Biofluorescent animals—those that absorb light, such as ultraviolet rays, and re-emit other types of light, such as neon green—include some flying squirrels, scorpions, sea turtles, and platypuses.

Bioluminescent organisms produce their own light through chemical reactions involving unstable, energetic molecules, while biofluorescent organisms almost immediately re-emit light shone on them, but at a different wavelength.

View a gallery of biofluorescent animals, which contain cells that emit various colors when exposed to ultraviolet light.

Because it is observed in organisms that are not closely related, biofluorescence is thought to have emerged independently many times in nature—over 100 in fish alone.

Bioluminescence provides organisms with a method of hunting, defense, or mating

Unlike glow sticks, bioluminescent reactions use renewable resources like oxygen and ATP. This ability allows fireflies to mate and deter predators, anglerfish to confuse and attract prey, and deep-sea shrimp to defend themselves by vomiting glowing slush.

Blacklights can illuminate certain biological materials, including blood, teeth, and fingernails, because they contain fluorophores—molecules that visibly glow immediately after exposure to higher-energy light.

View illustrations of bioluminescent functions in marine organisms

Bioluminescence can startle predators, camouflage, lure prey, confuse rivals, or facilitate mate recognition. One tactic—the burglar alarm—involves an organism releasing light to attract a larger predator to its attacker as a means of defense.

Bioluminescence became common in the ocean to support survival in dark environments

Despite seeming like a rare ability in land animals and unseen in plants, bioluminescence has evolved at least 29 times across marine species, indicating its necessity for survival where hiding spots are rare and highlighting how environments provide evolutionary pressure.

View a gallery of bioluminescent organisms, including jellyfish and mushrooms

Some species produce a quick flash of light, while others glow steadily with an eerie glow, often to seek attention or in response to being disturbed. Snails, worms, fungi, and other organisms highlight that this ability evolved independently, rather than from one common ancestor.

Virtually all plants are biofluorescent because their photosynthesis is powered by chlorophyll, a pigment that glows red as a way to get rid of excess energy when exposed to ultraviolet light.

View a gallery of plants made to shine using ultraviolet-induced visible fluorescence photography, in which organisms re-emit the ultraviolet light they are exposed to in vibrant, glowing colors.

Fireflies light up to provide mating signals and warnings to predators

Variations in the illumination patterns and flight paths while emitting light have been observed across firefly species. Some species instead rely on pheromones if they are primarily active during the day or have lost the ability to illuminate.

Why 75% of ocean animals glow

About 75% of ocean creatures can make their own light. It's called bioluminescence—and it all comes down to a special chemical reaction happening inside their bodies.

Massive blooms of microscopic algae called dinoflagellates produce the neon blue light seen in glowing tides.

Humans have used bioluminescence as a means of military advantage

During World War I, the British Navy sank a German U-boat after spotting the blue light forming at the sides and in the wake of the boat. Jellyfish slime was applied to a Roman walking stick for nighttime guidance, while bioluminescent fungi in Indonesia fulfilled the same purpose.

Watch David Attenborough's documentary on bioluminescent creatures, which have been observed using light for hunting, mating, communication, and self-defense, and number in the thousands of species.

View examples of luciferin, the light-emitting molecule behind bioluminescence

Bioluminescent marine organisms rely on various unique luciferins, including Cypridina-type luciferin in seed shrimp and chlorophyll-based dinoflagellate luciferin, to react with oxygen to produce light. These chemicals require unique catalysts to help them bind with oxygen.

The 2008 Nobel Prize in chemistry was awarded for discovering and developing uses for green fluorescent protein—a biomolecule found in Aequorea victoria, a jellyfish native to the Pacific Northwest.

Bioluminescent reaction enzymes are often used in biomedical research

Near-infrared luciferase systems allow researchers to image and analyze cellular activity in living animals because they penetrate tissue more deeply than visible light. This provides a means of studying gene expression and protein interactions without harming the animals.

View an animation of how certain chemicals fluoresce—that is, emit visible light after having absorbed higher-energy light, such as ultraviolet radiation.

When caught in the mouths of cardinal fish, seed shrimp release glowing, bioluminescent chemicals, which alert predators of the cardinal fish, prompting the shrimp's ejection.

Solutions of bioluminescent bacteria can create FOMO-inducing living art

A 2002 exhibition at Montana State University-Bozeman placed the bacteria onto petri dishes that served as macroscopic pixels to create images. Once the bacteria finished eating all the food in the sealed dishes, the light slowly faded away, ending the exhibit.

The first appearance of bioluminescence was at least 540 million years ago

After analyzing fossils, genetic data, and statistical methods, scientists believe octocorals were the first organisms to evolve light-producing abilities. As a result of independent evolution across at least 94 species, this phenomenon is connected to a diverse range of behaviors.

View a sample of the bioluminescent tree of life

This diagram shows 42 different light-producing organisms, from bacteria and fungi to worms, fish, and crustaceans. It illustrates how the ability to produce light has appeared multiple times across the tree of life, rather than stemming from a single ancestor.

