The Science of… Halloween: #3 Morphing Monsters
- Laura Feather
- Oct 18
- 3 min read
Welcome to our Halloween-themed science blog!
It’s Halloween season, so throughout October we’re untangling science from superstition each week with a blog exploring everything from potent potions to creepy creatures - and even eerie experiments you can try at home.
Check back each week during October to see what science is brewing behind the magic!
#2 MORPHING MONSTERS
Deep in the lakes of Mexico lurks a creature that looks like it swam straight out of a mad scientist’s lab. With feathery gills, a permanent grin, and the power to grow back lost body parts, the axolotl salamander is a real-life monster, and a medical mystery.
But beneath that cute smile lies a dark side. Baby axolotls are ravenous. If it moves, they’ll bite it - sibling, friend, or foe. Cannibalism is so common that breeders must separate the hatchlings early to avoid a full-on aquatic horror scene. Yet, in Halloween fashion, the victims don’t just survive… they regenerate.
Lost a leg? It’s back in weeks. Bitten tail? No problem. Even parts of their heart, spine, or brain can grow back, scar-free. It’s regeneration borders on the supernatural. There is a catch, though - after around five amputations, the magic starts to fade.
So what’s behind their self-healing superpower? Scientists are still piecing it together. The axolotl’s genetic code is ten times larger than ours, packed with genes we don’t have. One big difference is how they heal. When humans get a deep cut, scar tissue forms, blocking full repair. Axolotls skip that step entirely. Their wounds close quickly, thanks to immune cells called macrophages, which clean up damage without triggering scarring.
The cells near the injury “forget” what type of cell they were, e.g., muscle, skin, or bone, and revert to a stem cell-like state, just like in the embryo. These shapeshifting cells gather into a mound called a blastema - a tiny bud that grows into a brand-new limb.
But regeneration isn’t just about making new cells, it’s also about putting them in the right place. Axolotl cells have what scientists call positional memory. This means the cells retain information about their original location in the body. A gene called Hand2 helps coordinate this process, activating a molecular signal known as Sonic Hedgehog (Shh) that tells the cells which side is “front” and which is “back.”
So if we’ve got macrophages and stem cells too, why can’t humans do this? The answer is that our immune systems react too aggressively, our wounds scar too fast, and our cells have lost the ability to “rewind” to earlier embryonic-like states. Axolotls, on the other hand, keep their developmental programmes on standby, ready to reactivate when needed.
Understanding how they do this could someday revolutionise medicine - from regenerating spinal cords to healing hearts without scarring.
Long before scientists started studying them, though, axolotls were already legendary. In Aztec mythology, they were the god Xólotl, who escaped sacrifice by transforming into a salamander and hiding in Mexico’s Lake Xochimilco. That’s where these “water monsters” still live today, and are seen by modern day Mexicans as symbols of resilience, rebirth, and survival.
So, this Halloween, remember: monsters aren’t always fiction. Some live quietly in the shallows, smiling back with their superpower as masters of regeneration.
Would you choose regeneration as your superpower? If not, what super power would you have? Tell us your thoughts in the comments or tag us on socials @LitLabLondon
Looking for more spooky science fun?
Join us this Halloween and enjoy enough shots to wake the dead at the Lit Lab: Halloween Special on Sun, 26 Oct at Aquum, Clapham
Sources:
Axolotl Nerd. (2019). How Axolotl Regeneration Works? [online] Available at: https://axolotlnerd.com/axolotl-regeneration/.
Godwin, J.W., Pinto, A.R. and Rosenthal, N.A. (2013). Macrophages are required for adult salamander limb regeneration. Proceedings of the National Academy of Sciences, [online] 110(23), pp.9415–9420. doi:https://doi.org/10.1073/pnas.1300290110.
Nacu, E. and Tanaka, E.M. (2011). Limb Regeneration: A New Development? Annual Review of Cell and Developmental Biology, 27(1), pp.409–440. doi:https://doi.org/10.1146/annurev-cellbio-092910-154115.
ScienceDaily. (2025). Hand2: positional code that allows axolotls to regrow limbs found. [online] Available at: https://www.sciencedaily.com/releases/2025/05/250521124120.htm.
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