Pyrocystis fusiformis is a species of bioluminescent dinoflagellate known for its striking nighttime glow and unique physiology. Unlike many dinoflagellates, it is non-motile, meaning it does not use flagella for movement. Instead, it drifts with ocean currents, relying on its ability to regulate buoyancy to position itself in the water column. P. fusiformis is photosynthetic, absorbing sunlight during the day and converting it into energy. At night, it produces a mesmerizing blue-green bioluminescence when disturbed, a defense mechanism thought to startle predators or attract larger predators to feed on its attackers. This species has a distinctive elongated, spindle-shaped (fusiform) cell structure and is commonly found in tropical and subtropical waters. Due to its predictable bioluminescent cycle, Pyrocystis fusiformis is widely studied in marine research