Digital three-dimensional imaging techniques provide new analytical pathways for malacological research

Author Posting. © BioOne Complete, 2019. This article is posted here by permission of BioOne Complete for personal use, not for redistribution. The definitive version was published in Ziegler, A., Bock, C., Ketten, D. R., Mair, R. W., Mueller, S., Nagelmann, N., Pracht, E. D., & Schroeder, L. Digital three-dimensional imaging techniques provide new analytical pathways for malacological research. American Malacological Bulletin, 36(2), (2018):248-273, doi:10.4003/006.036.0205.
Research on molluscan specimens is increasingly being carried out using high-throughput molecular techniques. Due to their efficiency, these technologies have effectively resulted in a strong bias towards genotypic analyses. Therefore, the future large-scale correlation of such data with the phenotype will require a significant increase in the output of morphological studies. Three-dimensional (3D) scanning techniques such as magnetic resonance imaging (MRI) or computed tomography (CT) can achieve this goal as they permit rapidly obtaining digital data non-destructively or even entirely non-invasively from living, fixed, and fossil samples. With a large number of species and a relatively complex morphology, the Mollusca would profit from a more widespread application of digital 3D imaging techniques. In order to provide an overview of the capacity of various MRI and CT techniques to visualize internal and external structures of molluscs, more than twenty specimens ranging in size from a few millimeters to well over one meter were scanned in vivo as well as ex vivo. The results show that all major molluscan organ systems can be successfully visualized using both MRI and CT. The choice of a suitable imaging technique depends primarily on the specimen's life condition, its size, the required resolution, and possible invasiveness of the approach. Apart from visual examples derived from more than two dozen scans, the present article provides guidelines and best practices for digital 3D imaging of a broad range of molluscan taxa. Furthermore, a comprehensive overview of studies that previously have employed MRI or CT techniques in malacological research is given.
We would like to express our gratitude to Adam J. Baldinger, Thomas Bartolomaeus, Patrick Beckers, Rüdiger Bieler, Roger T. Hanlon, Carsten Lüter, Iliana Ruiz-Cooley, Tom Schiøtte, Andreas Schmidt-Rhaesa, and Sid Staubach for help with specimen collection or for providing access to museum material. Cornelius Faber, Julia Koch, Tony Stöcker, and W. Caroline West kindly facilitated use of scanning systems. We would also like to thank Julie Arruda, Scott Cramer, Jörg Döpfert, Charlotte Eymann, Bastian Maus, Malte Ogurreck, Christina L. Sagorny, Gillian Trombke, and Christopher Witte for support with data acquisition and analysis. We are particularly grateful to Elizabeth K. Shea for inviting the present contribution and for her extensive commentary on the manuscript. We also thank two anonymous reviewers for their helpful criticisms. Funding for this study was provided by the Ocean Life Institute, the Office of Naval Research, the Seaver Institute, and the Deutsche Forschungsgemeinschaft (INST 217/849-1 FUGG).