We consider the coupling of biological and acoustic models in the ocean (marine bioacoustics). A casual look at journal publications and meeting programs over the last 10 years shows the extraordinary growth in research. Consider these five examples: animats, which are virtual marine mammals, swim in simulated oceans, acting as acoustic dosimeters to simulate the exposure of real animals in the ocean. The animats themselves respond to the sound field, avoiding unpleasant noises or seeking out sounds that suggest feeding or reproductive opportunities. Meanwhile, the songs, whistles, clicks, rumbles, etc., of living mammals allow a listener to follow their paths, or even to coarsely image the ocean environment. As they move through the sound field they may also disrupt it, scattering energy. Thus we see an intimate coupling between the biological models and the sound field in both virtual and real worlds. This talk will present examples of each of these couplings.