The oral discs of anuran tadpoles are diverse and involved in feeding, sensing, and attaching to the substrate. The umbelliform oral discs in the tadpoles of the subfamily Megophryinae (Megophryidae) are highly specialized for feeding at the water surface and characterized by dorsally-oriented, laterally-expanded flaps decorated with arrays of papillae. The functionality of these oral discs remains understudied. Here, I report a hiding behaviour in Brachytarsophrys chuannanensis tadpoles, where the tadpoles attach themselves to a firm substrate underwater, using their oral disc as a suction cup. These tadpoles were positively buoyant when feeding at the water surface. If disturbed, they tried to hide underwater by attaching the oral disc to a solid substrate to prevent from floating up. The attachment was maintained with active buccal pumping, which reinforced the friction between oral disc and the substrate. Further observations suggest that the tadpoles gained positive buoyancy from air storage in their lungs, and they were negatively buoyant after deflating them. My results suggest that dorsally-oriented oral discs in Brachytarsophrys tadpoles can be used for substrate adhesion, which is likely an effective means to hide from potential threats or prevent passive displacement in the dynamic flow environment of mountain creeks.
The viability of many turtle species, including the European pond turtle (Emys orbicularis), is imperiled by nest depredation. Depredation rates of the E. orbicularis population in eastern Slovakia are high; therefore, we aimed to identify nest predators and to determine which sensory cues they use to find the nests. From the set of different experimental trials with artificial nests in the field, only the application of turtle-scented water imitating the female migration path to the nesting site suggested potential predation of turtle nests driven by olfactory cues. Although we did not observe depredation of the installed artificial nests, we identified badgers (Meles meles), wildcats (Felis silvestris) and wild boars (Sus scrofa) as potential predators. Our results also imply that the use of chemical repellents should be considered for nest protection of the study species in the Tajba National Nature Reserve.
