Enormous clouds of rich blue-green phytplankton swirl through the waters of the Bay of Biscay in this true-color Aqua MODIS image acquired April 29, 2005. Stretching across almost the entirety of the Bay, the phytoplankton reveal currents and eddies in the water. Phytoplankton are tiny single-celled organisms that feed off of sunlight and nutrients in the water; they use chlorophyll, like their land-based plant relatives, to drive this process. It is the chlorophyll that gives them their distinctive colors, and which in large-enough populations helps them stand out against the deep blue of clear water. More information about Earth Observatory website.
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