Tubeworms have an interesting lifestyle. The have no mouth or digestive system like other worms. They are essentially a sack (trophosome) of bacteria or endosymbionts, and a plume (the red structure) that captures hydrogen sulfide, carbon dioxide and oxygen. These gases are transported from the plume to the trophosome, where they are food (energy and carbon sources) for the bacteria. The chemolithoautotrophic bacteria oxidize the sulfide, and use the energy in that redox reaction to fix carbon dioxide into organic carbon. The tubeworm is then sustained by the endosymbionts organic carbon. Sulfide levels are quite low at Mariner relative to other deep-sea vent sites where tubeworms thrive, so it is indeed curious that we found them here.
|Notice the crabs eating the tubes|