Criterias of choices of the selected 3D numerised specimens

The selection of the 3D numerised specimen of Corallum fabrica is both bottom-up and top-down. For the top-down approach, we selected with Isabelle Domart-Coulon, researcher of the National Museum of Natural History (MNHN) of Paris, 39 specimens from the MNHN scleractinian collection. We payed attention to the history of evolution of reef corals and to showcase specimens from historical collections (from 1800’s Michelin collection to recent expeditions - ex: Tara Ocean) as well as type specimens (name-bearing specimens, first described to establish the species or genus name). For the bottom-up approach, Corallum fabrica collaborates with marine researchers who shared with us their personal collections linked to their research questions. We describe in this page the three groups of criteria of selection that we have taken into account for this 3D open-science archive. These are the followings: taxonomy, 3D technology (captation and visualization) and cultural interests.

List of the 3D numerised specimens

History of evolution criteria

Figure 1: Figure of a circular cladogram from KITAHARA, Marcelo V., FUKAMI, Hironobu, BENZONI, Francesca et HUANG, Danwei, 2016. The new systematics of Scleractinia: integrating molecular and morphological evidence. In : The cnidaria, past, present and future. Springer. pp. 41–59.

Figure 2: Figure of a cladogram from STOLARSKI, Jarosław, KITAHARA, Marcelo V., MILLER, David J., CAIRNS, Stephen D., MAZUR, Maciej et MEIBOM, Anders, 2011. The ancient evolutionary origins of Scleractinia revealed by azooxanthellate corals. BMC Evolutionary Biology.

Evolution shapes coral species emergence and divergence, via temporal accumulation of heritable mutations that are reflected in morphological (skeleton shape and microstructure) and molecular (genetic marker DNA or amino-acid sequences) characters. The history of the evolution of species (phylogeny) relies on the study of parental relationships among groups of organisms, here marine calcifying organisms conventionally referred to as “corals”. Shared characters can be acquired by inheritance from parents, defining a genetic lineage. Some characters can be independently acquired in multiple lineages. Within the order Scleractinia, phylogenetic analysis of multiple characters defined 3 major lineages, that is Basal / Robusta / Complexa, each encompassing several families (Kitahara et al., 2010, 2016; Stolarski et al., 2011) (see fig. 1 et fig. 2). This phylogeny is regularly revised with taxonomic changes (genus transfer in families, creation of new families).When available, those changes were incorporated into the Corallum fabrica website. Classification is subject to further changes (see reference website World list of Scleractinia https://www.marinespecies.org/scleractinia/) Within the order Scleractinia, there are more than 1600 valid described species divided into more than 30 families (see Hoeksema, B. W.; Cairns, S. (2022). World List of Scleractinia. Accessed at https://www.marinespecies.org/scleractinia on 2022-12-12 ). It was therefore important to select a first batch of specimens within a representative number (20) of scleractinian families.

Technological criterias

Figure 3: Scheme of X-ray tomography technology for 3D modelling. Credits: Sarah Blosse & Elise Rigot

With the collaboration of Toulouse Institute of Fluid Mechanics (IMFT), we used x-ray micro-tomography (EasyTom XL, see fig. 3) to image and numerically encode the 3D architecture and to render 3D inner cavities, porosities, and microstructures of coral skeleton. Reconstructed 3D models typically exhibit a high spatial resolution of 4-50 microns, depending on size and morphology. We have chosen this technology to build highly resoluted 3D models that can allow species recognition with microstructure details. We also chose this technology because it is non-destructive. Corallum fabrica gathers an inter-disciplinary community of physicists, biologists, taxonomists, environmental scientists, and designers. We propose the use of 3D technologies and engineering science in a project avoiding any techno-solutionism drift such as eco-engineering to promote a scientific posture of mediators of coral reef memory (facing the high local risk of extinction of many species of corals). Indeed, by applying advanced 3D technologies (CT-scan and 3d visualization) to visualize and reconstruct coral skeleton structures, we publicize their biodiversity and facilitate science in constructing an accessible coral 3D repository.

Cultural criterias

Figure 4: LACAZE-DUTHIERS Henri de, 1897, Archives de zoologie expérimentale et générale : histoire naturelle, morphologie, histologie, évolution des animaux, Série 3, Vol. V. Pl.1. Credit: The Observatoire océanologique de Banyuls-sur-Mer (Arago)

The objective of Corallum fabrica is the sharing and digital preservation of coral skeleton specimens for future generations and researchers. The ambition of the project is to preserve the common cultural heritage embedded in coral's art of building their skeletons. We also shared historical description (both drawings and labels) for each 3d scanned specimen within Corallum fabrica for science history reasons (see fig. 4). We decided to open the archive to a few coral bioeroding organisms and some octocorallia. As a matter of fact, coral biodiversity and viability are markers of environmental changes caused by historic and anthropic disturbances. The numerous reports on coral mortality after periodic warming events strongly suggest that many coral species are at risk of local extinction. Thus, we wanted to open our selection criterias for species that also build reefs and animal forest (ex: sponges, gorgonians). In the near future, we will archive narratives of attachment that coastal inhabitants maintain with coral reefs in this unsettling time of their potential disappearance. To do so, we are opening an "Anthropocene" section within this archive, adopting a multi-perspectival approach through collaborations across multiple oceans. The aim is to archive coral fragments connected to oral memory and to explore how archiving can become a medium of care, addressing the feeling of solastalgia in ways that art of memories can help transform (Niemeyer and Uhl 2024). We want to share the common heritage of coral’s architecture to a broad audience, thus we use Creative Commons licences. Also, as the project was leaded by Elise Rigot, researcher in design, some esthetical and subjective criterias are part of the project aiming at raising curiosity and sensibility for these marine animals.