Sensory Basis of Food and Predator Detection in the Tadpoles of the Indian Skipper Frog Euphlyctis cyanophlyctis (Schneider, 1799) (Anura: Dicroglossidae): an Empirical Study.

The majority of the amphibian larvae spend their early life stage in aquatic medium. In such system, they respond to a broad array of stimuli (tactile, chemical and visual cues) and exhibit suitable behavioural responses. The ability of detection of food and predator was studied in the tadpoles of the Indian skipper frog Euphlyctis cyanophlyctis in the laboratory setup by using a rectangular glass test tank with end compartments (stimulus zones) providing exclusively visual and and (or) chemical food (either boiled spinach or tadpoles of Duttaphrynus melanostictus) and predator (tadpoles of Hoplobatrachus tigerinus). A test tadpole E. cyanophlyctis was held at the centre of the test tank for 5 min (acclimation) to perceive visual and (or) chemical food or predator cues. Then it was released from the centre of the test tank and allowed to associate or stay away from the caged stimulus subjects (food or predator), which were placed at one end of the test tank either in a glass beaker (visual cues) or in a mesh cage wrapped with cheese cloth (chemical cues) for a period of 10 min. The test tadpoles failed to detect either food or predator through visual cues. They spent almost an equal amount of time in the zone housing food or predator in a glass beaker as compared to the opposite zone, which was kept empty. However, they detected both food and predator solely through chemical cues. In tests with chemical food cues (either boiled spinach or tadpoles of D. melanostictus), they spent the majority of their time (67.25 % of total time) near chemical food cues rather than empty or visual food cues. In contrast, in tests with chemical predator cues (tadpoles of H. tigerinus), they spent the majority of their time (68.89 % of total time) away from the chemical predator cues. Therefore, the findings show that E. cyanophlyctis tadpoles detect both food and predator through chemical sensory mechanism rather than visual ones. [ABSTRACT FROM AUTHOR]