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| Coccolithaceae | |
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| The coccolithophore Gephyrocapsa oceanica. | |
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| Class: | Prymnesiophyceae
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Coccoliths are the microscopic algae which form chalk. They are made by one of the most important eukaryote phytoplankton. These are single celled protists whose full name is coccolithophorids or coccolithophores. The spherical skeleton of coccoliths is a coccosphere.
Chalk makes up much of the marine strata in the Upper Cretaceous period, and is 95% to 99% made up of coccoliths, the calcium carbonate (CaCO3) plates which coccolithophorids produce.
Coccoliths were first examined by Cristian Gottfried Ehrenberg (1795–1875), who thought they were inorganic products. They were named, and identified as made by living organisms by Thomas Henry Huxley. He realised they were a major part of the rock we call chalk.[1] The story of how the tiny cell produces its coccosphere is told by Westbroek:
- "The tiny coccolith-generating alga... is geological dynamite, a formidable force helping to conduct vast fluxes of calcium and carbonate towards the ocean bottom".[2]
Coccolithophores are a major contributor to the carbonate in deep sea sediments. In the Northeast Atlantic during the last glacial-interglacial cycle (ice age), coccoliths make up 70-80% of the total carbonate during the warm periods, and less during glacial times.[3][4]
Coccoliths are first seen at the end of the Triassic period, 200 million years ago. It is interesting that another group of tiny algae, the diatoms, make their entry into the fossil record at almost the same time. The coccolith all-time peak was in the warm inland and continental shelf seas of the Cretaceous period. They are still of huge ecological and geological importance.[2]
- ↑ Huxley T.H. 1868. On a piece of chalk. British Association for the Advancement of Science.
- ↑ 2.0 2.1 Westbroek, Peter 1991. Life as a geological force. Norton N.Y. Chapter 6 The power of the small. p141
- ↑ van Kreveld S.A. et al 1996. Biogenic carbonate and ice-rafted debris (Heinrich layer) accumulation in deep-sea sediments from the Northeast Atlantic piston core. Marine Geology, 131.
- ↑ Lototoskaya A and Ziveri P 1995. Calcareous nanoplankton response to Termination II and Heinrich event (140-110 Ka BP) in the NE Atlantic. 6th International Nannoplankton Conference, Coopenaghen: 72–73.