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AxolotlAmbystoma mexicanum

Every figure, record and mechanism on the Axolotl profile was written from a source, and this is the working table behind it: 58 claims checked word for word against these sources. The left column is what the page says. The right column is the source's own words, copied, not paraphrased; a ... marks a cut and[brackets] an insertion. Open any source and check it yourself.

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Source
01

Animal Diversity Web, University of Michigan

Ambystoma mexicanum (axolotl). Animal Diversity Web, University of Michigan.

The page sayskeeps its larval gills as an adult
The source saysJuvenile and adult axolotls possess feathery, external gills and tail fins suited to an aquatic lifestyle.
The page saysA cyber-larva with feather-antenna gills it keeps into adulthood
The source saysJuvenile and adult axolotls possess feathery, external gills and tail fins suited to an aquatic lifestyle.
The page saysLake Xochimilco canal waterways at the southern edge of Mexico City
The source saysLake Xochimilco is now nothing more than a scattering of canals and swamps.
The page saysMollusks, fish, insects and other arthropods, even other axolotls
The source saysaxolotls will eat anything that they can catch, including molluscs, fishes, and arthropods, as well as conspecifics.Note: 'Insects' is from ADW's Animal Foods list (amphibians, fish, insects, mollusks, terrestrial worms, zooplankton); conspecifics means other axolotls.
The page sayskeeps its larval gills as a breeding adult
The source saysA. mexicanum is paedomorphic, which means that it retains larval characteristics in the reproductively mature adult form. Juvenile and adult axolotls possess feathery, external gills
The page saysIt usually keeps its larval features into adulthood and lives its whole life cycle in water, a condition called neoteny
The source saysAxolotls are paedomorphic or neotenic aquatic salamanders, meaning they retain certain larval characteristics in the adult, reproductive state.
The page saysIn the wild it rarely, if ever, metamorphoses.
The source saysIn the wild, axolotls rarely, if ever, metamorphose.
The page saysfeathery external gills
The source saysThey possess feathery external gills and finned tails for swimming.
The page saysThrough paedomorphosis, often called neoteny: axolotls keep larval features like their feathery external gills and finned tail into breeding adulthood
The source saysAxolotls are paedomorphic or neotenic aquatic salamanders, meaning they retain certain larval characteristics in the adult, reproductive state. They possess feathery external gills and finned tails for swimming.
The page saysin the wild they rarely, if ever, metamorphose
The source saysIn the wild, axolotls rarely, if ever, metamorphose.
The page saysGive an axolotl thyroid hormone and it can go through metamorphosis anyway.
The source saysMetamorphosis can be induced in axolotls via thyroid hormone injections.
The page saysnow a scattering of canals and swamps at the southern edge of Mexico City
The source saysLake Xochimilco is now nothing more than a scattering of canals and swamps.

Source
02

Ramos et al. 2025

Ramos et al. (2025). Movement ecology of captive-bred axolotls in restored and artificial wetlands: Conservation insights for amphibian reintroductions and translocations. PLOS ONE.

The page saysCritically Endangered
The source saysa critically endangered aquatic species endemic to Lake XochimilcoNote: Ramos et al. cite the IUCN Red List version 2024-1 for the status. iucnredlist.org refuses scripts, so the 2020 assessment itself was not read.
The page saysYes, critically endangered.
The source saysa critically endangered aquatic species endemic to Lake XochimilcoNote: Ramos et al. (2025) cite the IUCN Red List version 2024-1.
The page saysbut in the wild they live only in Lake Xochimilco
The source saysA. mexicanum is endemic to Lake Xochimilco, the last remnant of a once-extensive wetland system in the Central Valley of Mexico
The page sayswhile untreated wastewater, farm runoff and a spreading city have fouled the water and driven a marked decline
The source saysUrban expansion, environmental degradation, invasive species, and a severe decline in water quality—driven by untreated wastewater discharge, agricultural runoff, and surrounding urbanization—have led to a marked decline in axolotl populations

Source
03

Voss, Woodcock & Zambrano 2015

Voss, Woodcock & Zambrano (2015). A Tale of Two Axolotls. BioScience.

