nekton

Nekton refers to aquatic organisms that can swim actively and move independently of water currents. This functional group includes animals capable of sustained propulsion through the water, contrasting with plankton, which drift with currents, and benthos, which live on or near the seabed. Nekton primarily inhabit the pelagic zone, the open-ocean water column away from the bottom.

Examples of nekton include fish, cephalopods such as squids and octopuses, marine mammals like whales and dolphins, and marine reptiles such as sea turtles and some sea snakes. These organisms rely on muscular propulsion and specialized anatomy—such as fins, flippers, tails, and streamlined bodies—to maneuver, hunt, and escape predators. Buoyancy control and, in some groups, jet propulsion or powerful tail strokes, support their active lifestyle.

Nekton occupy a range of habitats from coastal shelves to the deep open ocean. Many perform diel vertical migrations, moving closer to the surface at night to feed and descending during the day to avoid predators. They play crucial roles in marine ecosystems as predators, prey, and as connections in nutrient cycles, often linking ocean surface processes with deeper waters.

In research and fisheries, nekton are studied as a functional component of the marine system. The term emphasizes swimming capability rather than taxonomic status, encompassing major groups that shape ocean dynamics and biodiversity.