Below the surface waters, the deep layer where sunlight penetrates with insufficient intensity to support primary production is called the mesopelagic zone. This zone is a particularly important habitat for the fauna controlling the depth of C02 sequestration. Below the mesopelagic zone, about 1,000 m deep, is the largest layer of the deep-sea water column and by far the largest ecosystem on our planet, the bat-hypelagic region.