The food web above represents feeding relationships in a biological community near a deep-sea hydrothermal vent. Hydrothermal ve
nts are geysers on the seafloor that gush super-heated, mineral-rich water. The seawater surrounding hydrothermal vents typically contains carbon dioxide (CO2), molecular hydrogen (H2), hydrogen sulfide (H2S), and methane (CH4). Sunlight, however, fails to reach the seafloor where deep-sea hydrothermal vents are located. As part of an investigation, researchers collected living specimens from an area near a deep-sea hydrothermal vent. Mussels in the collection were found to be dependent on molecular hydrogen in seawater. Also, the researchers discovered multiple species of bacteria living in the gills of the mussels. Mussels use gills for filter-feeding and gas exchange with the surrounding seawater. On the basis of their experimental results, the researchers hypothesized that some bacteria living in the gills of the mussels are capable of chemosynthesis. Which of the following best explains how biological communities near deep-sea hydrothermal vents can exist in a habitat lacking sunlight?
Answer: the bacteria in the habitat are the primary producer that relies on chemosynthesis (ability of organisms to produce their own food by anabolism of chemicals). Due to the the presence of h2S (hydrogen sulphide), the organisms are most probably Sulphur bacteria, liberating hydrogen as by products. This ability means that the bacteria can flourish without sunlight. The mussel are the secondary filter that feeds on the flourishing bacteria population. This build up to form a community whose primary energy source is from the minerals liberated by the vent and hence doesn't require sunlight.
