Biology:Axolotl

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The axolotl (/ˈæksəlɒtəl/ (About this soundlisten); from Classical Nahuatl: āxōlōtl nah; Ambystoma mexicanum) is a species of mole salamander. It is neotenic, reaching sexual maturity without undergoing metamorphosis, and the adults remain fully aquatic with obvious external gills. Axolotls may be difficult to distinguish from the larval stage of other neotenic adult mole salamanders, in particular the tiger salamander, or other species such as mudpuppies.[1]

Axolotls originally inhabited a system of interconnected wetlands and lakes in the highlands of Mexico. They were known to inhabit the smaller lakes of Xochimilco and Chalco and are presumed to have inhabited the larger lakes of Texcoco and Zumpango. The desiccation of these lakes, initiated by the Aztecs and accelerated during the 20th century,[2][3][4] has led to the destruction of much of the axolotl's natural habitat, an area now largely occupied by Mexico City. Wild axolotls have been driven to near extinction by the introduction of invasive species such as tilapia and carp; with a decreasing population of around 50 to 1,000 adult individuals, the species has been assessed as critically endangered by the International Union for Conservation of Nature (IUCN) and is listed under Appendix II of the Convention on International Trade in Endangered Species (CITES).[5]

There currently exists a large captive population of axolotls, with specimens used extensively in scientific research because of their unusual ability to regenerate body parts, including limbs, gills and parts of their eyes and brains. The species is also used as a model organism. As aquarium technology has developed, axolotls have become a common exhibit in zoos and public aquariums, as well as an occasional pet in home aquariums. The axolotl is a popular subject in contemporary culture, inspiring a number of works and characters in the media.

Nomenclature

The term "axolotl" is a Nahuatl word which has been translated variably as "water slave", "water servant", "water sprite", "water player", "water monstrosity", "water twin", or "water dog".[6][7][8] The word refers to Xolotl, the Aztec god who holds dominion over fire, lightning, the dead and the resurrected, dogs, games, grotesque or ugly beings, and twins (as he is the twin of Quetzalcōātl).[6][9]

Some sources prefer the term "Mexican axolotl" to refer to this species unambiguously, as "axolotl" may be used for unmetamorphosed individuals of other Ambystoma species,[8][10] although the word is most commonly used to refer to wild A. mexicanum and captive individuals.

Description

File:Axolot's head (Ambystoma mexicanum).jpg
Head of a dark-colored, perhaps wild type, axolotl

A sexually mature adult axolotl, at age 18–27 months, ranges in length from 15 to 45 cm (6 to 18 in); a size close to 23 cm (9 in) is most common, and any greater than 30 cm (12 in) is rare. Axolotls possess features typical of salamander larvae, including external gills and a caudal fin extending from behind the head to the vent.[11][12] Unlike most salamander species, axolotls retain their external gills when they mature into adulthood.[13] This is a type of neoteny.[14]

Axolotls have wide heads and lidless eyes. Their limbs are underdeveloped and possess long, thin digits. Three pairs of external gill stalks (rami) originate from behind the head and are used to move oxygenated water. These are lined with filaments (fimbriae) to increase the surface area for gas exchange.[13] Four gill slits lined with gill rakers are hidden underneath the external gills, which prevent food from entering and allow particles to filter through. Males can be identified by their swollen cloacae lined with papillae, while females have noticeably wider bodies when gravid and full of eggs.

Buccal pumping

Axolotls have barely visible vestigial teeth; other salamanders only develop these during metamorphosis. Their primary method of feeding is by suction, during which their rakers interlock to close the gill slits. Axolotls use their external gills for respiration; buccal pumping (gulping air from the surface) may also be used to provide oxygen to their lungs.[13] Buccal pumping can occur in a two-stroke manner, pumping air from the mouth to the lungs, or a four-stroke manner, reversing this pathway using compression forces.

Captive axolotl color morphs

The wild type animal (the "natural" form) is brown or tan with gold speckles and an olive undertone. They can subtly alter their color by changing the relative size and thickness of the melanophores, presumably for camouflage.[15] Axolotls have four pigmentation genes; when mutated, they create different color variants.[16] The four most common mutant colors are as follows:

  1. Leucistic: pale pink body, black eyes
  2. Xanthic: grey body, black eyes
  3. Albinistic: pale pink or white body, red eyes
  4. Melanistic: black or dark blue body with no gold speckling or olive tone

In addition, there is wide individual variability in the size, frequency, and intensity of the gold speckling, and at least one variant leads to the development of a black and white piebald appearance upon reaching maturity.[17] Pet breeders frequently cross the variant colors, and double homozygous mutants are common in the pet trade, especially white/pink animals with pink eyes that are double homozygous mutants for both the albino and leucistic genes.[18]

File:Cromatóforos de larva de axolote pardo (Ambystoma mexicanum).jpg
Melanophores of a larva axolotl

The 32 billion base pair long sequence of the axolotl's genome was published in 2018; the largest animal genome completed at the time, it revealed species-specific genetic pathways that may be responsible for limb regeneration.[19] Although the axolotl genome is about ten times the size of the human genome, it encodes a similar number of proteins (23,251,[19] compared with about 20,000 in the human genome). The size difference is mostly explained by a large fraction of repetitive sequences; these also contribute to increased median intron sizes (22,759 bp), which are 13, 16 and 25 times that observed in human (1,750 bp), mouse (1,469 bp) and Tibetan frog (906 bp), respectively.[19]

Physiology

Regeneration

The characteristic of the axolotl that attracts the most attention is its unusual healing ability; axolotls do not heal by scarring but are instead capable of tissue regeneration. Entire lost appendages, such as the limbs and tail, can regrow over a period of months. In certain cases, more vital structures can be regrown, such as tissues of the eye and heart.[20][21] Axolotls can even restore parts of their central nervous system, including non-vital parts of their brains. They can readily accept transplants from other individuals—including eyes and parts of the brain—restoring these "alien organs" to full functionality. In special cases, axolotls have been able to repair a damaged limb while also generating an additional limb, resulting in an extra appendage that makes them attractive to pet owners as a novelty.[22]

The three basic requirements for limb regeneration in an axolotl are: (1) the formation of a wound epithelium, (2) the presence of nerve signaling, and (3) the presence of cells from the different axes (lines of orientation) of the affected limb.[23] An epidermis quickly forms to seal the site of the wound. Over the next few days, the cells of the wound epidermis divide and grow, forming a blastema, at which point the wound is ready to heal and undergo patterning to form the new limb. It is believed that during limb generation, axolotls have a special system to regulate their internal macrophage level and suppress inflammation, as scarring would prevent proper healing and regeneration.[24] However, this belief has been questioned by other studies.[25]

