Thermophiles of the Norris Geyser Basin
Colorful thermophilic microbes in the Whirligig Geyser runoff waters, in the Norris Geyser Basin of Yellowstone.
On the left are phototrophic thermophilic algae (including Cyanidium) that live at temperatures of 38-56 °C (100-133 °F). The green color is due to the chlorophyll pigments in these photosynthetic microbes.
On the right are chemotrophic thermophilic microbes that that live at temperatures of 50-60 °C (122-140 °F). The red-ocre color comes from iron oxide deposits. These bacteria and archea are chemotrophs, getting their energy from the iron salts that abound in the hot acidic water.