{"id":715,"date":"2021-01-15T21:56:28","date_gmt":"2021-01-15T21:56:28","guid":{"rendered":"https:\/\/home.physics.wisc.edu\/gilbert\/?page_id=715"},"modified":"2026-03-09T02:30:01","modified_gmt":"2026-03-09T02:30:01","slug":"coral-biomineralization","status":"publish","type":"page","link":"https:\/\/home.physics.wisc.edu\/gilbert\/coral-biomineralization\/","title":{"rendered":"Coral Biomineralization"},"content":{"rendered":"

Coral Biomineralization<\/h1>
We study how corals form their skeletons in their natural environments or in aquaria.<\/span>\r\n
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Precursors phases<\/h3>\r\n
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We found that in all coral species thus far analyzed that aragonite (CaCO3) formation is preceded by particle attachment of amorphous calcium carbonate (ACC) precursors, hydrated and anhydrous (ACC-H2O and ACC). See papers 145 and 156. These are Mass et al. Procs Natl Acad Sci<\/i> 2017, and Sun et al. Procs Natl Acad Sci<\/i> 2020. More recently, we found that there are not only 2 amorphous but also 2 crystalline precursor phases. These are calcium carbonate hemihydrate (CCHH) and monohydrocalcite (MHC). See paper 175, Nature Communications<\/em> 2024.<\/div>\r\n
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Crystal orientations<\/h3>\r\n
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We found that in all 13 species thus far analyzed all mature coral skeletons are made of aragonite (CaCO3), and all crystals are arranged spherulitically, that is, as acicular crystals radiating from common centers, termed center of calcification (CoCs). First we gave a quantitative definition of spherulite (<35\u00b0 angle spread of c<\/em>-axes measured with PIC mapping in adjacent crystals), then used this definition to confirm that all 13 coral skeletons are spherulitic. We found that a subset of species also retains \u201csprinkles\u201d. That is, randomly oriented crystals, interspersed with spherulites. Using diverse coral skeletons as a model system, we figured out how all spherulites form: sprinkles are nucleated first at the growth front of a spherulite, then coarsening makes radially oriented crystals get larger at the expense of sprinkles. This growth mechanism applies to inorganic and organic spherulites, from coral skeletons, to geologic minerals, metals, aspirin, and chocolate (both sucrose and cocoa butter form spherulites in chocolate).<\/div>\r\n
Phase-field theory simulations by L\u00e1szlo Gr\u00e1n\u00e1sy confirm this formation mechanism for spherulites. See papers 144, 159, 160. These are Sun et al. ACS Nano\u00a0<\/i>2017, Lo et al. Procs Natl Acad Sci<\/i> 2021, Sun et al.\u00a0Acta Biomaterialia<\/i> 2021.<\/div>\r\n
We also found that small misorientation of adjacent crystals provides toughness to the biomineral, thus explaining why corals form their skeletons this way, that is, that the evolutionary advantage of spherulitic skeleton formation is increased toughness. See paper 172 in Advanced Materials <\/em>2023. That’s how corals get to be the supporting structure for entire reef ecosystems.<\/div>\r\n<\/div>\r\n
<\/div>\r\n<\/div>\r\n<\/div><\/div><\/div><\/div><\/div><\/div><\/div>","protected":false},"excerpt":{"rendered":"

We study how corals form their skeletons in their natural environments or in aquaria. Precursors phases We found that in all coral species thus far analyzed that aragonite (CaCO3) formation is preceded by particle attachment of amorphous calcium carbonate (ACC) precursors, hydrated and anhydrous (ACC-H2O and ACC). See papers 145 and 156. These are Mass…<\/p>\n","protected":false},"author":2,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_acf_changed":false,"_uw_migration_status":"in-progress","_uw_gutenberg_post_content_before_migration":"","footnotes":""},"class_list":["post-715","page","type-page","status-publish","hentry"],"acf":[],"_links":{"self":[{"href":"https:\/\/home.physics.wisc.edu\/gilbert\/wp-json\/wp\/v2\/pages\/715","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/home.physics.wisc.edu\/gilbert\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/home.physics.wisc.edu\/gilbert\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/home.physics.wisc.edu\/gilbert\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/home.physics.wisc.edu\/gilbert\/wp-json\/wp\/v2\/comments?post=715"}],"version-history":[{"count":9,"href":"https:\/\/home.physics.wisc.edu\/gilbert\/wp-json\/wp\/v2\/pages\/715\/revisions"}],"predecessor-version":[{"id":1181,"href":"https:\/\/home.physics.wisc.edu\/gilbert\/wp-json\/wp\/v2\/pages\/715\/revisions\/1181"}],"wp:attachment":[{"href":"https:\/\/home.physics.wisc.edu\/gilbert\/wp-json\/wp\/v2\/media?parent=715"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}