What is a Coccolithophore?

many CoccolithophoresLike any other type of phytoplankton, Coccolithophores are one-celled plant-like organisms that live in large numbers throughout the upper layers of the ocean. Coccolithophores surround themselves with a microscopic plating made of limestone (calcite). These scales, known as coccoliths, are shaped like hubcaps and are only three one-thousandths of a millimeter in diameter.

What coccoliths lack in size they make up in volume. At any one time a single coccolithophore is attached to or surrounded by at least 30 scales. Additional coccoliths are dumped into the water when the Coccolithophores multiply asexually, die or simply make too many scales. In areas with trillions of Coccolithophores, the waters will turn an opaque turquoise from the dense cloud of coccoliths. Scientists estimate that the organisms dump more than 1.5 million tons (1.4 billion kilograms) of calcite a year, making them the leading calcite producers in the ocean.

The picture at top shows the large numbers of detached coccoliths gathered by filtering the ocean with a fine mesh during a bloom. (Micrograph courtesy Jeremy Young)

next: Where do they live?


by John Weier
April 26, 1999


What is a Coccolithophore?
Where do they live?
What do they do to the environment?

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