Modelling colour constancy in fish: implications for vision and signalling in water

Area of Science:

• Aquatic animal vision
• Colour perception in fish
• Visual communication in marine environments

Background:

• Water distorts light, affecting underwater colour signals.
• Colour vision is crucial for aquatic animals.
• Photoreceptor spectral sensitivities and body colours are key to visual communication.

Purpose of the Study:

• To model how viewing distance and depth affect fish colour appearance.
• To investigate colour vision performance in aquatic environments.
• To explore the evolution of photoreceptor sensitivities and body colours for communication.

Main Methods:

• Modelling colour vision in three teleost species (one barracuda, two damselfishes).
• Applying the von Kries transformation to simulate light adaptation.
• Analyzing the impact of viewing distance and depth on colour perception.

Main Results:

• Light scattering impairs dichromatic vision within a meter.
• Colour saturation judgment is unreliable for trichromats with distance.
• The von Kries transformation largely offsets depth-induced colour shifts (0-30m).
• Remaining colour changes are complex, depending on receptor and reflectance spectra.

Conclusions:

• Evolutionary linkage between signalling colours and photoreceptor sensitivities is predicted.
• Body colours and visual systems likely co-evolve for effective communication.
• Understanding these relationships is vital for interpreting fish colour signals.