Well-draining beaches of medium- to fine-grained mobile sand, often (but not always) well sorted. Occasionally, a small fraction of coarse sand may be present. The biotope generally occurs on exposed open coasts, but sometimes in estuarine conditions, supporting populations of the isopod Eurydice pulchra and burrowing amphipods which frequently include Bathyporeia pilosa and Haustorius arenarius. The degree of drainage appears to be a critical factor in determining the presence of polychaetes, with only Scolelepis squamata capable of tolerating the well-drained sediments of this biotope. This biotope has two facies: drying upper and mid shore sands, and highly mobile lower shore and shallow sublittoral sand bars. Where this biotope occurs in estuarine conditions, H. arenarius is often highly abundant. Situation:This unit may occur on the mid and upper shore together with unit A2.2231, below A2.3223, or above A2.2233 and the A2.231 communities. Under more exposed, open conditions, this unit may be restricted to the lower part of the shore, with A2.3223, barren sand (A2.221) or barren shingle (A2.111) on the upper shore. Unit A2.211 may occur where driftlines of wracks or other debris accumulate on the upper shore. Temporal variation: 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.