A GOD IN DANGER
By Alejandro Prieto
The Mexican axolotl, an amphibian with the ability to regenerate mutilated body parts, is highly sought-after for its incredible power. Years of capture and environmental degradation have now brought this biologically-important species to the brink of extinction. Could it be too late to save it?
The axolotl is a unique species endemic to Mexico, capable of regenerating almost every part of its body. Thanks to this unique ability, it has become one of the most studied species in the world. The axolotl is a type of salamander that uniquely spends its whole life in larval form. It is the only species that never undergoes metamorphosis. As they age, axolotls simply get bigger and bigger, like amphibious Peter Pans.
Unfortunately, the number of axolotls in the wild has dropped dramatically through the years, and they are now considered critically endangered by the International Union for Conservation of Nature (IUCN). The main threats they face include habitat loss, water contamination by industrial practices, and the presence of invasive species in their habitat.
The long-term survival of the axolotl in the wild has now become critical, and demands urgent action to restore the animal’s numbers and habitat. The axolotl (Ambystoma mexicanum) belongs to the mole salamanders, a group of around 30 species endemic to North America, particularly the US, southern Canada, Alaska and Mexico. The axolotl, however, is only found in central Mexico, on the southern edge of Mexico City. It has now disappeared from most of its range and is classified as “Critically Endangered”.
A MEXICAN GOD
Besides the great biological value of this species, there is a historical value: The axolotl had a special importance in the culture of the ancient Mexicans. The spirit of this animal was recognised by ancient cultures, which saw it as a being that defies death. In Aztec mythology, the axolotl (Nahuatl: atl,
“water” and xolotl, “monster”, aquatic monster), is the aquatic equivalent of the god Xolotl, from which its name came.
Because of its strange shape and characteristics, which the ancient inhabitants of the Valley of Mexico attributed to mystical properties, the axolotl has been used for medicinal purposes in the treatment of asthma and bronchitis
Brother of Quetzalcoatl and monstrous because of the twin birth, Xolotl is associated with the idea of movement and life, according to the Legend of the Fifth Sun. Duality manifests itself in the transformations to which it resorts to avoid sacrifice. Bernardino de Sahagún, a Catholic missionary priest, tells that Xolotl refused death, fleeing the executioner by hiding in the cornfields, where he morphed into a corn plant with two stalks. When he was discovered, he ran again and took the form of a double maguey plant. Once again, the executioner found him and he escaped into the water, transforming into an axolotl. This was the last metamorphosis. Finally, the executioner caught Xolotl and killed him.
In Aztec culture, the axolotl is documented in several codices, among which is the Florentine Codex. The first scientific reference to the axolotl appears in a book of natural history from 1615 From then on, numerous works on the animal were published, but the scientific name was only given 200 years later.
The strange animal greatly impressed Alexander von Humboldt, a Prussian naturalist and explorer, who took two specimens from Mexico and brought them to Paris, giving them to the naturalist Georges Cuvier to study. He described with surprise the presence and persistence of the external gills on the sides of the head, and highlighted its anatomical resemblance to the salamander. Cuvier, true to the logic of comparative anatomy, concluded that the axolotl was no more than the larva of a large salamander. However, years later, in his famous classification of the animal kingdom, he was forced to classify it as a perennibranch, an amphibian that retains its gills throughout its life.
VALUE IN THE MARKET
Within culinary culture, and since pre-Hispanic times, the axolotl has been used in a variety of dishes, including tamales and broths. Up to a few years ago, it was still easily acquired in the Mexican markets of Xochimilco, Toluca, Pátzcuaro and Zumpango.
Because of its strange shape and characteristics, which the ancient inhabitants of the Valley of Mexico attributed to mystical properties, the axolotl has been used for medicinal purposes in the treatment of asthma and bronchitis. Its healing properties have afforded it renown that still persists to this day, and a trip to Sonora Market in Mexico City will allow you to get your hands on ointments and tonics with the Mexican axolotl as the main ingredient.
In Mexico, the axolotl is also valued as a unique aquarium pet, with the rare albino, gold and melanic varieties considered the most sought after. This overexploitation, together with the disruption and disappearance of its ecosystem, has put great pressure on the axolotl, driving the species steadily towards extinction.