A fundamental growth structure credited for the axolotl's ability to regenerate whole limbs in early development is the apical ectodermal ridge (AER), with the apical ectodermal cap (AEC).[26][clarification needed] The AER initiates the growth of appendages in embryos by signaling how they are shaped and extended.[26] Ectodermal cells are needed to form limbs in most tetrapods, amphibians and humans, but unlike most other animals the AEC in the axolotl can send signals through growth hormones to activate blastema cells, which can rebuild whole amputated or damaged limbs or organs.[27]

The axolotl has indeterminate growth, meaning it continues to grow throughout its life. Some consider this trait to be a direct contributor to the axolotl's regenerative ability, which declines with age but does not completely disappear. The ability to regenerate limbs is greatly diminished in metamorphosed individuals.[22]

Neoteny

Main article: Biology:Neoteny

Most amphibians begin their lives as aquatic animals unable to live on dry land, often called tadpoles. To reach adulthood, they go through a process called metamorphosis, in which they lose their gills and start living on land. The axolotl is unusual in that it has a lack of the thyroid-stimulating hormone that triggers the thyroid to produce thyroxine, which is needed for metamorphosis to take place; instead, the axolotl keeps its gills and lives in water all its life, even after becoming an adult and able to reproduce. The trait of reaching sexual maturity without undergoing metamorphosis is called neoteny.[33]

The genes responsible for neoteny in laboratory axolotls may have been identified; they are not linked to the genes of wild populations, suggesting artificial selection is the cause of complete neoteny in laboratory and pet axolotls.[34] The genes responsible have been narrowed down to a small chromosomal region called met1, which contains several candidate genes.[35]


Metamorphosis

Metamorphosed axolotls

Over evolutionary time, the axolotl has lost the ability to naturally undergo metamorphosis.[36] It has retained the capacity to undergo metamorphosis if provided with the necessary hormones through artificial administration.[37] Under modern laboratory conditions, metamorphosis is reliably induced by administering thyroid hormones, including thyroxine, triiodo-L-thyronine, or thyroid-stimulating hormones.[38][36]

Depending on the hormone used for induction, different outcomes may occur. Some hormones, such as triiodo-L-thyronine, can promote regenerative abilities while in some cases failing to produce complete metamorphosis.[36] In contrast, thyroxine can inhibit regenerative abilities and accelerate metamorphosis.[36]

After an axolotl undergoes hormonally induced metamorphosis and begins living on land, it experiences a number of physiological changes that help it adapt to terrestrial life. These include increased muscle tone in limbs, resorption of gills and fins into the body, the development of eyelids, and a reduction in the skin's permeability to water, allowing the axolotl to remain more effectively hydrated on land. The lungs of an axolotl, though present alongside gills after reaching non-metamorphosed adulthood, develop further during metamorphosis.[39] Axolotls that complete metamorphosis are similar in appearance to the adult plateau tiger salamander, though axolotls have longer toes.

In the absence of induced metamorphosis, larval axolotls begin absorbing iodide into their thyroid glands at around 30 days post-fertilization. Larval axolotls do produce thyroid hormones from iodide, but the amount appears highly variable. In contrast, adult axolotls do not produce detectable levels of thyroid hormone unless metamorphosis is triggered.[40]

Wild population

Lake Xochimilco, one of the last refuges of the wild axolotl

Axolotls are within the same genus as the tiger salamander (Ambystoma tigrinum), being part of its species complex along with all other Mexican species of Ambystoma.[41][42][43] Within the family Ambystomatidae, the closest relative of the axolotl is the Eastern tiger salamander.[44] The axolotl's habitat is like that of most[verify] neotenic Ambystoma species: a high-altitude body of water surrounded by a risky terrestrial environment, or other conditions unsuitable for the terrestrial form, with these conditions thought to favor the development of neoteny.[45] However, a population of terrestrial Mexican tiger salamanders occupies and breeds in the axolotl's habitat (the two species being sympatric). The axolotl is native to the freshwater lakes of Xochimilco and Chalco in the Valley of Mexico (though the species may have also once inhabited the larger Lakes of Texcoco and Zumpango).[46] Lake Chalco is an unstable ecosystem, often being drained as a flood control measure, and Lake Xochimilco is a remnant of its former self, now existing mainly as canals. The water temperature in Xochimilco rarely rises above 20 °C (68 °F), and may fall to 6–7 °C (43–45 °F) or lower in the winter.[47][verification needed] A population of Ambystoma inhabiting the artificial lake at Chapultepec was confirmed to contain axolotls; as of 23 October 2019, the extent of occurrence was 467 square kilometres (180 sq mi).[46] Overall, the wild axolotl prefers a system of water channels and deep-water lakes with abundant aquatic vegetation.[46]

Biology

File:Axolotl Wild Type.jpg
Wild form

The axolotl is carnivorous; in the wild, it consumes small prey such as mollusks,[48] worms, aquatic insects, other arthropods (such as crayfish),[48][49] and small fish, as well as other salamanders (including conspecifics).[48][50] Axolotls locate food by smell and will "snap" at any potential meal, sucking the food into their stomachs with vacuum force.[51]

The wild axolotl is thought to reach sexual maturity at 1.5 years of age, with a generation length of around 5.5 years.[46] The life expectancy of a wild axolotl is between 10 and 15 years.[45]

Threats

Axolotls are native only to the Mexican Central Valley, and the population once extended through most of the lakes and wetlands in this region. The axolotl's natural habitat is now limited to Lake Xochimilco as a result of the expansion of Mexico City and is under pressure from the city's growth. The axolotl is on the IUCN Red List of threatened species.[46]

Surveys conducted in 1998, 2003, and 2008 found populations of 6,000, 1,000, and 100 axolotls per square kilometer, respectively, in Lake Xochimilco.[52] A four-month-long search in 2013 found no surviving individuals in the wild, but one month later two were spotted in a network of canals leading from Xochimilco.[53]

Lake Xochimilco has poor water quality; tests have revealed a low nitrogen-to-phosphorus ratio and a high concentration of chlorophyll a, indicative of an oxygen-poor environment not well-suited to axolotls. This has been caused by the demands of local industries, such as aquaculture and agriculture, which maintain the lake's water levels through inputs of partially treated wastewater.[54] Intensively used agricultural pesticides eventually enter the lake through runoff, and these contain chemical compounds that sharply increase the mortality rate in axolotl embryos and larvae. Of the surviving embryos and larvae, there is also an increase in morphological, behavioral, and activity abnormalities.[55][when?]

