nature's symphony--1/15/25

15 Jan 2025

nature's symphony--1/15/25

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Today's selection--from The Miraculous from the Material by Alan Lightman. Fireflies and the magic of bioluminescence

“I grew up in Tennessee. On many a warm, humid summer night, I would go walking in a field near our house and become dazzled by the light show performed by fireflies. In the modern world, we're accustomed to incandescent light bulbs, LEDs, and other concentrated forms of light, all human made. But nature has been making fireflies for at least 100 million years. Finding yourself in the middle of a swarm of fireflies feels like attending a concert of light, where the cost of admission is simply the willingness to be present in the world and observe what's going on.

“How do they do it, those fireflies? It's a chemical reaction called bioluminescence, found in other organisms as well as in fireflies and discussed in the essay ‘Bioluminescence.’ When oxygen combines with two other chemicals, adenosine triphosphate and luciferin, the reaction produces light. The word ‘luciferin’ comes from the Latin words luc, meaning ‘light,’ and fer, meaning ‘bring’ or ‘carry.’ Essentially, the electrons in the atoms move to lower energy levels and release that energy differential in the form of light, just as when wood mixes with oxygen in a fire and produces light. But unlike fire, which produces heat as well as light, the chemical reactions in bioluminescence produce a cold fire.

“The chemical reaction in fireflies begins when oxygen is taken in and ends when the oxygen is cut off. That's how the flash of light scares and stops. Where does the oxygen come from? Fireflies don't have lungs, but they do have little cubes that transport oxygen from the outside and score it in small bodies inside each cell called mitochondria. (Mitochondria are the parts of biological cells where energy production takes place.) A firefly can release this stored energy quickly by producing an intermediate chemical, nitride oxide, which itself can be manufactured quickly and then dismantled quickly. The entire chemical reaction is completed in a fraction of a second, well-timed to give predators a chance to take note, but not long enough to exhaust the firefly.

Fireflies in Georgia, 8-second exposure

“Most of the unusual traits of animals, like the flashing of fireflies, were developed through the process of natural selection. In the long evolutionary history of the animal, such traits had survival benefit, or were by-products of traits that had survival benefit. Biologists believe that the flash of a firefly is a warning signal. Fireflies produce a chemical that is distasteful, but they have to communicate that distastefulness to potential predators. More directly, they have to identify themselves as fireflies. Hence the flashing. Say you're a predator, willing to make any small insect your dinner. If the menu is clearly labeled, you go for the tasty items and avoid the ones that sicken you.

“Fireflies also may use their flashing in the mating game. Different species have different flashing patterns, and a male firefly can use its distinctive flash to signal females of the same species.

“A peculiar and only partially understood aspect of the behavior of some species of fireflies is the synchronization of their flashing. When a bunch of such fireflies first find themselves together in a field on a summer night, each insect in the group flashes at different random times and at different races, like blinking Christmas tree lights. But after a minute or so, even without a boss firefly giving orders, all the fireflies of this species have adjusted their bodies so that they flash on and off in total synchrony. Such collective behavior cannot be understood by the analysis of a single firefly. It's an example of what scientists now call emergent phenomena-behaviors of complex systems chat are not evident in their individual parts. We understand all the biology and chemistry of individual fireflies, but the synchronization of flashings of a collection of the insects involves a complex interaction between many of them.

“A similar phenomenon is the massive dire mounds constructed by termites, called termite cathedrals. The mounds have elaborate passages and galleries to control air flow, temperature, and humidity. To build such a complex structure, there would seem to be some kind of master plan, overseen by a general contractor. But individual termites are blind, insensitive to the shape of the mound, much less its design. Somehow, these fantastic structures are created by the collective action of the full colony of termites.

“Personally, I find the flashing of fireflies just as beautiful when they do so at random as when they do so in unison, just as I find the shapes of clouds beautiful even when they are amorphous, or the random positions of stars in the sky. If we never went out of our human-made houses, we could never imagine fireflies, clouds, and stars. We would never experience the awe and wonder and exquisite unpredictability of the natural world.”