How do entire ecosystems thrive around volcanic vents on the ocean floor?

The answer

Hydrothermal vent ecosystems, first discovered in 1977 near the Galapagos Rift at 2,500 meters depth, operate on chemosynthesis rather than photosynthesis. Giant tube worms (Riftia pachyptila) up to 2.4 meters long lack mouths and digestive systems entirely, relying on chemosynthetic bacteria inside their trophosome organ that convert hydrogen sulfide into organic molecules. Vent fluids reach 400°C but don't boil due to immense pressure. Over 700 species have been cataloged at vents, with 95% found nowhere else. Pompeii worms survive on chimney walls at 80°C - the highest temperature tolerated by any known animal. These ecosystems have influenced theories about the origin of life itself.