Although they are truely plankton, i.e. the freely drift through the ocean, they are capable of movement. Some slowly cruise through the field of view, while others make sharp jumps from one location to another. It is as if they are swimming in syrup. It is therefore more efficient to jump and then glide. Although they are typically very small, approximately 1 mm or less, some zooplankton are capable of impressive swimming feats.
Many forms vertically migrate to adjust their ambient light environment.
To observe zooplankton in the ocean, Drs. Woods Hole Oceanographic Insititution developed a towed video camera that allows us to photograph zooplankton as they live in the water column. Herbivores - Direct users of the primary producers, i.e. the phytoplankton. Carnivores - Predators feeding on other zooplankton. Omnivores - Zooplankton that use a combination of food sources.