Aquatic organisms

Nekton or necton (from the ) is any aquatic organism that can actively and persistently propel itself through a water column (i.e. swim) without touching the bottom. Nekton generally have powerful tails and appendages (e.g. fins, pleopods, flippers or jets) that make them strong enough swimmers to counter ocean currents, and have mechanisms for sufficient lift and/or buoyancy to prevent sinking. Examples of extant nekton include most fish (especially pelagic fish like tuna and sharks), marine mammals (cetaceans, sirenia and pinnipeds) and reptiles (specifically sea turtles), penguins, coleoid