o·ka·da·ic acid 
(ō′kə-dāĭk)
(ō′kə-dāĭk)n.
A toxin, C44H68O13, produced by dinoflagellates and found in certain edible mollusks that consume them. It can cause diarrhea and other gastrointestinal symptoms in humans.
[(Halichondria) okadai, species name of the marine sponge from which it was first isolated (after Yaichiro K. Okada (1892-1976), Japanese zoologist) + -IC.]