Due to the dramatic reduction in the native population, there has been a significant loss of genetic diversity. This can be dangerous for the remaining population, as it causes increased inbreeding and reduced fitness and adaptive potential. Studies have found indicators of low interpopulation gene flow and higher rates of genetic drift. These are likely the result of multiple "bottleneck" incidents, where a sharp drop in the number of individuals in the population leads to decreased genetic diversity. The offspring produced after bottleneck events have a greater risk of poor fitness and are often less able to adapt. Several bottleneck events may even lead to extinction. Studies have also found high rates of relatedness indicative of inbreeding, which can cause an increase in the presence of deleterious, or harmful, mutations in genes.[56] The detection of introgressed tiger salamander (A. tigrinum) DNA in the laboratory axolotl population raises concerns about the suitability of the captive population as an "ark" for potential reintroduction purposes.[57]

Another factor that threatens the population is the introduction of invasive fish species, such as the Nile tilapia and the common carp. These fish eat the axolotls' young and compete for their food.[58] The presence of these species has changed axolotl behavior, causing them to be less active in an effort to avoid predation. This reduced activity greatly impacts the axolotl's foraging and mating opportunities.[59]

The fungus Batrachochytrium dendrobatidis has been detected in axolotls; this fungus causes the disease chytridiomycosis in amphibians and is a major concern for amphibian conservation worldwide. However, the axolotl displays resistance to both B. dendrobatidis and B. salamandrivorans, so chytridiomycosis is thought not to be a threat to this species.[46]

Conservation efforts

The condition of the native axolotl population has improved little over the years.[60][61] Many scientists are focusing their conservation efforts on the translocation of captive-bred individuals into new habitats or their reintroduction into Lake Xochimilco. Studies have shown that axolotls born in captivity and raised in a semi-natural environment are capable of surviving in the wild, catching prey and escaping predators with moderate success. These captive-bred individuals may be introduced into unpolluted bodies of water or returned to Lake Xochimilco; however, with the amount of pollution in the lake, the presence of invasive species and the region's continuing urbanization, the translocated axolotls might eventually have the same fate as the wild population.[62][63]

The Laboratorio de Restauracion Ecologica () of the National Autonomous University of Mexico has built up a population of 100 captive-bred axolotls, as of 2021. These are mostly used for research, but there are plans to establish a viable population in a semi-artificial wetland inside the university.[needs update][citation needed]

A 2025 study confirmed the viability of releasing captive-bred axolotls into the wild, with recaptured individuals having gained weight since their release. However, this practice risks losing the axolotls through predation, as several of those released were preyed on by great egrets.[64][65][66]

Relation to humans

Research history

German naturalist and explorer Alexander von Humboldt noted in the 19th century that the Mexicans, having been vanquished by the Spanish Empire, lived "in great want, compelled to feed on roots of aquatic plants, insects and a problematical reptile called axolotl".[67]

In 1863, a shipment of 34 adult axolotls was sent from Mexico City to the Jardin des Plantes in Paris, from which thousands of specimens were captive-bred and distributed around Europe for scientific research.[68] Unaware of their neoteny, French zoologist Auguste Duméril was surprised when, instead of the axolotl, he found in the vivarium a new species, similar to the salamander. This discovery was the starting point of research about neoteny. It is not certain that Ambystoma velasci specimens were not included in the original shipment.[clarification needed] In Prague, the Czech physician Vilem Laufberger used thyroid hormone injections to induce an axolotl to grow into a terrestrial adult salamander. Unaware that it had already been carried out, Englishman Julian Huxley repeated the experiment using ground animal thyroid glands.[69][70] Since then, experiments have often involved the injection of iodine or various thyroid hormones to induce metamorphosis.[14]

Use as a model organism

Stages of development (images captured using stereoscopic macrophotography)

Bred in captivity in large numbers, the axolotl is used extensively in research as a model organism. They are especially easy to breed compared with other salamanders in the Ambystomatidae family, which are rarely captive-bred because of the husbandry demands of terrestrial life. One attractive feature of the axolotl for research purposes is the large and easily manipulated embryo, which allows viewing of the full development of a vertebrate. Axolotls are used in heart defect studies due to the presence of a mutant gene that causes heart failure in embryos. Since the axolotl embryo survives almost to hatching with no heart function, the defect is very observable. Further research has been conducted to examine the axolotl's heart as a model of a single human ventricle and excessive trabeculation.[71] The axolotl is also considered an ideal animal model for the study of neural tube closure due to the similarities between human and axolotl neural plate and tube formation; the axolotl's neural tube, unlike that of a frog, is not hidden under a layer of superficial epithelium.[72] There are additional mutations affecting other organ systems, some of which are not yet well characterized.[73]

The regenerative abilities of the axolotl have led to its use as a model for the development of limbs in vertebrates, with the goal of understanding how humans can achieve better ways to heal from serious injuries.[74] This also makes the species an ideal model organism for studying the properties of stem cells and the process of neoteny. Current research can record specific examples of the axolotl's regenerative properties through tracking cell fates and behaviors, lineage tracing from skin triploid cell grafts, pigmentation imaging, electroporation, tissue clearing and lineage tracing from dye labeling. The newer technologies of germline modification and transgenesis are better suited for live imaging the regenerative processes that occur for axolotls.[75]

In a 2025 study, scientists found a new method of inserting and activating the genes inside the axolotl's brain and nervous system using special, harmless viruses called adeno-associated viruses (AAVs). It had previously been difficult for researchers to make specific genes work inside the axolotl, but this discovery allows them to explore how the axolotl's nervous system helps it regrow body parts such as the brain and spinal cord. Additionally, they found that the axolotl's nervous system has a unique two-way communication between the brain and eye.[76]

The genetics of the color variants of the axolotl have also been widely studied.[18]

Captive care

Template:How-to section

This animal was X-rayed several times as part of a research project over a period of two years. It was a normal healthy adult (26.3 cm; 159.5 gm) at the beginning of the project and lived several more years after the project ended.[26]

The axolotl is a popular exotic pet like its relative, the tiger salamander (Ambystoma tigrinum). Most axolotls under human care descended from that single group of under 36 individuals, with notable genetic differences from the wild population.[77] Like all poikilothermic organisms, lower temperatures result in slower metabolism and reduced appetite. Temperatures at approximately 16 °C (61 °F) to 18 °C (64 °F) are suggested for captive axolotls to ensure sufficient food intake; temperatures higher than 24 °C (75 °F) may lead to metabolic rate increase, also causing stress and eventually death.[78][79] Chlorine, commonly added to tap water, is harmful to axolotls.[80][81] A single axolotl typically requires a 150-litre (40-US-gallon) tank. Axolotls spend the majority of the time at the bottom of their tanks.[82]

