The mode and timing of reproductive events in marine invertebrates display a tremendous diversity. Various species have a variety of methods of asexual replication and/or sexual recombination. Sexual recombination may be followed by dispersive larvae, nondispersive larvae, or no larval stage at all. This diversity can be found among species living within the same habitat and challenges the most imaginative minds for reasonable ecological and evolutionary explanations. These reproductive events often show close temporal synchrony within species, so that spawning, for example, occurs at set times each year.

John Pearse's group examines the natural history of marine invertebrates (molluscs, annelids, crustaceans, echinoderms, corals, and anemones) to test current theories about the determinants of mode and timing of reproduction. Pearse maintains interest in the ecological mechanisms regulating community structure in the rocky intertidal and subtidal zones (kelp forests) of central California. His group continues a long-term study of the population dynamics in a kelp forest and ongoing studies on the stability of rocky intertidal communities.