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Mammoth Hot Springs Grand Prismatic Morning Glory Pool Handkerchief Pool Hot Spring Colors

Many of the bright colors found in Yellowstone’s hydrothermal basins come from “thermophiles” — microorganisms that thrive in hot temperatures. So many individual microorganisms are grouped together—trillions!—that they appear as masses of color.

Different types of thermophiles live at different temperatures within a hot spring and cannot tolerate much cooler or warmer conditions. Yellowstone’s hot water systems often show distinct gradations of living, vibrant colors where the temperature limit of one group of microbes is reached, only to be replaced by a different set of thermophiles.

Thermophilic microorganisms in hot spring runoff channels
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