The axolotl also known as a Mexican salamander (Ambystoma mexicanum) , is a neotenic (meaning they reach sexual maturity without undergoing metamorphosis.) salamander. Known as a "walking fish", it is not a fish, but an amphibian.
As of 2010, wild axolotls were near extinction due to urbanization in Mexico City and consequent water pollution
A sexually mature adult axolotl, at age 18–24 months, ranges in length from 15–45 cm (6–18 in), although a size close to 23 cm (9 in) is most common and 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.
The primary method of feeding is by suction, during which their rakers interlock to close the gill slits. External gills are used for respiration, although buccal pumping (gulping air from the surface) may also be used to provide oxygen to their lungs. 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.
As for all poikilothermic organisms, lower temperatures result in slower metabolism and a very unhealthily reduced appetite.
A single typical axolotl typically requires a 40-litre (11-US-gallon) tank with a water depth of at least 15 cm (6 in). Axolotls spend a majority of the time at the bottom of the tank.
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.
Axolotls have four pigmentation genes which when mutated create different color variants. The normal wild type animal is brown/tan with gold speckles and an olive undertone. The four mutant colors are leucistic (pale pink with black eyes), albino (golden with gold eyes), axanthic (grey with black eyes) and melanoid (all black 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 that develops a black and white piebald appearance on reaching maturity. Because pet breeders frequently cross the variant colors, animals that are double recessive 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 trait. Axolotls also have some limited ability to alter their color to provide better camouflage by changing the relative size and thickness of their melanophores
Axolotls are famous for their fabulous regeneration ability. Regeneration studies carried out around the world often involve the Axolotl. For example, a young axolotl that loses a foot to a sibling will usually grow it back over a period of a few weeks. This regeneration occurs via the formation of a "bud" at the end of the damaged appendage, followed by growth of the new foot. Entire limbs can be regenerated and even portions of the brain and spine.
Xolotl was a dog-headed god from Aztec mythology. God of all things grim, the deity would lead the souls of the dead to the underworld. As with all mythology, there a lot of mixed accounts about what happened next, but some believe that Xolotl was fearful of being killed and transformed into an axolotl to hide. The salamander is trapped in the water of Xochimilco, unable to transform and walk on land.