Sensory Basis of Food and Predator Detection in the Tadpoles of the Bicolored Frog Clinotarsus curtipes (Jerdon, 1854) (Anura: Ranidae).

Most of the anuran tadpoles spend their early phase of life in aquatic medium. In such system, they respond to a wide variety of stimuli (e.g., tactile, chemical and visual cues) and exhibit appropriate behavioural responses. The ability to detection food and predator was studied in the tadpoles of the bicolored frog, Clinotarsus curtipes in the laboratory by using a rectangular glass test tank with end compartments (stimulus zones) providing exclusively visual and/or chemical food (boiled spinach) or predator (Laccotrephes sp.) cues. A test tadpole, C. curtipes (either starved or fed; Gosner stage 25) 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 were unable to detect both food and predator through visual cues. They spent almost an equal amount of time in the zone housing food or predator in a glass beaker or opposite zone, which was kept empty. However, they detected both food and predator solely through chemical cues. In tests with chemical food cues, they spent a significantly higher period of time (70.42% of total time) near chemical food cues rather than empty or visual food cues. In contrast, in tests with chemical predator cues, they spent the majority of their time (69.32% of total time) away from the chemical predator cues. The findings thus show that C. curtipes tadpoles detect both food and predator solely through chemical cues rather than visual cues. [ABSTRACT FROM AUTHOR]