bioluminescence

A firefly's light seems rare and magical. Yet there are many living things that blink, glow, flash, and glitter. The deep-sea anglerfish lures prey with a glowing "lure." Cave-dwelling glowworms catch insects with their glimmering tails. Bioluminescent organisms range from sharks to mushrooms. They emit light from different body parts, in an array of colors, and for a variety of purposes. They may glow to attract mates, hunt, or defend themselves.

Stats

Definition: a chemical reaction in organisms that produces light
Organisms that use it: marine invertebrates, fish, fungi, insects, and bacteria
Where it's found: ocean, woods, fields, caves
Uses: light up or lure prey, communicate, attract mates, hide and defend from predators
Cool Fact: Light from the Sun, a fire, an electric bulb, comes with heat. Bioluminescence is "cold light." It gives off almost no heat.

Story

A Special Chemistry

Bioluminescence might seem like magic, but it's really just the product of a chemical reaction. In any chemical reaction, two or more molecules interact and create a substance that wasn't there before.

In bioluminescence, the main ingredients in this reaction are luciferin (loo-SIFF-er-in), luciferase (loo-SIFF-er-ace), and oxygen. The reaction between the three produces a new molecule called oxyluciferin.

It also produces energy in the form of photons, units of light. Some organisms make their own light-making molecules, luciferin and luciferase. Others get their luciferin from the organisms they eat.

Stumper

Most bioluminescent organisms live:

in forests

in the ocean

in dark, moist caves

Correct!

Bioluminescence is actually very rare on land. In the ocean, there are bioluminescent bacteria, plankton, coral, sea slugs, crustaceans, and octopuses . At certain depths, nearly all organisms make light.

Stumper

In the ocean, the light that glows from most bioluminescent organisms ranges from:

white to red

orange to yellow

green to blue

Correct!

Many marine animals in the deep-sea see only bluish-green light. Water acts like a filter, absorbing different colored light as the water gets deeper. First red light is absorbed, then orange and yellow, then violet. Deeper still, green light disappears, leaving only blue light.

Stumper

In the quiet waters of a lagoon in Puerto Rico, tiny marine organisms called dinoflagellates flash and glitter when:

it gets dark out

they're scared

something bumps into them

Correct!

The impact triggers a chemical reaction that ends in a burst of light. No one really knows why dinoflagellates flash on contact, but it may be to startle or expose predators.

Fact or Fiction

All animals that "glow" produce their own light.

Fact

Fiction

Some use fluorescence: they absorb one color of light and emit another. Many bioluminescent corals glow in orange and green when blue or violet light shines on them.

Fact or Fiction

The ponyfish glows because of tiny glowing organisms living inside it.

Fact

Fiction

Fact

A ring of tissue around its throat is packed with bioluminescent bacteria. Special structures channel the light to clear patches on its body.

Fact or Fiction

The stoplight loosejaw dragonfish shines a red light that is invisible to other organisms.

Fact

Fiction

Fact

Its red light helps it find prey without being seen. Red light is absorbed in shallow waters, so it does not reach the deep sea. Most deep-sea animals can only see blue and green light.

Image credits: main image, firefly, © Jeff J. Daly/Alamy; mushrooms, © Cassius V. Stevani; deep-sea anglerfish, courtesy of Edith Widder/HBOI; .

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