We know very little about life in the deep ocean, but we do know that in the pitch black at the bottom, creatures can thrive. Microbes with the capacity to metabolise the hydrogen sulphide and other compounds that spout from boiling hydrothermal vents form the base of a food chain.
In turn this attracts deep-ocean specialised crustaceans, gastropods, worms, eels and more in a place that was, up until the Sixties, thought to be uninhabitable. Incredibly, giant single-cell, amoebic organisms known as xenophyophores are found in their greatest numbers in the oceanic trenches.
Bottom-feeders in the dark regions of the ocean are usually scavengers, feeding off whatever falls from the waters above. But much of the taxa found in the extremes of the deep derive their energy from sources other than the Sun, in an environment that is analogous to those found on other planets in the Solar System. Indeed, extensive studies into these communities has breathed new hope into discovering life elsewhere in the cosmos.