Light-making life is everywhere – you just have to look in the dark. Here are some of the most remarkable glowing organisms on Earth, in the sea, on land and in the forest.
In the ocean
The ocean is where bioluminescence truly rules. Below about 200 meters, sunlight fades to almost nothing, and for many animals the only light they will ever see is light made by other living things.
Deep-sea anglerfish
Scientific name
Ceratioidei (a group of anglerfishes)
Found in
Deep open ocean, worldwide
Female deep-sea anglerfish carry a fishing-rod-like spine tipped with a glowing lure called an esca. The light is not made by the fish itself but by glowing bacteria living inside the lure. Each species has its own shape of rod and lure.
In the near-total darkness of the deep, the anglerfish waits while the glowing bait draws prey toward its mouth. Its very dark skin absorbs light, helping it stay hidden.
Vampire squid
Scientific name
Vampyroteuthis infernalis
Found in
Deep, low-oxygen waters of the world's oceans, often 600 to 900 meters down
Despite the name, the vampire squid is a gentle drifter that feeds on falling marine snow. It has no ink; instead, it can release a cloud of glowing fluid.
The glowing cloud may distract a predator while the squid swims off into the dark.
Lanternfish
Scientific name
Myctophidae (family)
Found in
Open oceans worldwide
Lanternfish are small fish covered in rows of light organs called photophores. The pattern of lights differs from species to species, which scientists use to tell them apart.
They are among the most abundant fishes of the deep open ocean, with at least 250 species. Most species rise into the upper 200 meters at night to feed and sink back down by day – part of a vast daily migration of ocean animals.
Crystal jelly
Scientific name
Aequorea victoria
Found in
Pacific coast of North America
This nearly transparent jellyfish glows green around the rim of its bell. A protein called aequorin makes blue light, and a second protein – green fluorescent protein, or GFP – turns that blue light into green.
GFP became a revolutionary tool for tagging and watching cells and genes. Its discovery and development earned the 2008 Nobel Prize in Chemistry.
Atolla jellyfish
Scientific name
Atolla wyvillei and relatives
Found in
Deep sea, worldwide
When attacked, this deep red jellyfish produces a pinwheel of blue light around its bell. Scientists think this "burglar alarm" display may attract a bigger predator that will go after the attacker.
An electronic lure that imitates the Atolla display, called the e-jelly, helped researchers film a giant squid in its deep-sea home for the first time, in 2012.
Hawaiian bobtail squid
Scientific name
Euprymna scolopes
Found in
Shallow waters around Hawaii
This small squid keeps glowing bacteria (Vibrio fischeri) in a special light organ on its underside. At night, it uses the light to match the moonlight from above, erasing its own shadow so predators below cannot see its silhouette.
The partnership runs on a daily rhythm: the squid releases many of its bacteria into the sea each day, and the ones left behind regrow.
Stoplight loosejaw
Scientific name
Malacosteus niger
Found in
Deep ocean, worldwide
Almost all deep-sea light is blue, and most deep-sea animals can only see blue. The stoplight loosejaw is a dragonfish that makes deep red light – and, unusually, it can see that red light itself.
That may give it a private searchlight for spotting prey that cannot see the beam.
Glowing sharks
Scientific name
Dalatias licha, Isistius brasiliensis and others
Found in
Deep and open ocean
Several sharks glow. The cookiecutter shark has a glowing belly with a dark collar, and one idea is that the collar looks like the silhouette of a small fish to hungry predators – which may then get a round bite taken out of them instead.
In 2021, researchers reported that the kitefin shark, which can grow to about 1.8 meters (about 6 feet) long, is the largest known glowing animal with a backbone.
Sea fireflies (ostracods)
Scientific name
Vargula hilgendorfii and relatives
Found in
Coastal waters, including Japan and the Caribbean
These tiny crustaceans squirt their light-making chemistry (a luciferin and a luciferase) into the water, where it makes a bright blue glow.
In the Caribbean, male sea fireflies court females with trains of glowing pulses in the water, in patterns specific to their species.
