words by Willow Defebaugh
Bioluminescence is a phenomenon exhibited by a myriad of species across kingdoms—illuminating even the unlikeliest of places.
“Hope is being able to see that there is light despite all of the darkness.”
On more than one morning this week, I found myself not wanting to get out of bed. Between President Biden approving a monstrous drilling auction in the Gulf of Mexico so soon after moving the disastrous Willow Project forward to the latest shooting and 435 bills attacking LGBTQIA rights in the U.S., the news lately has left me wondering: where are we going? In 2020, it felt as if there was a glimmer of hope that society might be starting to transform. Today, I would be lying if I said I didn’t have my moments of doubt. And when I feel shrouded in uncertainty, I turn to nature for answers. This week, I saw them flicker in the form of bioluminescence.
Bioluminescence refers to light produced by a living organism. The glow, almost always a greenish-blue, occurs from a reaction in which chemical energy is converted into radiant energy. It gives off little heat, which is why this luminescence is called “cold light.” It is most often demonstrated in service of the survival of a species: warding off predators, luring in prey, and communicating with kin. From deep-sea creatures to fairy-like critters of the forest, this phenomenon can be found in a whole host of animals, fungi, insects, invertebrates, and bacteria—a diverse display of the light of life.
Even in the crushing darkness of the deep, light can be found. Deep-sea anglers cast an eerie glow from lantern-like appendages that hang just inches in front of their terrifying jaws, drawing in unsuspecting prey. Firefly squid can be found lighting up Japan’s Tomaya Bay like galaxies, their bodies containing numerous lights, appearing to predators below as constellations above. Vampire squid, meanwhile, secrete clouds of dazzling luminescence to distract predators. And a myriad of hydroids and jellyfish cast their lights in waters around the world—while certain algae, bacteria, and plankton cause entire swaths of sea to glow. One famous crustacean, Vargula hilgendorfii, deploys a luminous substance when disturbed. Collected and dried, it continues emitting light indefinitely.
Not all bioluminescence is used to avoid or attract violence—it can also be used in service of love. Or, more accurately, mating; fluttering about fields and fens, North American fireflies use carefully-timed signals of flashing light to communicate with one another. Males fly overhead flashing lights every 5.5 seconds. After an interval of approximately two seconds, a watching female below may flash a light in response, signaling that she is available to mate. Rather than relying on timing, some firefly species use variations in color for courtship. Other insects use these strategies as well, including the cave-dwelling glow-worm (which is actually a species of bioluminescent beetle).
Is anything more enchanting than forest-dwelling fungi that glow in the dark? Of the 120,000 known species of fungi that exist, only around 100 are capable of this phenomenon. In this kingdom’s case, the why is more shrouded in mystery. It has been theorized that in some species, bioluminescence draws in insects to spread their spores; in others, like the ghost fungus, it may simply be an incidental chemical byproduct. Fitting for the otherworldliness of these beings, bioluminescence is most common among rot fungi that break down animal and plant matter, such as foxfire (also called fairy fire), often found in decaying wood and first described by Aristotle as a “cold fire” in the forest thousands of years ago.
Perhaps the most magical aspect of bioluminescence is that it has emerged in so many different forms. As The Light Pirate author Lily Brooks-Dalton told me in an interview for Atmos this week: “the beautiful thing about bioluminescence is that it is a chemical reaction that has evolved again and again, in totally disparate environments. That has occurred in the jungle, in the sea, in the fields of fireflies. It has popped up in all these places in this world, independent of each other. And there is something truly magic about that, and full of promise to me. Nature is arresting in the power of what it can do.”
It is natural for hope to flicker from time to time. When it does, I remind myself that we live on a planet where light blinks not only in the heavens above, but the one below our feet as well. I remember that evolution happens across oceans and eons, constellations of change. It winks at us in the darkest depths of the sea and nightfallen forests, alight with possibility. What is hope if not a pledge to that seemingly feeble word, a fealty to the unfathomable? We tend to associate darkness with despair, yet it is also a symbol of the unknown. And so I choose to find hope not only in the light, but in the promise of the shadows that surround it—in knowing that wherever one is, the other is sure to be found.