The Wonders of Bioluminescence

by Kirstyn Limsico

​People in Southern California have likely heard about bioluminescence, which is best seen during the summer months of the year along the coast. Bioluminescence is defined as the emission of light by a living organism. Thousands of species produce this light, from algae, worms, and sea stars, to fireflies, beetles, and even spiders. Although this phenomenon is most commonly seen in marine species, it is extremely diverse in its occurrence.

So how does this work? Bioluminescence is produced by the energy release in chemical reactions involving the substrate luciferin, and the enzyme luciferase. (National Oceanic and Atmospheric Administration, 2024). When the luciferin molecule reacts with oxygen, this creates a byproduct called oxyluciferin, which produces a glowing sensation. The enzyme luciferase has the ability to lower the activation energy and speed up this chemical reaction (Woods Hole Oceanographic Institution). Bioluminescence is typically seen as blue-green in the ocean because these wavelengths travel best through the water, but it can also be seen in various colors including red, yellow, and violet. Marine species control when they light up based on the movement of oxygen into the cells containing luciferin and luciferase. They regulate their chemistry and brain processes depending on their specific needs including communication, detecting prey, or attracting mates.

Bioluminescence benefits many living organisms and has evolved more than 27 times among fish lineages. Different creatures use this light to their advantage in a multitude of ways. Some use this light as a defense adaptation to startle or misdirect a predator. For example, the vampire squid ejects a sticky bioluminescent mucus which can confuse predators and allow the squid time to escape (National Geographic, 2019). Other organisms use bioluminescence as an offensive adaptation to search for prey. Anglerfish have a fleshy, long filament on the top of their heads that can light up. Its prey then becomes curious about the spot of light and is lured toward its predator. Many of these creatures use bioluminescence as a way to attract and reproduce. For instance, male fireflies can communicate their interest in mating by producing bioluminescent flash patterns.

In Southern California, people can view this glowing sensation through the bioluminescent waves in the spring to early fall seasons. This specific glow is produced by a species of phytoplankton called dinoflagellates, which are microscopic organisms that live in watery environments (NASA Earth Observatory). Phytoplankton growth depends on the amount of carbon dioxide, sunlight, and nutrients as they are primary producers and the foundation of the aquatic food web (PLOS One, 2016). On the shore, bioluminescent phytoplankton will glow when disturbed by a wave breaking or a splash of water at night.

Bioluminescence can be seen around the world, including certain places in Australia, Vietnam, Puerto Rico, and Jamaica. On the coast of San Diego, bioluminescence happens during the Red Tide, a period when dinoflagellates are in bloom, and use this light as a defense mechanism. This event is known as the Red Tide because these microorganisms come to the surface of the water for sunlight, and cause the waves to look reddish brown in coloration during the daytime (California Sea Grant, 2018).

Bioluminescence is used by organisms to communicate and adapt to the changing environment in which they live. This glowing sensation continues to be studied and will remain one of the great wonders of nature.

Sources:
Davis, M. P., Sparks, J. S., & Smith, W. L. (2016). Repeated and widespread evolution of bioluminescence in marine fishes. PloS One,11(6), e0155154. https://doi.org/10.1371/journal.pone.0155154
​Langley, L. (2019, May 2). How bioluminescence works in nature. Animals. https://www.nationalgeographic.com/animals/article/bioluminescence-animals-ocean-glowing
NASA Earth Observatory. (n.d.). What are Phytoplankton https://earthobservatory.nasa.gov/features/Phytoplankton
​Red Tides in California. (n.d.). California Sea Grant. https://caseagrant.ucsd.edu/our-work/resources/red-tides-california#:~:text=The%20majority%20of%20red%20tides,summer%20(August%2C%20September).