What amphibious species is named for the Aztec god of fire and lightning? Axolotls are known for their remarkable ability to regenerate parts of their body, from their limbs, tail, and gills to parts of their brain, heart, and spine. This unique trait makes them important to biomedical research. However, they are critically endangered in the wild because they are native to just one lake system in Mexico City, and that habitat is being threatened by climate change and human activity.