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

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.

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.

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.

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.

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 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.

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.

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.

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.

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.

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.

Evidence suggests the first cells on Earth were bacteria

About 4 billion years ago, these single-celled organisms harvested carbon dioxide and sunlight to produce their own food and oxygen, setting the stage for the evolution of oxygen-breathing life forms. Archaeabacteria, which thrive on inorganic molecules in extreme habitats on Earth today, were also among the earliest organisms.

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.

An analysis of fossilized reefs from northern Africa and Germany suggests that shallow water corals and photosynthetic algae formed the mutualistic partnership seen today between 419 and 359 million years ago.

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.

Genetic analysis indicates that every organism on Earth evolved from a single cell

LUCA—the last universal common ancestor—lived about 4.2 billion years ago and likely obtained energy through the conversion of carbon dioxide and hydrogen gas consumed from atmospheric gases at the ocean's surface or hydrothermal vents—openings on the seafloor where fluid warmed and enriched with minerals by Earth's interior is expelled.

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.

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

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.

The first coral reefs formed hundreds of millions of years ago from the carbonate skeletons deposited by hard corals.

Research has found that when their symbiotic algae are not producing oxygen via photosynthesis, corals twirl hairlike structures to circulate water and draw oxygen into their outer tissues.

Green algae have lived on Earth for about 1 billion years, roughly twice as long as the first plants.

Light pollution is giving oysters insomnia

Oysters, bivalve mollusks that have light-detecting cells along their skin, can't sleep with all this artificial light. According to a 2022 study, oysters' sleep cycles are disturbed by light dimmer than that provided by the full moon. As with humans, it's possible that these bouts of insomnia could have adverse health effects and contribute to the development of disease over time.

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.

Coral polyps reproduce via broadcast spawning, where entire reefs simultaneously release reproductive cells for about one hour, once a year.

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.

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.

The earliest known cardiovascular system dates to 520 million years ago.

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.

Deep water corals—located throughout the world's ocean basins at depths beyond 200 meters (660 feet)—slowly build small coral gardens in the dark with the help of underwater worms.

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.

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.

How humans evolved from single-cell organisms

Humans have had a long history. 3.8 billion years in the making, to be precise. From the primordial puddle to the modern day, here's how humans have evolved from the first life.

During coral bleaching, corals sacrifice their food source and expel colorful microorganisms to protect themselves, a phenomenon that resembles an organism's immune system attacking itself.

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.

Cell theory originated from microscopic observations of cork and dental plaque

In the mid-1600s, Robert Hooke identified compartment-like structures—which he called cells—in cork, and Anton van Leeuwenhoek discovered bacteria in samples of his dental scrapings. Almost 200 years later, Matthias Schleiden and Theodor Schwann showed that plants and animals, respectively, are composed of cells, proving that cells are the foundation of all living things.

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.

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.

Multiple species exhibit convergent evolution by developing crab-like features

Various organisms that appear to be different types of crabs, such as porcelain crabs and coconut crabs, have been shown to belong to distinct decapod lineages whose predecessors resemble shrimp or lobsters. Environmental pressures and other factors have caused these species to develop similar characteristics, which nature has shown are beneficial to survival.

The earliest evidence of cancer was found in a 1.7-million-year-old fossil—discovered in the toe of an ancestor of modern-day humans.

The world's largest coral, as seen from space

The world’s largest individual coral colony—measuring over 100 feet wide and 100 feet long—was discovered in the Solomon Islands. This coral is so large it can be seen from space, and is estimated to be between 300 and 500 years old. The coral's size and health provide hope amidst a global coral bleaching crisis, wherein three-quarters of coral reefs have experienced significant bleaching in recent decades. See the photos from space and learn more here.

Bacteria have been genetically engineered to bioluminesce when wine has spoiled

Developed by researchers at Hebrew University, the method involves the firefly enzyme luciferase, which emits light from within bacteria expressing when they are in the presence of acetic acid vapors produced by wine. The process provides affordable, on-site, real-time monitoring of fermentation quality.

Extremophiles were likely to have been Earth's first, and are expected to be its last, organisms

Their ability to survive in an enormous range of environmental conditions, including some resembling what has been modeled to have existed relatively shortly after Earth's formation, makes them the leading candidates for enduring the increasing solar intensity and the subsequent effects (e.g., zero-oxygen atmosphere, evaporated oceans) expected in the coming billions of years.

The 10 most amazing deep sea creatures

In this video, researchers from the world-renowned Monterey Bay Aquarium discuss the most fascinating deep sea creatures, and how they developed some of their strangest features.

Through sonoluminescence, concentrated sound waves can produce short, high-intensity flashes of light by rapidly collapsing microscopic bubbles to temperatures up to twice that of the sun's surface.

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

Lining up every microbe on Earth would stretch to about 105,000 light-years

There are about 10²⁷ such organisms on the planet, many of which are adapted to produce energy through uncommon reactions in unconventional environments, such as within rocks or near volcanoes on the ocean floor. Studies of these organisms have reframed astrobiologists' search for life beyond Earth by broadening the parameters under which life can exist.

Flowers have been around for 123 million years

Fossilized pollen grains reveal that flowering plants have existed on Earth for 123 million years, and their emergence considerably enriched the planet's biological diversity. They may also have been more widespread than initially thought—prior assumptions were that the eudicots, the first flowering plants, appeared 121 million years ago.