Since the first sparks of man-made fire ignited over 200,000 years ago, humans have been harnessing the power of light: from flames to filaments, this energy has guided us towards a world of innovation. However, it was only in recent eras of discovery that we learned that the true masters of light are those living deep underwater where the sun's rays cannot reach.
How it Works
Marine bioluminescence is a phenomenon controlled on a molecular level, principally by an active (requiring adenosine triphosphate) chemical reaction in which oxygen combines with luciferin in a luciferase-catalysed process. Luciferins differ depending upon the species, with luciferases aiding the oxidation of a range of chemiluminescent substrates, emitting photons. Due to this photon release, a charged ion is a necessary element of the reaction as ionisation is often a requirement for electrons to shift to a higher energy level, thus emitting light energy as electrons return to their ground state.
On a Large Scale...
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| Bathocyroe fosteri - Marsh Youngbluth |
Despite only being up to 40mm in length, the pictured resident of the mesopelagic zone is one of the larger bioluminescent aquatic invertebrates (the largest chemiluminescent marine animal being the kifetin shark at almost six feet.) On average, much of the light-emitting biomass is taken up by smaller plankton and bacterial colonies. Bathocyroe fosteri is a species of comb jelly utilising luciferins and luciferase as a combined photoprotein to emit shorter-wavelength visible light. The wavelength of this light and thus the colour is controlled by the size and the hydrophobicity of the attached isoleucine amino acid chain. Bathocyroe fosteri is located at depths of under 200m in the mesopelagic zone of the ocean but, despite their luminescence arguably improving hunting, this adaptation did not originally arise for this purpose. In the early atmosphere, oxygen is believed to have been highly toxic to organisms respiring anaerobically. Therefore, the oxidation of luciferin into the non-toxic product of oxyluciferin was an evolutionary adaptation to tackle this, with the side effect of chemiluminescence. It was long believed that comb jellies such as the Bathocyroe fosteri had no reception to light due to their lack of eyes. However, this luminescence may still prove useful since they possess photoreceptive opsins to detect light.
...and a Cellular Level
Bioluminescent bacteria would serve little purpose emitting light on their own, only wasting valuable energy. Instead, they must light as a joined colony for the effect of the luminescence to be fully visible. This is achieved by quorum sensing, in which autoinducers become stimulated to trigger the oxidation of luciferins in the presence of a high concentration of bacteria in a specific region. Bioluminescent bacteria have become highly useful in the wider world of research, employing various purposes ranging from bioindication of aquatic pollutants to monitoring the distribution of genetically engineered bacterial populations released into ecosystems. It is also a possibility that in the future, these microscopic yet powerful species could even provide the key that unlocks solutions to sustainable urban light generation.
sources:
science direct 6/28/23
bathocyroe 6/28/23