What is Biofluorescence?

When we think of nature’s vibrant colors, our minds often drift to the vivid feathers of tropical birds, the striking petals of flowers, or the shimmering scales of fish. But have you ever encountered the hidden glow of biofluorescence? This fascinating phenomenon occurs when a living organism absorbs light at one wavelength and reemits it at a longer, lower-energy wavelength, resulting in a beautiful, glowing display. Often triggered by ultraviolet (UV) light, biofluorescence manifests in a stunning array of colors—and though we’ve only just begun to explore it, there’s still so much more to uncover about this radiant natural wonder.

The Science of Biofluorescence

Biofluorescence happens when light is absorbed by an organism, exciting the electrons in its molecules. As the electrons return to their resting state, they release the absorbed energy as visible light, creating the organism’s glowing effect. Unlike bioluminescence—where light is produced through a chemical reaction—biofluorescence depends on light absorption and reemission.

This captivating phenomenon can be observed in a vast array of organisms, from fungi, lichens, and insects to fish, birds, reptiles, amphibians, corals, and even mammals. Each species has its own unique mechanism for producing biofluorescence, and there’s still so much we need to learn.

The Role of Biofluorescence in Nature

We still know so little about biofluorescence in the natural world, especially about any function it may serve in nature. It is best thought of as a natural light phenomenon, no different form polarisation or contrast. In itself it isn’t inherently functional and it seems very likely that in the large majority of cases there is no function to the fluorescence, it is just a by-product of chemistry.

But as with any natural light phenomemen there are likely to be organisms that have evolved to take advantage of it and to use it as a form of visual communication. This is a hot topic of debate in the scientific community that often divides researchers. There are a number of studies they seem to have shown a visual communication function to biofluorescence.

Below we will explore a few of the possible functions that have been suggested so far:

1) Camouflage

It is believed that some organisms use fluorescence as a form of camouflage. One of the first animals to be suggested doing this was a Scorpionfish, they fluoresce a bright red similar to the bright-red fluorescence emitted by the algae on the rocks on which they sit. This is only an observation, with no behavioural studies even having been carried out.

2) Reproduction

It has been suggested that Biofluorescence is also used as a means of communication between species to attract a mate. One of the first studies to suggest this was a 2002 paper showing the bright fluorescence found in Budgies. The study demonstrate sexual dimorphism in fluorescence and found that budgies that had their fluorescence covered up were less attractive to the opposite sex, suggested a potential role of fluorescence in decided how attractive a budgie appears to the opposite sex.

Similar results were also shown by a study from Sinagpore University looked at the role of fluorescence in mate selection in jumping spiders.

3) A Lure

A number of studies have found evidence to suggest that biofluorescence can act as a lure to attract prey. This makes sense given that many animals are attracted to bright lights.

The discovery of Green Fluorescent Protein (GFP) was thanks to fluorescence in flowerhat jellyfish. This discovery earned it’s founders a noble peace prize in chemistry and has gone on to revolutionise the world of medical research. A little less famous is a study that looked at the possible function of this fluorescence in the jellyfish and found that it acts as a lure to attract their prey.

A function of fluorescence acting as a lure to attract prey has been suggested in deep corals.

It has also been suggested in frogfish and deep-sea siphonophores.

Coming back on to land it has been suggested that rattlesnakes use fluorescence as a part of their tail lures to attract their prey.

4) Aposemtism

Some organisms may use biofluorescence as a means of protection. A common form of protection is to give off very bright warning signals that act as a marker to say either I am poisonous or I don’t taste good, stay away from me. The same way many animals have bright colours to signify they are toxic or venomous.

One of the first studies to suggest aposematism function to biofluorescence was one exploring fluorescence in Heterobranchs in the Mediterranean.

The Beauty of Biofluorescence

We can find stunning examples of biofluorescence in a wide range of environments here in the U.K. It is a very wide spread phenomenon in nature and can be seen in wild flowers, leaves, lichens, mushrooms, insects and more depending on the time of year and the seasons.
Biofluorescence not only potentially serves a visual function in nature, but it also adds a stunning beauty to the world around us. The glowing colours and patterns of fluorescing organisms can be breathtaking, leaving us in awe of the natural world.

Seeing Biofluorescence for the first time is a truly magical experience that is something everyone should get to enjoy at least once. It turns the world of colour upside down, green leaves rendered red, yellow lichens luminous orange, brown fungi bright green lights and green grasses turn bright blue.

Biofluorescent walks

Want to Biofluorescence for yourself? Click on the button below to view our upcoming Biofluorescent walks and secure your spot. Don’t miss out on this unique opportunity to experience the magic of biofluorescence firsthand!

Want to learn more about biofluorescence? Check out this article on biofluorescence and the surprising role it plays in the lives of carnivorous plants.