(Amphipoda) showed a clear synchrony with the nocturnal tide. In contrast, the pattern of Ericthonius sp. More than half of these patterns were not affected by the tidal cycle at all. A notable feature was that nocturnal patterns were very dominant. Although most patterns were much the same between the surface and bottom waters, the abundance of animals was different between the two depths.
By use of two impeller pumps installed in both surface and bottom waters, invertebrates were sampled continuously for 23 days. To characterize their emergence in the water column with regards to day/night, tidal, and lunar cycles, field investigations were carried out at the subtropical island (Iriomote-jima), Okinawa Prefecture. The subtidal zones near the shore are inhabited by many small invertebrates, including benthos and plankton.
