The ability to use oxygen from both air and water has been considered key to the colonization of terrestrial environments by invertebrates. The freshwater gastropod Pomacea figulina generally lives submerged, although females lay their eggs mainly above water during nighttime, on the stems of aquatic plants, and the embryos develop inside the air-exposed calcareous egg capsules. However, little is known about the physiological adaptations that the ovipositing females and the developing embryos have developed to breathe in air. In this study, we report sexual differences in the aerial and aquatic oxygen consumption of adults and embryonic respiration in aerially developing egg clusters. We found that the males and females of this species can obtain oxygen from both water and air, although uptake rates for both sexes were much lower in air than in water. Females in air consumed oxygen 42% faster than males, which may be related with the habit of egg laying above water level. Developing embryos inside calcareous eggs obtained oxygen faster when submersed under water than when exposed to air, although embryos near hatching were better able to use oxygen from both air and water than embryos at earlier stages of development. Our data suggest that for P. figulina, laying eggs in the terrestrial environment may be more a strategy for protecting embryos from predators than a respiratory adaptation.

中文翻译：

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父母生活在水中，胚胎在空气中发育：淡水腹足动物 Pomacea figulina (Gastropoda, Ampullariidae) 对两种环境的呼吸适应

利用空气和水中氧气的能力被认为是无脊椎动物在陆地环境中定居的关键。淡水腹足类 Pomacea figulina 通常生活在水下，尽管雌性在夜间主要将卵产在水面上，在水生植物的茎上，胚胎在暴露在空气中的钙质卵囊内发育。然而，关于产卵雌性和发育中的胚胎已经发展到呼吸空气的生理适应性知之甚少。在这项研究中，我们报告了成人空中和水中氧气消耗的性别差异以及空中发育的卵簇中的胚胎呼吸。我们发现这个物种的雄性和雌性都可以从水和空气中获取氧气，尽管两性在空气中的吸收率远低于在水中。女性在空气中消耗氧气的速度比男性快 42%，这可能与在水面以上产卵的习惯有关。在钙质卵中发育的胚胎在浸入水中时比暴露在空气中更快地获得氧气，尽管接近孵化的胚胎比早期发育阶段的胚胎更能利用空气和水中的氧气。我们的数据表明，对于 P. figulina，在陆地环境中产卵可能更像是一种保护胚胎免受捕食者侵害的策略，而不是呼吸适应。在钙质卵中发育的胚胎在浸入水中时比暴露在空气中更快地获得氧气，尽管接近孵化的胚胎比早期发育阶段的胚胎更能利用空气和水中的氧气。我们的数据表明，对于 P. figulina，在陆地环境中产卵可能更像是一种保护胚胎免受捕食者侵害的策略，而不是呼吸适应。在钙质卵中发育的胚胎在浸入水中时比暴露在空气中更快地获得氧气，尽管接近孵化的胚胎比早期发育阶段的胚胎更能利用空气和水中的氧气。我们的数据表明，对于 P. figulina，在陆地环境中产卵可能更像是一种保护胚胎免受捕食者侵害的策略，而不是呼吸适应。