Instead of taking up food with the mouth, little gutless tubeworms house sulfur bacteria in their body. They pick them up from the environment as soon as they settle on rocks after dispersing as larvae in the water. Tubeworms provide shelter for the bacteria. They feed their symbionts with inorganic gases so that they can grow like plants on land. In return the symbionts provide food to the tubeworm host so that they grow and reproduce in the absence of a digestive system. Both partners benefit from each other in this mutualistic relationship. However, life may be short because vent fluid eventually ceases. What happens to the bacteria after a tubeworm dies? They are trapped in a dead body that decays without gases to sustain autotrophic growth. Not to die with their host, the symbionts must leave the dead tubeworm.

How they manage we study in high-pressure aquaria where we incubate live symbionts in dead host tissue. We offer them food like sugar to investigate whether they can switch to a heterotroph life style during their escape.  Such experiments were done during the cruise to the East Pacific Rise with the research vessel Atlantis and collecting samples with the submersible Alvin in October 2016.

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