From Wikipedia, the free encyclopedia
Emiliania huxleyi, often abbreviated
to simply "EHUX", is a species of coccolithophore with a global
distribution from the tropics to subarctic waters. It is studied
for the extensive blooms it forms in nutrient depleted waters
after the reformation of the summer thermocline. Like other coccolithophores,
E. huxleyi is a single-celled phytoplankton
covered with uniquely ornamented calcite disks, coccoliths (also informally
known as liths or scales). Individual coccoliths are abundant in
marine sediments although complete coccospheres are more unusual.
In the case of E. huxleyi, not only the shell, but also
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.
Landsat
image from 24th July 1999 of an
Emiliania huxleyi
bloom
Named after Thomas Huxley and Cesare
Emiliani, it is the most numerically abundant and widespread
coccolithophore species. Its coccoliths are transparent and commonly
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 complementary shipboard measurements indicating
that E. huxleyi is by far the dominant phytoplankton
species under these conditions.
This species has been the inspiration for James Lovelock's
Gaia
hypothesis which claims that living organisms somehow may be
able to self regulate their own conditions of chemistry and climate
at a state favourable for life.
See also
External
links
References
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