Mainly on the mid and lower shore on wave-exposed or moderately wave-exposed coasts of medium and fine sand, sometimes with a fraction of coarse sand, which remains damp throughout the tidal cycle and contains little organic matter. The sediment is often rippled and typically lacks an anoxic sub-surface layer. The infauna is dominated by burrowing amphipods, most notably Pontocrates arenarius, as well as Bathyporeia pelagica, Haustorius arenarius and the isopod Eurydice pulchra. The polychaete fauna is poor, dominated by Scolelepis squamata, which tolerates the exposed and mobile sediment conditions. The presence of polychaetes may be seen as coloured burrows running down from the surface of the sediment. Situation: This biotope may be present on the lower shore, where units A2.221, A2.2232, or A2.2231 are present higher up. Where this unit occurs on the mid shore in relatively sheltered conditions, unit A2.231 may be present on the lower shore. Unit A2.211 may be present where driftlines of fucoids and other debris occur on the upper shore. Temporal variation: This biotope may change to unit A2.2232, which is very similar in character, if P. arenarius decreases in abundance. Winter storms may reduce the number of or temporarily remove macroinvertebrates from exposed sandy beaches, with the sediment becoming re-colonised during the summer months.