In captivity, axolotls eat a variety of readily available foods, including trout and salmon pellets, frozen or live bloodworms, earthworms, and waxworms. Axolotls can also eat feeder fish, but care should be taken as fish may contain parasites.[83]

Substrates are another important consideration for captive axolotls, as axolotls (like other amphibians and reptiles) tend to ingest bedding material together with food[84] and are commonly prone to gastrointestinal obstruction and foreign body ingestion.[85] Some common substrates used for animal enclosures can be harmful for amphibians and reptiles. Gravel (common in aquarium use) should not be used, and is recommended that any sand consists of smooth particles with a grain size of under 1mm.[84] One guide to axolotl care for laboratories notes that bowel obstructions are a common cause of death, and recommends that no items with a diameter below 3 cm (or approximately the size of the animal's head) should be available to the animal.[86]

There is some evidence that axolotls might seek out appropriately-sized gravel for use as gastroliths[87] based on experiments conducted at the University of Manitoba axolotl colony.[88][89] As there is no conclusive evidence pointing to gastrolith use, gravel should be avoided due to the high risk of impaction.[90]

Salts, such as Holtfreter's solution, are often added to the water to prevent infection.[91] Among hobbyists, the process of artificially inducing metamorphosis can often result in death during or even following a successful attempt, and so casual hobbyists are generally discouraged from attempting to induce metamorphosis in pet axolotls.[39] Morphed pet axolotls should be given solid footholds in their enclosure to satisfy their need for land. They should not be given live animals as food.[92]

  • These axolotls at Vancouver Aquarium are leucistic, with less pigmentation than normal.
    These axolotls at Vancouver Aquarium are leucistic, with less pigmentation than normal.
  • Axolotls in a pet store in Melbourne, Australia
    Axolotls in a pet store in Melbourne, Australia
  • Axolotls in a pond with Pistia, Kew Gardens
    Axolotls in a pond with Pistia, Kew Gardens

Cultural significance

File:Edoardo Aldama.jpg
Axolotl graffiti in Mexico City

The species is named after Xolotl, the Aztec god of fire and lightning, who transformed himself into an axolotl to avoid being sacrificed by fellow gods. Axolotls continue to play a substantial cultural role in Mexico.[93] For example, they appear in the works of Mexican muralist Diego Rivera, as well as in a number of murals throughout Mexico City.[77] It became the official emoji of Mexico City in 2017.[94] In 2021, Mexico released a new design for the 50-peso banknote featuring an axolotl on its reverse.[95][96] It was recognized as "Bank Note of the Year" by the International Bank Note Society.[97] The banknote has become a collectable item because of its design; the Bank of Mexico reported in 2025 that up to 50 million were being kept out of circulation, as millions of people were choosing to hoard the notes rather than spend them.[98]

In Japan, the creatures are commonly known as "wooper loopers" (ウーパールーパー) following a 1980s marketing campaign by Nissin Foods featuring an axolotl with that name.[99][100] In 1999, the video games Pokémon Gold and Silver, made by Japanese developer Game Freak, introduced a Pokémon named Wooper, which is directly based on an axolotl.[93][101] Additionally, in 2002, Pokémon Ruby and Sapphire introduced the Pokémon Mudkip and its evolutions, which take some visual inspiration from axolotls.[93][additional citation(s) needed]

File:Minecraft Axolotl.jpg
Axolotl as seen in an official Minecraft animation

Starting in the late 20th and early 21st century, the axolotl became popularized as a cultural icon, with its likeness appearing in or inspiring various aspects of contemporary media, such as television shows, movies, or video games. Axolotls were added to the video game Minecraft in 2020 (depicted as troglofauna in-game), following Mojang Studios' trend of incorporating endangered species to raise awareness,[102] and they were included in its spin-offs Minecraft: Dungeons and Lego Minecraft.[103][104] In the How to Train Your Dragon movie franchise, the dragon Toothless was also modeled after axolotls.[93] They also feature prominently in the game Axie Infinity.[77]

Julio Cortázar wrote a short story titled "Axolotl", in which the narrator encounters axolotls in the aquarium at the Jardin des Plantes de Paris.[105][106]

In 2019, a star in the equatorial constellation of Cetus was named Axólotl.[107][108]

