Information Feedback from Photophores and Ventral Countershading in Mid-Water Squid

Abstract

The arrangement of photosensitive vesicles and photophores in two species of mid-water squid suggests that the vesicles function in detecting the intensity of downward-directed surface light and the intensity of light from their own photophores. This information is precisely what is required for an animal to eliminate its ventral shadow by the production of a ventral bioluminescent glow. This arrangement, therefore, offers strong support for the theory of ventral countershading in mid-water animals.