DOI: 10.5061/dryad.6mk023c0
title: Data from: Functional constraints on coiling geometry and aperture inclination in gastropods

description: We studied the morphological diversity of gastropod shell forms from the
 viewpoint of theoretical morphology, emphasizing the relationships of
 shell form to postural stability and the available space for soft body,
 which we assessed in terms of the moment of force and soft-tissue ratio
 calculations, respectively. The results of computer simulations suggest a
 functional trade-off between postural stability and available space for
 soft body: a compact shell possessing a low spire and small umbilicus
 exhibits high postural stability, whereas a less overlapped shell form
 with a high spire and large umbilicus makes available space for soft body.
 A functional morphospace analysis using theoretical models reveals that
 outward and downward inclination of the aperture moderates the functional
 trade-off between these parameter values and permits compatibility between
 stable posture and efficient shell construction. The hypothetical optimum
 that realizes this compatibility is consistent with the observed range of
 forms estimated from 359 extant gastropod species. The biometric results
 also suggest that land snails are more highly constrained than marine
 species in achieving a balance between postural stability and available
 space for soft body.
description: Supplementary Table
 1Specimens examined,
 habitat and measured values of parameters: M = marine species; F =
 freshwater species; L = land species; SUM = Shizuoka University; SHIN =
 Shinshu University; BPBM = Bishop Museum; SPMN = Network for Shizuoka
 Prefecture Museum of Natural History; UMUT = University Museum, University
 of Tokyo.Table_without_sp Supplementary
 Table. 1.pdfSupplementary Table
 2Lists of repeated
 measurement of the Raup’s parameter. These lists were obtained from
 30-repeated measurement of each specimen.Table_without_sp Supplementary
 Table. 2.pdfSupplementary Table
 3Statistics for each the
 Raup’s parameter of each specimen: Min = minimum; Q1 = lower quartile; Q3
 = upper quartile; Max = maximum; SD=standard deviation; CV=coefficient of
 variation.Table_without_sp Supplementary
 Table. 3.pdfSupplementary Figure
 1Three-dimensional
 contour diagrams depicting the postural stability (1/Λ) and the available
 space for soft-body (E) values on the Γ-Δ apertural inclination
 morphospace for various combinations of the translation rate T and
 umbilical width D (for the whorl translation rate W = 100.2). The
 positions of actual specimens with parameters close to the values depicted
 on the diagrams are plotted by symbols representing their respective
 habitats (land, freshwater, and marine). The criterion for including a
 specimen on the diagram is that the measured parameters (W, T, and D) fall
 within a certain range of the plotted values ( , Ts, and Ds), such that W
 = , T = Ts ± 0.5, and D = Ds ± 0.1.supplementary_fig_1.pdfSupplementary Figure 2Contour diagrams of 1/Λ (above) and E (below) on the same morphospace shown in Supplementary Figures 1, but with a whorl translation rate of W = 100.6 (see Supplementary Fig. 1 for details.)supplementary_fig_2.pdfSupplementary Figure 3A, B. Nerita chamaeleon (interim number 700). C, D. Terebra areolata (interim number 2141). E, F. Achatina fulica (interim number L-288). G, H. Acavus haemastoma (interim number L-523). I, J. Aegista vermis (interim number L-93). A, C, E, G, and I. Model parameters are determined from measurements of specimens viewed from lateral (A, C, E, G, and I) and umbilical (B, D, F, H, and J) perspectives. All scale bars, 2 cm.supplementary_fig_3.pdfSupplementary Figure 4Box and whisker diagrams of each ’of Raup’s parameters. These plots summary sample minimum (Min), lower quartile (Q1), median, upper quartile (Q3), and sample maximum (Max). Black cross (×) indicates the mean of sample.supplementary_fig_4.pdf