we sequenced the transcriptome of C. challengeri under two different tidal conditions, the first condition (atmosphere group) including the individuals immediately exposed to atmosphere from falling tide (0h), 2.5 h in atmosphere and after 5 h in atmosphere and the second condition (seawater group) including individuals immediately immersed in seawater from rising tide (0h), after 2.5 h under seawater, and 5 h under seawater, to identify gene expression differences between high and low tide