What types of microorganisms are down there?
Some of the chemosynthetic bacteria grow in a “symbiotic” association with many of the larger vent animals (e.g. tube worms, clams, and mussels). Within certain organs inside these creatures there are sacs of microorganisms that grow in symbiosis or in a mutual agreement with these animals. Microbes live in there, metabolizing the hydrogen sulfide in the seawater and then excrete organic compounds that the host animals use as food. The microbes get a place to live in return.
