“The pelagic zone is the water column in the open ocean, rather than near the coast or the sea floor.
- The top layer (from the surface down to 200 metres), where sunlight penetrates, is known as the epipelagic zone.
- The middle layer (200 to 1,000 metres) is the mesopelagic.
Almost all ocean life is part of a huge food web linked to the epipelagic zone. This is where microscopic plant organisms, known as phytoplankton, convert sunlight into food. Phytoplankton are eaten by zooplankton, tiny animals which are in turn eaten by other creatures. At the top of this food web are oceanic fish.” -X
[Wikipedia: Pelagic zone]