The deepest ocean trenches, up to 11 km beneath the surface, are the least explored marine ecosystems. They are also one of the most extreme, with no sunlight, low temperatures, nutrient scarcity and hydrostatic pressures of 600 to 1100 atmospheres, extending beyond the limits to vertebrate life. The major sources of nutrients and carbon are fallout from upper layers, drifts of fine sediment and landslides. Most organisms are scavengers and detrivores, like the supergiant amphipod, with abundance of predatory fish and crustaceans diminishing with depth.