Name the deep-sea ecosystem that does not rely on sunlight.

The deep-sea ecosystem that does not rely on sunlight is indeed the hydrothermal vent ecosystem. This ecosystem is found along mid-ocean ridges, where tectonic plates are pulling apart. In these unique locations, seawater seeps into the crust, gets heated by magma, and then erupts back into the ocean through hydrothermal vents.

The organisms living in hydrothermal vent ecosystems, such as tube worms, clams, and certain species of bacteria, are able to thrive in complete darkness thanks to chemosynthesis. Chemosynthetic bacteria convert the chemicals found in the vent fluid, such as hydrogen sulfide, into energy, forming the base of the food web in this ecosystem. This process is in stark contrast to the majority of marine life that relies on the sun for energy through photosynthesis.

In contrast, coral reef ecosystems are vibrant environments that heavily depend on sunlight for the growth of the symbiotic algae living in coral tissues. Estuarine ecosystems, which are located where freshwater meets saltwater, and intertidal ecosystems, which are found along coastlines, also rely on sunlight as they are subject to tidal influences and generally support a variety of photosynthetic organisms. Thus, hydrothermal vent ecosystems are unique for their ability to sustain