Armour-covered floating beauty

The stunning plankton is the most abundant coccolithophore in the ocean. Image: PLoS Biology/ Wikimedia Commons

‘Ehux’ is a micro-organism vital to marine food chains — it is also visually mesmerising.

This is an image of a scanning electron micrograph of a single Emiliania huxleyi (Ehux) cell. Ehux is a species of coccolithophore, which are single celled algae, protists and phytoplankton belonging to the division of haptophytes. They are spherical cells that range in size from five to 100 micrometres and are distinguished by their intricately patterned calcium carbonate surface plates (also known as liths). The species is named after Thomas Huxley and Cesare Emiliani, who discovered the coccolith in sea-bottom sediment in the early 1980s.

Ehux is globally distributed found drifting in marine sediment from the tropics to subarctic waters. Along with around 5000 or so different types of photosynthetic plankton, it forms the basis of many oceanic food webs.

Although usually transparent, these organisms are actually visible from space because of their calcite shells, which refract light efficiently in the water columns. They also continuously shed their coccoliths (scales), making Ehux phytoplankton blooms easy to monitor using satellites.

Scientists have predicted that the changing ocean chemistry caused by global warming will affect phytoplankton, but whether they will adapt or perish is not yet known. When fossil fuel derived carbon dioxide gets dissolved in the ocean it forms carbonic acid, which results in a drop in pH and more acidic water. Ocean acidification poses a potential threat to Ehux and all marine organisms that produce calcareous skeletons as it changes the bioavailability of nutrients and can also dissolve the acid-sensitive compounds in their shells.

Source: PLOS Biology

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