Sponges are different from all other animals in the extreme simplicity and homogeneity of their construction. They are also one of the most diverse, abundant, a nd colorful groups in a variety of hard substratum marine systems, and many of their functional roles in these systems are not duplicated by members of other gr oups. I study the ecology of sponges and the organisms with which they interact as mutualistic partners, competitors, and prey, especially in coral reefs, seag rass meadows, and mangroves. I have been focusing on several conceptual issues that are especially intriguing for sponges: a) ecology and evolution of mutualis ms; b) biogeographic and habitat patterns of diversity and abundance, and how these are influenced by interactions and life histories; and c) effects of physica l disturbance and pathogens on population and community dynamics, focusing especially on the importance of different growth forms and life histories. My primar y approaches to research are experimental manipulations in the field, combined with biogeographic comparisons; and most of my field work is in Belize, Panama, a nd the Florida Keys.