SYNOPSIS. Deep-sea sediments contain less particulate organic matter and lower biomass than shallow-water sediments, but the dissolved organic matter in pore water varies less with depth and may provide a significant food source for deep-sea benthos. Pogonophora are a phylum of predominantly deep-sea animals, all without an internal digestive system. Experiments show that one or two species ought to be able to live by uptake of dissolved organic matter from pore water in deep-sea deposits: some other species may need local enrichment of the habitat for such uptake to be useful. Less is known about nutrition of other deep-sea animals, but dissolved organic matter may supplement a conventional diet in several groups. Chemoautotrophy, using endosymbiotic bacteria, may be important for the large vestimentiferan Pogonophora in the high-sulfide conditions of the hydrothermal vents.