dinoflageller

Dinoflagellates are a diverse group of mostly single-celled protists that form an essential component of aquatic ecosystems. They belong to the phylum Dinophyta (also called Dinoflagellata) within the supergroup Alveolata. Most species are aquatic plankton; many possess a theca, a cellulose plate armor that gives a distinctive shape. They have two flagella arranged in grooves: a transverse flagellum in the cingulum that encircles the cell and a second flagellum in a sulcus that trails behind, enabling a spinning or serpentine motion.

Dinoflagellates display a wide range of nutritional strategies. Many are photosynthetic, using pigments such as chlorophyll a and c and the carotenoid peridinin; others are mixotrophic, combining photosynthesis with ingestion of prey, and some are strictly heterotrophic. They are widely distributed in oceans and freshwater and often dominate phytoplankton in certain regions and seasons. Some species are bioluminescent, emitting light when disturbed.

Ecology and life history: dinoflagellates can form large blooms, some of which produce toxins that affect marine life and human health (for example brevetoxins and saxitoxins). Red tides caused by these blooms can discolor water and lead to shellfish poisoning. Life cycles vary from rapid asexual reproduction to the formation of resting cysts that persist in sediments and reseed blooms. As primary producers in many ecosystems, dinoflagellates influence marine food webs and carbon cycling, with their populations modulated by light, nutrients, temperature, and water chemistry.