See also

References

  1. ↑ Malacinski, George M. (Spring 1978). "The Mexican Axolotl, Ambystoma mexicanum: Its Biology and Developmental Genetics, and Its Autonomous Cell-Lethal Genes". American Zoologist 18 (2): 195–206. doi:10.1093/icb/18.2.195. 
  2. ↑ Alcocer, J.; Williams, W. D. (1 March 1996). "Historical and recent changes in Lake Texcoco, a saline lake in Mexico" (in en). International Journal of Salt Lake Research 5 (1): 45–61. doi:10.1007/BF01996035. ISSN 1573-8590. https://doi.org/10.1007/BF01996035. "The Aztecs started the desiccation of Lake Texcoco by constructing low banks, levees or large hydraulic structures such as the Albarradón de Nezahualcóyotl. [...] In 1521, its area was almost 700 km2, by 1608, it was only 410 km2, by 1856, 350 km2, by 1904, 267 km2, and by 1966, only 140km2.". 
  3. ↑ Lewis, Alan Christopher; Torres, Janet (September 2013). "The Ghosts of Lake Texcoco Still Haunting Mexico City". The Drop (Water management & hydrological science program. Texas A&M University) 5. https://www.researchgate.net/publication/273762995_The_Ghosts_of_Lake_Texcoco_Still_Haunting_Mexico_City. "The lakes never stood a chance, and by the mid-20th Century, the last vestiges of Lake Texcoco were completely drained.". 
  4. ↑ "Regeneración del Rio La Piedad_Resumen Ejecutivo" (in es). 28 June 2011. https://issuu.com/taller13/docs/regeneracion_del_rio_la_piedad_resumen_ejecutivo/5. 
  5. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named CITES
  6. ↑ 6.0 6.1 Majchrzak, Amy. "Ambystoma mexicanum Salamandra ajolote". University of Michigan. https://animaldiversity.org/accounts/Ambystoma_mexicanum/. 
  7. ↑ "Meet the Peter Pan of salamanders, the axolotl". World Wildlife Fund. https://www.worldwildlife.org/magazine/issues/summer-2021/articles/meet-the-peter-pan-of-salamanders-the-axolotl. 
  8. ↑ 8.0 8.1 Humphrey, Rufus R. (1975). Robert C. King. ed. Handbook of Genetics Volume 4: Vertebrates of Genetic Interest (4 ed.). New York: Springer. pp. 3–17. doi:10.1007/978-1-4613-4470-4. ISBN 978-1-4613-4470-4. https://link.springer.com/chapter/10.1007/978-1-4613-4470-4_1. Retrieved 4 June 2025. 
  9. ↑ "Why Aztecs Revered the Axolotl". 17 February 2026. https://www.history.com/articles/axolotl-ancient-aztec-mythology. 
  10. ↑ "Axolotl". Merriam-Webster Dictionary. https://www.merriam-webster.com/dictionary/Axolotl. Retrieved 4 June 2025. 
  11. ↑ San Francisco Examiner (San Francisco, California) 7 August 1887, page 9, authored by Yda Addis
  12. ↑ McIndoe, Rosemary; Smith, D.G. (1984). "4. Functional morphology of gills in larval amphibians". in Seymour, Roger S. (in en). Respiration and metabolism of embryonic vertebrates: Satellite Symposium of the 29th International Congress of Physiological Sciences, Sydney, Australia, 1983. Perspectives in vertebrate science. Dordrecht: Springer Netherlands. pp. 55–69. doi:10.1007/978-94-009-6536-2_4. ISBN 978-94-009-6536-2. 
  13. ↑ 13.0 13.1 13.2 Kardong, Kenneth V (2019) (in English). Vertebrates: comparative anatomy, function, evolution. McGraw-Hill Education. ISBN 978-1-259-70091-0. OCLC 1053847969. 
  14. ↑ 14.0 14.1 Safi, Rachid; Bertrand, Stéphanie; Marchand, Oriane; Duffraisse, Marilyne; de Luze, Amaury; Vanacker, Jean-Marc; Maraninchi, Marie; Margotat, Alain et al. (1 February 2004). "The Axolotl (Ambystoma mexicanum), a Neotenic Amphibian, Expresses Functional Thyroid Hormone Receptors". Endocrinology 145 (2): 760–772. doi:10.1210/en.2003-0913. PMID 14576183. 
  15. ↑ Pietsch, Paul; Schneider, Carl W. (1985). "Vision and the skin camouflage reactions of Ambystoma larvae: the effects of eye transplants and brain lesions". Brain Research 340 (1): 37–60. doi:10.1016/0006-8993(85)90772-3. PMID 4027646. 
  16. ↑ Frost, S. K. (1984). "The pigmentary system of developing axolotls. I. A biochemical and structural analysis of the wild-type pigment phenotype". J Embryol Exp Morphol 81 (1): 105–125. PMID 6470605. 
  17. ↑ "18 Types of Axolotl Colors You Can Own (Axolotl Color Guide)". 14 August 2019. https://exopetguides.com/axolotl/axolotl-colors/. 
  18. ↑ 18.0 18.1 Frost, Sally K.; Briggs, Fran; Malacinski, George M. (1984). "A color atlas of pigment genes in the Mexican axolotl (Ambystoma mexicanum)". Differentiation 26 (1–3): 182–188. doi:10.1111/j.1432-0436.1984.tb01393.x. 
  19. ↑ 19.0 19.1 19.2 Nowoshilow, Sergej; Schloissnig, Siegfried; Fei, Ji-Feng; Dahl, Andreas; Pang, Andy W. C.; Pippel, Martin; Winkler, Sylke; Hastie, Alex R. et al. (24 January 2018). "The axolotl genome and the evolution of key tissue formation regulators". Nature 554 (7690): 50–55. doi:10.1038/nature25458. ISSN 1476-4687. PMID 29364872. Bibcode: 2018Natur.554...50N. 
  20. ↑ Weird Creatures with Nick Baker (Television series). Dartmoor, England, UK: The Science Channel. 11 November 2009.
  21. ↑ Caballero-Pérez, Juan; Espinal-Centeno, Annie; Falcon, Francisco; García-Ortega, Luis F.; Curiel-Quesada, Everardo; Cruz-Hernández, Andrés; Bako, Laszlo; Chen, Xuemei et al. (January 2018). "Transcriptional landscapes of Axolotl (Ambystoma mexicanum)" (in en). Developmental Biology 433 (2): 227–239. doi:10.1016/j.ydbio.2017.08.022. PMID 29291975. 
  22. ↑ 22.0 22.1 Sandoval-Guzmán, Tatiana (August 2023). "The axolotl" (in en). Nature Methods 20 (8): 1117–1119. doi:10.1038/s41592-023-01961-5. ISSN 1548-7091. PMID 37553398. https://www.nature.com/articles/s41592-023-01961-5. 
  23. ↑ Vieira, Warren A.; Wells, Kaylee M.; McCusker, Catherine D. (2020). "Advancements to the Axolotl Model for Regeneration and Aging". Gerontology 66 (3): 212–222. doi:10.1159/000504294. PMID 31779024. 
