Everse translocation" of carbon compounds, the transfer of metabolites from host to symbiont, though it is known that isolated symbionts can take up a range of organic and inorganic molecules from the surrounding medium (39, 40, 82, 89, 151, 344). The uptake of 35S by symbiotic dinoflagellates from food ingested by Aiptasia sp. suggests that the reverse translocation of organic compounds does happ