all hail the wonderous light organ

a lot of bacteria use signaling for cell to cell communications. one species (V. fischeri) uses this signaling pathway in order to regulate its bioluminescence. At low cell densities, the bacteria doesn't produce much light. At high cells densities there is more signaling molecule released into the environment, and the cells turn on the lights. One of the places where V. fischeri can reach such high densities is the light organ of squid.



Light-emitting organ of E. scolopes. Shown is a ventral dissection of an adult specimen revealing the mantle cavity, within which lies the large bilobed silver and black bioluminescent organ. Every morning the contents of the organ, composed of symbiotic V. fischeri cells and the fluid surrounding them, are expelled from a pair of pores (arrows) on the lateral surfaces of the organ.