Final answer:
The ocean floor hosts extremophiles like bacteria living around hydrothermal vents that perform chemosynthesis, which provides nutrients for deep-sea ecosystems.
Step-by-step explanation:
The types of organisms that live on or in the ocean floor encompass a range of extremophiles, particularly around hydrothermal vents, including unique bacteria and archaea that obtain energy through chemosynthesis. These extremophiles form the base of a food web that supports a variety of deep-sea organisms, such as tubeworms, clams, and certain species of fish and crustaceans. Nutrients for most of the deep ocean are not supplied by sunlight and plankton, as it is in the shallower parts of the ocean, but rather by the process of chemosynthesis at hydrothermal vents and the detritus from the upper layers of the ocean that falls to the depths.