The shell-eyes of the chitonAcanthopleura granulata(Mollusca, Polyplacophora) use pheomelanin as a screening pigment

Certain species of chiton (Mollusca, Polyplacophora) have hundreds of small (< 100 µm) eyes embedded in their dorsal shell plates. These eyes each contain a retina, a layer of screening pigment, and a lens. Previously, we demonstrated that the eyes of chitons provide spatial vision. As in other camera-type eyes, the screening pigments in the eyes of chitons absorb off-axis light in order to preserve the contrast of images formed on the retina....