Colorful microbial mats coat terraces of Grand Prismatic Spring in Yellowstone National Park, Midway Geyser Basin, Wyoming, USA.
Colorful microbial mats coat terraces of Grand Prismatic Spring in Midway Geyser Basin, Yellowstone National Park, Wyoming, USA. Grand Prismatic is the largest hot spring in the United States, and the third largest in the world, next to those in New Zealand. The sterile blue water in the pool’s center is too hot to support life (87 degrees Centigrade or 188 F). Pure water selectively absorbs red wavelengths of visible light, making the center deep blue. But in cooler water along the edges, microbial mats of thermophilic (heat-loving) cyano-bacteria and algae thrive. Yellow, orange, and red pigments are produced by the bacteria as a natural sunscreen. As a result, the pool displays a spectrum of colors from the bright blue water of the center to the orange, red, and brown algal mats along the edges. Summer mats tend to be orange and red, whereas winter mats become dark green. Yellowstone was the first national park in the world (1872), and UNESCO honored it as a World Heritage site in 1978.Add to Cart Add to Lightbox Download