The organisms that form the base of most open-ocean food webs are?

The organisms that form the base of most open-ocean food webs are phytoplankton, which are microscopic plant-like organisms that use sunlight to produce their own food through the process of photosynthesis. Phytoplankton come in various forms, including diatoms, coccolithophores, dinoflagellates, and cyanobacteria. These tiny organisms are abundant in the sunlit surface waters of the ocean and serve as a vital source of food for zooplankton, small animals that drift or swim weakly in the water column. Zooplankton, in turn, are consumed by larger organisms, such as fish and whales, forming the intricate food web that sustains the diverse marine life in the open ocean.