Around hydrothermal vents thriving invertebrate communities exist, supported by the activity of microorganisms:

Tubeworms over 2m in length, & large numbers of clams & mussels. Vents do not discharge organic matter. Rather, reduced inorganic material. Animal communities are dependent on lithotrophic bacteria which grow at the expense of inorganic energy sources. We can find: Sulphur-oxidising lithotrophs, Nitrifying bacteria, Hydrogen-oxidising bacteria, Iron & manganese oxidising bacteria, Methylotrophic bacteria, microbes thus use inorganic material to gain energy