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How do hydrothermal-vent ecosystems obtain energy without sunlight?

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Zenaida macroura: mouring doves — ecology Mourning doves (*Zenaida macroura*) on their nest protected within the prickly branches of a cactus in the Sonoran Desert, Arizona, U.S.

Hydrothermal-vent ecosystems do not rely on sunlight; instead, they are supported by geothermal energy. These unique communities exist in the aphotic zone, where they depend on chemosynthesis rather than photosynthesis to produce organic carbon.123

The process functions as follows:
* Energy Source: Seawater circulates through cracks in the seafloor, where it is heated by magma and becomes enriched with hydrogen sulfide.24
* Primary Production: Sulfur-oxidizing bacteria (chemoautotrophs) thrive in this environment. They derive chemical energy by oxidizing the sulfide to fix carbon dioxide, forming the base of the food web.12
* Symbiosis: Many vent organisms, such as giant tube worms and bivalves, maintain symbiotic relationships with these bacteria, harboring them within their bodies to obtain direct nutrition.12

This reliance on chemical reactions allows these ecosystems to flourish in total independence from solar energy.34