Corneal iridescence in fishes: light-induced colour changes in relation to structure

The iridescent corneas of 31 species of teleost fish were investigated for light-induced colour changes. Thirteen were found to shift the spectral reflection of their corneas to shorter wavelengths when dark-adapted and to longer wavelengths when illuminated. The structures of the corneas were examined by electron microscopy and categorized according to the type of structure modified to produce the iridescence. Six previously identified structures were found and a seventh type is described here.