  24. ↑ Goodwin, James W.; Pinto, Alexander R.; Rosenthal, Nadia A. (4 June 2013). Olson, Eric N.. ed. "Macrophages are required for adult salamander limb regeneration". Proceedings of the National Academy of Sciences of the United States of America 110 (23): 9415–9420. doi:10.1073/pnas.1300290110. PMID 23690624. Bibcode: 2013PNAS..110.9415G. 
  25. ↑ Pedersen, Katherine; Rasmussen, Rikke Kongsgaard; Dittrich, Anita; Pedersen, Michael; Lauridsen, Henrik (17 April 2020). "Modulating the immune response and the pericardial environment with LPS or prednisolone in the axolotl does not change the regenerative capacity of cryoinjured hearts". The FASEB Journal 34 (S1): 1. doi:10.1096/fasebj.2020.34.s1.04015. 
  26. ↑ 26.0 26.1 26.2 Kulbisky, Gordon P; Rickey, Daniel W; Reed, Martin H; Björklund, Natalie; Gordon, Richard (1999). "The axolotl as an animal model for the comparison of 3-D ultrasound with plain film radiography". Ultrasound in Medicine and Biology 25 (6): 969–975. doi:10.1016/s0301-5629(99)00040-x. PMID 10461726. 
  27. ↑ Adamson, Carly J.; Morrison-Welch, Nikolas; Rogers, Crystal D. (June 2022). "The amazing and anomalous axolotls as scientific models". Developmental Dynamics 251 (6): 922–933. doi:10.1002/dvdy.470. ISSN 1097-0177. PMID 35322911. 
  28. ↑ Boron, Walter F.; Boulpaep, Emile L. (2012). "49. Synthesis of Thyroid Hormones". Medical Physiology (2nd ed.). Elsevier/Saunders. p. 1044. ISBN 978-1-4377-1753-2. 
  29. ↑ Swingle, W. W. (November 1923). "Iodine and Amphibian Metamorphosis". The Biological Bulletin 45 (5): 229–253. doi:10.2307/1536749. https://archive.org/details/sim_biological-bulletin_1923-11_45_5/page/n3. 
  30. ↑ Ingram, W. R. (1 December 1928). "Metamorphosis of the Colorado Axolotl by Injection of Inorganic Iodine.". Experimental Biology and Medicine 26 (3): 191. doi:10.3181/00379727-26-4212. 
  31. ↑ Dvoskin, Samuel (May 1947). "The Thyroxine-Like Action of Elemental Iodine in the Rat and Chick1". Endocrinology 40 (5): 334–352. doi:10.1210/endo-40-5-334. PMID 20245954. https://archive.org/details/sim_endocrinology_1947-05_40_5/page/334. 
  32. ↑ Krylov, O. A. (January 1961). "The role of haloids (bromine and iodine) in the metamorphosis of amphibia". Bulletin of Experimental Biology and Medicine 50 (1): 724–727. doi:10.1007/BF00796048. 
  33. ↑ Ley, Willy (February 1968). "Epitaph for a Lonely Olm". Galaxy Science Fiction: 95–104. https://archive.org/stream/Galaxy_v26n03_1968-02_modified#page/n37/mode/2up. 
  34. ↑ Malacinski, George M. (1 May 1978). "The Mexican Axolotl, Ambystoma mexicanum: Its Biology and Developmental Genetics, and Its Autonomous Cell-lethal Genes". American Zoologist 18 (2): 195–206. doi:10.1093/icb/18.2.195. 
  35. ↑ Crowner, Anne; Khatri, Shivam; Blichmann, Dana; Voss, S. Randal (12 April 2019). "Rediscovering the Axolotl as a Model for Thyroid Hormone Dependent Development". Frontiers in Endocrinology 10. doi:10.3389/fendo.2019.00237. PMID 31031711. 
  36. ↑ 36.0 36.1 36.2 36.3 Lazcano, I.; Olvera, A.; Pech-Pool, S. M.; Sachs, L.; Buisine, N.; Orozco, A. (10 July 2023). "Differential effects of 3,5-T2 and T3 on the gill regeneration and metamorphosis of the Ambystoma mexicanum (axolotl)". Frontiers in Endocrinology 14. doi:10.3389/fendo.2023.1208182. ISSN 1664-2392. PMID 37492199. 
  37. ↑ Demircan, Turan; Ovezmyradov, Guvanch; Yıldırım, Berna; Keskin, İlknur; İlhan, Ayşe Elif; Fesçioğlu, Ece Cana; Öztürk, Gürkan; Yıldırım, Süleyman (20 July 2018). "Experimentally induced metamorphosis in highly regenerative axolotl (Ambystoma mexicanum) under constant diet restructures microbiota" (in en). Scientific Reports 8 (1): 10974. doi:10.1038/s41598-018-29373-y. PMID 30030457. Bibcode: 2018NatSR...810974D. 
  38. ↑ Gale, Jen (5 November 2025). "What happens if an axolotl larva is placed in water containing sufficient iodine?" (in en-US). https://iere.org/what-happens-if-an-axolotl-larva-is-placed-in-water-containing-sufficient-iodine/. 
  39. ↑ 39.0 39.1 "Axolotls – Metamorphosed & Tiger Salamanders". https://www.axolotl.org/tiger_salamander.htm. 
  40. ↑ Brown, Donald D. (25 November 1997). "The role of thyroid hormone in zebrafish and axolotl development". Proceedings of the National Academy of Sciences 94 (24): 13011–13016. doi:10.1073/pnas.94.24.13011. PMID 9371791. Bibcode: 1997PNAS...9413011B. 
  41. ↑ Woodcock, M. Ryan; Vaughn-Wolfe, Jennifer; Elias, Alexandra; Kump, D. Kevin; Kendall, Katharina Denise; Timoshevskaya, Nataliya; Timoshevskiy, Vladimir; Perry, Dustin W. et al. (31 January 2017). "Identification of Mutant Genes and Introgressed Tiger Salamander DNA in the Laboratory Axolotl, Ambystoma mexicanum". Scientific Reports 7 (1): 5. doi:10.1038/s41598-017-00059-1. ISSN 2045-2322. PMID 28127056. Bibcode: 2017NatSR...7....6W. 
  42. ↑ "Mexican Walking Fish, Axolotls Ambystoma mexicanum". http://www.aquariumindustries.com.au/wp-content/uploads/2012/07/Mexican-Walking-Fish.pdf. 
  43. ↑ "Axolotols (Walking Fish)". Aquarium Online. http://www.aquariumonline.com.au/topics/creatures/mexican.htm. 
  44. ↑ Shaffer, H. Bradley (December 1993). "Phylogenetics of Model Organisms: The Laboratory Axolotl, Ambystoma mexicanum". Systematic Biology 42 (4): 508–522. doi:10.2307/2992486. https://www.jstor.org/stable/2992486. 
  45. ↑ 45.0 45.1 Dunning, Hayley (29 August 2025). "Axolotls: Meet the amphibians that never grow up" (in en). https://www.nhm.ac.uk/discover/axolotls-amphibians-that-never-grow-up.html. 
  46. ↑ 46.0 46.1 46.2 46.3 46.4 46.5 Cite error: Invalid <ref> tag; no text was provided for refs named iucn status 12 November 2021
