Hydrothermal vent fluids from the Gorda Ridge spreading center in the Pacific Ocean create a biological hub of activity in the deep sea. There in the dark ocean, a unique food web thrives not on photosynthesis but on chemical energy from the venting fluids. Among the creatures having a field day is a diverse assortment of microbial eukaryotes, or protists, that graze on chemosynthetic bacteria and archaea. This protistan grazing, a key mechanism for carbon transport and recycling in microbial food webs, exerts a higher predation pressure at hydrothermal vent sites than in the surrounding deep-sea environment, a U.S. National Science Foundation-funded paper reports. “Our findings provide a first estimate of protistan grazing pressure in hydrothermal vent food webs, highlighting the important role diverse protistan communities play in deep-sea carbon cycling,” according to the paper in Proceedings of the National Academy of Sciences.