Fireflies, mushrooms, anglerfish of the abysses and a number of other animals exhibit bioluminescence, which has been linked until now solely to a chemical activity i.e. the oxydation of organic materials such as luciferin. It is obvious that the investigations did not extend to researching other elements in these species. The simple answer is the deliberate accumulation by these species of naturally occurring radioactive elements in the soil, or in seawater, together with an appropriate phosphor. Alpha emitters produce a much more powerful light with fewer materials as the energy involved in alpha decay is magnitudes superior to the existing natural sources for beta decay.
Luciferin is used as a fluid that allows the animal to be shielded of the decay, while making visible the phosphorescence as it is usually a well-hydrogenated material that acts as a glass. Firefly luciferin is not only a glass but mainly a material where sulfur is the phosphor, as for ZnS:Cu in radium dials. The hydrogen and oxygen around the sulfur and nitrogen atoms in firefly luciferin constitute 1. a buffer protecting the body of the insect from the vibration of the atoms of sulfur after impact of the alpha particles 2. a channel to drive the alpha particles into the atoms of sulfur (the molecule works as a bottleneck) and 3. much more importantly, a protection of the animal itself against the alpha decay. For insects producing small flashes of green light, for instance, the mechanism is simply a compression of the alpha-emitting source into the “phosphor” by the muscular system of the insect. This compression system confirms definitively that it is alpha decay, with its very short range, that is involved in these animals, together with the very small size of the animal as compared with the light output (not compatible with the much less powerful beta sources). Fireflies are akin to very small flying nuclear bombs… which need compression to increase the yield, too.
Looking at all bioluminescent organisms shows how the source of light is heavy and makes them plow (in general, as a trend).
Mushrooms can use their long filaments to slowly accumulate radioactive elements from the ground and worms scavenge as well the soils, forming slowly their pocket. For fish, the scavenging happens at relatively great depths where the natural uranium and the other radioactive elements tend to fall down, below the strong currents, which is why in the oceans, bioluminosity happens mostly in the abysses. The behaviour of the great anglerfish, for instance, is an evident testimony : its open mouth serves for filtration of water and accumulation of radioactive elements. The « filaments » around the body are obviously accumulators. The use of silver collected from the seawater can be expected as a phosphor producing a blueish light. In these other animals and mushrooms too, alpha sources are more likely for they are more available and much more powerful. Mushrooms, for instance, may as well be expected to slowly collect and concentrate radon 222 and radon 220 and their decay products, directly through their body.