The marine food chain is a series of organisms that depend on each other for food in ocean ecosystems. It starts with phytoplankton, tiny plants that use sunlight to produce energy through photosynthesis. These primary producers are eaten by small fish and zooplankton, which are then consumed by larger fish and marine animals. At the top of the marine food chain are apex predators like sharks and orcas, which have few natural enemies. Each level of the food chain plays a crucial role in maintaining the balance of marine life, ensuring that energy flows from the sun to the largest creatures in the ocean.