In nutrient-rich marine waters, dinoflagellates, a type of plankton, can flourish. At night, these tiny organisms are responsible for incredible blue light displays in the water. The dinoflagellates produce two chemicals – luciferase and luciferin – that, when combined, produce a distinctive blue glow. The plankton use this as a defense against predators, creating a flash of blue light when triggered by the shear stress of something swimming nearby. The dinoflagellates respond to any sudden application of shear stress this way, so they glow not only for predators, but for any disturbance – mobula rays (above), sea lions, boats, or even just a hand splashing in the water. In person, the experience feels downright magical. I had the opportunity to experience bioluminescence in the Galapagos last year. The light from the dinoflagellates is incredibly difficult to film because it can be so dim, but as the BBC demonstrates, it’s well worth the effort it takes to capture. (Image credit: BBC from Blue Planet II and Attenborough’s Life That Glows; video credit: BBC Earth)