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Updated: May 11, 2026
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Multimodal Optical Microscopy Methods Reveal Polyp Tissue Morphology and Structure in Caribbean Reef Building Corals
Published on: September 5, 2014
Microstructural evolution and nanoscale crystallography in scleractinian coral spherulites
Renée van de Locht1, Andreas Verch, Martin Saunders
1Department of Physics, The University of York, Heslington, York YO10 5DD, United Kingdom. rvdl500@york.ac.uk
Journal of Structural Biology
|May 21, 2013
Summary
Coral skeletons form intricate structures through biogenic calcium carbonate accretion. This study reveals how coral microstructure correlates with daily growth cycles, offering insights into coral biomineralization.
Area of Science:
- Marine Biology
- Geochemistry
- Materials Science
Background:
- Reef-building corals accrete calcium carbonate, forming complex mineral/organic composites.
- The nano- and microstructure of coral skeletons are sensitive to environmental growth conditions.
Purpose of the Study:
- To investigate the nano- and microstructure and crystallographic orientation of aragonite in scleractinian coral skeletons.
- To correlate coral skeletal microstructure with diurnal growth patterns.
Main Methods:
- Transmission electron microscopy (TEM) was used on focused ion beam (FIB) prepared lamellae of adult and juvenile Porites lobata specimens.
- Analysis focused on nano/microstructure and crystallographic orientation of aragonite.
Main Results:
- Adult Porites lobata exhibited microstructural evolution: random nanocrystals, partly aligned nanocrystals with high porosity, and dense acicular crystals aligned near the [001] direction.
- For the first time, observed microstructures were directly correlated with diurnal growth bands.
- No evidence of mesocrystal structure (self-assembly of nanocrystalline units) on the micrometer scale was found.
Conclusions:
- Coral skeletal microstructure is strongly controlled by the organism, correlating with the diurnal growth cycle.
- The observed mineral structure sequence is hypothesized to be linked to the photosynthetic diurnal cycle of zooxanthellae, regulating oxygen and organic molecule transport.
- These findings advance the understanding of coral biomineralization processes and environmental influences.