THREATS TO SURVIVAL
In Mexico, the main cause of environmental pollution is the exploitation of natural resources by industrial, agricultural, economic, social, political and cultural activities. Such unsustainable practices have altered the natural conditions of the air, water, and soils.
The axolotl breathes through its gills, mouth, skin and lungs. While this ability has made the axolotl an evolutionary monster, it has caused axolotls, and amphibians in general, to be extremely sensitive to the presence of pollutants as they enter the body via these four routes.
Ambystoma mexicanum inhabits the famous canals of Xochimilco, one of Mexico City’s 16 boroughs. This area has been completely invaded by urban sprawl – only a few hectares remain that haven’t been touched. Populations of the axolotl are in decline as the demands ofthe city’s human population have led to the draining and contamination of the waters of Xochimilco Lake.
PRESENCE OF AN INVASIVE SPECIES
About 20 years ago, African tilapia were introduced into Xochimilco’s canals in a misguided effort to create fisheries. Together with the Asian carp, the two species now dominate the ecosystem, further pushing the axolotl towards extinction. This nonnative species not only eats the axolotl’s eggs, but also competes with it for food.
The axolotl is a very popular pet around the world, particularly in Japan. They are also commonly distributed to labs for research, acting as the white mice of amphibians thanks to their unique genetic profile. As long as the demand for captive axolotls continues, their numbers will continue to fall. In Mexico City, a black market of animals sells a variety of illegal species such as snakes, lizards, turtles, and different types of amphibians – including axolotls.l
Thousands of wild axolotls are fished every year in different areas of Mexico. This species has been present in Mexican culture from the time of the Aztec Empire till today, thus it has been caught for food and medicine for hundreds of years. Although the axolotl is now a protected species, enforcement is lacking and illegal fishing of the critically-endangered species continues.
A CURE FOR CANCER?
The axolotl is the most widely-researched salamander in the world, making this amphibian a permanent resident in laboratories. Regeneration of limbs is not an uncommon trait in several amphibious species, but the axolotl can rebuild its brain, spinal cord and heart – organs which cannot be rebuilt by other species. Scientists are conducting experiments in an attempt to harness the ability of regeneration for the treatment of human diseases. The axolotl’s DNA could someday aid in curing cancer.
A team of scientists has recently discovered one of the axolotl’s secrets: It has the largest genome that has been sequenced so far, much larger than ours. The axolotl genome contains 32 billion base pairs of DNA, 10 times larger than the human genome, which has around 3 billion base pairs. This finding will be a powerful tool to study the molecular basis of limb regeneration and other forms of regeneration.
THE WORK OF THE DOMINICAN NUNS
For the past 150 years, the Dominican nuns in Patzcuaro, Michoacan have been sustainably raising axolotls, locally known as achoques. The amphibian is a crucial ingredient in a mysterious medicine the convent makes. It is believed to cure coughs, asthma and anaemia. The sisters breed the axolotls to keep the tradition alive. These nuns are one of various different groups contributing their work to axolotl conservation. Through the development of an experimental culture of the species, they encourage the active participation of the local community and collaborate with academic, governmental and community institutions interested in its conservation. This is the only religious organisation that actively participates in conservation projects in Mexico.
Other conservation groups have been focusing on restoring axolotl habitats through conservation education and a nature tourism initiative. Groundwork on habitat restoration and bioremediation has also been conducted.
RIGHT The silhouette of a wild axolotl found in Manantlan Reserve
ABOVE Axolotl served at Cinco de Mayo market in Puebla, Mexico. It has been a source of protein for the Mexicans since ancient times, and believed to be a powerful remedy against many diseases TOP An axolotl mural at Xochimilco market in Mexico City
BELOW The waste that is discharged illegally in the rivers of Puebla causes great damage to the flora and fauna. This waste is generated by irresponsible companies, and the Mexican government rarely does anything to stop them
ABOVE Inside Mercado Mixhuca, the black market of animals located in Mexico City, you can find countless illegal species for sale, including axolotls
BELOW Besides the loss of thousands of axolotls in fishermen’s nets every year, the introduction of non-native species is pushing this unique salamander to the brink of extinction