This is a moon jellyfish swimming through seawater seeded with hollow glass spheres (10um diameter). The spheres are illuminated by a laser to show the fluid structures created by the swimming jellyfish and recorded by a high speed camera at 1000 frames per second. See: Gemmell BJ, Costello JH, Colin SP, Stewart CJ, Daviri JO, Tafti D and Priya S. Passive energy recapture in jellyfish contributes to propulsive advantage over other metazoans. PNAS doi: 10.1073/pnas.1306983110