  47. ↑ "Lake Xochimilco, Borough of Xochimilco in southern México City" (in en-GB). https://biotope-aquarium.info/aquariums/lake-xochimilco-borough-of-xochimilco-in-southern-mexico-city-162-l/. 
  48. ↑ 48.0 48.1 48.2 Majchrzak, Amy (21 June 2004). "Ambystoma mexicanum (Salamandra ajolote)". https://animaldiversity.org/accounts/Ambystoma_mexicanum/. 
  49. ↑ AmphibiaWeb 2025 Ambystoma mexicanum: Mexican Axolotl <https://amphibiaweb.org/species/3842> University of California, Berkeley, CA, USA. Accessed May 9, 2026.
  50. ↑ AmphibiaWeb 2025 Ambystoma mexicanum: Mexican Axolotl <https://amphibiaweb.org/species/3842> University of California, Berkeley, CA, USA. Accessed May 9, 2026.
  51. ↑ Wainwright, P. C.; Sanford, C. P.; Reilly, S. M.; Lauder, G. V. (1989). "Evolution of motor patterns: aquatic feeding in salamanders and ray-finned fishes". Brain, Behavior and Evolution 34 (6): 329–341. doi:10.1159/000116519. PMID 2611639. 
  52. ↑ Stevenson, Mark (28 January 2014). "Mexico's 'water monster' may have disappeared". Mexico City. http://www.sfgate.com/news/science/article/Mexico-s-water-monster-may-have-disappeared-5182823.php. 
  53. ↑ Gander, Kashmira (24 February 2014). "Endangered 'water monster' Axolotl found in Mexico City lake" (in en-GB). The Independent. https://www.independent.co.uk/environment/axolotl-found-in-mexico-city-lake-after-scientists-feared-it-only-survived-in-captivity-9148775.html. 
  54. ↑ Nandini, Sarma; García, Pedro Ramirez; Sarma, S. S. S. (2016). "Water quality in Lake Xochimilco, Mexico: zooplankton indicators and Vibrio cholerae" (in en). Journal of Limnology 75 (1). doi:10.4081/jlimnol.2015.1213. ISSN 1723-8633. https://www.jlimnol.it/index.php/jlimnol/article/view/jlimnol.2015.1213. 
  55. ↑ Robles-Mendoza, C.; García-Basilio, C.; Cram-Heydrich, S.; Hernández-Quiroz, M.; Vanegas-Pérez, C. (1 February 2009). "Organophosphorus pesticides effect on early stages of the axolotl Ambystoma mexicanum (Amphibia: Caudata)" (in en). Chemosphere 74 (5): 703–710. doi:10.1016/j.chemosphere.2008.09.087. ISSN 0045-6535. PMID 19012946. Bibcode: 2009Chmsp..74..703R. https://www.sciencedirect.com/science/article/pii/S004565350801223X. 
  56. ↑ Parra-Plea, G; Zamudio, K.R.; Recuero, E.; Aguilar-=Miguel, X.; Huaxuz, D.; Zambrano, L. (2011). "Conservation genetics of threatened Mexican axolotls (Ambystoma)". Animal Conservation 15 (1): 61–72. doi:10.1111/j.1469-1795.2011.00488.x. 
  57. ↑ Woodcock, M. Ryan; Vaughn-Wolfe, Jennifer; Elias, Alexandra; Kump, D. Kevin; Kendall, Katharina Denise; Timoshevskaya, Nataliya; Timoshevskiy, Vladimir; Perry, Dustin W. et al. (31 January 2017). "Identification of Mutant Genes and Introgressed Tiger Salamander DNA in the Laboratory Axolotl, Ambystoma mexicanum" (in en). Scientific Reports 7 (1): 6. doi:10.1038/s41598-017-00059-1. ISSN 2045-2322. PMID 28127056. Bibcode: 2017NatSR...7....6W. 
  58. ↑ "Mexico City's 'water monster' nears extinction". November 2008. http://www.uswaternews.com/archives/arcglobal/8mexicity11.html. 
  59. ↑ Alcaraz, Guillermina; López-Portela, Xarini; Robles-Mendoza, Cecilia (1 July 2015). "Response of a native endangered axolotl, Ambystoma mexicanum (Amphibia), to exotic fish predator" (in en). Hydrobiologia 753 (1): 73–80. doi:10.1007/s10750-015-2194-4. ISSN 1573-5117. Bibcode: 2015HyBio.753...73A. 
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  62. ↑ Ramos, A.G.; Mena-Gonzalez, H.; Zambrano, L (2021). "The potential of temporary shelters to increase survival of the endangered Mexican axolotl". Aquatic Conservation: Marine and Freshwater Ecosystems 31 (6): 1535–1542. doi:10.1002/aqc.3520. Bibcode: 2021ACMFE..31.1535R. 
  63. ↑ Paúl, María Luisa (1 December 2023). "Mexico wants you to adopt an axolotl, the amphibian that never grows up" (in en-US). Washington Post. ISSN 0190-8286. https://www.washingtonpost.com/nation/2023/12/01/axolotl-mexican-salamander-adoption-campaign/. 
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  66. ↑ Gill, Victoria (30 April 2025). "Endangered axolotl release raises hopes for rare amphibian". https://www.bbc.co.uk/news/articles/cm2xr2jzelyo. 
  67. ↑ Tickell, Sofia Castello Y. (30 October 2012). "Mythic Salamander Faces Crucial Test: Survival in the Wild". The New York Times. https://www.nytimes.com/2012/10/31/world/americas/struggle-of-axolotls-mexicos-mythical-salamander.html. 
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  72. ↑ Gordon, R. (1985). "A review of the theories of vertebrate neurulation and their relationship to the mechanics of neural tube birth defects". Journal of Embryology and Experimental Morphology 89 (Supplement): 229–255. PMID 3913733. https://journals.biologists.com/dev/content/89/Supplement/229. 
  73. ↑ Armstrong, John B. (1985). "The axolotl mutants". Developmental Genetics 6 (1): 1–25. doi:10.1002/dvg.1020060102. 
  74. ↑ Roy, S; Gatien, S (November 2008). "Regeneration in axolotls: a model to aim for!". Experimental Gerontology 43 (11): 968–73. doi:10.1016/j.exger.2008.09.003. PMID 18814845. 
  75. ↑ Masselink, Wouter; Tanaka, Elly M.. "Toward whole tissue imaging of axolotl regeneration". Developmental Dynamics 250 (6): 800–806. doi:10.1002/dvdy.282. PMID 33336514. 
  76. ↑ Lust, Katharina; Tanaka, Elly M. (11 March 2025). "Adeno-associated viruses for efficient gene expression in the axolotl nervous system" (in en). Proceedings of the National Academy of Sciences 122 (10). doi:10.1073/pnas.2421373122. ISSN 0027-8424. PMID 40042904. Bibcode: 2025PNAS..12221373L. 
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  78. ↑ "Axolotls – Requirements & Water Conditions in Captivity". https://www.axolotl.org/requirements.htm. 
