Fig. 2. Percent settlement of Holopneustes purpurascens larvae (mean ± s.e.m.; N=50 larvae per treatment) during exposure to 10 µmol l^–1 histamine for varying time periods (black bars) and percent metamorphosis in SSW, 24 h after commencing the experiment (grey bars). The responses of larvae at 7 days old (A), 14 days old (B) and 21 days old (C) are shown. ^*, not tested.