Octocorals are major contributors of terpenoid chemical diversity in the ocean. Natural products from other sessile marine animals are primarily biosynthesized by symbiotic microbes rather than by the host. Here, we challenge this long-standing paradigm by describing a monophyletic lineage of animal-encoded terpene cyclases (TCs) ubiquitous in octocorals. We characterized 15 TC enzymes from nine genera, several of which produce precursors of iconic coral-specific terpenoids, such as pseudopterosin, lophotoxin and eleutherobin. X-ray crystallography revealed that coral TCs share conserved active site residues and structural features with bacterial TCs. The identification of coral TCs enabled the targeted identification of the enzyme that constructs the coral-exclusive capnellane scaffold. Several TC genes are colocalized with genes that encode enzymes known to modify terpenes. This work presents an example of biosynthetic capacity in the kingdom Animalia that rivals the chemical complexity generated by plants, unlocking the biotechnological potential of octocorals for biomedical applications.

八角珊瑚是海洋中萜类化学多样性的主要贡献者。来自其他固着海洋动物的天然产物主要由共生微生物而非宿主生物合成。在这里，我们通过描述在八珊瑚中普遍存在的动物编码的萜烯环化酶 (TC) 的单系谱系来挑战这一长期存在的范例。我们对来自 9 个属的 15 种 TC 酶进行了表征，其中一些产生标志性的珊瑚特异性萜类化合物的前体，例如拟珊瑚素、lophotoxin 和 eleutherobin。X 射线晶体学显示珊瑚 TC 与细菌 TC 共享保守的活性位点残基和结构特征。珊瑚 TC 的鉴定使得能够有针对性地鉴定构建珊瑚独有的 capnellane 支架的酶。几个 TC 基因与编码已知修饰萜烯的酶的基因共定位。这项工作展示了动物界生物合成能力的一个例子，它可以与植物产生的化学复杂性相媲美，从而释放了八角珊瑚在生物医学应用中的生物技术潜力。