Fig. 1. Top view of experimental setup. Two behavioral arenas were cleared in the seagrass canopy where PVC stakes marked set distances from experimental shelter openings (25 and 50 cm). Two experimental shelters provided simultaneous delivery points for either an odorant or a negative (seawater) control in a modified Y-choice configuration with corresponding shelter assignments randomized. A submersible infrared camera was mounted on each shelter's rear end-cap and directed outward. Polyethylene tubing was connected to the odorant injection and water-sampling ports, with odorants and controls injected via peristaltic pumps to respective shelters. Baseline snapper activity was established prior to any odorant delivery. The order of odorants was randomized for each individual gray snapper to prevent treatment order effects, and the positive control was always delivered last. Overall tank flow was directed away from shelters with inflow pipes facing a reef-like structure, behind which was the tank drain pipe. Gray snappers generally hovered within the reef structure.