The axolotl is only native to Lake Xochimilco and Lake Chalco in central Mexico.
Habitat and ecology:
Unfortunately for the axolotl, Lake Chalco no longer exists as it was artificially drained to avoid periodic flooding, and Lake Xochimilco remains a diminished glimpse of its former self, existing mainly as canals. The wild population has been put under heavy pressure by the growth of Mexico City. Axolotls are also sold as food in Mexican markets and were a staple in the Aztec diet. They are currently listed by CITES as an endangered species and by IUCN as critically endangered in the wild, with a decreasing population.
Feeding & Habits:
The axolotl is carnivorous, consuming small prey such as worms, insects, and small fish in the wild. Axolotls locate food by smell, and will "snap" at any potential meal, sucking the food into their stomachs with vacuum force.
Axolotls exhibit a property called neoteny, meaning that they reach sexual maturity without undergoing metamorphosis. Many species within the axolotl's genus are either entirely neotenic or have neotenic populations. In the axolotl, metamorphic failure is caused by a lack of thyroid stimulating hormone, which is used to induce the thyroid to produce thyroxin in transforming salamanders. The genes responsible for neoteny in laboratory animals may have been identified; however, they are not linked in wild populations, suggesting artificial selection is the cause of complete neoteny in laboratory and pet axolotls.
Use as a model organism:
The feature of the salamander that attracts most attention is its healing ability: the axolotl does not heal by scarring and is capable of the regeneration of entire lost appendages in a period of months, and, in certain cases, more vital structures. Some have indeed been found restoring the less vital parts of their brains. They can also readily accept transplants from other individuals, including eyes and parts of the brain—restoring these alien organs to full functionality. In some cases, axolotls have been known to repair a damaged limb as well as regenerating an additional one, ending up with an extra appendage that makes them attractive to pet owners as a novelty. In metamorphosed individuals, however, the ability to regenerate is greatly diminished. The axolotl is therefore used as a model for the development of limbs in vertebrates.