Fig. 1.

Day 10 images from a time course of embryonic development of the freshwater common pond snail L. stagnalis under control (a dechlorinated MDTW, 310 μmol l⁻¹ Ca²⁺ and 680 μmol l⁻¹ HCO₃ ⁻), nominally HCO₃ ⁻-free (b 310 μmol l⁻¹ Ca²⁺ and 7.5 μmol l⁻¹ HCO₃ ⁻), and nominally Ca²⁺-free (c 3 μmol l⁻¹ Ca²⁺ and 680 μmol l⁻¹ HCO₃ ⁻) conditions. Eggs were placed in the media within 24 h post-oviposition and maintained for the duration of the development with daily water replacement. Morphological characters are identified in a (a, embryo; b, perivitelline fluid; c, egg capsule (membrana interna and membrana externa); d, tunica interna; e, double-layer outer membrane, i.e., tunica capsulis; f, Pallium gelatinosum). Scale bar 1 mm