Mechanical Resistance in Decapod Claw Denticles: Contribution of Structure and Composition

Rosen, Miranda N.; Baran, Kerstin A.; Sison, Justin N.; Steffel, Brittan V.; Long, W. Christopher; Foy, Robert J.; Smith, Kathryn E.; Aronson, Richard B.; Dickinson, Gary H.

doi:10.1016/j.actbio.2020.04.037

Cited by 21 publications

(34 citation statements)

References 43 publications

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“…Its thickness covering the denticle was about 37 μm, forming a twisted-plywood-patterned structure of Sh ≈ 0.8–2.8 µm. This characteristic is also found in the red king crab, Paralithodes camtschaticus [ 37 ], of the same infraorder, Anomura, as the coconut crab. The microstructures within the endocuticle layer on the pinching side of all specimens are shown in Figure 17 .…”

Section: Resultsmentioning

confidence: 71%

“…The denticles of the fixed finger in general are larger than these of the movable finger. These denticles have little or no epi- or exocuticle in this region in various crabs: Cancer borealis , Callinectes sapidus , Chionoecetes opilio , Paralomis birsteini , Paralithodes camtschaticus , and Scylla serrata [ 37 , 38 ]. Nevertheless, the hardness was 2.5 to 10 times higher in the denticle than in the endocuticle.…”

Section: Introductionmentioning

confidence: 99%

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Structural Changes and Mechanical Resistance of Claws and Denticles in Coconut Crabs of Different Sizes

Inoue

Oka

Nakazato

et al. 2021

Biology

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The exoskeleton of the pinching side of claws with denticles and of the outer side without them on the coconut crab, Birgus latro, which is a rare organism, were studied using a materials science approach. The mechanical resistance of three claws of different sizes was investigated along the exoskeleton thickness from the outer surface to the inner surface, and the results were compared, including the contribution of the microstructure and chemical compositions. Mechanical properties, hardness (H) and stiffness (Er), were probed through nanoindentation tests. The results showed the H, Er, microstructures, and chemical components of the exocuticle and endocuticle layers were almost the same, in a BW range of 300 g to 1650 g. At the same time, the H and Er near the surface of the denticles of a small coconut crab of 300 g were lower than those of other large coconut crabs. The microstructure of the denticles was clearly different from that of the exocuticle, but the maximum mechanical properties near their surface indicated almost the same values, Hmax = 4 GPa and Er(max) = 70 GPa, regardless of being on the pinching side or the outer side. A denticle can be regarded as a bulge of the cuticle without phosphorus and with high magnesium. The results provided novel information that expanded our knowledge about the claw microstructure of coconut crabs with different body sizes, and may be used in further studies

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Section: Resultsmentioning

confidence: 71%

Section: Introductionmentioning

confidence: 99%

Structural Changes and Mechanical Resistance of Claws and Denticles in Coconut Crabs of Different Sizes

Inoue

Oka

Nakazato

et al. 2021

Biology

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“…Despite a reduction in endocuticle hardness in both species at reduced pH, calcium content was not affected by exposure pH in P. platypus, and in P. camtschaticus, calcium content of the claw was actually greater at reduced pH. A number of other properties can influence cuticle hardness in decapods, including: the packing density of twisted plywood structures; phosphate content (including the presence of calcium phosphate); cross-linking and other modifications of the protein portion; density of pore canals; and the orientation, density and structural integrity of mineralized protein-chitin fibers (Melnick et al, 1996;Chen et al, 2008;Fabritius et al, 2011;Lian and Wang, 2011;Fabritius et al, 2012;Bentov et al, 2016a,b;Rosen et al, 2020). It remains to be determined which, if any, of these properties are driving the observed reduction in claw microhardness at reduced seawater pH seen here and by Coffey et al (2017).…”

Section: MMmentioning

confidence: 99%

“…As shown by Kunkel et al (2012), removal of the epicuticle leads to an increase in ion flux from the mineralized cuticle. Waugh et al (2006) and Rosen et al (2020) documented in multiple crab species that normal wear on the denticles results in loss of the epicuticle, as well as the exocuticle, from the denticle surface, which could leave the mineralized endocuticle susceptible to dissolution. The presence of epicuticle on the denticle surface was not assessed before exposure in our study, but given that the crabs used here were already past their terminal molt when collected from the field, it is likely that the epicuticle covering the denticles was absent at the start of the experimental exposure.…”

Section: MMmentioning

confidence: 99%

“…Structure, elemental composition and mechanical properties of the decapod cuticle can vary among body regions (Boßelmann et al, 2007;Chen et al, 2008;Lian and Wang, 2011;Coffey et al, 2017;Steffel et al, 2019), among species (Boßelmann et al, 2007;Steffel et al, 2019;Rosen et al, 2020) and with environmental conditions (Taylor et al, 2015;Coffey et al, 2017;Glandon et al, 2018;Bednaršek et al, 2020). For example, in blue and red king crabs (Paralithodes platypus and Paralithodes camtschaticus, respectively), hardness of the claw is about twice that of the carapace, and calcium content is elevated in the claw in both species (Coffey et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

