slow down aging, fight cancer, and maybe help us regrow an arm or two. Here’s the origin story of the humble axolotl, how it became the key to all  kinds of crucial research, and why the species needs our help in return. [ intro music ] Axolotls are pretty much everywhere these days. Or at least, their merch is everywhere.

You can find them on  everything from mugs to money. Heck, the script writer for this  episode saw an axolotl plushie, a bookbag, and a statue  while working on this script. Before they became ubiquitous, though, all axolotls lived around Lake Texcoco in Mexico.

Axolotls are amphibians,  specifically a type of salamander, that probably evolved roughly 10,000 years ago. For centuries, humans and  axolotls lived side-by-side. The Mexica people, or Aztecs  as the Europeans called them, built their city and farming islands on the lake.

These so-called floating islands, or chinampas, had extensive canals running between them. And the canals happened to be  the perfect habitat for axolotls. By the way, the name axolotl is pronounced  more like “ash-uu-lots” in Nahuatl, the language of several Indigenous  groups from Central Mexico.

For now we’re gonna stick with the  anglicized pronunciation of axolotl but , whatever you call them They were so abundant in the Valley of Mexico that they were a favorite food  of the people living in the area. Minecraft devs if you’re listening, you  could have that historically accurate feature Just saying But then, as most stories go in  Latin America, the Spanish came. Today, Lake Texcoco doesn’t really exist anymore.

It’s been drained and drilled over the years to make space for the ever-expanding Mexico City. And, all axolotls that live in the wild are in or near the Xochimilco floating gardens, consisting of just 170 kilometers of canals. So there’s not a whole lot of axolotls  left in their natural habitat, because there’s not a whole lot  of natural habitat to speak of.

In 1998, a study estimated that there were around 6,000 axolotls  per square kilometer in the canals. Today, that number is more like 35, at least according to one study, which would mean that there are only an estimated 50 to 1,000 axolotls left. But if that’s the case, then why  did I see one in a cafe in scotland? why does everyone’s next door  neighbor seem to own one as a pet?

Well, while there might not be a whole  lot of axolotls left in the wild, there are a lot of them being  bred in labs all over the world. But before we get into all that, all research needs funding, including ours. So here’s a quick ad break!

I’m interrupting this online learning experience to tell you about a totally new  kind of online learning experience. Introducing the new Brilliant! It’s coding instruction for the AI era.  Brilliant still fits into your life and  gives everyone the tools to be a math person.  But now, they’re offering even more.

In this new era of Brilliant,  a visual interactive tutor sits  right on the screen with you.  It can see what you’re doing, draw  diagrams, ask guiding questions,  and adapt in real time to how you think. It makes private tutors more accessible. Click the link below or scan the QR code to  get started with Brilliant’s tutor for free.

You can upgrade to Premium to unlock all courses. And right now, SciShow viewers can  save 20% off an annual subscription at brilliant.org/scishow. Axolotls first got a webbed foothold in  scientific laboratories in the 1800s.

And in 1864, a French expedition  to Mexico captured 34 axolotls, brought them back to Europe and bred them. Today, almost all captive axolotls  are descended from that 1864 crew. And western scientists have been  enamoured with the axolotl ever since, because they're pretty weird as far as  amphibians, or even vertebrates, go.

For one thing, they never really  grow up, at least not all the way. Most amphibians go through a standard life cycle where they start as eggs, turn into tadpole-like-things, and eventually transform into land-based animals. Think, frogs.

Axolotls don’t do this, or at least, most don’t. For whatever reason, the species is neotenic, meaning they never metamorphose into  an adult terrestrial form. Instead, they stick to a comparatively juvenile state where they have arms and legs, and can reproduce, but they hold on to their gills.

That’s why they’re so cute. They’re practically babies! Look at those gills!

Weirdly enough, this whole forever-young-thing helped scientists discover  what thyroid hormones do. In 1919, British scientists fed two  axolotls pieces of an ox thyroid. Which made perfect sense at the time.

The axolotls that ate the thyroid  went through metamorphosis – losing their gills, changing color, and becoming fully land-compatible. Thanks in part to these experiments, we now know that thyroid hormones are essential for metamorphosis in amphibians. And we now know that thyroid hormones  are important in human development, too.

For instance, some help with  fetal brain development. Axolotls have also been essential  for studying embryonic development. Axolotl eggs are up to 30  times bigger than human eggs, so scientists can see what's  going on in there pretty easily, making them great model organisms for studying.

From the 1920s through 1950s, research on developing axolotls  helped scientists investigate things like neural crest cells, which are a group of cells in embryos that later become everything  from cartilage to neurons. And of course, there’s the fact  that axolotls can regrow body parts. That’s not entirely unique in the animal kingdom.

Invertebrates like seastars can regrow their arms, and certain species of worms can  regrow just about everything. Some vertebrates can do this too,  though to a more limited degree. Think, lizards that regrow tails.

