THE POTENTIAL APPLICATIONS OF 3D MODELING IN TAXONOMIC ANALYSES OF TESTATE AMOEBAE

Testate amoebae, also known as thecamoebians, are unicellular protozoa that produce mineralized shells either by the secretion of an organic matrix or by the agglutination of pre-existing mineral grains. These organisms are considered to be valuable bioindicators of pollution and environmental stress and are frequently used in ecological and paleoecological studies. The primary goal of this research project was to build on previous research, moving beyond sample collection and population analysis into micropaleontologic taxonomy using scanning electron microscopy (SEM) photogrammetry and 3D modeling to produce printed models of testate amoebae shells. The ability to produce macro-scale 3D testate amoebae models will aid in a variety of applications: taxonomic research, teaching applications, and improved ecological understanding of these organisms. Three species were selected for this project: Centropyxis aculeata, Mediolus corona, and Difflugia oblonga. These species are of taxonomic interest due to their local abundance and because they indicate eutrophication and increases in organic matter in local waterbodies. Each of these species has an agglutinated shell comprised of minerals grains, called xenosomes, that were found within the organism’s environment. The arrangement and size of xenosomic minerals is no longer believed to be random and 3D modeling could potentially contribute to an understanding of the ability of the organism to build its shell. This project aimed to create macro models for taxonomic study as the 3D images and models enable analysis of important morphological features and agglutination patterns in detail, furthering our understanding of testate amoebae and continuing to develop their use as ecologic tools. The primary programs used in this process were Adobe Photoshop, 3DF Zephyr, and Autodesk Mudbox. Photoshop was used to process the raw SEM images and correct for Zephyr to generate dense point clouds for each specimen. These will then be exported as .obj files and edited in Mudbox to remove any remaining error or background and finalized for printing. Models will be printed with a filament based Makerbot Replicator 2 as well as a resin-based FormLabs 2 printer.