The Mexican axolotl ( Ambystoma mexicanum ) is a fascinating and intriguing creature. It is the only vertebrate animal capable of regeneration. With its appearance of a giant tadpole with legs and a tail, it usually measures around 15 cm in total length, although rare specimens that reach 30 cm have been found. There are more than 30 species of salamanders in the genus Ambystoma.
Its only natural habitat is the basin of Mexico and although there may be a few hundred individuals in the wild, tens of thousands can be found in home aquariums and research laboratories around the world. They are so widely bred in captivity that certain restaurants in Japan even serve them fried. It is probably the most widely distributed animal in the world and yet it is on the brink of extinction in the wild.
And it is that, we have already advanced it before. Thanks to its unique physiology and ability to regenerate severed limbs, the axolotl has become a very popular laboratory model, whether for tissue repair or development and even cancer.
While many amphibians can regenerate body parts, axolotls have a unique ability to perfectly regenerate limbs. No matter how many times they lose a leg or tail, they can always regenerate it without leaving scars. They can also regenerate your spinal cord or even parts of your brain.
Activity
Axolotls can be active throughout the day. They have feathery external gills and finned tails for swimming. They breathe like fish, through their gills, but also through gills that absorb oxygen from the water. Although they have lungs, they spend their entire lives underwater. They never go to dry land. In extremely rare cases, such as when its habitat dries up, the axolotl will emerge from the water to become a fully adult Mexican salamander.
Life expectancy
In captivity, axolotls live an average of 5 to 6 years, but some have lived up to 17 years, according to The Animal Aging and Longevity Database at the University of Liverpool (UK).
What do they eat?
Mollusks, fish, and arthropods such as insects and spiders. They even eat each other.
Reproduction
The reproduction of the axolotl is carried out by means of a mating dance. After the female and male jostle and caress each other’s urogenital opening, they begin to dance in a circle in a kind of waltz, according to the University of Michigan Animal Diversity Website. When the two dance partners get together, the male releases a small white capsule filled with sperm called a spermatophore. With the female in tow, the male advances until the female simply passes over the spermatophore and picks it up with her cloaca (sex organs of the axolotl). This curious courtship takes place once a year, normally from March to June. The female will lay 100-300 eggs that she will coat with gelatin from aquatic plants or rocks. Around 10-14 days later, the eggs will hatch and the young will begin their solitary life from that moment on . In a year, they will be adults.
The creature that never grows
Unlike most amphibians, axolotls never transform into adult terrestrial salamanders. They stay in “sexually mature tadpoles” mode because they retain their youthful characteristics forever. This phenomenon of “eternal youth” is called paedomorphosis or neoteny.
A great genome
A team of researchers led by scientists in Vienna, Dresden and Heidelberg discovered yet another curiosity about axolotls: their genome is huge. They have approximately 32,000 million pairs of DNA nucleotides, greatly overshadowing the human genome (about 10 times smaller), they explained in their work in the journal Nature published in 2018. It is the largest genome ever sequenced.
Inspiration for writers
The Argentine novelist Julio Cortázar made a story about the axolotl. It refers to a man who comes to identify powerfully with these creatures after seeing them in a Parisian botanical garden. The story begins with a memorable phrase: “There was a time when I thought a lot about axolotls. I went to see them in the aquarium of the Jardin des Plantes and I stayed for hours watching them, observing their immobility, their weak movements. Now I am an axolotl ”.
State of conservation
The axolotl is critically endangered according to the International Union for Conservation of Nature (IUCN) due to loss of habitat, the introduction of exotic fish, pollution or overexploitation.
