Behavioural manipulations with a biomimetic robot – the Robofish system

Live animals, especially when in a group of conspecifics, can hardly be forced to change their behaviors as intended by the experimenter. Hence, experimental manipulations are difficult and often lacking to underpin proposed theoretical assumptions on collective movement, decision-making or leadership. One elegant solution is to replace live individuals in a group by biomimetic robots. In a multidisciplinary group, we thus developed an interactive fish robot – the so-called RoboFish.

Through the interactive behaviors based on real time tracking of the fish shoal, our system can be adjusted to imitate different individual characteristics of live fish and is accepted as a conspecific by live guppies (Poecilia reticulata). This allows us to use RoboFish to investigate many different ethological questions.

Social interactions in many fish species rely mostly on visual cues. However, some fish species colonized habitats where visual cues are omitted. In the South of Mexico, surface-dwelling mollies (Poecilia mexicana) successfully invaded caves and adapted to dark conditions. While almost colorless, these cave mollies possess smaller but still functional eyes. Although previous studies found cave mollies to show reduced shoaling preferences with conspecifics in light it is assumed that they possess specialized adaptations to maintain some kind of sociality also in their dark habitats

Size-dependency of follower-leader relationship

Guppies prefer to follow large (robot) leaders irrespective of own size (Bierbach, Mönck, Lukas, et al. 2018)

Social responsiveness and leadership

Using a robotic fish to investigate individual differences in social responsiveness in the guppy (Bierbach, Landgraf, Romanczuk, Lukas et al. 2018)

Social behavior of surface and cave-dwelling fish

Insights into the Social Behavior of Surface and Cave-Dwelling Fish (Poecilia mexicana) in Light and Darkness through the Use of a Biomimetic Robot (Bierbach, Lukas et al. 2018)

Social networks of surface and cave-dwelling fish

Social networks in the absence and presence of visual cues (Bierbach, Krause, Romancuk, Lukas, et al. 2018)