A scanning electron micrograph of Emiliana huxleyi, a species which commonly forms phytoplankton blooms. Photo used by permission from owner: Jeremy Young.
Coccolithophorids ("round-stone-bearers") are named after their coccoliths, CaCO 3 scales that form the cell wall. The coccoliths of different species have diverse shapes and ornamentations and can be used for taxonomic identification. Coccolithophorids are small organisms - their cells range in size from only 0.2-2µm - and so are difficult to view in the context of a classroom setting. You need a great microscope (usually only a scanning electron microscope will do), a book of micrographs, or some time looking at websites to be able to appreciate the diversity and beauty of these stunning organisms.
Like many phytoplankters, coccolithophorids can form immense blooms - in this case, the blooms are so distinctive, they can be seen from satellite pictures. When the coccoliths from these blooms settle down to the ocean floor, they create thick deposits which, through geological processes, form chalk - including chalk used for classroom chalkboards! The famous white cliffs of Dover, in southern England, are the result of coccolithophorid blooms and coccolith deposits.
Cell size: 2-20 m m
Cell wall: CaCO 3 coccoliths or scales
Chloroplasts: none, single thylakoid membrane
Photo-pigments: chlorophyll a & c, carotenoids
Reproduction: simple cell division, rarely sexual reproduction
Ecological roles: biflagellated, produce chalk deposits
Common genus: Emiliana
© 2001 Caren E. Braby