Algae are a diverse group of aquatic organisms that can be microscopic, or in the case of kelp, more than 50 feet long. Some algae are attached to rocks or other submerged structures. This is the slippery green stuff most people call “moss.” Other algae live free-floating in the water, and many species can even “swim.”
Algae, like plants, create their own food through photosynthesis, the process by which the sun’s energy is captured by the pigment chlorophyll and used to combine carbon dioxide and water to form simple sugars. The algae can later break the sugar molecules apart, releasing the stored chemical energy for growth and reproduction. Other organisms are also welcome to those sugars; all they have to do is eat the algae.