Soldier crabs learn from the repetition of simple exploratory tasks

Abstract Learning is a very important function for the survival of animals and is believed to occur in most species. Crustaceans are no exception, with several studies concluding that crabs and crayfish exhibit the ability to learn. The soldier crab, a species that lives on a remote island in Okinawa, Japan, forms groups ranging from several hundred to several tens of thousands of individuals when foraging. However, few studies have examined the learning ability of crustaceans that form such large groups. In this study, to examine the learning ability of individual soldier crabs, we conducted an experiment in which individuals in a laboratory environment were tested with a simple task: crabs were placed in a bisected arena, half with sand that allowed them to burrow underground and half with sand that did not. The significant results indicated that crabs may exhibit learning in response to the environment.