Seeing the Flow: Analyzing Coral–Flow Interactions Through Particle Image Velocimetry

Little is known about the precise physics governing octocoral interactions with their surrounding fluid environments. Here, we investigate how the morphological features of this group of corals alter surrounding flow fields allowing them to effectively feed. We use a 200-gallon in-house flow tank to simulate ocean flow fields, live Octocorals for experiments, and PIV to visualize flow. We find that the network-like structure of a Gorgonian redirects incoming laminar currents and restructures velocity fields, producing vortex shedding and dynamic wake patterns. These behaviors likely increase the success rate of particle capture by individual polyps on the coral and enhance nutrient exchange without the requirement of active feedback and modulation. These findings provide a deeper understanding of how octocorals resist warming ocean conditions that otherwise harm other coral types.