The Role of Shell Color in Visually Mediated Substrate Selection of Hermit Crabs

Abstract

Many organisms are reliant on sensory structures to be able to sense and interact with their environment. Such as in, marine invertebrates have many structures that are related to mechanoreception, olfaction, and chemosensation. Another sensory mechanism, vision, is crucial for invertebrates living in the intertidal due to rapidly changing environmental conditions. To look more closely, hermit crabs have compound eyes that allow them to see the world around them. Although past research has focused on their chemosensory abilities, increasing evidence suggests that visual cues also influence their behavior, such as predator avoidance and shell selection. This paper will evaluate if hermit crabs display a preference for different colors of sand and if they display behavior that suggests they would prefer to be on a low-contrast sand color in comparison to their already occupied shell color. Using a 1-gallon tank with split black and white sand on either side, a 10-minute experimental trial was conducted using 19 hermit crabs of the species Pagurus granosimanus and Pagurus hirsutiusculus. Wilcoxon signed-rank tests revealed no significant preference for black or white sand and no significant preference for low-contrast sand relative to shell coloration. These findings suggest that substrate color alone may not be a primary factor influencing habitat selection in hermit crabs, although additional environmental cues may be necessary to elicit visually mediated habitat-selection behavior.