Glow fact 1 of 18
Fireflies are beetles
Fireflies are not flies at all. They are beetles, and many species flash in a pattern unique to their species to find a mate.
Glow facts
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Glow fact 2 of 18
Glowing mucus instead of ink
The vampire squid does not squirt ink in the deep sea. Instead, it can release a sticky cloud of glowing mucus from its arm tips to confuse predators.
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Glow fact 3 of 18
Most deep-sea animals glow
In a big survey of Monterey Bay, California, roughly three-quarters of the animals observed between the surface and about 4,000 meters deep could make light.
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Glow fact 4 of 18
A jellyfish won a Nobel Prize
Green fluorescent protein from the crystal jelly became such an important tool for watching cells that its discovery and development won the 2008 Nobel Prize in Chemistry.
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Glow fact 5 of 18
The biggest glowing vertebrate is a shark
The kitefin shark, which can reach about 1.8 meters (about 6 feet) long, is the largest known glowing animal with a backbone.
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Glow fact 6 of 18
A fish with a secret red searchlight
Most deep-sea animals cannot see red light. The stoplight loosejaw dragonfish makes red light and can see it, giving it a private searchlight for hunting.
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Glow fact 7 of 18
A squid that erases its own shadow
The Hawaiian bobtail squid uses glowing bacteria in its belly to match the moonlight from above, so predators below cannot see its silhouette.
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Glow fact 8 of 18
Glowworms are fly larvae that fish with light
New Zealand's famous glowworms are the larvae of a fungus gnat. They glow to lure insects into sticky silk threads hanging from cave ceilings.
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Glow fact 9 of 18
Light was invented many times
Bioluminescence has evolved independently many separate times in different groups of living things -- dozens of times at least, and perhaps close to 100.
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Glow fact 10 of 18
Firefly femme fatales
Some Photuris firefly females copy the flash signals of other firefly species to lure in males -- and then eat them.
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Glow fact 11 of 18
Aristotle noticed glowing wood
The ancient Greek thinker Aristotle wrote about a light from decaying wood that gave off no heat. Today we call it foxfire, the glow of fungi.
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Glow fact 12 of 18
Bacteria that count before they glow
Glowing bacteria only light up when enough of them are packed together. Studying this led to the discovery of quorum sensing, how bacteria sense their own numbers.
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Glow fact 13 of 18
Why the sea glows blue
Blue-green light travels farthest through seawater, so most ocean creatures make and see blue or blue-green light.
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Glow fact 14 of 18
A larva with a red headlamp
The railroad worm, a beetle larva from the Americas, has green-yellow lights along its sides and a red light on its head, like a tiny train at night.
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Glow fact 15 of 18
Glowing scorpions are not bioluminescent
Scorpions shine under ultraviolet light, but that is fluorescence: they re-emit light that hits them. Bioluminescent creatures make their own light, even in total darkness.
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Glow fact 16 of 18
Seas that glow white for miles
Sailors have long reported "milky seas", where the ocean glows a steady white across huge areas. Satellite images confirmed one in 1995, and glowing bacteria are the leading explanation.
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Glow fact 17 of 18
Tiny crustaceans that write in light
Male sea fireflies (ostracods) in the Caribbean leave trails of glowing dots in the water as a courtship display, with patterns specific to their species.
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Glow fact 18 of 18
A bay that fills with glowing squid
Every spring, firefly squid gather in Toyama Bay, Japan, to spawn, lighting the water with blue sparks.