The page saysAxolotls are a much-loved aquarium pet and lab animal around the world
The source saysThe Mexican axolotl (Ambystoma mexicanum) is an icon of culture, a revered aquarium pet, and a highly valued animal model in biomedical research.
The page saysAxolotls are a much-loved aquarium pet and lab animal around the world
The source saysthe laboratory populations that are needed to sustain research efforts around the world

Source
04

Contreras et al. 2009

Contreras et al. (2009). Recent decline and potential distribution in the last remnant area of the microendemic Mexican axolotl (Ambystoma mexicanum). Biological Conservation.

The page saysLake Xochimilco canal waterways at the southern edge of Mexico City
The source saysThe last remnant of its distribution is in a highly heterogeneous urban-rural water system in the Xochimilco region, at the southern edge of Mexico City.
The page saysnow a scattering of canals and swamps at the southern edge of Mexico City
The source saysin the Xochimilco region, at the southern edge of Mexico City
The page saysA 2009 habitat model picked out just 11 sites there still suitable for them, and surveys at the time had found only one axolotl in the whole study area.
The source saysResults indicated that potential distribution of the axolotl in Xochimilco is limited to 11 sites in six reduced, isolated, and scattered areas ... Recent surveys found only a single organism in the whole study region, in one of the predicted sites

Source
05

Zambrano, Valiente & Vander Zanden 2010

Zambrano, Valiente & Vander Zanden (2010). Food web overlap among native axolotl (Ambystoma mexicanum) and two exotic fishes: carp (Cyprinus carpio) and tilapia (Oreochromis niloticus) in Xochimilco, Mexico City. Biological Invasions.

The page saysIntroduced carp and tilapia came to dominate the canals and overlap heavily with axolotls in what they eat
The source saysTwo exotic fishes, common carp (Cyprinus carpio) and tilapia (Oreochromis niloticus), were introduced more than 20 years ago into Xochimilco for aquaculture, and now dominate the system in terms of biomass and numbers.
The page saysIntroduced carp and tilapia came to dominate the canals and overlap heavily with axolotls in what they eat
The source saysStable isotope analysis revealed substantial trophic niche overlap among axolotl and the exotics.

Source
06

Crowner et al. 2019

Crowner et al. (2019). Rediscovering the Axolotl as a Model for Thyroid Hormone Dependent Development. Frontiers in Endocrinology.

The page saysWhile its close relative the tiger salamander is known to always go through metamorphosis and head for a boring, mostly land-based adult life
The source saysThe ancestral mode of development in salamanders is generally thought to include a single, obligate metamorphosis which partitions the life cycle between an early aquatic phase and a more terrestrial adult phase. Indeed, close tiger salamander ... relatives of the axolotl are known to invariably undergo a metamorphosis
The page saysIt usually keeps its larval features into adulthood and lives its whole life cycle in water, a condition called neoteny
The source saysthe axolotl does not typically undergo a metamorphosis. Instead, the axolotl exhibits a paedomorphic mode of development that enables a completely aquatic life cycle.
The page saysThyroid hormone drives amphibian metamorphosis, and in the tiger salamander a rise in it triggers the change.
The source saysMetamorphosis in the tiger salamander is regulated by the hypothalamus-pituitary-thyroid (HPT) axis. At a critical time during larval development, corticotrophin releasing hormone (CRH) from the hypothalamus stimulates thyrotrophic cells in the pituitary to release thyroid stimulating hormone (TSH), which in turn stimulates the thyroid gland to secrete thyroid hormone (TH). Increasing TH (+) triggers metamorphic changes in target cells.
The page saysThyroid hormone drives amphibian metamorphosis
The source saysThyroid hormones play a central role in regulating amphibian metamorphosis
The page saysAn axolotl's thyroid hormone stays low through larval development and doesn't rise at the point where its close relative, the tiger salamander, metamorphoses.
The source saysTH levels in the axolotl remain low throughout larval development and do not increase at the time metamorphosis occurs in related tiger salamanders.
The page saysStudies suggest a fault in the chain of signals from the hypothalamus to the pituitary to the thyroid gland, perhaps at the hypothalamus or pituitary, but the exact mechanism is still unknown.
The source saysCollectively, these and other results suggest a defect in the regulation of the HPT axis, perhaps at the level of the hypothalamus or pituitary
The page saysStudies suggest a fault in the chain of signals from the hypothalamus to the pituitary to the thyroid gland, perhaps at the hypothalamus or pituitary, but the exact mechanism is still unknown.
The source saysthe mechanism associated with its unique paedomorphic mode of development remains unknown
The page saysGive an axolotl thyroid hormone and it can go through metamorphosis anyway.
The source saysthe axolotl is capable of initiating and completing metamorphosis when thyroid hormone and other endocrine factors of the HPT axis are administered

