Waterdogs and axolotls are cousins. Both are species of leopard salamander that do not grow past their juvenile form. They retain their external gills and tadpole-like tail and live their entire lives underwater. But this is far from the only difference between these three!
Salamanders are amphibians and are found everywhere in the world. The axolotl is a species of the tiger salamander. These are the most common species of salamander found throughout the U.S., Canada, and Eastern Mexico.
Axolotls and water puppies are both species of salamander that do not reach an adult form and stay in the larval state. While mudpuppies are found in many locations, the axolotl is only found in one Mexico lake region.
There are studies that suggest that the specific lake region where this species is found is the reason for their unique life cycle. Researchers believe that the region meets an overly complex series of requirements to produce axolotls. One study found that increasing iron intake will force an axolotl into metamorphosis into an adult salamander.