Crystal organisation and material properties of Chama and Glycymeris myostraca and shells

Hoerl, Sebastian ; Moine, Thomas le ; Peter, Nicolas J. ; Amini, Shahrouz; Griesshaber, Erika; Wang, J.; Harper, Elizabeth M.; Salas, Carmen ; Checa, António Gerardo ; Schwaiger, Ruth und Schmahl, Wolfgang Wilhelm (2024): Crystal organisation and material properties of Chama and Glycymeris myostraca and shells. In: Materialia, Bd. 36, 102149

Abstract

Movement of bivalve hard and soft tissue requires muscular action. Despite diverse bivalve lifestyles and living environments, the myostracum, a specific hard tissue formed where muscles attach to the shell, appears similar in structure for species of many bivalve orders. We investigated myostracal and non-myostracal, valve, microstructure, texture and material properties of Chamidae and Glycymerididae species with electron-backscatter-diffraction, laser-confocal and backscatter electron imaging and nanoindentation testing. Chamidae and Glycymerididae follow different lifestyles and live in distinct environments. Chamidae are cemented to substrate and live in wave-swept, shallow, waters. Glycymerididae dwell in calm water and burrow into sandy/muddy sediment. We found that myostracal aragonite of all investigated species has a crystal assembly pattern that reflects crystal growth through growth competition. Aragonite is extensively twinned in the myostracum and nonmyostracal, valve, layers, not in the calcitic ornamentation. For myostracal aragonite, we found cyclic twinning, for non-myostracal aragonite the twinning was polysynthetic or polycyclic. We show how twinning and crystallographic texture are transmitted between myostracal and non-myostracal, valve, layers. Relative to nonbiological aragonite, myostracal and non-myostracal, valve, indentation elastic modulus is reduced by 10–15 % and 15–20 %, respectively; myostracal and valve hardness is increased by 15–20 % and 5–10 %, respectively. Comparing modulus and hardness between aragonitic microstructures, we found that, relative to other microstructures, myostracal modulus is increased by 5 % and myostracal hardness by 15 %. Hence, the myostracal material shows a unique and specific microstructure, texture, modulus, and hardness that might be necessary for muscle attachment to enable the lifestyle-controlled requirements posed onto the organism.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Geowissenschaften > Department für Geo- und Umweltwissenschaften > Kristallographie und Materialwissenschaft
• Themengebiete: 500 Naturwissenschaften und Mathematik > 550 Geowissenschaften, Geologie
• ISSN: 25891529
• Sprache: Englisch