Emiliania huxleyi is a species of coccolithophore, single-celled phytoplankton that are covered with uniquely ornamented calcite disks. Individual plates are common in marine sediments although complete specimens are more unusual. In the case of E. huxleyi, not only the shell, but the soft part of the organism may be recorded in sediments. It produces a group of chemical compounds that are very resistant to decomposition. These chemical compounds, known as alkenones , can be found in marine sediments long after other soft parts of the organisms have decomposed. Alkenones are used by earth scientists as a clue to past sea surface temperatures.
Named after Thomas Huxley, it is the globally most significant coccolithophore. Its coccoliths are transparent and colourless, but they are formed of calcite which refracts light very efficiently in the water column. This, and the high concentrations caused by continual shedding of their coccoliths makes E. huxleyi blooms easily visible from space. Satellite images show that blooms can cover large areas (possibly >100,000 square kilometers), with complimentary shipboard measurements indicating that E. huxleyi is by far the dominant phytoplankton species under these conditions.
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