Source
07

McCusker, Bryant & Gardiner 2015

McCusker, Bryant & Gardiner (2015). The axolotl limb blastema: cellular and molecular mechanisms driving blastema formation and limb regeneration in tetrapods.

The page sayscan regrow whole legs
The source saysThe axolotl is one of the few tetrapods that are capable of regenerating complicated biological structures, such as complete limbs, throughout adulthood.
The page saysRegrows whole limbs
The source sayscapable of regenerating complicated biological structures, such as complete limbs, throughout adulthood
The page saysThe new limb comes from a blastema, a mass of stem-like cells that grows, lays out the pattern and turns into the missing parts.
The source saysUpon injury the axolotl generates a population of regeneration-competent limb progenitor cells known as the blastema, which will grow, establish pattern, and differentiate into the missing limb structures.Note: 'stem-like cells' paraphrases 'progenitor cells' for the 11-14 audience.
The page saysCut off a limb and cells from the stump form a blastema of stem-like cells that rebuilds the whole thing.
The source saysMultiple cell types from the mature limb stump contribute to the blastema at different stages of regeneration
The page saysScientists study them in the hope of better regenerative treatments for humans.
The source sayswith the goal of translating these concepts to developing better human regenerative therapies
The page saysAt a lost limb, cells from the stump form a blastema, a mass of stem-like cells that grows, lays out the pattern and turns into the missing parts.
The source saysUpon injury the axolotl generates a population of regeneration-competent limb progenitor cells known as the blastema, which will grow, establish pattern, and differentiate into the missing limb structures.

Source
08

Andersson, Dittrich & Lauridsen 2023

Andersson, Dittrich & Lauridsen (2023). Continuous anesthesia for 60 days in an isosmotic environment does not impair limb or cardiac regeneration in the axolotl. Scientific Reports.

The page saysparts of its own brain and heart
The source saysNo differences were detected in the axolotl's ability to regenerate amputated limbs and cardiac cryo-injury while anesthetized
The page saysable to regrow its limbs and parts of its heart and brain
The source saysNo differences were detected in the axolotl's ability to regenerate amputated limbs and cardiac cryo-injury while anesthetized
The page saysIn one lab study, most adult axolotls had regrown a complete front leg by 60 days after amputation.
The source saysRepresentative photos of amputated right front limb in anesthetized and unanesthetized axolotls at 0, 10, 24, 35, 48 and 60 days post amputation (dpa). Most axolotls showed complete limb regeneration except from one animal from each of the anesthetized and unanesthetized groups
The page saysIn one lab study, most adult axolotls had regrown a complete front leg by 60 days after amputation.
The source saysthe present study was performed using adult axolotls
The page sayspart of a damaged heart
The source saysAll groups showed functional regeneration of the heart expressed as a decrease in the non-contraction fraction
The page sayspart of the heart's ventricle
The source saysThe non-contraction fraction of the ventricle in axolotls with a cardiac cryoinfarction housed in either tap water or Ringer's solution with or without feeding for 60 days. All groups showed functional regeneration of the heart
The page saysSixty days to a new leg
The source saysRepresentative photos of amputated right front limb in anesthetized and unanesthetized axolotls at 0, 10, 24, 35, 48 and 60 days post amputation (dpa). Most axolotls showed complete limb regeneration except from one animal from each of the anesthetized and unanesthetized groupsNote: blockquote lead-in; 60 days from the same study

Source
09

Godwin et al. 2017

Godwin et al. (2017). Heart regeneration in the salamander relies on macrophage-mediated control of fibroblast activation and the extracellular landscape. npj Regenerative Medicine.

