The base of the ocean's food chains is formed by plankton/algae.
The correct answer is plankton/algae. Plankton and algae are the primary producers in the ocean, meaning they convert sunlight into energy through photosynthesis. They are microscopic plants that float near the surface of the water, and serve as the foundation of the marine food chain. Plankton are consumed by small organisms like krill, which are then eaten by larger animals such as fish, and the food chain continues from there. Blue whales primarily eat krill, not plankton directly. Coral reefs, although rich in biodiversity, are not at the base of the ocean's food chains.
