Seaward migration and larval release of the land hermit crab Coenobita brevimanus Dana, 1852 (Anomura: Coenobitidae) on Iriomote Island, Japan

Research on Iriomote Island, Japan, reveals that the land hermit crab Coenobita brevimanus exhibits distinct seaward migration and larval release patterns tied to lunar cycles. Peak activity occurs around new moons (particularly 0.82 days post-new moon) and spring tides (1.34 days after full moon), with migrations primarily happening between June and November, especially during warmer months (July–September). Crabs appear on beaches between 19:00 and 23:10, entering seawater approximately two hours after nighttime high tide. Nearly half of the crabs that emerge release larvae or display swimming behavior. This study highlights the species' semi-lunar rhythms and seasonal adaptation, aligning with broader observations of coenobitid crabs in the Ryukyu Islands.

Nio, T., Doi, W., Mizutani, A., & Kohno, H. (2019). Seaward migration and larval release of the land hermit crab Coenobita brevimanus Dana, 1852 (Anomura: Coenobitidae) on Iriomote Island, Japan. Crustacean Research, 48(0), 67–80. https://doi.org/10.18353/crustacea.48.0_67