Tidepool Tim says, "Horned krill shrimp are zooplankton (zoo=animal, plankton=they can't swim against water current). They live at the mercy of ocean currents! The Eastern Maine Coastal Current delivers water, krill, and their food (phytoplankton) from the deep waters of the Gulf of Maine. The current also carries abundant dissolved nitrate and phosphates which feed the phytoplankton!

While they can't swim against currents, zooplankton do have control over their position in the water column. During the day they tend to stay in deep water where they're safer from large predators. At night they rise to the surface and graze on phytoplankton (plant particles suspended in the water)."