Ocean plants

Ocean plants are critical to marine life—they are an important food source, they provide oxygen to surrounding marine life, and they supply refuge and nursery grounds.

The high diversity of phytoplankton has puzzled biological oceanographers for a long time. There are over 200,000 species of of these tiny marine plants that use sunlight and nutrients to grow and reproduce at the ocean's surface. (Courtesy of Samantha DeCuollo,University of Rhode Island)

Key Takeaways

Ocean plants and plant-like organisms include microscopic phytoplankton, seagrasses, algae, and seaweeds that photosynthesize in the sunlit ocean.
They produce a large share of Earth’s oxygen, form the base of marine food webs, and draw carbon dioxide out of the atmosphere.
WHOI studies these primary producers to understand ocean productivity, food webs, and the sea’s role in the carbon cycle.

The ocean’s ‘plants’ — from microscopic phytoplankton to sprawling seagrass meadows, algae, and seaweed — quietly power life on Earth. Through photosynthesis they generate much of the oxygen we breathe, anchor marine food webs, and pull carbon from the atmosphere.

Ocean plants have adapted to living in the marine environment and can vary from single cell organisms to thick forests of kelp. These plants are an important food source for invertebrates and fish, they provide oxygen to surrounding marine life, and they support many marine creatures by providing refuge and nursery grounds.