Axolotl (Ambystoma mexicanum)
Image credit: © San Diego Zoo Wildlife Alliance. All rights reserved.
Taxonomy |
Physical Characteristics |
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Kingdom: Animalia Phylum: Chordata Class: Amphibia &mash; amphibians Order: Caudata — salamanders Family: Ambystomatidae — mole salamanders Genus: Ambystoma Species: Ambystoma mexicanum — axolotl, Mexican axolotl, salamandra axolote |
WeightMale: about 125–130g (4.4–4.6 oz) Total Lengthup to 30 cm (12 in) Head Length40–46 mm (1.6–1.8 in) Tail Length97–120 mm (2.4–3.0 in) General AppearanceLarge body with wide trunk. Large head with wide-set eyes and feathery external gill branches. Tadpole or eel-like tail. ColorationWild: black to dark brown with black spots |
Distribution & Status |
Behavior & Ecology |
RangeOnly found at 3 isolated sites in the southern Mexico City. (Also present worldwide in research laboratories, zoos, and pet collections.) Historically found in permanent lakes, wetlands, and watersheds of the Mexican Central Valley; absent from most of its former range. HabitatDeep-water lakes, wetlands, and canals (formed by erosion and excavated by humans). Also associated with cold-water springs in Xochimilco. IUCN StatusCritically Endangered (2019 assessment) CITES AppendixAppendix II Other DesignationsProtected in Mexico as an endangered species. Populations in the WildRoughly 50–1,000 adults remaining; approximately 36 per km2 in a 2014 population census. Threats to SurvivalLoss and degradation of habitat; poor water quality; urbanization; introduced fish. Formerly traded for food, traditional medicine, and as biomedical specimens. |
LocomotionLarvae and adults mostly benthic and typically rest on the bottom of lakes or canals. Adults usually walk but also swim by undulating their body and tail with eel-like movement. Adapted for maneuverability through lake vegetation, rather than speed. Activity PatternsNot reported in detail for wild populations. In managed care, some reports of higher nighttime activity. CommunicationUsing chemical cues/odors, detect sex and reproductive status of other axolotls. Little known about communication using other senses. Diet (wild populations)Adults and juveniles: Small fish and invertebrates, including insects, worms, and crustaceans; also semiaquatic flies and algae. PredatorsFew native predators. Introduced fish and native crayfish feed on larvae and juveniles. Also possibly aquatic birds and snakes. Relationship with HumansInternationally used as a model organism for biomedical, developmental, and regeneration research. Common in zoos and educational settings. Also kept as pets. Pop culture icon. Prominent in Mexican history and Latin American identity. Represented in Aztec art and mythology. Previously traded in Mexico for food and traditional medicines. |
Reproduction & Development |
Species Highlights |
Sexual MaturityApproximately 1.5 years old; possibly shorter in managed care Incubation PeriodInfluenced by water temperature. In managed care, eggs hatch after about 2 weeks at 20°C (70°F) but can take up to 4 weeks under cooler conditions. Clutch SizeWidely variable. In managed care, females can lay several hundred to sometimes more than 1,000 eggs at a time. Interclutch IntervalIn managed care, females can lay several clutches per year. Hatchling SizeLarvae approximately 2–3 mm in diameter Typical Life ExpectancyWild populations: not reported |
Feature Facts
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© 2023 San Diego Zoo Wildlife Alliance
How to cite: Axolotl (Ambystoma mexicanum) Fact Sheet. c2023. San Diego (CA): San Diego Zoo Wildlife Alliance; [accessed YYYY Mmm dd]. http://ielc.libguides.com/sdzg/factsheets/axolotl.
(note: replace YYYY Mmm dd with date accessed, e.g., 2019 Dec 31)
Disclaimer: Although San Diego Zoo Wildlife Alliance makes every attempt to provide accurate information, some of the facts provided may become outdated or replaced by new research findings. Questions and comments may be addressed to library@sdzwa.org.
Thank you to Profs. Luiz Zambrano and Diana Laura Vázquez Mendoza for providing content review of this fact sheet.
Zambrano, a professor of biology at the National Autonomous University of Mexico (UNAM/Universidad Nacional
Autónoma de México) in Mexico City, has investigated axolotl ecology and conservation for more than 20 years. In the early 2000s, he conducted census counts that documented severe declines in wild axolotl populations. Zambrano continues to help lead axolotl conservation projects, with a focus on collaboration with local communities in Mexico City. These projects include partnering with local farmers to create axolotl refuge habitat areas and promoting sustainable agriculture.
Internationally, Zambrano contributes his expertise to axolotl conservation action plans, IUCN Red List assessments, education and outreach efforts, and through interviews, such as for Nature, Smithsonian, NPR, National Geographic, and other journalistic outlets. In 2021, he co-authored the book Xochimilco en el Siglo XXI (Xochimilco in the 21st Century), which explores the history of Xochimilco and axolotl conservation.
Zambrano’s research encompasses areas of trophic ecology (food webs), predator–prey relationships, agriculture and biodiversity planning, urban ecological restoration, and conservation genetics. View a list of Prof. Zambrano's publications.
Vázquez Mendoza is an adjunct professor at the National Autonomous University of Mexico (UNAM/Universidad Nacional
Autónoma de México) in Mexico City and coordinator of axolotl conservation programs, such as Etiqueta Chinampera and “Adopt an Axolotl.” These programs aim to maintain the axolotl “chinampa refuge” program, which protects axolotl habitat, and promote the health of axolotls in local assurance colonies.
Vázquez Mendoza’s socio-ecological research interests include urban agriculture, wetland restoration, sustainable cities, climate change, and natural resource management, particularly in communities near Mexico City. She is also an accredited environmental educator.
Her bachelor’s thesis at UNAM investigated the use of chinampera practices and the conservation of biodiversity in Lake Xochimilco.
Thank you to Prof. David W. Weisrock for reviewing and contributing his knowledge to the Evolutionary History section of this fact sheet.
Weisrock, a professor at the University of Kentucky, has investigated the genetics, genomics, and evolutionary biology of amphibians, including the axolotl and other North American tiger salamanders. Recent systematics and population genetics studies have been published in PNAS, Molecular Ecology, and Systematic Biology.
Learn more about Prof. Weisrock's laboratory and published research.
Thank you to Joseph Boucree for sharing his knowledge of axolotl husbandry for the Managed Care section of this fact sheet.
Boucree leads the team caring for axolotls at the San Diego Zoo. He has worked as a wildlife care specialist in herpetology and ichthyology with San Diego Zoo Wildlife Alliance since 2021. Prior to this position, Boucree served in SDZWA's Wildlife Care Professional Development Program for 2 years and earned a M.A. in Conservation Biology through the joint SDZWA–Miami University Advanced Inquiry Program.
Sharing a passion for unique species and their life histories is part of Boucree's personal mission. He enjoys talking with guests, using facts about anatomy and evolutionary relationships to highlight the beauty of amphibians and reptiles.
In addition to axolotl care, Boucree likes working with the dwarf caiman at Wildlife Explorers Basecamp and the oldest residents at the San Diego Zoo, the Galapagos tortoises.
Clean, clear water supports axolotl health and helps them visually detect prey.
Because these amphibians live near a large city, axolotls face many water quality problems: excessive bacteria and nutrients, heavy metals, and sewage/waste pollution.
Conservation biologists and local farmers (chinamperos) are working to improve water quality and exclude introduced fish from axolotl habitat.
Image credit: © San Diego Zoo Wildlife Alliance. All rights reserved.
