Speaker
Description
Rebecca A Metzler1, Sarah Traenkle1, Edlin Davis1, Beatriz Orihuela de Diaz2, Daniel Rittschof2, and Gary Dickinson3
1Department of Physics and Astronomy, Colgate University, 13 Oak Dr., Hamilton, NY 13346, USA
2Duke University Marine Lab, 135 Duke Marine Lab Rd., Beaufort, NC 28516, USA
3Department of Biology, The College of New Jersey, 2000 Pennington Rd., Ewing, NJ 08628, USA
Corresponding author e-mail address: rmetzler@colgate.edu
Introduction
Barnacles, such as Amphibalanus amphitrite studied here, are found throughout marine intertidal communities. As adults, Amphibalanus amphitrite have a calcified exoskeleton consisting of multiple plates: parietal or lateral plates surrounding the body, a base plate securing the barnacle to its substrate, and an operculum that opens and closes for feeding. However, barnacles begin life as unmineralized free-floating larvae that then undergo two metamorphoses, before settling onto a substrate, adhering for life, ad forming a mineralized exoskeleton. Despite their importance in intertidal communities and the role they play in biofouling, little is known about the formation process of barnacles’ exoskeletons. Through the combination of synchrotron based techniques x-ray photoemission electron microscopy (X-PEEM) and x-ray absorption near-edge structure spectroscopy (XANES) with scanning electron microscopy (SEM) we were able to provide an unprecedented view of the early stages of mineralization within the exoskeletal plates.
Results
X-PEEM [1, 2] and SEM show that 1-day after metamorphosis, the parietal and opercular plates have already begun the mineralization process, with both parietal and opercular plates consisting of small calcite crystallites of varied orientation. In comparison, the parietal and opercular plates of a 6-day post-metamorphosis barnacle appears to have larger co-oriented crystalline domains and a thicker mineralized region within the parietal plates. These results begin to provide hints to how mineralization progresses within the barnacle exoskeleton and provides a baseline for on-going experiments into how predicted changes in ocean temperature will impact the barnacle exoskeleton mineralization process.
References
[1] C. Y. Sun, M. A. Marcus, M. J. Frazier, A. J. Guiffre, T. Mass and P. U. P. A. Gilbert. ACS Nano 11 (2017), 6612-6622.
[2] R. A. Metzler, M. Abrecht, R. M. Olabisi, D. Ariosa, C. J. Johnson, B. H. Frazer, S. N. Coppersmith and P. U. P. A. Gilbert. Phys. Rev. Lett. 98 (2007) 268102.
