Are marine isopods picking favorites with colors? The role of color sensing in food preference in Pentidotea wosnesenskii

Abstract

The marine isopod Pentidotea wosnesenskii is one of many species that can change its color throughout its life. The variety of colors it can take on allows it to match the species of algae it lives on and consumes. While this isopod can change its color when moved to a new substrate, this requires it to build a new cuticle and molt, a process that takes weeks. It seems likely that it would be more efficient for an isopod to seek out algae that it is already matched to. This species is highly likely to have color sensing abilities as a way of adjusting their chromatophores, so they may use those abilities to search for a substrate that they can match. I placed isopods in containers where they had access to three different colors of algae. I hypothesized that adult isopods would show a preference for algae that was similar in color to their cuticles. However, the results of this study do not suggest that isopods use color sensing to move to matching backgrounds. Instead, they may be choosing substrates based on its quality as a food source or how well they can attach themselves to it. Because they can adjust the shade of their body with their chromatophores, these other factors may be a higher priority than a wellmatched color.