The Aztecs called it “water monster.” Its tiny legs make it look more like a walking fish than an amphibian, and gills flare out from behind its jaw. But this fascinating salamander, called the axolotl, is critically endangered. It has a very small range, and invasive carp and pesticides may be part of the reason its numbers are dwindling. Scientists are partnering with local farmers to improve the axolotl’s habitat. They hope that keeping non-native plants and pesticides away from the water will help the salamander population grow.