Global Change Institute

Corals and many other reef invertebrates such as giants clams, gorgonians, sponges and hydroids live in a symbiotic relationship with dinoflagellates, also referred to as "zooxanthellae", that provide them with an important part of their daily energy requirement through photosynthesis. The genotype of dinoflagellates (Symbiodinium) plays an important role in determining the environmental tolerance range of their host. The genus Symbiodinium consists of nine broad genetic groups or clades that are genetically highly distinct (clades A-I).