Relationships between phytoplankton biomass and recruitment strength of benthic invertebrates with feeding larvae have been considered only in the numerical sense, not in terms of the condition of individuals at settlement. Since material and energy in some larval structures is transformed at metamorphosis into post-larval structures, and since their development is food-dependent, we hypothesized that plankton food availability links the ecology of the transition between invertebrate larvae and juveniles. We tested this hypothesis in laboratory and field experiments with the sea star Asterina miniata. Sibling larvae were reared in sea water containing natural phytoplankton at three concentrations simulating either (1) oligotrophic offshore, (2) temperate nearshore, or (3) eutrophic bloom water masses. Other siblings were reared in mesh-covered field chambers with naturally varying nearshore plankton assemblages. Competent larvae were produced in ail food conditions, but exhibited differences related to feeding history. Those in oligotrophic water had small, transparent bodies and juvenile rudiments, few or no body ossicles, and small brachiolarian arms and papillae. In contrast, larvae reared at higher food levels were progressively larger, more opaque, pigmented and ossified, and had developed further. Competent larvae differed in swimming and substrate searching behaviors and the times to complete settlement and metamorphosis were inversely related to larval food abundance. The preferred type and orientation of substrates settled on by larvae also appeared to be related to larval feeding history, as did initial juvenile size and appearance. Differences in larval food availability appear to have a strong influence on the ecological and life history transitions occurring before, at, and after settlement and metamorphosis.