Editing Coccolithophore (section)

=== Formation ===
Coccoliths are produced by a [[biomineralization]] process known as coccolithogenesis.<ref name=Moheimani2012 />  Generally, calcification of coccoliths occurs in the presence of light, and these scales are produced much more during the exponential phase of growth than the stationary phase.<ref name=Linschooten1991>{{citation |journal=Journal of Phycology |volume=27 |issue=1 |year=1991 |pages=82–86 |title=Role of the light-dark cycle and medium composition on the production of coccoliths by Emiliania huxleyi (haptophyceae) |first=Cornelis |last=Linschooten |doi=10.1111/j.0022-3646.1991.00082.x |s2cid=84368830 |display-authors=etal  }}</ref> Although not yet entirely understood, the biomineralization process is tightly regulated by [[calcium signaling]]. [[Calcite]] formation begins in the [[golgi complex]] where protein templates nucleate the formation of CaCO<sub>3</sub> crystals and complex acidic [[polysaccharides]] control the shape and growth of these crystals.<ref name=deVargas2007>{{cite book |last1=de Vargas |first1=C. |last2=Aubrey |first2=M.P. |last3=Probert |first3=I. |last4=Young |first4=J. |editor1-last=Falkowski |editor1-first=P.G.|editor2-last=Knoll |editor2-first=A.H. |title=Origin and Evolution of Coccolithophores |chapter=From coastal hunters to oceanic farmers. |pages=251–285 |year=2007 |publisher=Elsevier |location=Boston}}</ref>  As each scale is produced, it is exported in a Golgi-derived [[vesicle (biology)|vesicle]] and added to the inner surface of the coccosphere. This means that the most recently produced coccoliths may lie beneath older coccoliths.<ref name=Young2003>{{cite book |last1= Young |first1= J.R. |last2=Karen |first2=H. |editor1-last=Dove |editor1-first=P.M. |editor-link1=Patricia M. Dove |editor2-last=Yoreo |editor2-first= J.J. |editor3-last=Weiner |editor3-first=S. |title=Reviews in Mineralogy and Geochemistry |chapter=Biomineralization Within Vesicles: The Calcite of Coccoliths |pages=189–216 |publisher=Mineralogical Society of America |year=2003 |location=Washington, D.C.}}</ref>
Depending upon the phytoplankton's stage in the life cycle, two different types of coccoliths may be formed.  Holococcoliths are produced only in the haploid phase, lack radial symmetry, and are composed of anywhere from hundreds to thousands of similar minute (ca 0.1&nbsp;μm) rhombic [[calcite]] crystals.  These crystals are thought to form at least partially outside the cell.  Heterococcoliths occur only in the diploid phase, have radial symmetry, and are composed of relatively few complex crystal units (fewer than 100).  Although they are rare, combination coccospheres, which contain both holococcoliths and heterococcoliths, have been observed in the plankton recording coccolithophore life cycle transitions.  Finally, the coccospheres of some species are highly modified with various appendages made of specialized coccoliths.<ref name=Young2009>{{citation |journal=Journal of Phycology |volume=45 |issue=1 |year=2009 |pages=213–226 |title=Coccolith function and morphogenesis: insights from appendage-bearing coccolithophores of the family syracosphaeraceae (haptophyta) |first= J.R. |last=Young |doi=10.1111/j.1529-8817.2008.00643.x |pmid=27033659 |s2cid=27901484 |display-authors=etal  |doi-access= }}</ref>
<!-- Deleted image removed: [[File:Figure 1.jpg|frame|alt=Figure 1|Figure 1: Main types of coccoliths produced.  Adapted from Figure 1 of Figure 1 of (Young, et al., 2003)<ref name=Young2009 />]] -->
<!-- Deleted image removed: [[File:Figure 2.jpg|frame|alt=Figure 2|Figure 2: Specialized coccolith structures, adapted from Figure 1 of (Young, et al., 2009).<ref name=Jordan1997 />]] -->