Figure 2.

Population densities of Diadema antillarum in sea urchin and algal zones at five sites along the north coast of Jamaica. (Bars = mean population densities; error bars = 1 SE; see Fig. 1 for site designations.) The size–frequency distribution of Diadema pooled across all sites (sea urchin zones only) is shown in the Inset graph with the percent occurrence of nine size classes based on the maximum test diameter. Size-class designations represent the following ranges of maximum test diameters: 1 < 20 mm, 2 = 20–29 mm, 3 = 30–39 mm, 4 = 40–49 mm, 5 = 50–59 mm, 6 = 60–69 mm, 7 = 70–79 mm, 8 = 80–89 mm, and 9 = 90–99 mm.