Planktons, nektons and benthos are all marine organisms. The term “Plankton” represents all the organisms that drift with ocean currents: algae (phytoplankton), animals (zooplankton). They are numerous and very abundant in the marine fauna and they represent the majority of Earth’s biomass. They cannot swim against current, but they can move vertically within the water column. Ctenophora and diatoms are examples of planktons. Nekton refers to all the animals able to move independently of the ocean currents, by swimming or other means, to determine their position within the ocean but also of long migrations. It includes most adult fish and squid, marine mammals and reptiles. Squids or sharks are good examples of nektons. Finally, the last category is about benthos, which refers to the organisms living in or on the ocean bottom. This category include many different species who are moving across the bottom from the shore into deeper water. Those animals live in perpetual darkness and they must feed on each other. As their environment is cold, dark and still, life progresses very slowly, and those animals are usually widely distributed around the globe because those physical conditions vary very little on the deep ocean floor.Sea stars, green sea urchin or crabs are examples of benthos.