1. When fireflies blink, they might be flirting.
2. These crystal jellies led to a Nobel Prize (and many green-hued animals).
3. Deep-sea angler fish lure prey with a lit fleshy fishing pole.
Remember that terrifying fish that Nemo and Dory encountered in Finding Nemo? That's an angler fish, and it actually looks like a nightmare in real life, too.
Only the ladies have that dangling luminous fishing rod, which is part of their dorsal spine (and where they get their name). And for a while, scientists weren't sure why they only kept pulling females out of the ocean.
Here's the fun sexy fact: Male anglers are much smaller than females, and after they attach to the female using their teeth, they fuse into her permanently over time as a parasite, leaving behind just a pair of gonads. Aww!
4. Ostracods eject light when they're threatened.
5. These Californian millipedes ooze cyanide.
These little guys, known as Motyxia, are blind. But that doesn't stop them from going about their business: As the sky darkens, the rust-orange critters emerge to snuffle for food and a mate.
With a photoprotein similar to crystal jellies' GFP, light from these millipedes is greenish-blue. But if disturbed, the light intensifies — and if that isn't enough of a message, its pores start to leak toxic cyanide.
But unlike some luminescent critters, they may glow as a warning to bugger off.
Motyxia are blind and mostly eat decomposing plant matter. So who are they wooing with their luster?
A group of scientists suspected that the glow might be aposematic, or warning coloration. In a Current Biology study, researcher Paul Marek and his team used a bronze cast (left) to create hundreds of fake clay millipedes, half of which were coated with a glow-in-the-dark paint. They also dampened the glow of real Motyxia with paint and set the fake critters next to them.
The next day: "It was just – carnage," Marek told UANews of the aftermath (middle and right). They found that non-luminescent millipedes, both real and fake, were more likely to be attacked than those that glowed.
6. Railroad worms look like train cars.
Speaking of creepy crawlers, railroad worms (specifically Stenophrixothrix fusca, shown here) have eight pairs of lamps that glow a sprightly yellow-green spread along the body, giving the image of a train's windows as it choo-choos by.
7. These trippy mushrooms glow all the time.
Aptly nicknamed "eternal light," Mycena luxaeterna was found in the dark depths of Brazilian rain forests and is just one species among dozens of other radiant fungi detailed in a 2010 Mycologia study.
The ground was so illuminated, looking down was like looking at the sky, lead study author Dennis Desjardin told National Geographic. Desjardin suspects the glow attracts nighttime critters, which then help disperse the mushroom's spores so that they can propagate.