Some zooplankton spend their whole lives as plankton, but others are only plankton for certain stages of their lives. Many benthic (sea floor) creatures have larvae that live in the water column as zooplankton for a while to allow them to disperse to new areas before settling to the sea floor since many of the adult animals are stationary or very slow moving such as barnacles and sea urchins. The larvae often look completely different than the adults. These are barnacle larvae called nauplii.