Mussels Mussels are often the first shellfish to colonize hydrothermal vent sites. They clump together in cracks in the seafloor.
Symbiotic microbes live in the mussels' gills.
Like the microbes living inside tubeworms, these microbes use energy from chemicals in the vent fluids to produce sugars. The mussels use sugars produced by the symbiotic bacteria. Mussels can also filter food from the water, so if hydrothermal fluid stops flowing, mussels can survive for a short period of time. When mussels want to move, they shoot out a thread, much like a spider shoots out a web strand. The end of the thread sticks to hard a surface such as a rock or another mussel.