Author: Harry Yoon
Editors: Flynn Ma and Kevy Chen
Artist: Alvina Zheng
Taking a stroll through Puerto Rico’s Mosquito Bay during the day is like any other beach trip. The warm rays of the descending sun, mixed with the cool breeze, make for a pleasant family vacation. However, despite the picturesque views of the setting sun, people say the real beauty transpires during the cold, dark night. The ocean waves suddenly transform into a blue sea of color with specks of blue light that shine like stars in space. The source of this light comes from dinoflagellates, a microorganism that emits light because of a special chemical reaction. Some unique organisms have the remarkable ability to produce and emit light from their bodies naturally. These creatures are bioluminescent, and their ability to produce light helps them in many ways.
Light becomes especially useful when there isn’t any of it. About one thousand meters below the sea, we enter the midnight zone. All light has been extinguished, and the creatures that live here swim in complete darkness. Organisms at this level have evolved to survive in the lightless world, and they have features that make them look almost alien-like. The dragonfish is an excellent example of such a creature. They are about 50 cm long and are known to have some of the blackest scales in nature to help them camouflage their surroundings. Like the anglerfish, they have a light that dangles from their chin and lures surrounding fish for them to prey on. At the tip of their lure is a photophore, which is the organ they use to produce light. The chemicals luciferin and luciferase combine to create oxyluciferin and light. The dragonfish and anglerfish use this method to lure their prey into the midnight zone. Similarly, the siphonophore lures its prey by exhibiting a fascinating light show. Their toxic tentacles wrap around their food, and they are digested quickly. For some creatures, light is a resource they use to be able to lure in their food.
If we journey out of the ocean and take a look at bioluminescent creatures on land, we instantly think of the firefly. Many features of a firefly’s bioluminescence make it unique. Scientists have linked the lights of these fireflies to the sexual signals they send each other. According to numerous studies, the lights of these fireflies are also used to ward off predators. They use the same chemicals, luciferin and luciferase, to emit their light, and they also use ATP, the cellular source of energy. The modern light bulb we use today releases both light and heat. This heat created is an unnecessary byproduct of the light bulb and, therefore, takes away from the system's efficiency. Fireflies are fascinating because they emit what is called a “cold light." They don’t lose much energy in the form of heat, which means they can preserve their energy longer. It also means their body doesn’t go to temperatures that they can’t handle. Another species that uses its bioluminescence to reproduce is the fungus. There are many species of fungi, but more than one hundred species were found to be bioluminescent. Drawing in these insects can help spread the spores of the fungi, growing their population and helping them survive.
As we can see, a creature’s natural ability to create light allows them to thrive in environments where others can’t. These bioluminescent creatures use their natural light to their ability to catch food, reproduce, and survive in the environments they are suited to live in. It is truly amazing what they can benefit from having such a phenomenon. Even in the ocean's darkest depths, life finds a way to illuminate its surroundings.
Citations:
TED-Ed. “The Brilliance of Bioluminescence - Leslie Kenna.” YouTube, 15 May 2013,
Visceral_Dev_Admin. “Dragonfish.” MBARI, 7 Nov. 2023,
“How and Why Do Fireflies Light Up?” Scientific American, 21 Feb. 2019,
Blakemore, Erin. “The Secret Behind Bioluminescent Mushrooms’ Magic Glow.” Smithsonian
Magazine, 27 Apr. 2017, www.smithsonianmag.com/smart-news/heres-secret-behind-
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