Bioluminescence

Bioluminescence is the amazing ability of some living things to make their own light. This happens because of a special chemical reaction inside their bodies. Many animals and tiny organisms can glow this way. You can find them in the ocean, like some fish and jellyfish, and on land, such as fireflies and glowing mushrooms.

The light comes from a reaction between two important parts: a substance called luciferin and an enzyme called luciferase. When these two mix, they make light. This light can help the creatures in many ways. For example, some animals use it to hide, while others use it to find friends or food.

People have known about bioluminescence for a long time. Even ancient thinkers like Aristotle and Pliny the Elder wrote about glowing wood. Scientists later learned more about how this light works and why it is useful. Today, researchers use these glowing chemicals in labs to study genes and help with medical research.

History

Before safety lamps were used in coal mines, people in Britain and Europe used dried fish skins to make a weak light. This helped avoid sparks from candles that could cause explosions. In 1920, an American scientist named E. Newton Harvey wrote a book called The Nature of Animal Light. He shared what was known about bioluminescence at the time. He mentioned that ancient thinkers like Aristotle and Pliny the Elder had seen light from dead fish and damp wood.

Famous explorer Charles Darwin saw glowing lights in the sea during his travels. Later, scientists studied how creatures like click beetles and sea animals made light. They found that this light comes from a special chemical reaction. This reaction uses a compound called luciferin. Important discoveries in this area helped scientists, including Osamu Shimomura, Martin Chalfie, and Roger Y. Tsien, win the 2008 Nobel Prize in Chemistry for their work on green fluorescent protein. This tool is used in biological research today.

Evolution

In 1932, a scientist named E. N. Harvey thought about how bioluminescence might have first started, but we now know his idea was not right. Today, scientists have two main ideas about how it evolved, especially in sea creatures.

One idea, by Howard Seliger, says that special enzymes called luciferases might have changed over time to help animals make light. Another idea, by Rees and others, suggests that bioluminescence began as a way to protect animals from harmful substances in their environment.

Bioluminescence has developed separately many times — at least 94 times in total. It first appeared in soft corals called octocorals about 540 million years ago. In fish, it began at least by the Cretaceous period, and about 1,500 fish species can make their own light. Some fish get this ability from bacteria they take in from the water, while others make the light themselves through chemical reactions. These light-producing abilities help fish attract food, hide from predators, and talk to each other in the deep ocean.

Chemical mechanism

Main article: Luciferase

Bioluminescence is when a special chemical reaction makes light. This reaction needs a pigment called luciferin and an enzyme called luciferase. Often, oxygen is needed, and sometimes carbon dioxide (CO₂) is made.

Some animals, like the jellyfish Aequorea victoria, use a different protein called a photoprotein, such as aequorin. When calcium ions are added, this makes a quick flash of light. Later, the luciferin can be used again.

Distribution

Further information: List of bioluminescent organisms

Bioluminescence is found in many animals, especially in the open sea, such as fish, jellyfish, comb jellies, crustaceans, and cephalopod molluscs. It also occurs in some fungi and bacteria, as well as in many land insects, mostly beetles. In the deep sea, many animals can produce light, and this light is often blue or green. Some special fish can even make red or infrared light.

One common example of bioluminescence is the sparkling glow seen in seawater at night, caused by tiny organisms called dinoflagellates. These can light up the surface layers of the ocean. There are also large areas of the ocean that glow because of bioluminescent bacteria, creating a milky sea effect.

Uses in nature

Bioluminescence, the ability to make light, helps animals in many ways. In the ocean, it can help animals hide from danger, catch food, or find a partner. For example, deep-sea squid use light to blend in with the glow from above, making it harder for predators to see them.

On land, fireflies use light to find mates. Males and females send signals to each other. Some insects and fungi also glow to attract others or scare away predators. This natural light show helps animals live in dark places.

Main article: Counterillumination

Biotechnology

Further information: optogenetics

Scientists study glowing organisms to learn new things. They use special genes from glowing animals, like fireflies, in experiments. They also use these genes to make pictures of living things inside bodies. Some tiny water animals have special bacteria that help them glow. These bacteria are used to study how living things work.

Researchers are trying to make glow-in-the-dark plants and tiny germs. They hope to use these to light up streets or homes without electricity. Some companies have made glowing lights using special germs, but they only work for a few days. Scientists are still finding new ways to make things glow brighter and longer.