Seafoam formed by wave action from the remainders of colonial Phaeocystjs globosa may contain high numbers of meiofauna. In foam collected in the Wadden Sea near the Island of Sylt (FRG) In June 1988, the harpacticolds (Copepoda) Tachidius discipes and Harpacticus flexus dominated in abundance. Both species rest in superficial sediment layers at low tide and swim in the water column at high tide, preferentially at night. From the water colunmn they pass into the foam, together with some planktonic species. Currently it is not clear if they actively enter the foam or become passively enclosed. Field experiments indicated that Phaeocystis colonies and foam may influence their diurnal activity rhythms. Possibly these species feed on organic compounds of the foam or on enclosed micro-organisms. Occasionally other benthic taxa also occurred in the foam. Once in the foam, these specimens may become dispersed over wide areas.