Final answer:
Photosynthetic organisms in the ocean are primarily found in the photic zone, the intertidal zone, the neritic zone, and the upper areas of the oceanic zone, where sunlight penetrates.
Step-by-step explanation:
The ocean zones are categorized into several areas that differ in water depth, distance from the shoreline, and light penetration. Photosynthetic organisms, which require sunlight to produce energy, are found primarily in areas of the ocean where there is sufficient sunlight. The photic zone is the top layer of the ocean reaching down to about 200 meters where sunlight can penetrate, making it the primary habitat for photosynthetic organisms.
The intertidal zone, which extends from high to low tide, and the neritic zone, which extends from the intertidal zone out to around 200 meters depth where the continental shelf ends, are also conducive to photosynthesis. Lastly, the upper parts of the oceanic zone, which is the open ocean beyond the neritic zone, also receive enough sunlight for photosynthesis to occur.