The axolotl (Ambystoma mexicanum) is a species of swimming salamander that can be found in numerous lakes, such as Lake Xochimilco underlying Mexico City. As of 2010, wild axolotls were near extinction due to urbanization in Mexico City and consequent water pollution, as well as the introduction of invasive species such as tilapia and perch. They also have the amazing ability to regrow limbs.
Axolotls have wide heads, and their eyes are lidless. Their limbs are underdeveloped and possess long, thin digits. Males are identified by their swollen underside lined with papillae, while females are noticeable for their wider bodies full of eggs. Three pairs of external gill stalks originate behind their heads and are used to move oxygenated water. The external gill rami are lined with filaments to increase surface area for gas exchange. Four gill slits lined with gill rakers are hidden underneath the external gills. Axolotls have four pigmentation genes; when mutated they 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.
The axolotl is a popular pet like its relative, the tiger salamander. Lower temperatures result in slower metabolism and a very unhealthily reduced appetite. According to Wikipedia, “temperatures at approximately 16 °C (61 °F) to 18 °C (64 °F) are suggested for captive axolotls to ensure sufficient food intake; stress resulting from more than a day’s exposure to lower temperatures may quickly lead to disease and death, and temperatures higher than 24 °C (75 °F) 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 40-litre (11-US-gallon) tank with a water depth of at least 15 cm (6 in). Axolotls spend the majority of the time at the bottom of the tank. Salts, such as Holtfreter’s solution, are usually added to the water to prevent infection. 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.”The axolotl has been categorized as critically endangered by the IUCN Red List due to invasive species’ and urbanization in Mexico.