Dinoflagellates
Scientific name
Pyrodinium bahamense, Noctiluca scintillans and others
Found in
Coastal waters and bays worldwide
These single-celled plankton are behind most glowing waves and bioluminescent bays. Each cell flashes when the water around it is disturbed – for example by a grazer or a breaking wave – so a paddle, a fish or a breaking wave lights up in blue.
A widely accepted idea is the "burglar alarm" again: a flash may startle small grazers or draw in bigger predators that eat them.
On land
Glowing life on land is much rarer than in the sea – it is mostly insects and fungi – but it includes some of the best-loved sights in nature.
Fireflies
Scientific name
Lampyridae (family)
Found in
Warm and temperate regions around the world
Fireflies are not flies; they are beetles. Many species flash in a pattern unique to their species, and males and females use these codes to find each other in the dark.
Some predatory Photuris females mimic the flash replies of other species to lure in males – and then eat them. Firefly larvae glow too; they are chemically defended, and their glow is thought to warn predators away.
New Zealand glowworms
Scientific name
Arachnocampa luminosa
Found in
Caves and damp forest gullies in New Zealand
These "glowworms" are the larvae of a fungus gnat. Each one hangs down silk threads beaded with sticky droplets and glows blue-green from the end of its body.
Small flying insects are drawn to the light and get caught in the threads. A cave ceiling full of them looks like a starry night sky.
Railroad worm
Scientific name
Phrixothrix (genus)
Found in
The Americas
Not a worm but a beetle larva, the railroad worm has rows of green lights along its body and a red light on its head – like the windows and headlamp of a train at night.
It is one of very few animals known to make red light.
Glowing millipedes
Scientific name
Motyxia (genus)
Found in
A few counties in California
These blind millipedes glow a soft green-blue at night. They also defend themselves with cyanide, and the glow appears to warn nocturnal predators: in one study, glowing millipedes were attacked far less often than ones painted to hide their glow.
Glowing click beetles
Scientific name
Pyrophorus and relatives
Found in
Tropical Americas, including the Caribbean
Some click beetles have a pair of green lights behind the head, like two glowing eyes, plus an orange light on the underside that shows only when they fly.
Glowing fungi
Glowing fungi shine a steady green, usually brightest at night. You usually need a very dark forest, a moonless night and a few minutes for your eyes to adjust before you notice them.
Foxfire
Scientific name
Armillaria, Panellus and other wood-decay fungi
Found in
Forests worldwide
Foxfire is the eerie green glow of rotting wood infected with fungal threads. People have noticed it for thousands of years; the ancient Greek writer Aristotle described light given off by rotting wood.
Ghost mushroom
Scientific name
Omphalotus nidiformis
Found in
Southern Australia
A pale mushroom that glows a ghostly green at night. It is poisonous, and so are its glowing relatives the jack-o-lantern mushrooms (Omphalotus olearius in Europe and Omphalotus illudens in eastern North America).
Glowing bonnet mushrooms
Scientific name
Mycena (genus)
Found in
Forests worldwide, especially in the tropics
About 130 kinds of glowing fungi are known, and most of them are small bonnet mushrooms in the genus Mycena and their close relatives. Some glow from the cap, some from the stem, and some only from their threads hidden in wood.
Research on one Brazilian glowing mushroom found that lit-up decoy mushrooms attracted more insects than dark ones, which may help spread its spores.
Glowing bacteria
Many glowing sea creatures do not make light themselves. They farm it. Anglerfish, bobtail squid and some other sea animals host glowing bacteria in special organs, giving the bacteria food and shelter in exchange for light.
Glowing bacteria also taught scientists something big. Studies of Vibrio fischeri in the early 1970s showed that the bacteria only switch on their light once enough of them are crowded together. They track their own numbers by sensing a chemical signal, a process now called quorum sensing, which turned out to be used by many other kinds of bacteria.
On rare occasions, sailors have reported huge patches of ocean glowing a steady milky white through the night. These "milky seas" are thought to be caused by vast numbers of glowing bacteria. Satellite images of one seen by a ship in 1995, analyzed and published in 2005, showed it covered at least 15,400 square kilometers – roughly the size of the US state of Connecticut.