Earth Science – Earth’s Waters Practice Test

Sunlight in the ocean creates a light-rich layer where photosynthesis can happen. This photic zone, also called the epipelagic zone in the open ocean, extends to about 200 meters. In this layer, phytoplankton and other photosynthesizers use light to produce energy, forming the base of marine food webs. Below this, light becomes too weak for photosynthesis (aphotic zone), while the benthic zone refers to the ocean floor and the intertidal zone is the coastal strip between high and low tides. So the zone that is characterized by sunlight and supports photosynthesis is the photic/epipelagic zone.