Abstract
A peculiar feeding habit of opening mollusk shells was observed in Calappa gallus capellonis LAURIE in the field (Murote Bay faced to the Bungo Channel) and in the laboratory (Ehime University). It is sure that the box crabs can skillfully open the shells by using the tubercles of the right chela and thus feed on the soft parts or hermit crabs. The shell-opening mechanism observed is not basically different from the result reported by SHOUP (1968). When there are no shells in the surrounding, the box crabs take the other foods.