The page saysA patch of heart damaged by freezing heals without a permanent one too, as long as immune cells called macrophages are there early on: remove them and the heart scars for good.
The source saysUsing a cardiac cryo-injury model we show that heart regeneration is dependent on the innate immune system, as macrophage depletion during early time points post-injury results in regeneration failure. In contrast to the transient extracellular matrix (ECM) that normally accompanies regeneration, this intervention resulted in a permanent, highly cross-linked extracellular matrix scar

Source
10

McHedlishvili et al. 2012

McHedlishvili et al. (2012). Reconstitution of the central and peripheral nervous system during salamander tail regeneration. Proceedings of the National Academy of Sciences.

The page saysits tail and spinal cord
The source saysafter tail amputation in Ambystoma mexicanum (Axolotl) the correct number and spacing of dorsal root ganglia are regenerated ... implantation of a clonally derived spinal cord neurosphere can result in reconstitution of all examined cell types in the regenerating central spinal cord
The page saysAxolotls can also regrow a tail with its spinal cord
The source saysimplantation of a clonally derived spinal cord neurosphere can result in reconstitution of all examined cell types in the regenerating central spinal cord

Source
11

Kramer et al. 2024

Kramer et al. (2024). Axolotl mandible regeneration occurs through mechanical gap closure and a shared regenerative program with the limb. Disease Models & Mechanisms.

The page saysa missing section of lower jaw
The source saysAxolotls, unlike humans, are capable of regenerating their lower jaws ... we used morphological, histological and transcriptomic approaches to analyze the regeneration of lateral resection defects in the axolotl mandible. We found that this structure can regenerate all missing tissues in 90 days

Source
12

Amamoto et al. 2016

Amamoto et al. (2016). Adult axolotls can regenerate original neuronal diversity in response to brain injury. eLife.

The page saysparts of its own brain and heart
The source saysThe axolotl can regenerate multiple organs, including the brain.
The page saysparts of its heart and brain
The source saysupon mechanical injury to the adult pallium, axolotls can regenerate several of the populations of neurons present before injury
The page saysseveral kinds of neuron lost from an injured patch of brain
The source saysupon mechanical injury to the adult pallium, axolotls can regenerate several of the populations of neurons present before injury
The page saysseveral kinds of neuron lost from an injured patch of the pallium
The source saysupon mechanical injury to the adult pallium, axolotls can regenerate several of the populations of neurons present before injury
The page saysa forebrain region likely to hold basic versions of some neuron types found in our cerebral cortex
The source saysthe gross neuroanatomy of the axolotl pallium, organized around two ventricles, shows clear similarities to that of the mammalian telencephalon. In addition, while the evolutionary origin of the mammalian cerebral cortex remains controversial ( Molnár, 2011 ), it is likely that the axolotl pallium contains a basic representation of several of the neuronal subtypes found in the mammalian cerebral cortex
The page saysThe brain has a limit: its new neurons don't rebuild their old long-distance connections.
The source saysnewborn neurons organize within altered tissue architecture and fail to re-establish the long-distance axonal tracts and circuit physiology present before injury

Source
13

Seifert et al. 2012

Seifert et al. (2012). Skin Regeneration in Adult Axolotls: A Blueprint for Scar-Free Healing in Vertebrates. PLoS ONE.

The page saysheals deep skin wounds without a scar
The source sayswe have investigated the wound repair process in adult axolotls and demonstrate that they are capable of perfectly repairing full thickness excisional wounds made on the flank
The page saysMammals like us patch a deep skin wound with a permanent scar
The source saysthe skin is injured more frequently than any other tissue and resulting damage, while repairable, leads to permanent scarring in mammals
The page saysan adult axolotl regrows the skin with no scar at all
The source saysHere we demonstrate that both aquatic and terrestrial axolotls are capable of perfect, scar-free skin regeneration.
The page saysDeep skin wounds heal without a scar.
The source saysthey are capable of perfectly repairing full thickness excisional wounds made on the flank

How the table was made: a writer drafted the profile from these sources and logged each claim with its quote, a reviewer with nothing but this table checked every sentence said no more than its quote, and a script confirmed each quote appears word for word in the source. The method is in the site'sAbout page.