YELLOWSTONE’S HOT SPRING
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Located in America’s Yellowstone National Park, the Grand Prismatic Spring is the third-largest spring in the world, spanning almost 113 metres in diameter. Thanks to a crack in the Earth’s surface around 37 metres deep, hot subterranean waters can travel up to form this sweltering pool, which is around 87 degrees Celsius. At its border the ground has been coloured in bands of orange, yellow and green. These hues are the result of different heat-loving bacteria species, called thermophiles. As photosynthetic bacteria, these single-celled organisms use pigments called carotenoids to turn sunlight into energy in the same way that plants use green chlorophyll pigment. Carotenoids are seen in a range of colours in different species of bacteria. As the water fans out from the centre of the spring, the temperatures cool, allowing bacteria species with individual temperature tolerances to thrive and produce these varied colour bands.