Life in the royal classes has its perks. In some ancient cultures, that even included their own color: purple. The upper crust of the Mediterranean often wore garments dyed purple or a closely related shade of blue with pigments that were worth more than gold. Anyone not of the right class who was caught wearing the colors could be severely punished—even executed.
Deep below the ocean’s surface, some corals emit an otherworldly glow called fluorescence, but for years, scientists have wondered about the purpose of these glowing colors. Among the hypotheses biologists have proposed is that fluorescence might optimize photosynthesis, shield against the sun’s radiation, protect plant-eating marine life that lives among the corals, or attract algae that live inside the coral and provide them with energy through photosynthesis. Now, researchers have come up with a different hypothesis: fluorescence attracts the plankton that corals capture and eat.
