Predatory animals can move nimbly to accurately target prey animals. While hunting, predators must distinguish between their prey and objects in the surrounding environment in realtime, and therefore mobilize all of their sensory organs to recognize living prey. In particular the visual system is often assigned the crucial role of making the final determination. Predators use vision to identify size, shape, color, and movement and to discern between unrelated objects and the prey they should be hunting.  For example, in the aquatic environment small predatory fish must be able to distinguish between particulate matter in the water column and the zooplankton they prey upon. However which parameters are used for this distinction have been wrapped in mystery. Associate Professor Eiji Watanabe and Researcher Wataru Matsunaga of the National Institute for Basic Biology have focused on the functioning of a small predatory fish (medaka) while capturing zooplankton prey (Daphnia), and have shown that medaka instantly single out the patterns characteristic of live food from the Daphnia’s movement while hunting. By converting the movement of Daphnia into a mathematical model and using modern virtual reality techniques they have discovered that the movement pattern of medaka’s live prey can be characterized as biologic 1/ƒ noise.  The results of this research were reported in the scientific journal Scientific Reports.  These results could have practical applications in developing more efficient methods of fishing and angling. For details please see the journal article here.