Dinoflagellates are microorganisms that are regarded as algae. Their wide array of exotic shapes and, sometimes, armored appearance is distinct from other algae. The closest microorganism in appearance are the diatoms.

Dinoflagellates are single-celled organisms. There are nearly 2000 known living species. Some are bacterial in size, while the largest, Noctiluca, can be up to two millimeters in size. This is large enough to be seen by the unaided eye.

Ninety percent of all known dinoflagellates live in the ocean, although freshwater species also exist. In fact, dinoflagellates have even been isolated from snow. In these environments, the organisms can exist as free-living and independent forms, or can take up residence in another organism. A number of photosynthetic dinoflagellates inhabit sponges, corals, jellyfish, and flatworms. The association is symbiotic. The host provides a protective environment and the growth of the dinoflagellates impart nutritive carbohydrates to the host.

As their...