The Taiwanese tree frog Kurixalus eiffingeri lays its eggs in small water pools on plants, such as tree hollows or bamboo stumps . The larvae feed exclusively on the trophic eggs laid by their mothers and spend their entire larval period in tiny phytotelmata of less than 50 cm2 of surface area and 2.5 cm of water depth .

Interestingly, during laboratory rearing, we observed that K. eiffingeri larvae do not seem to defecate until metamorphosis (Figure 1c), and that larvae accumulate solid feces in their gut during whole larval period .

From this finding, we hypothesized that this is a unique sanitation strategy to avoid potentially harmful ammonia contamination in a small, closed, water system.