Lessons on transparency from the glassfrog

Description Transparency in glassfrogs has potential implications for human blood clotting An obvious feature of life on Earth is that most animals and plants can be seen. This visualization is important for predation, feeding, and mating but does not apply to all animals, some of which are transparent. The origins of this phenomenon and how it has been evolutionarily selected are unclear. One such species is glassfrogs, so called because of their transparent bodies and translucent skin. These nocturnal arboreal frogs sleep during the day on green leaves. Previous work (1) found that they exhibit dynamic transparency, camouflaging themselves against the leaves where they sleep, likely to escape from predators. On page 1315 of this issue, Taboada et al. (2) report the distinct optical properties of the glassfrog Hyalinobatrachium fleischmanni and uncover the surprising physiological mechanism behind their transparency. This finding provides insights into mechanisms of camouflage but also could lead to development of new anticoagulant drugs.