An entire species survives nowhere on Earth except one narrow desert pool

The Devils Hole pupfish lives only in a single water-filled cavern opening in the Nevada desert, a rock shelf just a few metres wide where the whole wild population, sometimes fewer than 100 fish, has bred in isolation for thousands of years. First described in 1930, the species is closely monitored today because a single drought or flash flood could wipe it out entirely.

— Joseph H. Wales, Biometrical studies of some races of cyprinodont fishes from the Death Valley region, with description of Cyprinodon diabolis, n. sp. — Copeia, no. 3, 1930