Certain coral genera have few forms in common: e.g., Acropora were predominantly branching in form, with lesser amounts of tabular, submassive and encrusting forms, whereas Montipora were predominantly encrusting and foliaceous (Table 6). Thus it is not possible to determine if differences in preference of starfish for these two most commonly observed genera are due to genus or form differences. In the analyses, we initially examined preferences for genera, ignoring form effects. Thus the estimated preferences for the different genera are based on the assumption that the observed forms are representative of those genera. The effects of size differences between prey and neighbouring corals were then examined, as were the effects of relative abundance and individual reefs. Preferences for the different forms of coral were then estimated, ignoring genera effects. These estimates were then adjusted for size differences between prey and neighbours. To demonstrate that preference for form is not solely an artefact of genera preferences, the form preferences for Acropora were estimated by considering only the data for which both prey and neighbour are Acropora. Finally the dependence of genus and form preferences were assessed by examining the relative preferences for Acropora and Montipora when the two genera were of the same form.