Coral reefs seem to defy many of the paradigms which characterise less complex biological communities. While there is general agreement that the biota of coral reefs exhibit high species diversity, some authors have characterised coral reef assemblages by selecting species with high population densities (Sale, 1974; 1976; 1977; 1984; Sale and Dybdahl, 1975; Connell, 1978). Other authors have included rarer species (Kohn, 1959; 1968; Den Boer, 1971;...