The scientific term for a microscopic organism that photosynthesizes is phytoplankton. These tiny organisms, primarily found in aquatic environments, play a critical role in the Earth’s ecosystem by being primary producers. Through photosynthesis, they convert sunlight, carbon dioxide, and nutrients into energy, sustaining marine food webs and contributing significantly to oxygen production. Phytoplankton diversity is essential for ecological balance in oceans, and their populations can vary due to environmental factors such as nutrient availability and temperature, impacting entire marine ecosystems.