From individual cells to whole organisms, O-2 transport unfolds across micrometer- tomillimeter-length scales and can change within milliseconds in response to fluid flows and organismal behavior. The spatiotemporal complexity of these processes makes the accurate assessment of O-2 dynamics via currently availablemethods difficult or unreliable. Here, we present "sensPIV,'' a method to simultaneously measure O-2 concentrations and flow fields. By tracking O-2-sensitive microparticles in flow using imaging technologies that allow for instantaneous referencing, wemeasuredO(2) transportwithin (1) microfluidic devices, (2) sinkingmodel aggregates, and (3) complex colony-forming corals. Through the use of sensPIV, we find that corals use ciliarymovement to link zones of photosynthetic O-2 production to zones of O-2 consumption. SensPIV can potentially be extendable to study flow-organism interactions across many life-science and engineering applications.