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Ocean acidification alters properties of the exoskeleton in adult Tanner crabs, Chionoecetes bairdi

Dickinson

Bejerano

Salvador

et al. 2021

Journal of Experimental Biology

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Ocean acidification can affect the ability of calcifying organisms to build and maintain mineralized tissue. In decapod crustaceans, the exoskeleton is a multilayered structure composed of chitin, protein and mineral, predominately magnesian calcite or amorphous calcium carbonate (ACC). We investigated the effects of acidification on the exoskeleton of mature (post-terminal-molt) female southern Tanner crabs, Chionoecetes bairdi. Crabs were exposed to one of three pH levels – 8.1, 7.8 or 7.5 – for 2 years. Reduced pH led to a suite of body region-specific effects on the exoskeleton. Microhardness of the claw was 38% lower in crabs at pH 7.5 compared with those at pH 8.1, but carapace microhardness was unaffected by pH. In contrast, reduced pH altered elemental content in the carapace (reduced calcium, increased magnesium), but not the claw. Diminished structural integrity and thinning of the exoskeleton were observed at reduced pH in both body regions; internal erosion of the carapace was present in most crabs at pH 7.5, and the claws of these crabs showed substantial external erosion, with tooth-like denticles nearly or completely worn away. Using infrared spectroscopy, we observed a shift in the phase of calcium carbonate present in the carapace of pH 7.5 crabs: a mix of ACC and calcite was found in the carapace of crabs at pH 8.1, whereas the bulk of calcium carbonate had transformed to calcite in pH 7.5 crabs. With limited capacity for repair, the exoskeleton of long-lived crabs that undergo a terminal molt, such as C. bairdi, may be especially susceptible to ocean acidification.

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Meta‐analysis suggests negative, but pCO₂‐specific, effects of ocean acidification on the structural and functional properties of crustacean biomaterials

Siegel

Kaur

Grigal

et al. 2022

Ecology and Evolution

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Crustaceans comprise an ecologically and morphologically diverse taxonomic group. They are typically considered resilient to many environmental perturbations found in marine and coastal environments, due to effective physiological regulation of ions and hemolymph pH, and a robust exoskeleton. Ocean acidification can affect the ability of marine calcifying organisms to build and maintain mineralized tissue and poses a threat for all marine calcifying taxa. Currently, there is no consensus on how ocean acidification will alter the ecologically relevant exoskeletal properties of crustaceans. Here, we present a systematic review and meta‐analysis on the effects of ocean acidification on the crustacean exoskeleton, assessing both exoskeletal ion content (calcium and magnesium) and functional properties (biomechanical resistance and cuticle thickness). Our results suggest that the effect of ocean acidification on crustacean exoskeletal properties varies based upon seawater p CO 2 and species identity, with significant levels of heterogeneity for all analyses. Calcium and magnesium content was significantly lower in animals held at p CO 2 levels of 1500–1999 µatm as compared with those under ambient p CO 2 . At lower p CO 2 levels, however, statistically significant relationships between changes in calcium and magnesium content within the same experiment were observed as follows: a negative relationship between calcium and magnesium content at p CO 2 of 500–999 µatm and a positive relationship at 1000–1499 µatm. Exoskeleton biomechanics, such as resistance to deformation (microhardness) and shell strength, also significantly decreased under p CO 2 regimes of 500–999 µatm and 1500–1999 µatm, indicating functional exoskeletal change coincident with decreases in calcification. Overall, these results suggest that the crustacean exoskeleton can be susceptible to ocean acidification at the biomechanical level, potentially predicated by changes in ion content, when exposed to high influxes of CO 2 . Future studies need to accommodate the high variability of crustacean responses to ocean acidification, and ecologically relevant ranges of p CO 2 conditions, when designing experiments with conservation‐level endpoints.

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Mechanical Resistance in Decapod Claw Denticles: Contribution of Structure and Composition

Cited by 21 publications

References 43 publications

Structural Changes and Mechanical Resistance of Claws and Denticles in Coconut Crabs of Different Sizes

Structural Changes and Mechanical Resistance of Claws and Denticles in Coconut Crabs of Different Sizes

Ocean acidification alters properties of the exoskeleton in adult Tanner crabs, Chionoecetes bairdi

Meta‐analysis suggests negative, but pCO₂‐specific, effects of ocean acidification on the structural and functional properties of crustacean biomaterials

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Mechanical Resistance in Decapod Claw Denticles: Contribution of Structure and Composition

Cited by 21 publications

References 43 publications

Structural Changes and Mechanical Resistance of Claws and Denticles in Coconut Crabs of Different Sizes

Structural Changes and Mechanical Resistance of Claws and Denticles in Coconut Crabs of Different Sizes

Ocean acidification alters properties of the exoskeleton in adult Tanner crabs, Chionoecetes bairdi

Meta‐analysis suggests negative, but pCO2‐specific, effects of ocean acidification on the structural and functional properties of crustacean biomaterials

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Product

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Meta‐analysis suggests negative, but pCO₂‐specific, effects of ocean acidification on the structural and functional properties of crustacean biomaterials