Locomotor and electric displays associated with electrolocation during exploratory behavior in mormyrid fish

Area of Science:

• Ethology
• Neuroethology
• Sensory Ecology

Background:

• Mormyrid fish utilize electrosensory information for navigation and foraging.
• Novel stimuli elicit specific motor probing acts (PMAs) in mormyrid fish.
• The role of electroreception in mediating exploratory motor behaviors is not fully understood.

Purpose of the Study:

• To investigate the motor probing acts (PMAs) of mormyrid fish in response to novel stimuli.
• To determine the influence of the electric organ on PMA expression and probing distances.
• To explore the relationship between electric organ discharge (EOD) modulation and exploratory behavior.

Main Methods:

• Observation of *Marcusenius cyprinoides* and *Gnathonemus petersii* responding to aluminum and plastic rods.
• Comparison of PMA behavior between intact fish and 'silent fish' (electric organ inoperative).
• Measurement of probing distances and analysis of electric organ discharge (EOD) rates.

Main Results:

• Fish displayed distinct PMAs: 'chin probing', 'radial', 'lateral va-et-vient', 'lateral probing', 'tangential probing', and 'stationary probing'.
• 'Silent fish' showed reduced PMA repertoire and shorter probing distances (1.8-2.6 cm) compared to intact fish (2.5-4.5 cm).
• Intact fish exhibited a regularized EOD rate (28-30 ms interdischarge interval) during PMAs.

Conclusions:

• Motor probing acts are a key component of exploratory behavior in mormyrid fish.
• The electric organ plays a significant role in modulating the expression and parameters of PMAs.
• EOD regularization during PMAs suggests a link between electric signaling and active sensing of novel environments.