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The mesmerising Grand Prismatic Spring

The Grand Prismatic Spring, the largest hot spring in the Yellowstone National Park, radiates extremely hot water and has a stunning rainbow-like colour flowing from it's center dominated by a fiery orange hue at its edges.

There are heat-loving microbes that thrive at the hot water spring and for every change of colour, there are rings of different bacteria, each group adapted to the conditions, such as temperature and pH present.

The center of the Grand Prismatic Spring is aquamarine blue in colour with a water temperature of 87°C which is too high for any microbe to grow. Hence, this is mostly just clear water and appears blue to the eye because of the sky.

The yellow colour, which is about 74°C is due to cyanobacteria called Synechococcus and sunlight. The intense sunlight causes the bacteria to produce carotenoids, which act as sunscreen for the bacteria thus giving the yellowish appearance.

The orange ring, comparatively cooler with 65°C, consists of Synechococcus and Chloroflexus bacteria, which contain both chlorophyll, for photosynthesis, and carotenoids. Two other bacteria, Phormidium and Oscillatoria, are also responsible for the orange colour.

At the farthest end from the center is 55°C, and the reddish burgundy colour is caused due to the presence of Deinococcus-Thermus. This bacteria creates bright red or orange streamers.


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