Axolotls, also known as the Mexican walking fish, range from 6-18 inches in length. They have 3 protruding pairs of gill stalks on each side used to move oxygenated water. 

They range in color due to mutations in their 4 pigmentation genes; the normal, unmutated color is brown, and the mutated axolotls can be anywhere from albino to a dark blue to almost black color.

Adult axolotl males have large and wide heads with eyes without eyelids. They also possess a longer tail than females caused by the presence of an enlarged cloaca that takes up more space in their bodies when compared with females’ smaller cloaca. Females also tend to have round and plump bodies.

Axolotls are found only around a freshwater lake called Lake Xochimilco in southern Mexico City. The lake is best known for its canals, and is left over from an extensive and ancient lake and canal system that connected most of the settlements of the Valley of Mexico.

Axolotls are carnivorous and feed on arthropods and small fish. Their teeth are a vestigial trait as the axolotl does not chew its food, but instead uses suction to suck up its prey. This is done by closing off gills with rakers that interlock and close as the prey enters into the mouth.

Because of this, they frequently can ingest gravel, but they use this gravel to provide a grinding action on food to help break it up for digestion. In addition, they also use gravel to control how they float in the water, also called buoyancy.

Axolotl’s mating ritual involves a “courtship dance”, and after this romantic encounter, the female takes up the sperm capsule that has been deposited by the male. As many as 1,000 eggs can be laid by a female during one reproductive event. 

Their eggs hatch after 2 weeks, and the larvae almost immediately are on the hunt to capture prey.

Axolotls are frequently studied by medical professionals in order to understand how they regenerate. In as little time as a few weeks, they are able to grow back lost limbs. They can even regenerate organs like their lungs, heart, and parts of the brain without any scarring.  

Despite this amazing trait, however, there may be an upper limit on how many times they can regenerate usable limbs. Research by Harvard University showed that by the fifth time, limbs couldn’t regrow to their previous strength, and began to show instances of scar tissue.

The axolotl was named after a dog-headed Aztec God in mythology called Xolotl, who, in order to escape being sacrificed, transformed himself into a salamander.