Fluorescence of a sea spider and a small benthic amphipod. Both the green fluorescence of the whole exoskeleton, as well as weak red of the gut content, are examples of non-functional fluorescence. The cyan fluorescence of the amphipod’s eye is most probably the consequence of visual pigment presence and is also unlikely to have any specific biological function. Top image courtesy of Charles Mazel / Johnson Sea Link I. Bottom image courtesy of Mikhail Matz.