Karenia brevis (formerly known as Gymnoinium breve and Ptychodiscus brevis) is a marine dinoflagellate common in Gulf of Mexico waters, and is the organism responsible for Florida red tide. K. brevis is a microscopic, single-celled, photosynthetic organism that can "bloom" (see algal bloom) frequently along Florida coastal waters. Each cell has two flagella that allow it to move through the water in a spinning motion. K. brevis naturally produces a suite of potent neurotoxins collectively called brevetoxins, which are responsible for large die-offs of marine organisms and seabirds.