Nekton is a community of swimming organisms that are large enough to win the main oceanic currents. The large size is the result of long-dimensional growth in their life histories, but this also means that nekton hosts individuals who have been plankton in their early life stages (as eggs or larvae). The evolution of powerful swimming abilities requested the abandonment of ciliary-based movement and the acquisition of alternative propulsion, as those based on a fast squirt of part of the body (jet propulsion), the paddling of adapted appendages (rowing propulsion), or, more commonly, on lateral movement of a tail appendage (tail propulsion). Nekton organisms are all heterotrophic and are generally carnivores. Due to their movement capacity, nekton species are distributed in larger geographic areas than plankton species and show more spatially extended behaviours as interregional migrations. Reproductive areas are those suitable for the growth of larvae and juveniles (which are plankton) and generally are situated in oligotrophic areas where a trophic supply for a rich community is absent, ensuring the absence of potential predators.