Most of us have seen or at least heard of geckos dropping their tails as a defense mechanism and regrowing them later on. Similar examples of regeneration can be seen among lizards and amphibians that can regrow limbs in addition to their tails. The most powerful regenerative abilities are seen in worms and starfish, who can regenerate any part of their body. However, these creatures do not possess complex organs and have very basic nervous systems.
This leaves the Axolotl in a class of its own. The Axolotl is a species of salamander that is capable of regenerating not only its legs, but also the heart, lungs, spinal cord and parts of its brain. Due to these abilities, scientists have been fascinated with Axolotls for over 2 centuries.
The Secret Behind the Axolotls Regenerative Capabilities
The key behind the Axolotls healing capabilities is the fact that they do not heal by scarring. In humans, scar tissue is formed over the site of a wound to stop the bleeding, but this tissue is different to the surrounding tissues. Upon losing a limb, Axolotls use cells around the wound to form a cover called a “wound epidermis”. The cells in the wound epidermis begin dividing rapidly, healing the wound and preparing to create a new limb.
Even without its regeneration ability, the axolotl is a strange creature. Most salamanders have gills in their child stage and become an adult through a process called metamorphosis. During metamorphosis, they adapt to live on land. This is similar to the way that tadpoles transform into frogs. However, Axolotls remain stuck in a permanent childhood, keeping their feathered gills throughout their lives.
This permanent childhood, known as neoteny, may explain the Axolotl’s regenerative abilities. Other amphibians like frogs can also grow back their legs, but the new leg is never as well-formed as the old one. As these animals grow older their regenerative abilities worsen as well. Some older salamanders can only grow back a small spike after losing a limb. When an Axolotl regrows a part of its body, the new part will be identical to the old one.
The feathered gills around the Axolotl’s face, coupled with its wide head and lidless eyes gives the Axolotl a unique appearance that some people find attractive. Thus it is a very popular pet in some parts of the world.
But don’t let its cute appearance deceive you, the Axolotl is a vicious predator in its own habitat. In fact, in addition to hunting down smaller creatures, Axolotls have also been known to engage in cannibalism. Since they are limited to a small number of habitats, axolotls have a large population density. So when food is scarce, they turn to eating the limbs of their siblings. Some researchers believe cannibalism is why the axolotl has evolved to regenerate its limbs.
Unfortunately, regeneration does nothing to protect Axolotls from predators. They are native to just 2 lakes in Mexico and with the growth of Mexico City, many new fish species have been introduced to the Axolotls’ habitat. These fish have preyed on the Axolotls’ young, making them an endangered species.
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