Fireflies Blink and Zooplankton Rise -Md. Kausar Uddin Ahmed

I have always been fascinated by light. The soft glow that does not demand attention yet changes everything it touches. I am talking about fireflies and zooplankton. One dances in the evening air. The other rises silently through the ocean at night. Both live by light. Both depend on darkness. And both are now struggling because we no longer respect the night.

There was a time when evening arrived gently with the slow withdrawal of sunlight. The dusk felt patient, and in that darkness, small lights appeared. There were fireflies blinking across fields, gardens, and roadside bushes. It felt ordinary then. Only later did I understand that it was extraordinary chemistry performed freely in the open air.

Fireflies produce light through a chemical reaction between luciferin and the enzyme luciferase. Nearly all the energy from this reaction is released as visible light rather than heat, making it one of the most efficient light-producing systems known in nature. But their glow is not decoration. It is language.

Each flash is a message. Each pattern is a signature. Males send signals into the darkness. Females reply from the grass. Some predators even recognise these signals. Entire reproductive futures are negotiated through pulses of green-yellow light. A civilisation of communication built on a natural night.

When I learned this, I realised that darkness is a communication space. Their existence assumes the presence of real night. Remove the night, and their language collapses.

This is exactly what we are doing.

Artificial lighting has become so normal that we no longer recognise it as an ecological phenomenon. Streets, billboards, windows, towers, vehicles, and phones all feature artificial lighting. We have flooded our environment with light that does not follow the planet’s natural rhythm. In many places, the night sky is never truly dark. Stars fade, and along with them, the ancient signals of fireflies.

We all read this Bengali aphorism in childhood:

Light says, “Darkness, you are very black.”

Darkness says, “Brother, that is why you are light.”

This simple couplet holds a quiet ecological truth. Light cannot be defined or appreciated without its counterpart. Darkness is not merely the absence of light. It is the condition that gives light its meaning.

Light pollution does not crash or explode. It quietly interferes. A male firefly flashes. A female does not see. Reproduction fails. Populations decline. No headlines announce it. No emergency sirens warn us. Just fewer flickers each year. Then none.

Habitat loss adds another burden. Wetlands drained. Riverbanks reshaped. Pesticides seep into soil where larvae grow. Each intervention seems small alone. Together they form a slow erasure.

I often wonder whether a generation from now will know fireflies as living creatures or only as textbook illustrations. I often ponder whether the evening will still evoke a sense of life or turn into a never-ending shopping mall. When we remove darkness, we also remove more than just light. We remove a habitat. A language. A rhythm.
If fireflies taught me that night is a communication space, zooplankton taught me that night is a migratory highway.

Most people never think of zooplankton. These tiny drifting organisms are often invisible to the naked eye. Yet they perform the largest daily migration on Earth. Day by day, they sink into deeper water. By night they rise toward the surface. This vertical movement is guided primarily by changes in natural light.

The fading sun provides timing cues. This migration protects them from visual predators and allows them to feed on surface phytoplankton. But its importance goes far beyond their survival.

By transporting carbon-rich material from surface waters into deeper layers, zooplankton contribute to long-term carbon sequestration in the ocean. They form the foundation of marine food webs. Fish, whales, seabirds, and entire fisheries depend on this nightly ascent. Human economies depend on it too.

Again, light is the conductor. Introduce strong artificial coastal lighting, and confusion begins. The sea surface no longer becomes properly dark. Zooplankton may delay or reduce their ascent. Feeding patterns shift. Food chains adjust. Carbon transport may also undergo changes over time.

When I realised that city lights on coastlines can influence oceanic migration, I felt a quiet discomfort. Our lights do not remain on land. They spill into the sea and sky. They enter the physiology of creatures we will never see.

Conservation often focuses on forests, rivers, and endangered animals. We seldom discuss the need to protect darkness. Yet darkness is as ecological as water or soil. It is a condition required for countless life processes.

Protecting darkness does not mean rejecting technology. It means intelligent restraint. It involves shielding lights and reducing their brightness. Lights are turned off when unnecessary. Dark-sky reserves. Seasonal lighting rules near sensitive habitats. Coastal lighting management. These are practical measures already used in parts of the world.

Pesticide regulation matters too. Soil-dwelling larvae cannot survive chemical saturation. Habitat restoration matters. Wetlands, leaf litter, and riverbanks are nurseries for organisms that glow like living stars.

Tourism must learn humility. People travel to see fireflies, yet boats and torches used to observe them often damage their environment. Awe without responsibility becomes exploitation.

All these efforts point to a broader idea. Non-human organisms possess an inherent right to darkness. A right to natural rhythms. Non-human organisms have a right to maintain their ancient communication systems without being overwhelmed by unnecessary human brightness.

We speak proudly of progress. Yet progress that forgets its biological foundations becomes fragile. The rhythms that shaped life are older than any civilisation. We cannot overwrite them without consequences.

Protecting darkness is not nostalgia. It is ecological literacy. It recognises that human convenience is not the only measure of environmental design. Other species have needs too. When we flood the world with constant artificial brightness, we silence parts of this symphony. Not suddenly or dramatically. Instead, it happens steadily, quietly, and occasionally irreversibly.

The stars still shine. The moon still rises. The question is whether we will continue to align with it or insist on composing our own discordant tempo. To restore darkness is to return language to fireflies and direction to zooplankton. Perhaps, by restoring darkness, we are also restoring something within ourselves. Ultimately, we are inextricably linked to this narrative. If we remember this, saving the night becomes more than conservation. It becomes an act of belonging.