The Digital Fish Library

These species primarily feed on plankton, which includes drifting organisms (animals, plants, archaea, or bacteria) that inhabit the pelagic zone. While some plankton are capable of independent movement and can swim hundreds of meters vertically in a single day, their horizontal position is primarily determined by the surrounding currents. Although most types are microscopic in size, plankton includes organisms covering a wide range of sizes, including large organisms such as jellyfish.