  79. ↑ "Caudata Culture Species Entry – Ambystoma mexicanum – Axolotl". http://www.caudata.org/cc/species/Ambystoma/A_mexicanum.shtml. 
  80. ↑ "Axolotl Care". Royal Veterinary College. https://www.rvc.ac.uk/Media/Default/small-animal/documents/Axolotl%20care.pdf. 
  81. ↑ Cirit, Şeyma S.; Deniz, Şinasi B.; Cirit, Burhan; Bayraktar, Abdulahad (May 2025). "Management of Hydrocoelom in an Axolotl (Ambystoma mexicanum)". Veterinary Medicine and Science 11 (3). doi:10.1002/vms3.70373. PMID 40387063. PMC 13045757. https://onlinelibrary.wiley.com/doi/10.1002/vms3.70373. Retrieved 20 May 2026. 
  82. ↑ Wiegert, Joshua. "Axolotls: Keeping a Water Monster". https://www.tfhmagazine.com/articles/freshwater/axolotls-keeping-a-water-monster-full. 
  83. ↑ Strecker, Angela L.; Campbell, Philip M.; Olden, Julian D. (2011). "The Aquarium Trade as an Invasion Pathway in the Pacific Northwest". Fisheries 36 (2): 74–85. doi:10.1577/03632415.2011.10389070. Bibcode: 2011Fish...36...74S. https://pdxscholar.library.pdx.edu/esm_fac/40. 
  84. ↑ 84.0 84.1 Pough, F. H. (1992). "Recommendations for the Care of Amphibians and Reptiles in Academic Institutions". Washington, D.C.: National Academy Press. https://netvet.wustl.edu/species/reptiles/pough.txt. 
  85. ↑ Clayton, Leigh Ann; Gore, Stacey R. (2007). "Amphibian Emergency Medicine". Veterinary Clinics of North America: Exotic Animal Practice 10 (2): 587–620. doi:10.1016/j.cvex.2007.02.004. PMID 17577564. 
  86. ↑ Gresens, Jill (2004). "An Introduction to the Mexican Axolotl (Ambystoma mexicanum)". Lab Animal 33 (9): 41–47. doi:10.1038/laban1004-41. PMID 15457201. 
  87. ↑ Wings, Oliver (2007). "A review of gastrolith function with implications for fossil vertebrates and a revised classification". Acta Palaeontologica Polonica 52 (1): 1–16. http://www.dinosaurhunter.org/files/app-2007-wings-gastrolith_function_classification.pdf. 
  88. ↑ "Gastroliths – How I Learned to Stop Worrying and Love Gravel". 10 September 2015. https://embryogenesisexplained.org/2015/09/10/gastroliths-how-i-learned-to-stop-worrying-and-love-gravel/. 
  89. ↑ Björklund, Natalie K. (1993). "Small is beautiful: economical axolotl colony maintenance with natural spawnings as if axolotls mattered". Handbook on Practical Methods. Department of Biology, Indiana University: Bloomington. pp. 38–47. 
  90. ↑ Loh, Richmond (15 May 2015). Common Disease Conditions in Axolotls. https://www.vin.com/apputil/content/defaultadv1.aspx?pId=14365&catId=73681&id=7259254. Retrieved 21 January 2022. 
  91. ↑ Clare, John P.. "Health and Diseases". https://www.axolotl.org/health.htm. 
  92. ↑ "Transition & Feeding" (in en). https://www.morphedaxolotls.com/transition-and-feeding. 
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  94. ↑ Penman-Lomeli, Andrea (1 August 2017). "Summing Up Mexico City Using Only Emojis" (in en). Bloomberg.com. https://www.bloomberg.com/news/articles/2017-08-01/summing-up-mexico-city-using-only-emojis. 
  95. ↑ "Mexican axolotl will be the new image of the 50 peso bill" (in en-US). 21 February 2020. https://www.theyucatantimes.com/2020/02/mexican-axolotl-will-be-the-new-image-of-the-50-peso-bill/. 
  96. ↑ "Billete de 50 pesos de la familia G" (in es). https://www.banxico.org.mx/billetes-y-monedas/billete-50-pesos-familia-g.html. 
  97. ↑ "Banknote of 2021 Nominations". https://www.theibns.org/joomla/index.php?option=com_content&view=article&id=809:banknote-of-2021-nominations&catid=39:banknote-of-2021&Itemid=51. 
  98. ↑ Graham, Thomas (21 November 2025). "A lot of axolotls: the amphibian-themed banknote Mexicans don't want to spend". The Guardian. https://www.theguardian.com/world/2025/nov/21/axolotl-banknote-mexico-amphibian. 
  99. ↑ Kojima, Akira (28 June 2021). "神戸新聞NEXT｜連載・特集｜話題｜「ウーパールーパー」を覚えていますか “昭和”に一世風靡した不思議な生き物、今もペットとして根強い人気" (in Japanese). http://www.kobe-np.co.jp/rentoku/omoshiro/202106/0014451008.shtml. 
  100. ↑ Adamson, Carly J.; Morrison‐Welch, Nikolas; Rogers, Crystal D. (April 2022). "The amazing and anomalous axolotls as scientific models". Developmental Dynamics 251 (6): 922–933. doi:10.1002/dvdy.470. ISSN 1058-8388. PMC 9536427. https://doi.org/10.1002/dvdy.470. 
  101. ↑ Renard, Jean-Bruno (February 2010). "L'axolotl. De la controverse scientifique au mythe littéraire". Cairn.info 108 (2): 19–32. doi:10.3917/soc.108.0019. https://www.cairn.info/revue-societes-2010-2-page-19.htm. Retrieved 15 February 2026. 
  102. ↑ Minecraft (3 October 2020). ""Minecraft Live: Caves & Cliffs – First Look"". https://www.youtube.com/watch?v=DBvZ2Iqmm3M&t=2486s. ""And then we also found out that axolotls are endangered in the real world, and we think it's good to add endangered animals to Minecraft to create awareness about that." – Agnes Larsson" 
  103. ↑ "The Guardian Battle 21180" (in en). https://www.lego.com/en-us/product/the-guardian-battle-21180. 
  104. ↑ "The Axolotl House 21247" (in en). https://www.lego.com/en-us/product/the-axolotl-house-21247. 
  105. ↑ "Axolotl: The Real Julio Cortazar". Harvard University. https://hum11c.omeka.fas.harvard.edu/exhibits/show/readings/axolotl--the-real-julio-cortaz. 
  106. ↑ "Axolotl, Xolotl, and Religion". Harvard University. https://hum11c.omeka.fas.harvard.edu/exhibits/show/readings/axolotl--xolotl--and-religion. 
  107. ↑ "Approved names" (in en). https://www.nameexoworlds.iau.org/final-results. 
  108. ↑ "100 000s of People from 112 Countries Select Names for Exoplanet Systems In Celebration of IAU's 100th Anniversary". 17 December 2019. https://www.iau.org/news/pressreleases/detail/iau1912/. 

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