Despite their never-ceasing grins, axolotls have been at risk of extinction for years.
Over two decades ago, there were about 6,000 of these tiny salamanders for every square kilometer in Lake Xochimilco in Mexico City. In the last count from 2014, there were only about 36 axolotls per square kilometer, according to Luis Zambrano, who was involved in the axolotl census.
