Scent-driven self-recognition in caecilian amphibians (Gymnophiona): an experimental study in Gegeneophis

Chemical communication is important in amphibians, contributing to various functions such as social interactions, foraging, parental care, mate recognition, and predator deterrence. Unlike most anurans (frogs and toads) and caudatans (salamanders and newts), most gymnophionan amphibians (caecilians) lead a secretive, burrowing life and have reduced visual systems; hence, they are expected to make substantial use of chemical communication. In addition, caecilians uniquely possess a protrusible pair of little-studied and poorly understood chemosensory tentacles that connect to the vomeronasal organs, suggestive of reliance on (vomer-)olfaction communication. However, current knowledge of the behaviour of (vomer-)olfaction and chemical communication in caecilians is almost non-existent, having been studied briefly in only two species previously. We investigated the role of olfactory cues in self-recognition in a terrestrial Indian caecilian Gegeneophis sp., using a Y-maze behavioural choice experiment. We analysed choices made under self vs. blank chemical-cue conditions. Individuals expressed a significant preference for self-cues over no cues. This is only the second study on self-recognition in caecilians mediated by olfactory cues, and the first to test it in a terrestrial, soil-dwelling species with highly reduced eyes.