College of Mines and Earth Sciences
68 Analyzing the Differences between Paper Nautilus (Argonauta) Shells and Their Climatic Implications
Megan Jones; Kathleen Ritterbush; and Nick Hebdon
Faculty Mentor: Kathleen Ritterbush (Geology and Geophysics, University of Utah)
Paper Nautilus or Argonauts are open-water octopi with a unique feature. The females biomineralize an egg case that doubles as a shell they swim with throughout their life. Lacking an outer covering, Argonauta shells are more susceptible to changes in pH in the ocean. These egg cases grow with a delicate ridged ornamentation that radiates out from the center. The pattern and ornamentation of these ridges is known to vary between different species and individuals, but the implications of these different patterns are not well understood.
This project utilizes 3D scanning technology to create digital models of Argonauta shells. We analyzed six shell models across four different species: Argonauta nodosa, A. hians, A. argo and A. nouryi. Using a log spiral fit analysis, we measured multiple aspects of ornamentation to provide insight into variances of shell structure and formation between species. These aspects included rib amplitude, rib frequency, and arc length.
We will continue on to use computational fluid dynamics to analyze differences in fluid flow around our shell models. I am beginning to be trained on how to use the software and set up the fluid flow simulations. We will compare differences in drag and flow paths around the egg case at both the intraspecies and interspecies levels. These differences may highlight a tradeoff between shell surface and vulnerability to pH effects versus hydrodynamic advantage. Understanding differences of hydrodynamic advantages between Argonauta shells can help us understand how different species may be affected by changing pH in the oceans, if species are unable to reach their hydrodynamic advantages due to ocean changes.
Bibliography
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Checa, A. G., Linares, F., Grenier, C., Griesshaber, E., Rodríguez-Navarro, A. B., & Schmahl, W. W. (2021). The Argonaut constructs its shell via physical self-organization and coordinated cell sensorial activity. iScience, 24(11), 103288. https://doi.org/10.1016/j.isci.2021.103288
Finn, J. K. (2013). Taxonomy and biology of the argonauts (Cephalopoda: Argonautidae) with particular reference to Australian material. Molluscan Research, 33(3), 143–222. https://doi.org/10.1080/13235818.2013.824854
Finn, J. K. (2018). Recognising variability in the shells of argonauts (Cephalopoda: Argonautidae): The key to resolving the taxonomy of the family. Memoirs of Museum Victoria, 77, 63–104. https://search.informit.org/doi/10.3316/informit.433037531258010
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Ma, D., Gregor, L., & Gruber, N. (2023). Four decades of trends and drivers of global surface ocean acidification. Global Biogeochemical Cycles, 37, e2023GB007765. https://doi.org/10.1029/2023GB007765
Ritterbush, K. A., & Hebdon, N. (2023). Hydrodynamic trade-offs in potential swimming efficiency of planispiral ammonoids. aleobiology, 49(1), 131-152. ProQuest, https://doi.org/10.1017/pab.2022.13
Wolfe, K.,Smith, A. M., Trimby, P., & Byrne M. (2012). Vulnerability of the Paper Nautilus (Argonauta Nodosa) shell to a climate-change ocean: Potential for extinction by dissolution. Biological Bulletin, 223(2), 236–44. JSTOR, http://www.jstor.org/stable/41759010
