Description and significance Alexandrium fundyense is a photosynthetic marine dinoflagellate that lives in the upper water column (photic-zone) of coastal waters. It is a part of the Thecate group or “armored dinoflagellates”, meaning it has thecal plates (made of cellulose) surrounding the cell like armor. Like all dinoflagellates it has two flagella. One is the transverse flagellum, which wraps around the cell in a groove in the thecal plates and provides propulsion and a spinning motion. The other is a longitudinal flagellum that extends from the posterior end of the cell and acts as a steering system. Alexandrium fundyense is a very significant microbe on the eastern seaboard as it causes Red tide events when there are high nutrients and low grazing pressures in the coastal waters. These large coastal blooms of A. fundyense cause problems because they produce a neuromuscular toxin called a saxitoxin, which accumulates up the food chain and concentrates in the tissue of filter-feeding shellfish and fish. The consumption of these toxic shellfish by humans can lead to Paralytic Shellfish Poisoning (PSP), which can be fatal. It also leads to the shut down of coastal fishing in affected areas, which has large economic consequences for the fishing industry in those areas.