Abstract
Distribution and movement of Littoraria intermedia, L. scabra, and L. pallescens were investigated in the Fukido Mangal and on the coast of Miyara Bay on Ishigaki Island, Okinawa, southern Japan. Significant differences were detected between these three species in their vertical distribution, distribution on different mangrove trees, distribution on different kinds of substratum on the trees, and density on a concrete wall, but differences were not in most cases found between the two color types of L. pallescens. Obvious differences were also found between L. intermedia and L. pallescens in their patterns of vertical movement related to tide, and in their locomotive activity in rain. These ecological characteristics are consistent with the taxonomic scheme of mangrove littorinids by Reid (1986), and provides preliminary data on the diversification of littorinids in mangrove swamps.
