Although the two words are easily confused, the difference between biofluorescence and bioluminescence is simple enough.
Bioluminescence is the production of light by living organisms. Biofluorescence happens when light shines on a living organism, then is absorbed and reflected or re-emitted as a different wavelength, like a glow-in-the-dark poster.
Bioluminescence is the process by which living organisms emit light. It is a form of light produced due to a chemical reaction. Bioluminescence occurs when an enzyme called luciferase reacts with a substrate called luciferin.
Synthetic bioluminescence is when scientists create this chemical reaction artificially without needing living organisms.
What Are The Types Of Biofluorescent Organisms?
Biofluorescent organisms are animals, plants, and bacteria that emit light of one colour when stimulated by another colour. The emitted light is typically shorter in wavelength than the stimulation.
Most biofluorescent organisms are marine animals that live in coral reefs or other underwater environments. Biofluorescence can be found in a variety of marine invertebrates and fish, including corals, jellyfish, squid and plankton.
Biofluorescent fish emit a blueish-green light from their scales or body tissue when illuminated with certain colours of ultraviolet light, usually from above the water’s surface. Some species have been found to use biofluorescence for intraspecific communication by flashing patterns at each other during mating rituals or as warnings during territorial disputes.
Biofluorescence also occurs in some plants, algae and fungi, where the production of a fluorescent pigment causes the cell walls to become transparent. In fact, chlorophyll is actually the most widely-distributed fluorescent molecule, producing red emission under a range of wavelengths.
It is a form of chemical defence that organisms use against predators by attracting the attention of potential prey with bright colours or via chemical signalling. Many marine invertebrates such as jellyfish and cnidaria are capable of this defence.
The South African springhare (Pedetes capensis), is found in the grasslands of Africa. These medium-sized rodents were recently found to have patches of fluorescent fur colour blended in with the long, soft, reddish-brown fur covering their body.
The patches glow in red and pink shades under ultraviolet light. Researchers are still unsure if their glow serves some purpose.
“We speculate that, if their predators are UV sensitive – the unique patterning we observed could function as a sort of camouflage from predators. However, there is a chance that this trait has no ecological significance whatsoever. It is purely speculation, and until there are behavioural studies and studies assessing the spectral sensitivity of springhare and their predators, it will be hard to confirm,”
said the study’s lead author Erik Olson, speaking to IFLScience.
The platypus is unique for being one of the only semi-aquatic mammals, laying eggs, sweating milk, and having a bill like a duck. As if that wasn’t weird enough, in 2020, researchers discovered that it is also biofluorescent. Its thick fur is brown coloured under normal light but glows greenish-blue when exposed to ultraviolet light.
The researchers are not sure what function the glow serves for platypus either since these animals have evolved to use their mechanoreception and electrostimulation systems for navigating their dark, aquatic environments rather than their visual system.
New World flying squirrels and marsupial opossums are the only other mammals with biofluorescence. However, preliminary experiments indicate that Tasmanian devils and wombats may also biofluoresce.
Amphibians And Insects
In the amphibian family, certain salamanders and frogs have the gift of glowing. The polka-dot tree frog (Hypsiboas punctatus), widely found in South America, was the first amphibian discovered to be fluorescent. (in 2017)
More recently, the Tiger Salamander (Ambystoma tigrinum), the Marbled Salamander and Cranwell’s horned frog (Ceratophrys cranwelli) and about 30 other species were found to glow under black light. Most of the fluorescence appears to be from skin pigments, but some have also been observed to emit from mucus excretions or bones.
Many spiders biofluoresce under UV light and have a wide diversity of fluorophores. In some spiders, ultraviolet cues are useful in hunting, communication, and camouflaging against equally fluorescent flowers.
In the ocean, fluorescent proteins in corals exist in corals, mantis shrimp, certain squid species, the crystal jellyfish (Aequorea victoria), and the deep-sea dragonfish Malacosteus niger.
Lightning bugs, also called fireflies, are a family of bioluminescent beetles. This can be seen as flashes when they are near any source of light and it is believed that this helps them with camouflage and mating. They live in temperate regions across North America. Glow-worm is a common name for various types of insect larvae and adult larviform females that glow through bioluminescence.
The ghost fungus (Omphalotus nidiformis) is a type of mushroom known for its bioluminescent properties that is found in southern Australia and Tasmania.
There are various fish living in the deep ocean that are bioluminescent, including Anglerfish, Viperfish, the Gulper eel, Lanternfish, and Pineconefish.
Bioluminescent organisms are a subject of interest in many areas of scientific research. For example, luciferase systems are currently widely used in genetic engineering as reporter genes, each producing a different colour by fluorescence, and bioluminescent activated destruction is an experimental cancer treatment.
Difference Between Biofluorescence and Bioluminescence
Bioluminescent animals use bioluminescence for different purposes: Some are using it as a form of communication, others as camouflage, and some for attracting prey or mates.
Biofluorescence is observed in 3 distinct mammal species, representing three continents and a range of different ecosystems; it appears across different phylogeny, which suggests that biofluorescence may be an ancestral mammalian trait. The purpose in mammals is not yet known.
Scientists suspect that biofluorescence may have important functions in mating, signalling and communication, camouflage, UV protection and antioxidation, and in coral health.
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