The life forms living hear hydrothermal vents, unlike any other life forms on Earth, do not rely on photosynthesis and the sun for their energy but on chemicals coming from beneath the surface of the earth.
The floor of the deep ocean is almost devoid of life, because little food can be found there. But around hydrothermal vents, life is abundant because food is abundant. Hot, mineral-rich fluids supply nutrient chemicals. Microbes, some of which eat these chemicals, form the base of the food chain for a diverse community of organisms. These vents are the only places on Earth where the ultimate source of energy for life is not sunlight but the inorganic Earth itself.
Did life begin at deep-sea vents?
This is one theory, and it is supported by several lines of evidence. First, some of the thermophilic, or heat-loving, vent microbes are the most primitive organisms known on Earth. They include Archaea, which belong to a third domain of life and are as different from bacteria as bacteria are from all other organisms. Second, complex organic molecules, the building blocks of life, are found at the vents. Third, the deep ocean was one of the few places on the early Earth that was protected from frequent meteorite bombardments and lethal radiation.