Gastropod shell size and architecture influence the applicability of methods used to estimate internal volume

Author(s)

Ragagnin, Marilia Nagata ^[1] ; Gorman, Daniel ^[1] ; McCarthy, Ian Donald ^[2] ; Sant'Anna, Bruno Sampaio ^[3] ; de Castro, Claudio Campi ^[4] ; Turra, Alexander ^[1]

Affiliation

^[1] Univ Sao Paulo, Inst Oceanog, Sao Paulo, SP - Brazil

^[2] Bangor Univ, Sch Ocean Sci, Menai Bridge, Anglesey - Wales

^[3] Univ Fed Amazonas UFAM, Inst Ciencias Exatas & Tecnol, Itacoatiara, AM - Brazil

^[4] Univ Sao Paulo, Hosp Univ, Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: SCIENTIFIC REPORTS; v. 8, JAN 11 2018.
• Web of Science Citations: 0

Abstract

Obtaining accurate and reproducible estimates of internal shell volume is a vital requirement for studies into the ecology of a range of shell-occupying organisms, including hermit crabs. Shell internal volume is usually estimated by filling the shell cavity with water or sand, however, there has been no systematic assessment of the reliability of these methods and moreover no comparison with modern alternatives, e.g., computed tomography (CT). This study undertakes the first assessment of the measurement reproducibility of three contrasting approaches across a spectrum of shell architectures and sizes. While our results suggested a certain level of variability inherent for all methods, we conclude that a single measure using sand/water is likely to be sufficient for the majority of studies. However, care must be taken as precision may decline with increasing shell size and structural complexity. CT provided less variation between repeat measures but volume estimates were consistently lower compared to sand/water and will need methodological improvements before it can be used as an alternative. CT indicated volume may be also underestimated using sand/water due to the presence of air spaces visible in filled shells scanned by CT. Lastly, we encourage authors to clearly describe how volume estimates were obtained. (AU)

• FAPESP's process: 10/20550-7 - Comparison between methods for the determination of the internal volume of gastropod shells used by hermit crabs
• Grantee: Marilia Nagata Ragagnin
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• FAPESP's process: 14/21804-3 - Integrating consistent individual differences theory into ecological and evolutionary studies related to global and local environmental change
• Grantee: Alexander Turra
• Support Opportunities: Research Grants - Visiting Researcher Grant - International