Weird and Mysterious Animals: Axolotls

by Shruthi Ravichandran and Jessica Chang

Hi! It’s us again–Shruthi and Jessica, back again for a second edition!! This week, we have a special double edition!! (Check out the awesome article about the Immortal Jellyfish under our column!) Last edition, we brought you the awesome article about the tardigrades. This week, we’re bringing an equally (and arguably even more) lovable creature: the axolotl, better known as the Mexican Salamander!

Super confused on how to pronounce that? You’re not alone: “Ax-oh-lot-el.” The name has its roots in Aztec mythology. “Atl” means water and “Xolotl” refers to the Xolotl, a dog-headed god of death leds dead souls to the underworld in Aztec myths. Some believe that the Xolotl was afraid of being killed and transformed into an axolotl to hide, a grim past for such an adorable creature. For this reason, axolotls are also called water dogs.

Axolotls have been known to eat small fish, worms, and anything else that will fit in their mouth. They are one of the only organisms that are neotenous, meaning that they can achieve maturity without metamorphosing. Axolotls will keep their gills, which are the little filaments on the side of their heads, and stay in the water even after maturing. These little critters are found in only one place in the entire world – the lakes and canals of Xochimilco, Mexico. Sadly, due to habitat loss, pollution, and invasive species, they are endangered and being pushed closer and closer to extinction every day. However, they will continue to thrive in captivity, which is great for the scientists studying them, because we have a lot to learn from them.

Axolotls are not only 1000 times more resistant to cancer than mammals, they have the capability to regenerate. This isn’t just your everyday typical regeneration: axolotls can regenerate anything – limbs, jaws, tails, spinal cords, and skin, all without any sort of scarring whatsoever. They can even accept transplanted organs from other axolotls without any of the typical rejection issues seen in other organisms. Cut off an entire arm, crush the spinal cord, or even remove part of it, and the axolotl will regenerate perfectly, replacing every single tissue. Unlike other regenerative organisms, axolotls can regenerate the same body part hundreds of times perfectly every single time. Studying axolotls could help scientists on the road to perfect human regeneration in ten or twenty years, which would be the crowning achievement of all medical research.

One of the first regenerative steps in an axolotl is the de-differentiation of cells, which essentially “converts” cells at the amputation site back into stem cells. These cells that create a blastema, which covers the wound, and where the new de-differentiated cells are. This structure then develops into an exact replica of whatever limb was lost before. What we’ve learned so far is that two compounds, p53, and transforming growth factor beta one, (TGF-β1) are heavily involved in axolotl regeneration. In humans, TGF-β1 helps with cell differentiation, while p53 is a compound found to be mutated in more than half of all human cancers.

Know of a weird creature you want to share with the world? Leave a comment below and we’ll write an article about it!!

Until next time! Happy Sciencing!

Shruthi and Jessica 🙂