Dinoflagellate

Dinoflagellate, single-celled organism that occurs in vast numbers in fresh and salt water. Each one is covered by a layer of cellulose that is a distinctive, and often elaborate, shape. Some contain chlorophyll while others do not, so they may be classed as animals or plants. Dinoflagellates are important as food for many animals, but some are poisonous. Swarms of one form, the “red tide” of tropical waters, kill fish and damage beaches. Certain dinoflagellates create the phosphorescence of the sea.