Final answer:
The mussels that live at the NW Eifuku volcano are examples of chemoautotrophs, relying on chemoautotrophic bacteria and chemosynthesis for energy.
Step-by-step explanation:
The mussels that live at the NW Eifuku volcano are examples of chemoautotrophs. They rely on chemoautotrophic bacteria to obtain energy from inorganic compounds, such as hydrogen sulfide, through a process called chemosynthesis. This allows them to survive in the deep-sea hydrothermal vent ecosystem where sunlight is absent.