they are plants, and do not consume other organisms for energy. therefore, they must produce their own energy using the sun through photosynthesis.
they started to appear better
humans have to grow, hunt, and gather food, but many living things aren't so constrained. plants, algae and many species of bacteria can make their own sustenance through the process of photosynthesis. they harness sunlight to drive the chemical reactions in their bodies that produce sugars. humans have complicated digestive system and are not designed to use photosynthesis to process their food.
i hope this .