Foraminifera and radiolarians iii. Holoplankton live their entire life cycle in the plankton. Meroplankton live only part of their lives as plankton. The larvae of oysters, clams, barnacles, crabs, worms, and snails are a part of the zooplankton called meroplankton. The currents carry larvae to new locations and so disperse the population.
Planktonic larvae are an important food source for some organisms.
Nekton are organisms that can swim strongly enough to move independently of the ocean currents. Many are potential food sources, and their populations are harvested by humans. Many species are threatened or endangered. Marine Mammals iii. In the area of swimming they have undergone fin modification to balance the need for speed and manuverability.