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. 2024 Nov 19;15:9445. doi: 10.1038/s41467-024-53110-x

Fig. 6. The observed orientation, size, and shape of the aragonite crystals allow them to transmit more photosynthetically active radiation (400–700 nm) than other morphologies.

Fig. 6

We conducted parameter sweeps in simulation and validated the simulations by measuring transmission of 400–700 nm light through 300 μm thick polished shell windows (Supplementary Fig. 1; gray rectangle in (a), (d), and (e) = mean experimental transmission ±1 sd). a More light is transmitted through shell windows with a higher proportion of fibers rather than planes. Simulations of 100% fibers match experimental measurements (gray rectangle). b, c Light propagates differently through shells composed primarily of fiber-optic-cable-shaped (left) compared to planar (right) aragonite. d Transmission increases with fiber width. Simulations of the observed 1 μm width match the experimental measurements (gray rectangle). e Orientation along one of the two higher refractive indices (b or c), the observed arrangement (Fig. 5), transmitted significantly more light than orientation along the a-axis (two-sample two-sided paired t tests: a vs. c, p = 0.00092, 95% CI = [2.26, 7.55], mean diff. = 4.91, df = 21, t = 3.85, Cohen’s d = 0.55; a vs b, p = 0.00058, 95% CI = [3.62, 11.3], mean diff. = 7.44, df = 21, t = 4.05, Cohen’s d = 0.79; b vs c, no significant difference). Boxplots show median, quartile 1, quartile 3, and whiskers that extend to the largest and smallest values ≤ |1.5 * interquartile range|. N = 22 wavelengths were simulated. f Light propagation depends on a fiber’s optical orientation (for both fibers, ny = 1.681; left, nx = 1.530; right, nx = 1.686). We conducted FDTD simulations in Ansys Lumerical for (a–d) and FEM simulations in COMSOL for (e, f). Results were consistent when we varied the width and complex refractive index of the organic matrix (see Supplementary Fig. 8 and Methods). Illustrations in (b, c) by Nuria Melisa Morales Garcia, Science Graphic Design LTD. See Source Data for Fig. 6 in Lumerical_planar_vs_columnar_simulations_V2.csv, COMSOL_VaryRefractiveIndex_Simulation_Results_V11.csv, Lumerical_vary_pillarwidth_simulations_V1.csv, planarvscolumnar.zip (Supplementary Data 1.zip).