Correlation between bioluminescent blinks and swimming behavior in the splitfin flashlight fish Anomalops katoptron

Area of Science:

• Marine Biology
• Animal Behavior
• Bioluminescence

Background:

• The light organs of Anomalops katoptron are essential for schooling, maintaining distance, and feeding in low light.
• Blink frequencies are context-dependent and regulated by mechanical occlusion of light organs.
• Laboratory shoaling reveals moderate blink rates around 100 blinks per minute.

Purpose of the Study:

• To correlate bioluminescent blinks with the three-dimensional spatio-temporal dynamics of swimming profiles.
• Investigate the behavioral responses of Anomalops katoptron to light organ occlusion during shoaling.

Main Methods:

• Utilized a stereoscopic, infrared camera system to track fish movements.
• Recorded and analyzed bioluminescent blink frequencies and correlated them with swimming dynamics.
• Observed changes in swimming speed, profile curvature, and direction during light organ occlusion and re-exposure.

Main Results:

• Flashlight fish exhibited intermediate polarization and distances to the group centroid.
• Swimming speeds and profile curvature increased during light organ occlusion.
• Significant changes in swimming direction were observed when light organs were darkened, with a return to straight-line movement upon light organ exposure.

Conclusions:

• A change in movement direction linked to light organ occlusion is a key behavioral trait in Anomalops katoptron shoaling.
• This behavior likely plays a significant role in maintaining group cohesion and navigation during social interactions.