Scientists long thought life in the deepest ocean trenches depended mostly on scraps of sunlight-fed life drifting down from above — but at 9,500 metres beneath the Pacific, researchers found whole communities of tubeworms and clams powered instead by methane and hydrogen sulfide seeping from cracks in the seafloor.

Scientists long thought life in the deepest ocean trenches depended mostly on scraps of sunlight-fed life drifting down from above — but at 9,500 metres beneath the Pacific, researchers found whole communities of tubeworms and clams powered instead by methane and hydrogen sulfide seeping from cracks in the seafloor.

For much of modern ocean science, the deepest trenches were treated as places where life survived on leftovers. Sunlight does not reach the hadal zone, the region of ocean below about 6,000 metres. No plants grow there. Photosynthesis cannot run. The familiar explanation was that animals living on or near the deepest seafloor depended largely on what NOAA calls marine snow: dead organisms, faecal material, and other organic particles falling slo…