English naturalist Henry Baker in 1753 identified the source of the phosphorescent “burning of the seas,” like the glow off the Taiwanese coast in figure 1, that had mesmerized nautical explorers for centuries. His prowess in microscopy led him to identify a unicellular “illuminous animal,” Noctiluca scintillans, that emits light when disturbed, perhaps by a ship’s bow or a rower’s oar. Understanding of the biochemical processes that generate luminescence in N. scintillans and other bacteria or dinoflagellates in marine and freshwater environments progressed rapidly. But what mechanisms ultimately trigger bioluminescence? American zoologist E. Newton Harvey in 1920 commented, “That problem must be left to the physicist.”
The complex series of chemical reactions through which bioluminescent marine organisms produce light begins when calcium ions enter the cell through channels in the cell wall. Biologists hypothesize that fluid flow outside the cell causes the cell’s outer wall to stretch, which...
