Organisms that make their own food classify as autotrophs, and include many types of plants, bacteria and fungi. These organisms live on land and in water, and use light, water, carbon dioxide or other chemicals to make their food.
Autotrophs also go by the name of "producers," and include most species of plants, which rely on sunlight for food production. These plants perform photosynthesis, which turns light from the sun into usable energy. Plants first absorb sunlight, then use the energy to create glucose, which forms when plants combine water and soil with sunlight. Glucose, a type of sugar, gives plants energy and helps them make cellulose, which enables building and reparation of cell walls. Plants with green leaves, including evergreens, conifers and small flowering herbs, perform photosynthesis to make food, as do phytoplankton, various species of algae and certain bacteria.
Some organisms make food through the process of chemosynthesis. This action does not require sunlight for food production. Instead, plants make food using several chemical reactions, such as the combination of oxygen and methane or hydrogen sulfide. Plants using chemosynthesis live in harsh environments like lava flows and volcanoes, where requisite chemicals abound.
A small and rare group of fungi, called radiotrophs, produce food using bands of high-frequency radioactive waves.