Bioluminescence: Cell physiology, diversity, and new evolutionary insights

Bioluminescence, or the production of light by a living organism, has intrigued and inspired humans for centuries. It conjures imagery of glowing blue, crashing ocean waves, or the starlight-like dazzlement of fireflies in a field. Bioluminescence, however, is much more than a beautiful novelty; it plays a crucial role in many organisms' existence. It is used for a variety of functions, ranging from offense, defense, and communication. Bioluminescence is present in all habitats on earth, but it is virtually ubiquitous in the marine environment. Bioluminescence is estimated to have evolved independently upwards of 94 times across living taxa with representatives in a broad diversity of phyla (e.g., Bacteria, Dinoflagellata, Ctenophora, Cnidaria, Arthropoda, Annelida, Chordata, and Fungi). The many independent origins invariably lead to a variety of regulatory mechanisms used to control the intensity of light emission (e.g., quorum sensing, action potentials, pH, Ca2+ channels, and oxygen regulation). Furthermore, recent investigations into organisms previously known to possess bioluminescence reveal novel functions and may even drive higher rates of species evolution. In this chapter we review the diversity, cell biology, biochemistry, and regulation of well-described systems, briefly highlight understudied taxa, and catalog the many forms and functions for bioluminescence across life.