Every year throughout the season mostly near warm coastal waters, the surface of the ocean changes to a bright red. This occurrence is due to what is called the red tide. The Old Testament might have the earliest known reference to a red tide when it describes the waters of the Nile turning to blood (1a). .
Red tides actually have nothing to due with tides. The red tide is a naturally occurring concentration of a rapidly producing "bloom" of microscopic algae known as Gymnodinium breve, a type of dinoflagellate (5). When this reproduction happens they are visible and become discolored patches of ocean water, usually red, but can also be orange, brown, or bright green. Gymnodinium breve is a type of harmful algal blooms (HABs) that is a single-celled organism, which photosynthesizes using chlorophyll and has two flagella that propels it through a water column (5). Given the right condition when temperature, salinity and nutrients reach a certain level, the increase of G. breve will occur (3). Some also think that high temperature with a lack of wind and rainfall might be the case of red tide blooms.
Dinoflagellates are the microscopic organism that is the cause of a red tide and belong to the division Pyrrhophyta. They contain chlorophyll A and C and can store glucose as starch (11). They are also a part of the "invisible forest" known as phytoplankton and sometimes called the "bad boys." Dinoflagellates are unicellular, flagellated and prefer warm water areas. They can also come in different forms. They are responsible for poisoning forms of sea and human life, but not all dino's are bad. Some dino's are photosynthetic, which means they can produce their own food using the energy from the sun. By doing that, they also are able to provide food for other organisms. Zooxanthellae are also good dino's and can be found in coral and anemones. They provide food for their "hosts" in the structure of glucose.