Even humans and mice can regenerate  the very tip of amputated fingers, but mostly when we’re babies. But for most vertebrates, healing  involves fixing what you can, like bones, and then making  everything else into scar tissue. Axolotls, on the other hand, can more  or less regrow whatever they want.

Scientists have found that axolotls can regenerate their hearts, spinal cords, parts of their brain, and of course, their arms and legs. A young axolotl can fully regrow  an amputated arm in just 45 days. Most research around regeneration in axolotls has focused around blastemas, basically the nub that forms  when an axolotl loses a limb.

By studying this, researchers have discovered that a chemical called transforming growth  factor beta is essential to regeneration. What’s cool about that is that  we have that growth factor too. So if axolotls can regenerate their  body parts thanks to that growth factor, and we can make it too, can we figure  out how to use it to regrow our limbs?

Maybe. Axolotls aren’t that different from us. They are vertebrates and they do seem to have at least some similar genes and chemical pathways, so it’s not like we’d be  starting at the ground floor.

But any real movement on the  whole grow-back-your-arm front is definitely a ways off. But that doesn’t mean that studying this stuff can’t be helpful in the short term. Regeneration science could also help  us deal with the stress of aging.

Take our immune system. Most of our body systems get  less effective as we age. One of the things that  suffers is our immune system, in part because our bodies get  less good at producing T-cells.

These cells are made from stem cells  that are formed in the bone marrow and mature in the thymus, a gland  that sits in the middle of the chest, behind your sternum. In 2025, researchers discovered that axolotls can actually regrow their entire thymus gland. By learning how axolotls do this, researchers hope to hack into our thymus and keep it pumping out that  immune juice even as we get older.

And it's not just regeneration that  makes axolotls biological superstars. Research suggests that axolotls  might be extra resistant to cancer. And in a 2025 paper, scientists discussed how they’d tried to find out how axolotls do this, in exactly the way you’re thinking.

By say it with me, ‘gently massaging’ their skin and then scraping off their mucus.” Statistically at least one person  out there said that with me. From this, the team found three  promising immunity molecules called antimicrobial peptides, or AMPS. Not only could these AMPS fend off  breast cancer cells in a petri plate, but they also inhibited the growth of MRSA, an antibiotic-resistant staph bacteria  that causes major issues in hospitals.

That means that not only  axolotls help us fight cancer, but they could give us a  whole new set of antibiotics. They really are the GOAT of the amphibian world. Or, they would be, if they weren’t in trouble.

Remember how those captive axolotls are descended from something like 34  individuals from the 19th century? Well, because of that they’re pretty inbred now. Captive axolotls have an  inbreeding coefficient of 35%.

That’s more than the infamous Spanish Hapsburgs. The problem with this is that it makes captive  axolotls really susceptible to disease. Like, you know how we almost lost an entire species of banana to one disease?

Scientists are pretty worried that  this could happen to wild axolotls, and the lab animals, too. It’s also kind of concerning  because all this inbreeding means they’re probably not the same  genetically as their wild cousins. They were even bred with tiger  salamanders in the 1960s, so they might not even be the same thing anymore.

Which means we might be missing some  valuable biological insights here. Normally, the way to deal with this is to  get some fresh blood into a population. But that’s not so easy with axolotls.

Remember, it’s estimated that there are  1,000 of them left in the wild, at most. So taking them out of their habitat to  breed with lab animals isn’t a great idea. And meanwhile, the threats to wild  axolotls aren’t going anywhere.

One issue is that axolotls have  simply lost most of their habitat. Their lakes are now city streets. And every time it rains, Mexico City’s canals are  flooded with trash, pollutants, and waste water from the city, since, like a lot of places around the world, their sewer system was built a long time ago.

The overflowing waste is making the water  low on oxygen and suffocating axolotls. Then there’s invasive species. See, there was a well-intentioned campaign to provide cheap food to people in Mexico City which introduced carp and halibut  into the canals in the 1970s.

Unfortunately, researchers think that these  fish might be eating axolotl eggs or doing other things that  upset their environment, and they’re just so abundant  that not much else can compete. So, what can we do? Well, if labs want to keep axolotls, they should probably focus on  conserving wild populations.

Some scientists are releasing  captive axolotls into the lakes to help improve genetic diversity  and test habitat health, but that doesn’t address the larger  challenges that axolotls still face. Long-term, we will need to  go after invasive species and upgrade Mexico City’s waste water system to keep the axolotl’s habitat cleaner. All of this is possible, and  people are working to get it done.

For instance, there’s a conservation project called Chinampa Refugio that’s working  to restore these ancient waterways, and in doing so, support the  restoration of axolotl habitats. It’s a long road to recovery, but  with enough motivation and funding, there’s a chance we can save  them before it’s too late. Here’s hoping that with enough  help from human intervention, they’ll one day be as common in their  own habitat as they are in Minecraft. [ outro ]