Medetomidine, a chemical that activates the octopamine receptors (similar to adrenaline receptors) in barnacle larvae, causing them to flee. Barnacle larvae are free-floating and harden only after they have attached to a surface. Researchers at the University of Gothenburg in Sweden mixed small Plexiglas capsules filled with medetomidine into boat paint, young barnacles were scared away, and the hulls remained pristine. At high levels, medetomidine can lighten the color of fish scales, making them more vulnerable to predators. But the capsules ensure that the chemical is released slowly, so it lasts longer and minimizes environmental damage.