Interactive robotic experiments to assess the spatial logic of electric signalling in a gymnotiform knifefish

• Applicants: Professor Dr. Rüdiger Krahe; Professor Dr. Tim Landgraf
• Subject Area: Sensory and Behavioural Biology
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 577401533

Weakly electric fish use self-generated electric fields for navigation and communication. In the South-American brown ghost knifefish (Apteronotus leptorhynchus), short modulations of electric field frequency known as “chirps” have traditionally been interpreted as social signals encoding aggression, dominance, or courtship availability (“communication hypothesis”). Our recent experimental work challenges this long-held view, suggesting that chirps may be used, at least in large part, for sensory probing purposes in complex environments. Chirps may help brown ghosts to resolve the electrosensory input resulting from the electric fields of nearby conspecifics. This project aims to test this “probing hypothesis” using a robotic fish replica that can interact with brown ghost knifefish through motion as well as the generation of species-typical electric signals. This approach offers the unique advantage to allow the re-creation of specific behavioral situations through a feedback loop controlling motion and electric signaling of the robot. The situations to be tested are selected following an extensive analysis of recorded fish-fish and fish-robot interactions using machine-learning approaches. The temporal and spatial parameters of chirping will be evaluated to assess whether chirps are more likely to match probing behaviors or, conversely, emotionally-laden displays - as most communication signals do - such as aggression or submission, for instance. By comparing chirp emission with other active sensing strategies, this project aims to provide new insights into how animals use active signals not only for communication, but also to explore and interpret their social environment.

• DFG Programme: Research Grants
• International Connection: USA
• Co-Investigator: Dr. Jan Grewe
• Cooperation Partner: Federico Pedraja, Ph.D.