Chemosynthesis refers to the process by which certain organisms, such as some bacteria and archaea, create organic compounds using energy derived from chemical reactions, rather than from sunlight as in photosynthesis.
When referring to "living in the dark," it typically pertains to environments where sunlight does not penetrate, such as deep-sea ecosystems or underground habitats. In these environments, organisms rely on chemosynthesis to produce food and energy.
These chemosynthetic organisms often use chemical energy derived from substances such as hydrogen sulfide, methane, or ammonia, which are found in their surroundings. For example, in deep-sea hydrothermal vent ecosystems, certain bacteria use the hydrogen sulfide emitted from the vents to produce energy, which in turn supports a whole community of life, including giant tube worms, clams, and other organisms that rely on these bacteria for nourishment.
Thus, chemosynthetic organisms are pivotal in supporting ecosystems that thrive in complete darkness, where traditional photosynthesis cannot occur.