The geysers and hot springs of Yellowstone National Park host an array of thermophillic, or heat-loving, microorganisms that can tolerate temperatures as high as 175 degrees Fahrenheit. These bacteria, along with other microorganisms like archaea, create the vivid color palettes of some of Yellowstone’s famed springs and geysers, like the Grand Prismatic Spring pictured here.
The blue center is the heart of the spring, where nearly boiling water makes it impossible for anything to survive, resulting in a startlingly blue hue. As the temperature dips farther out from the hot spring’s superheated center, though, more and more kinds of bacteria, fungi, and other microorganisms are able to endure. The different rings of color emanating from the steaming epicenter represent different microbial communities that call the spring home.
The most heat-tolerant cyanobacteria dominate the still-extreme temperatures in the yellow-colored ring, while the outer, orange layer hosts an array of organisms that can’t stand the heat quite as well as their neighbors. The colors of these rings also change in response to the time of year and other environmental factors. The cooler outer rings, meanwhile, form ecosystems of their own, hosting flies, mites, spiders, and other animals. Ephydrid flies feast on the bacterial communities and lay their eggs there, while predators like wolf spiders and parasites such as mites are drawn here because of the presence of the flies.
