Abstract
Freshly isolated zooxanthellae from a wide range of marine coelenterates liberated soluble organic $^{14}$C to the medium when incubated in the light in NaH$^{14}$CO$_{3}$ for 30 to 120 min. Most algae released [$^{14}$C]glycerol as the major extracellular product. Other $^{14}$C-labelled compounds liberated were alanine, glucose, fumaric acid, succinic acid, glycolic acid and two other unidentified organic acids. Evidence provided demonstrates that extracellular products are not produced as a result of lysis of the algae.