Research history Alexander von Humboldt noted 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". Six adult axolotls (including a leucistic specimen) were shipped from
Mexico City to the
Jardin des Plantes in Paris in 1863. Unaware of their neoteny,
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. Vilem Laufberger in Prague used thyroid hormone injections to induce an axolotl to grow into a terrestrial adult salamander. The experiment was repeated by Englishman
Julian Huxley, who was unaware the experiment had already been done, using ground thyroids. Since then, experiments have often been done with injections of iodine or various thyroid hormones used to induce metamorphosis.
Use as a model organism ) Today, the axolotl is still used in research as a
model organism, and large numbers are bred in captivity. They are especially easy to breed compared to other salamanders in their family, which are rarely captive-bred due to the
husbandry demands of terrestrial life. One attractive feature for research 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 embryos survive almost to hatching with no heart function, the defect is very observable. Further research has been conducted to examine their heart as a model of a single human
ventricle and excessive trabeculation. 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 a
frog's, is not hidden under a layer of superficial
epithelium. There are also mutations affecting other organ systems, some of which are not yet well characterized. 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 understand how humans can achieve better ways to heal from serious injuries. They also leave the species as the perfect model to study the process of
stem cells and neoteny. Current research can record specific examples of these regenerative properties through tracking cell fates and behaviors, lineage tracing 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. In a 2025 study, scientists found a new way to insert and activate the genes inside the axolotl's brain and nervous system using special, harmless viruses called Adeno-Associated Viruses (AAVs). Before this, it was hard 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 like its brain and spinal cord. Additionally, they found that the axolotl's nervous system has a unique two-way communication between the brain and eye. The genetics of the color variants of the axolotl have also been widely studied. The axolotl is a popular
exotic pet like its relative, the tiger salamander (
Ambystoma tigrinum). As for all
poikilothermic organisms, lower temperatures result in slower metabolism and reduced appetite. Temperatures at approximately to are suggested for captive axolotls to ensure sufficient food intake; temperatures higher than may lead to metabolic rate increase, also causing stress and eventually death.
Chlorine, commonly added to
tapwater, is harmful to axolotls. A single axolotl typically requires a tank. Axolotls spend the majority of the time at the bottom of their tanks. 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.
Substrates are another important consideration for captive axolotls, as axolotls (like other amphibians and reptiles) tend to ingest bedding material together with food 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. 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. There is some evidence that axolotls might seek out appropriately-sized gravel for use as
gastroliths based on experiments conducted at the University of Manitoba axolotl colony. As there is no conclusive evidence pointing to gastrolith use, gravel should be avoided due to the high risk of
impaction. Salts, such as
Holtfreter's solution, are often added to the water to prevent infection. 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. File: Ambystoma mexicanum at Vancouver Aquarium.jpg|These axolotls at
Vancouver Aquarium are
leucistic, with less pigmentation than normal. File:Axolotl in a Pet store in Melbourne.jpg|Axolotls in a pet store in Melbourne, Australia File:Axolotls in Kew Gardens.jpg|Axolotls in a pond with
Pistia,
Kew Gardens Cultural significance in Mexico City The species is named after the
Aztec deity Xolotl, the god of fire and lightning, who transformed himself into an axolotl to avoid being sacrificed by fellow gods. They continue to play an outsized cultural role in Mexico. For example, axolotls appear in the works of Mexican muralist
Diego Rivera. In 2021, Mexico released a new design for its 50-
peso banknote featuring an axolotl, along with
maize and
chinampas, on its back. It was recognized as "Bank Note of the Year" by the
International Bank Note Society. 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. In 1999,
Pokémon Gold and Silver, made by Japanese developer
Game Freak, introduced the Pokémon
Wooper, which is directly based on an axolotl. Additionally, in 2002,
Pokémon Ruby and Sapphire introduced the Pokémon
Mudkip and its evolutions, which take some visual inspiration from axolotls. and were included in its spin-offs
Minecraft: Dungeons and
Lego Minecraft. The dragon Toothless in the
How to Train Your Dragon movies was modeled after axolotls as well.
HD 224693, a
star in the
equatorial constellation of
Cetus, was named Axólotl in 2019. ==See also==