Even in diurnal animals with good vision the number and spectral tuning of photoreceptors varies greatly. Cephalopods have one receptor type while many stomatopod crustaceans have twelve. In many vertebrates, some insects and stomatopods intraocular filtering by oil droplets narrows photoreceptor spectral sensitivities, while mammals and honeybees lack these filters. The bee's three receptor spectral sensitivities are the equally spaced while primates' are not. We will consider how uses of colour vision for signalling and for encoding 'background' spectra might have led to this diversity, and suggest that colour cannot be regarded simply as another dimension in scene statistics. In particular, an appreciation of how reflectance spectra identify biological signals is important for understanding the evolution chromatic coding by different eyes.
Reference
Osorio D, Vorobyev, M. (1997). Sepia tones, stomatopod signals and
the uses of colour. Trends Ecol Evol. 12, 167-168.