The traits of glowing in the dark are called bioluminescence and biofluorescence, and they’re more common in nature than people think. In fact, some animals found ways to utilize this ability for camouflage, hunting, and other purposes.
In this article, we’ll be listing down all the animals that glow in the dark.
- Glow Worms
- Sierra Luminous Millipedes
- Plain False Moray
- Marine Hatchetfish
- Crystal Jelly
- Bolitaeninae Octopuses
- Bobtail Squid
- Colossal Squid
- Firefly Squid
- Latia Snails
- (Some) Flying Squirrels
- Virginia Opossums
- Tasmanian Devils
- Polka-dot Tree Frogs
Scientific name (order): Scorpiones
It’s been known for quite some time that scorpions glow in distinct light blue or light green colors when exposed to ultraviolet light. This has helped scientists a lot as they can easily find them in the dark with an ultraviolet lamp.
This fluorescent ability is a consequence of fluorescent chemicals in the animals’ bodies, one of which is called beta-carboline.
Although the exact purpose of this in the life of a scorpion is still unknown, it is suspected that these land animals that glow in the dark use that ability to detect light.
Scientific name (family): Lampyridae
Possibly the most famous animals that glow in the dark, fireflies are known for light production during the mating process. The light is produced by light-emitting organs, and the colors range from yellow and green to red.
The purpose of producing lights lies in mating – both male and female fireflies light to signal their readiness to mate to another insect.
There are distinct differences in duration, color, and rate of repetitions when it comes to the mating dance of fireflies.
There is no scientific name for glowworms as they’re an informal grouping made up of various larvae and beetles that glow in the dark.
There are four beetle families that glow in the dark, which are all closely related, and they emit green, yellow, and orange lights.
The most recognizable representative of this group is the railroad worm, which has a streak on each side of its body. It usually glows a distinct yellow-green, and when alight, the worm is reminiscent of train cars at night.
The exact purpose of these larvae that glow in the dark isn’t yet clear, but it could be an attempt to frighten possible predators.
4. Sierra Luminous Millipedes
Scientific name (genus): Motyxia
These millipedes are truly fascinating creatures, endemic to the south of Sierra Nevada and the Santa Monica mountain range.
Although there are 12,000 species of millipedes in the world, the species within this genus are one of the very few millipedes that glow in the dark.
The exoskeleton is where the light is emitted from, and the effect is a byproduct of a biochemical process.
It’s been determined that the strong light is a warning signal to predators, implying that the animal is poisonous.
These millipedes belong to an order of millipedes capable of producing a cocktail of poisons, including cyanide, and predators seem to have learned that it’s best not to bite things that glow in the dark.
Scientific name (order): Lophiiformes
This fish uses its luminous abilities to catch prey. They have a long line of tissue starting at the forehead with a luminescent organ at the end of it, called the esca.
These fish that glow in the dark can move the line with the organ independently.
By doing this, they mimic fish movement, attracting prey close to themselves. When prey is finally close enough, the carnivorous fish will jump it and eat it in a single bite.
Scientific name (family): Myctophidae
These appropriately named fish use their bioluminescence to communicate when mating, but it’s possible that they can use this ability for camouflage too.
They can turn up or tone down the light they’re emitting according to the light around them, effectively masking themselves in the water.
They emit mostly blue light, but yellow and green were also documented. Patterns can vary between males and females.
7. Plain False Moray
Scientific name: Kaupichthys hyoproroides
A very recent discovery in the scientific community, this eel was determined to be glowing in the dark in 2011, although it was first discovered in the 19th century.
Even though the moray itself is brown and partly transparent, it glows a bright green in the dark. It is believed that the purpose of the glow is to find mating partners, but more research is necessary to prove or disprove this.
8. Marine Hatchetfish
Scientific name (subfamily): Sternoptychinae
They’re found in warm waters of all the world’s oceans, where they can grow up to 4.7 inches. The bioluminescent properties they developed help them escape predators by camouflaging themselves.
Just like a few other species on this list – it matches the color of its lights to the color of its surroundings.
Scientific name (genus): Chauliodus
Viperfishes are a carnivorous genus using their bioluminescent properties to camouflage themselves, but also for hunting. They produce light on the dorsal fin, which attracts prey. When prey nears, the fish strikes and eats it.
They also use the lights to attract mates and to tell rival fish in the area to back off. The hunting strategy of this fish is quite advanced – they usually lie still in the dark, flicking their light and waiting for prey to come closer.
Interestingly, they often eat lanternfish, another bioluminescent fish species.
10. Crystal Jellyfish
Scientific name: Aequorea victoria
This species of jellyfish that glows in the dark is found on North America’s west coast, where they produce blue and green lights. These lights are only partly visible in water, but they’re noticed much more easily under UV light.
For the most part, jellies are transparent, but they start glowing when they’re disturbed to warn off predators.
Their bioluminescent properties were actually very useful for advancements in medicine, as they helped cell and bacteria research massively.
