An autotroph is an organism that can produce its own food using light, water, carbon dioxide, or other chemicals. Because autotrophs produce their own food, they are sometimes called producers.

A heterotroph is an organism that eats other plants or animals for energy and nutrients. The term stems from the Greek words hetero for “other” and trophs for “nourishment.”

Saprotroph, also called saprophyte or saprobe, organism that feeds on nonliving organic matter known as detritus at a microscopic level.

Chemoheterotrophs: microbes that use organic chemical substances as sources of energy and organic compounds as the main source of carbon.

Source: Lucent