Prey catching in the archer fish: does the fish use a learned correction for refraction?

Area of Science:

• Ethology
• Animal Behavior
• Sensory Perception

Background:

• Archer fish (Toxotes spp.) accurately strike aerial insects despite light refraction at the water's surface.
• The mechanism by which archer fish compensate for visual distortion remains poorly understood.
• Previous hypotheses suggest learned corrections based on prey capture feedback.

Purpose of the Study:

• To investigate if archer fish utilize learned corrections for light refraction using the virtual image.
• To determine the effect of practice deprivation on the performance of archer fish squirting accuracy.
• To test the hypothesis that archer fish employ learned corrections for refraction.

Main Methods:

• Measuring the accuracy of water squirting in 30 archer fish subjects.
• Comparing performance between experimental subjects deprived of practice and control subjects with daily practice over 6 months.
• Observing aiming behavior and squirting success rates.

Main Results:

• Elevation failures were common, but over- and under-squirting frequencies did not differ significantly.
• Depriving subjects of practice did not affect overall hitting accuracy.
• Experimental subjects showed increased aiming frequency before squirting only in the initial session.
• Abnormal mandible development in some subjects led to consistent high-angle shots.

Conclusions:

• Findings do not support the hypothesis that archer fish use learned corrections for light refraction.
• Feedback from prey capture efficacy does not appear to drive learned refractive compensation.
• Practice deprivation has minimal impact on the fundamental accuracy of archer fish hunting.