Biological Control of Ca-Carbonate Crystal Microstructure and Texture: Adapting Crystal Morphology, Orientation, and Arrangement to Biomaterial Function
The mineralized cover of chiton (Polyplacophora) soft tissue consists of aragonite, developed as shell-plates, girdle-scales, and girdle-spicules. This study characterizes crystallographic aspects of the girdle-spicules of the species <i>Ischnochiton rissoi</i>, <i>Rhyssoplax oliva...
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| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-05-01
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| Series: | Crystals |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2073-4352/15/5/466 |
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| Summary: | The mineralized cover of chiton (Polyplacophora) soft tissue consists of aragonite, developed as shell-plates, girdle-scales, and girdle-spicules. This study characterizes crystallographic aspects of the girdle-spicules of the species <i>Ischnochiton rissoi</i>, <i>Rhyssoplax olivacea</i>, <i>Acanthopleura vaillantii</i>, and <i>Acanthopleura spinosa</i>. Spicule crystal arrangements and texture variations are described. Different misorientations between the spicule crystals are shown and are discussed with respect to the physical properties of the biomaterial. Characterization was performed with electron backscattered diffraction (EBSD), as well as with laser confocal and Field emission scanning electron microscopy (FE-SEM) imaging. All investigated species had porous spicules and distinct structural characteristics. Spicule crystal co-orientation strength was strongly increased for <i>R. olivacea</i> and <i>I. rissoi</i>, and it was almost random for <i>A. vaillantii</i>. <i>R. olivacea</i>, <i>I. rissoi</i>. <i>A. spinosa</i> spicule crystal texture was axial, whereas <i>A. vaillantii</i> spicule crystals were almost untextured. For all species investigated, spicule aragonite was twinned, as demonstrated with the strong 63°/64° peak in the misorientation angle distribution diagram, indicating a {110}-twin relationship. <i>R. olivacea</i> and <i>I. rissoi</i> spicules consisted of few twinned crystals and twin boundaries; <i>A. vaillantii</i> and <i>A. spinosa</i> spicules showed an abundance of twinned crystals and twin boundaries. We observed a difference in spicule dimension, morphology, arrangement on the girdle, and crystal organization for the investigated species, but always the generation of twinned aragonite. |
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| ISSN: | 2073-4352 |