Structure, composition and mechanical relations to function in sea urchin spine

Moureaux, Claire; Pérez‐Huerta, Alberto; Compère, Philippe; Zhu, Wenzhong; Leloup, Thierry; Cusack, Maggie; Dúbois, Philippe

doi:10.1016/j.jsb.2010.01.003

Cited by 100 publications

(92 citation statements)

References 38 publications

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“…Despite exhibiting sponge-like morphologies and curved surfaces, which are features normally associated with amorphous materials, each element behaves as a single crystal of calcite as judged by techniques such as polarized light microscopy (1), X-ray Diffraction (XRD) (2), and electron backscatter diffraction (3). Prior to recent studies which demonstrated that morphologically complex calcite single crystals can be produced synthetically using templating methods (4-6), such crystals were believed to be restricted to the biological world.…”

mentioning

confidence: 99%

Structure-property relationships of a biological mesocrystal in the adult sea urchin spine

Seto

Davis

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

277

350

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Structuring over many length scales is a design strategy widely used in Nature to create materials with unique functional properties. We here present a comprehensive analysis of an adult sea urchin spine, and in revealing a complex, hierarchical structure, show how Nature fabricates a material which diffracts as a single crystal of calcite and yet fractures as a glassy material. Each spine comprises a highly oriented array of Mg-calcite nanocrystals in which amorphous regions and macromolecules are embedded. It is postulated that this mesocrystalline structure forms via the crystallization of a dense array of amorphous calcium carbonate (ACC) precursor particles. A residual surface layer of ACC and/or macromolecules remains around the nanoparticle units which creates the mesocrystal structure and contributes to the conchoidal fracture behavior. Nature’s demonstration of how crystallization of an amorphous precursor phase can create a crystalline material with remarkable properties therefore provides inspiration for a novel approach to the design and synthesis of synthetic composite materials.

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mentioning

confidence: 99%

Structure-property relationships of a biological mesocrystal in the adult sea urchin spine

Seto

Davis

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

277

350

View full text Add to dashboard Cite

show abstract

“…Indeed, growth rate influences the density of the skeleton (Smith, 1980) and, as a consequence, its mechanical properties. In this context, it is important not to limit the studies to breaking forces but to characterize other important variables like the Young modulus, which expresses the material stiffness or the second moment of area that quantifies the distribution of the material around the neutral fiber (see Burkhardt et al, 1983;Moureaux et al, 2010). In ecotoxicological studies, both these parameters were shown to be affected (Moureaux et al, 2011).…”

Section: Discussionmentioning

confidence: 99%

The Skeleton of Postmetamorphic Echinoderms in a Changing World

Dúbois

2014

The Biological Bulletin

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Abstract. Available evidence on the impact of acidification and its interaction with warming on the skeleton of postmetamorphic (juvenile and adult) echinoderms is reviewed. Data are available on sea urchins, starfish, and brittle stars in 33 studies. Skeleton growth of juveniles of all sea urchin species studied so far is affected from pH 7.8 to 7.6 in seawater, values that are expected to be reached during the 21st century. Growth in adult sea urchins (six species studied) is apparently only marginally affected at seawater pH relevant to this century. The interacting effect of temperature differed according to studies. Juvenile starfish as well as adults seem to be either not impacted or even boosted by acidification. Brittle stars show moderate effects at pH below or equal to 7.4. Dissolution of the body wall skeleton is unlikely to be a major threat to sea urchins. Spines, however, due to their exposed position, are more prone to this threat, but their regeneration abilities can probably ensure their maintenance, although this could have an energetic cost and induce changes in resource allocation. No information is available on skeleton dissolution in starfish, and the situation in brittle stars needs further assessment. Very preliminary evidence indicates that mechanical properties in sea urchins could be affected. So, although the impact of ocean acidification on the skeleton of echinoderms has been considered as a major threat from the first studies, we need a better understanding of the induced changes, in particular the functional consequences of growth modifications and dissolution related to mechanical properties. It is suggested to focus studies on these aspects.

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“…Mechanically, the spines have been shown to preferentially fail at the proximal end when tested in a bending mode, which was found to be associated with the relatively higher concentration of magnesium at the base of the spine [168]. This, coupled with the fact that sea urchins are capable of repairing and regenerating spines that have been damaged or completely severed [169,170], suggests that the spines themselves are designed to fracture when stressed, potentially remaining within a predator to deter further attack.…”

Section: Sea Urchin Spinesmentioning

confidence: 99%