The science of nail polish

From Smithsonian: "Since the 1940s, nail polish has been an invaluable tool in a scientists' (sic) toolbox. It's cost-effective, can be found just about anywhere and comes in a full range of colors, which makes it useful in marking organisms in research studies. Scientists have used nail polish to mark snails, lobsters, crabs, lizards, tortoises, insects and birds in studies investigating growth, mortality, movement and distribution, habitat preference, sexual selection, nestling behavior, predator-prey interactions and foraging behavior."