Caves in the Gunung Mulu National Park, Sarawak, contain at least four types of living-spaces, or habitats, each of which is consistently used by a particular group of animal species. The structure of each group of animals carries information about the adaptations of individual species, the history of the group as a whole and the character of the habitat. This information can be measured in terms of the ‘species diversity’ of the group. In this study the species diversities of several groups were compared with the stability, predictability, food supply and complexity of their habitats. The aim was to test a model which predicted that species diversity is promoted by high habitat stability, predictability, heterogeneity and an abundant supply of food. Only habitat predictability was shown to affect species diversity. Low species diversity was correlated with unpredictable floods which disturb or destroy the structure of the group.