Photo of the Day 6 November 2007

Midges in Cueva de Villa Luz, Mexico, 2001
Photograph by Stephen Alvarez
Millions of iridescent-winged midges like these throng the inky depths of Cueva de Villa Luz cave in southern Mexico. Hydrogen sulfide, which is poisonous to humans, permeates the cave's walls, streams, and air, sustaining a rich variety of bizarre organisms. Midges, bats, spiders, mites, amblypygids, and small, hemoglobin-rich fish thrive in the sulfur-saturated environment.