Chlorophyta, commonly known as green algae, is a diverse group of photosynthetic organisms found in various aquatic environments. They are primarily characterized by their green color, which comes from chlorophyll pigments. These algae play a crucial role in ecosystems, producing oxygen and serving as a food source for many aquatic organisms, including small fish and invertebrates. Green algae can be unicellular or multicellular, with some species forming large, visible colonies. They are closely related to land plants, sharing similar cellular structures and reproductive methods. Notable examples of Chlorophyta include Chlamydomonas, a single-celled green alga, and Ulva, commonly known as sea lettuce, which can be found along coastlines.