nektonic

Nekton is a term used in aquatic biology to describe animals that can swim actively and independently of currents. Nektonic organisms inhabit the water column and are capable of sustained locomotion, in contrast to plankton, which drift with currents, and benthos, which live on or near the bottom. The category spans marine and freshwater environments and includes many large and mobile species.

Nektonic animals utilize various propulsion methods, such as tail-driven undulation in fish, fin-assisted propulsion in manta rays, jet propulsion in cephalopods like squid and octopuses, and fluke-driven propulsion in cetaceans. They range from small schooling fish to large mammals, as well as sea turtles and many cephalopods. Nekton can be pelagic, living in the open water column, or demersal, inhabiting the water near the bottom; many undertake long-distance migrations and seasonal movements in search of food or favorable temperatures.

Ecologically, nekton occupy mid-to-high trophic levels and play key roles as predators and prey. They influence energy transfer from primary producers and zooplankton to larger predators, including humans. Distribution and abundance vary with depth, latitude, and oceanic conditions; nektonic communities are shaped by currents, temperature, salinity, and prey availability.

The concept is functional rather than taxonomic: nekton groups together diverse lineages united by swimming ability, rather than shared ancestry.