 However, due to its capacity for photosynthesis, the photic zone has the greatest biodiversity and biomass of all oceanic zones.Nearly all primary production in the ocean occurs here.Any life forms present in the aphotic zone must either be capable of movement upwards through the water column into the photic zone for feeding, or must rely on material sinking from above, or must find another source of energy and nutrition, such as occurs in chemosynthetic archaea found near hydrothermal vents and cold seeps.