In 2008, Osamu Shimomura, Martin Chalfie, and Roger Tsien were awarded the Nobel Prize for chemistry because of their research – a great part of which included the luminescent properties of the crystal jellyfish.
11. Bolitaeninae Octopuses
Scientific name (subfamily): Bolitaeninae
Mature male octopuses of this family develop light-producing organs in the shape of a ring which they use to attract male mates. Only females have this adaptation (as far as we know now), and it usually develops around the mouth.
Since they live in very deep waters where there’s absolutely no light, this is the only way to find mates in pitch black. This octopus that glows in the dark emits a light of a specific wavelength – that way, it doesn’t attract predators, only male mates.
12. Bobtail Squid
Scientific name (order): Sepiolida
These squids are very small – never larger than 3.15 inches – and they can be found near the coast of the Pacific Ocean, as well as parts of the Atlantic and Indian Oceans.
Their lighting ability actually isn’t their own, as they let bioluminescent bacteria infest a light organ in the squid. This symbiotic relationship allows the squid to regulate the light.
The squid feeds the bacteria with a solution of sugar and amino acids, while the bacteria hides the squid from any animals found below.
13. Colossal Squid
Scientific name: Mesonychoteuthis hamiltoni
Although very little is known about the feeding habits of the colossal squid, they’ve been documented to use bioluminescence to attract prey. They mostly feed on large fish and smaller squid.
These squids that glow in the dark have a very large beak and incredibly long tentacles which they use to subdue and kill prey after attracting it with their light.
Since they usually drop to incredible depths, their light is often the only light in that dark of an environment and other fish can’t help but investigate it.
14. Firefly Squid
Scientific name: Watasenia scintillans
The name of this squid is self-explanatory, and it can be found in the deep waters of the western Pacific Ocean.
There, they use blue, green, and yellow lights to match the brightness of the water above them. That way, they can stay safe from predators from below as they often can’t notice them.
Counter-illumination camouflage is seen with a few other marine animals on this list, but none of them have developed it to these levels.
Each eye of the squid can allow more light to enter it, allowing them to see a greater light spectrum and change its light color accordingly.
It is also possible that they use their bioluminescence for communication and attracting prey, but that is still unclear.
15. Latia Snails
Scientific name (genus): Latia
These snails are the only known species of freshwater bioluminescent mollusks in the entire world.
Endemic to the North Island in New Zealand, these snails usually live in streams and rivers where they can be seen glowing in the dark when they’re disturbed.
The purpose of the glow is to deter predators – they release a bioluminescent slime, and the idea is that the predator will follow the glow instead of eating the snail.
It’s possible that the slime can stick to the predator and cause panic (it also makes the predator more visible to other predators).
16. (Some) Flying Squirrels
Scientific names: Glaucomys sabrinus, Glaucomys volans, Glaucomys oregonensis
The three species of New World’s flying squirrels all glow in the dark. Both males and females demonstrate this ability, usually glowing in variations of pink.
Whatever the case may be, flying squirrels are the only squirrels that glow in the dark.
Scientific name: Ornithorhynchus anatinus
Another species of mammals that glow in the dark, platypuses glow when put under black light. The color is a combination of blue and green. This is a very new discovery, as this was only found out in 2020.
Both living and preserved platypuses glow in the dark, and more research is needed to determine what’s the purpose of this trait.
18. Virginia Opossums
Scientific name: Didelphis virginiana
Another recent discovery is that Virginia opossums glow pink when put beneath UV light.
Unfortunately, it is still unknown why these animals glow, but it’s suspected that they might be using it as camouflage.
Scientific name (genus): Macrotis
The discovery of the glowing platypus urged scientists from around the world to start testing animals for glowing properties under UV light. One such animal is the bright-eared bilby.
Just like with other animals with newly-discovered glowing properties, it is unknown why they glow in the dark.
Something that has been noted, however, is that they’re all nocturnal animals, and there’s probably a link between their nightlife and their glowing properties.
20. Tasmanian Devils
Scientific name: Sarcophilus harrisii
Unlike the pink glow apparent with most mammals that glow in the dark, Tasmanian devils display a light blue glow inside the ears and around the eyes and the whiskers.
It’s likely that the entirety of the animal is fluorescent, but it only shows on the thinnest parts of the skin.
Just like with other mammals, it is unknown why they glow.
21. Polka-dot Tree Frogs
Scientific name: Boana punctata
This South American tree frog is the final entry to the list, and it’s well known for its fluorescence.
They are the first amphibians to actually be identified as bioluminescent. Since then, it was found that fluorescence is very common among amphibians.
Even though the frog is normally yellow, it starts glowing a bright green when put beneath UV light. It’s likely that the glow plays a part in the mating rituals of these frogs that glow in the dark, but more research is needed.
Although it is still unknown why some species glow (it might as well be a consequence of some chemical mix-ups), some species use this ability to their advantage when it comes to hunting, camouflage, and mating.
Fireflies are by far the most well-known glowing animals, using their light for attracting mates, while fish species use them for both prey attraction and camouflage.
Newly discovered glowing mammalian species still need more research to determine the exact purpose of the glow.