Turning the tide: Rhythmic aggregation behaviour in Anurida maritima (Collembola) is entrained by inundation

Numerous foreshore species evolved the ability to predict tidal change and adjust behaviour and metabolism accordingly. The intertidal collembolan Anurida maritima (Guérin-Méneville, 1836) shows endogenously controlled rhythmic changes in behaviour that anticipate the tides. Animals forage during low tide and hide in large aggregations in the substrate during high tide. Here, artificial tidal environments and time-lapse photography were used to investigate if this behaviour is responsive to key environmental cues. It is shown that the precise rhythmicity of aggregation behaviour is dependent on periodic inundations. In the absence of such inundations, rhythmic aggregation patterns dissipate and are no longer accurate after 14 days. Slowly shifting the artificial tides, showed that rhythmic aggregation behaviour in A. maritima is responsive and adjusts to a newly-imposed tidal regimen. This suggests that the species has the ability to synchronise to newly encountered tidal conditions under natural conditions. The findings provide a robust foundation for advancing detailed chronobiological research on A. maritima as a model organism to gain a deeper understanding of biological time-keeping.