Bio-luminescence is one of those things, literally meaning bio and light, it refers to the production of light by living creatures.
There’s something a bit magical and otherworldly about light anyway. It fuels so much of our existence that deifying the sun actually kind of makes sense.
If the sun disappeared, so would we. We can control our little light switches, we can install our own garden lighting, but we could never control the sun.
This is why when you imagine a creature emitting natural light you imagine fantasy, something otherworldly, touched by something higher than us. You think of Harry Potter, or Star Wars, of the Northern Lights, or of myth…
But my friends, bio-luminescence is no myth, read on to discover more about the world’s mysterious light-emitting creatures.
Ten Million Fireflies Lighting up the World as you Sleep
Fireflies and glow worms both belong to the aptly named species ‘Lampridae’. Glow worms are the larvae of fireflies.
Glow worms have specialised organs in their lower abdomens to emit light as a warning signal to predators to back off. Many also contain poisonous chemicals so their light is a good clue to poachers that they’ll get hurt if they pursue.
In adult fireflies, light functions more for mate selecting purposes. Not only can they just light up, they talk through light by alternating steady glows and flashing to their prospective partners from the sky.
Talk about body language.
But beware, boys, of a certain femme fatale firefly, who takes the idea of eating her men alive literally. These species mimic the communicative flashes to entice a male along and then gobble him up…charming!
The Bobtail Squid’s Invisible Cloak
Now the Bobtail Squid is interesting.
It has a special light organ in its mantle, but any light is a result of great teamwork.
The bobtail squid has a particular kind of relationship with bacteria called Vibrio Fischeri, who inject the squid with…themselves.
The squid then draws out relevant bacteria needed to colonise its light organ, intensifies the light and directs it outwards.
The Bobtail’s mantle works as an invisible cloak, because from below, it looks like the light shining down from the moon and stars.
If fish are on the lookout below, they don’t see the squid because no shadow is cast. This has to be one of nature’s most thought about illusions!
But it gets even cleverer. The Bobtail can filter its light to match the downwards shining moonlight and starlight, and then when dawn comes, it breathes out the bacteria. When night comes again, the bacteria run back to their squid!
Ever loyal to the Bobtail, not only do the Fischeri do all this, they also initiate the baby Bobtails into adulthood. After colonising the baby Bobtail light-organs for the first time, the little squids are ready to begin their journey into adulthood.
Emitting light when disturbed: The Whirling Scourge
I guess there are various different bodily clues we might give off to express that we’ve been disturbed, like going red in the face. But I think giving off light would be cooler.
Dinoflagelletes, translated in Greek to mean the ‘whirling scourge’, sounds pretty ominous. Actually the light emitted by these plankton when physically moved by boats, swimming or waves, is more beautiful than scary.
In 1753, explorer Henry Baker described his first experience of this plankton as causing the ‘Sparking Light in Sea Water’ and this is exactly what the sea looks like lit up by these organisms. Their flashing lights are meant to startle predators so they turn away but to us it just looks pretty. Kind of makes you want to disturb them!
So, there you have some of the magical, mystical light bearers of our world, spanning the night sky and buried deep beneath the ocean.
I’m not sure which is my favourite, but I do know that if evolution and biology made all this possible once upon a time, could us humans get a share of this light-emission power one day?