Fig. 3: Salinity limits sheet presence in nature.

a, The location of Shete Boka National Park (turquoise star). b, Splash pools (white arrowheads). c, Schematic of the splash pool evaporation, desiccation and refilling cycle. d, Maps showing the sampled splash pools in Exped-A and Exped-B (n = 150). In Exped-A, the samples were collected from splash pools along around 2 km of coastline (n = 79). Ten splash pools with sheets (pink) and five without sheets (turquoise) on day 1 were randomly selected for daily monitoring during 8 days (stars, n = 15). In Exped-B (inset), the samples were collected from splash pools within a 4 m × 10 m quadrant (purple pin, n = 71). e, The distribution of salinity of splash pools in Exped-A (circles), Exped-A daily monitoring (dm, triangles) and Exped-B (squares). For Exped-A daily monitoring, all measurements are shown, except those in cases in which splash pools were dry. The grey area indicates salinity saturation (>280 ppt). Statistical analysis was performed using the Mann–Whitney U-test. f, Bright-field image of a splash pool sheet. n = 4 biological replicates (n = 18 sheets). Scale bar, 50 μm. g, A representive splash pool (Sp15, Exped-A) that was followed for 8 days (top left, salinity). The dashed line shows the splash pool outline. h, The salinity (top) and depth (bottom) of three daily monitored splash pools (n = 15). i, Recovery of sheets from soil collected from a desiccated splash pool (Sp12, Exped-A). n = 6 desiccated splash pools, at least three independent rehydration (rh) experiments per splash pool. j, Bright-field image of a soil-recovered sheet in i. Scale bar, 5 μm. k, Bright-field image of a soil-recovered sheet from soil 18 in Exped-C. Scale bar, 20 μm. n = 26 splash pools. Inset: magnified view, showing collar–collar contacts (black arrowhead). Green pseudocolour, collars; yellow pseudocolour, cell bodies. The figure is related to Extended Data Figs. 1–4, Supplementary Videos 14–16, Supplementary Tables 1 and 2 and Supplementary Data 1–4.