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Nektonic” refers to a category of aquatic organisms that are capable of independent and active swimming throughout their lives. These organisms are not passively carried by currents but have the ability to move and navigate within aquatic environments, such as oceans, lakes, and rivers. Nektonic organisms play vital roles in marine and freshwater ecosystems and can include a wide variety of species, from fish to marine mammals and even some cephalopods.


Nektonic organisms are characterized by their ability to control their movements and actively swim in aquatic environments. They are not restricted by currents or tides and can move in various directions and depths. Nektonic organisms are often predators, feeding on other organisms within their ecosystems.

Key characteristics of nektonic organisms include:

  1. Active Swimming: Nektonic organisms have developed adaptations, such as fins, flippers, and streamlined bodies, that enable them to propel themselves through the water efficiently.
  2. Controlled Movement: Unlike planktonic organisms, which are at the mercy of water currents, nektonic organisms have the ability to navigate and change their direction of movement.
  3. Size Range: Nektonic organisms vary greatly in size, from small fish to large marine mammals. Examples include herring, sharks, dolphins, and tuna.
  4. Ecological Roles: Nektonic organisms occupy various trophic levels within aquatic food webs. They can be primary consumers (herbivores), secondary consumers (carnivores), or even top predators.
  5. Habitats: Nektonic organisms inhabit a wide range of aquatic habitats, including oceans, lakes, rivers, and estuaries. Some species may migrate between different habitats seasonally.
  6. Respiration: Nektonic organisms need efficient respiratory systems to extract oxygen from water. Fish, for example, use gills to extract dissolved oxygen from water as it passes over their gill membranes.

Nektonic organisms are of great ecological significance. They contribute to energy transfer within aquatic food webs, help regulate prey populations, and influence the distribution and abundance of other organisms. They are also important economically, as many nektonic species are harvested for food, sport, and commercial purposes.

The study of nektonic organisms falls within the realm of marine biology and fisheries science. Scientists study their behavior, migration patterns, reproductive strategies, and interactions with other species to gain insights into the functioning of aquatic ecosystems and the impact of human activities on these systems.