Common name: Whirling whipScientific name: DinoflagellatesThese unicellular protists can occur in all kinds of environments. Most of them are marine planktons, but common in fresh water habitat as well . These form a large group of flagellate protists, which show great diversity in form. They cut through by lashing the water with two thread-like whips, known as flagella, which forces the cell to propel in a distinctive whirling motion. They are the most common source of bio-luminescence, emitting blue-green light when stimulated mechanically. 1. They play an important role in the aquatic food chain. 2. They are also friends with many marine animals , living as endo-symbionts. 3. Often an algal bloom of dinoflagellates results in red tide, emanating from the sea surface, causing harmful effects on many organisms.