Scientists can tag distinct proteins with fluorescent probes that emit different colors, allowing them to visualize multiple biochemical processes simultaneously.

Starting with red, colorful objects will appear to lose their colors the deeper they are submerged because water scatters light, reducing the amount available to reflect off objects and be observed.

Some corals absorb harmful ultraviolet radiation and re-emit it as visible light, thereby protecting symbiotic algae within their tissues and providing them with energy for photosynthesis.

Some North American bats can glow in the dark

After examining 60 museum specimens from six different species, scientists found that all of them emitted light after being exposed to ultraviolet radiation. Researchers are perplexed by this natural phenomenon and are currently unable to deduce the reason behind it.

Some female fireflies mimic the signals of other species to lure in and eat them

The genus Photuris does not produce its own defensive pheromones to ward off predators, so it has developed mimicry to attract males of firefly species that do. Unsuspecting males are consumed after these chemicals—lucibufagins—are extracted.

Blood color differs across the animal kingdom, with some animals producing blood that appears green (a group of lizards in New Guinea) or blue (horseshoe crabs).

Bioluminescence may provide a sustainable alternative to electric lighting

French start-up Glowee is experimenting with lights made from bioluminescent microorganisms in public spaces to reduce energy use. While the technology shows promise, challenges remain with brightness, maintenance, and scaling it for widespread use.

Catfish have taste buds spread across their entire skin, making their whole body function like a tongue that can taste food several feet away.

Synchrotron radiation has revealed the fur color of creatures millions of years old

When electrons are accelerated in the loop, they produce intense X-rays that can reveal properties of a sample struck by them, just as X-rays can be used to show bone structure in humans. Studying the reflected light from fossils can uncover the presence of known pigmentation compounds.

Electrogenic animals generate their own electricity within an electric organ by changing the pattern of electrical charges in disc-shaped cells called electrocytes.

Evolution doesn't want you to see these animals

Invisibility is an oft-coveted superpower that many creatures throughout the animal kingdom have evolved to mimic through transparent camouflage. This article explores the science of this seemingly magical ability. The two critical ingredients in...

As immobile animals, corals and the organisms that live on them have evolved a suite of chemical compounds to prevent disease and ward off predators they cannot outrun.

View the fluorescently stained internal structures of a tardigrade

The photograph won the Olympus Global Life Science Light Microscopy Americas regional award in 2019. Using chemicals from biofluorescent organisms, the image illuminates internal structures with multiple hues in an otherwise mostly colorless organism.

Synthetic pheromones may protect coral reefs by attracting their predators

Researchers in Australia and Japan have developed these nontoxic chemicals to attract crown-of-thorns starfish, which consume corals that make up the Great Barrier Reef. As of 2026, synthetic pheromones have been shown to be effective in lab trials, and future field trials will attempt to lure starfish into areas for mass removal.

Chameleons change color by altering the spacing of nanocrystals under their skin, which changes what colors of light are absorbed and reflected.

Satellites can be used to measure photosynthetic activity worldwide by observing the red, biofluorescent light emitted by chlorophyll in plants.

Blood has evolved many times over hundreds of millions of years, resulting in different blood colors and compositions—and there are even some organisms that don't need blood at all.

Glow sticks feed energy released in chemical reactions to fluorescent dyes

When bent, the glass tube inside the stick breaks, releasing hydrogen peroxide into the surrounding solution. The ensuing reaction creates unstable molecules that decompose and release energy, which is then absorbed by molecular dyes that emit light when their excited electrons return to lower energy states.

View a gallery of animals found on abyssal plains, hydrothermal vents, seamounts, and other deep-sea habitats.

Over 1 million fish, marine mammals, and invertebrate species depend on coral reefs for habitats, camouflage, and food.

Spiders may manipulate captured male fireflies into mimicking female mating signals

Rather than killing a male firefly captured in its web, the Araneus ventricosus spider bites into it, which researchers believe injects a venom that disrupts normal flashing behavior and produces a form of mimicry to attract additional males. (Some readers may experience a paywall.)

Coral reefs get their colors from zooxanthellae—photosynthetic algae that line corals' digestive tracts and provide them with sugars in exchange for a home within this protective tissue.

Some animals possess sensitive hearing to help pinpoint prey and map the world

Bats and dolphins produce sound to reflect off surfaces and create a mental image of their surroundings. Owls' faces are dish-shaped to help funnel sounds to their ears, including that of mice moving along leaves or snow. Pinnipeds, such as seals and walruses, hear in both air and water.

The fish can climb walls

Scientists in Brazil captured rare footage of bumblebee catfish climbing waterfalls. How they do it is clear, but why remains a mystery.

Research shows that during total solar eclipses, some animals change their behavior to match their nighttime activities.

In the 1950s, Alan Turing developed a mathematical model to explain why animals have stripes, spots, and other patterns based on differences in how quickly two interacting chemicals spread throughout a developing organism.

Although they rely on radioactive elements to operate, everyday technologies such as electronic exit signs, some wristwatches, and smoke detectors are not dangerous, unless they are damaged and their radioactive material is inhaled or swallowed.