This report describes a series of experiments designed to determine if terpene biosynthesis is inducible in two families of marine terpenes, pseudopterosins from the gorgonian coral Pseudopterogorgia elisabethae and fuscol from Eunicea fusca. Since we have recently shown that terpene biosynthesis is not under the control of the invertebrate host, but rather occurs within a dinoflagellate preparation, we examined the terpene content of the dinoflagellate symbiont following a decrease in UV/vis radiation as well as in response to the addition of methyl jasmonate, salicylic acid and gibberellic acid. We demonstrated that pseudopterosin and fuscol biosynthesis can be markedly increased through the addition of the plant bioactive substances. We also demonstrated that, while the terpene content of P. elisabethae increases in response to decreased UV/vis light, this is due primarily to an increase in the concentration of the dinoflagellate rather than simply an induction of terpene biosynthesis.