A fluorescent flea

Almost daily we have to deal with arthropods such as insects, spiders and their kind around us. Yet we realize less often that these animals can provide a beautiful light show.

Fireflies and other bioluminescent animals produce their luminous shine through a chemical reaction. Other arthropods produce light via fluorescence. At certain wavelengths of light including ultraviolet light, molecules in their exoskeleton absorb this light and radiate it again in a different color with a (longer) wavelength, (there are 'excited electrons' involved, but let's skip the details here)

Some interesting ideas have been suggested as to why some arthropods glow or fluoresce. This is also often done under ultra violet light. It is also known that most insects can also see ultra violet light, in contrast to us humans. Much of the world around us looks very different in ultraviolet light. Like we can often see this in a bar or discotheque.

Sometimes the usefulness of glowing or fluorescing can be explained, for example, because the animals can easily find and recognize each other. In other cases we cannot discover its usefulness, as is the case with the flea in the images shown. When the flea is illuminated with blue light, the FITC filter lets green light pass, which is radiated by the exoskeleton of the insect. When illuminated with green-yellow light, the Texas Red Filter lets red light pass.