Autotroph

Definition

An organism that synthesizes complex organic compounds from simple inorganic precursors (typically CO₂) using energy derived from non-living sources—either light (photoautotroph) or inorganic chemical reactions (chemoautotroph)—thereby serving as the primary source of fixed carbon and energy in food webs.

Etymology

From Greek autos (self) + trophos (feeder, nourisher).

Example

Aquatic insects and their larvae in sunlit ponds depend directly on algal and cyanobacterial autotrophs for nutrition; even predatory dragonfly nymphs ultimately trace their energy to these primary producers.

Synonyms

• primary producer

Related Terms

• heterotroph
• photoautotroph
• chemoautotroph
• producer
• Trophic level
• Photosynthesis
• chemosynthesis

Usage Notes

Contrasts with heterotroph, which requires pre-formed organic carbon. In entomology, autotrophs are rarely the organism under study but are critical context: herbivorous insects consume autotrophs directly, while parasitoids and predators depend on them indirectly. The term is absolute—an organism is either capable of autotrophy or not—though some mixotrophs combine autotrophic and heterotrophic nutrition. Avoid using "autotroph" loosely for any organism that appears self-sufficient; the metabolic capability must be demonstrated.