Previous conceptual models relating feeding and swarming all assume that euphausiids do not feed in swarms because food is limiting, particularly in dense swarms. Present field data and shipboard experiments were designed to test this limitation and other laboratory based predictions (Antezana et al., 1982). Results strongly suggest that feeding and swarming are co-occurring events north of Elephant Island. Three lines of evidence suggest intense, active feeding behavior of swarming krill: (1) the distribution of elevated stomach pigments is consistent with an abrupt "southeast-northwest" chlorophyll a gradient; (2) pigment-laden stomachs predominate in the area for hours, days, and even weeks; and (3) egestion rates in the absence of food suggest that animals should empty their stomachs within a few hours. Based on feeding and egestion behavior, stomach capacities, pigment content of feces, krill densities, and ambient chlorophyll a, the feeding potential of krill within the swarming area north of Elephant Island is evaluated. Because exceptionally full krill stomachs can not be explained by feeding on phytoplankton alone, we suggest that coprophagy may be occurring within the swarm. We propose that swarming may have adaptive feeding advantages not unlike those occurring in organisms of various phyla which exploit ephemeral, patchy food sources.