Pyrocystis fusiformis is a unicellular eukaryotic algae belonging to the dinoflagellate phylum. It’s a protist species characterized by having two flagella, one oriented longitudinally and the other transversely, which enable it to move through water. This species is a type of marine plankton capable of producing bioluminescence in response to water movement and high shear flow, typically triggered by the presence of ships, breaking waves, or the movement of predators. The cells of Pyrocystis fusiformis are elongated and fusiform in shape, with tapered ends, and they have an average length and width of 970 x 163 µm. Their equivalent spherical diameter is approximately 374 µm³. While P. fusiformis possesses a cell wall, it lacks the additional protective covering of rigid polysaccharide plates known as thecae.