Sensory modalities involved in food detection in tadpoles of Rhinella arenarum

During larval development, anuran amphibians must exploit environmental resources to maximize growth. Although the olfactory and visual systems develop early during ontogeny, little is known about their relative contribution to food detection. We conducted behavioral experiments to determine the sensory modality used by Rhinella arenarum tadpoles to detect food. In a two-choice arena with food enclosed in either a glass cylinder (visual stimulus only) or a mesh cylinder (chemical stimulus only), tadpoles approached the chemical stimulus faster and spent significantly more time displaying foraging behavior around it. In contrast, no oriented responses were directed toward the visual-only stimulus. Complementary experiments assessing food localization ability under light and dark conditions showed that animals tested in total darkness exhibited higher latency to locate the food source compared to those tested in light; however, this was accompanied by a reduction in overall exploratory activity. Together, these results indicate that olfaction would be the primary sensory modality driving food detection in R. arenarum larvae, while visual input might enhance overall exploratory behavior. However, whether vision acts as a direct cue for food localization or purely as a contextual modulator of activity would require further investigation.