The axolotl—a foot-long amphibian reputed by the Aztecs to be a transformed god (but eaten anyway)—is in danger of disappearing for good, like so many of its fellow amphibians. A recent survey by Mexican scientists showed that the population of the amphibians—which look like a cross between a fish with a mane and a salamander, with a miniature alligator's tail for swimming and has a remarkable talent for regenerating lost body parts—in Mexico City's waterways and canals has dropped from 1,500 to just 25 per square mile over the past decade.

A combination of polluted water and an aggressive invasion by African tilapia and Asian carp fish has pushed it to the brink. Without sanctuaries—and an aggressive effort to eliminate the invaders—the namesake of the Aztec god of death may soon follow the dog-headed deity into oblivion.