Zooplankton - (n.)
A large variety of non-photosynthesizing organisms comprise the zooplankton, creatures that drift with the currents at all depths in the ocean. Zooplankton is concentrated especially in surface waters, where they feeds on phytoplankton. The smallest zooplankton consists of unicellular organisms such as foraminifers and radiolarians. The most commonly caught zooplankton, using nets with a mesh of 0.5 mm, consists of various kinds of copepods and other small crustaceans, like Antarctic krill. The largest zooplankton are among the jellyfish, which reach a diameter of several feet, and trail tentacles tens of feet long to ensnare smaller zooplankton and small fish.