The plumes at the top of the worm's body are red because they are filled with blood, which contains hemoglobin that binds hydrogen sulfide and transports it to the bacteria housed inside the worm. In return, the bacteria oxidize the hydrogen sulfide and convert carbon dioxide into carbon compounds that nourish the worm. Biologists don't know how the infant worm acquires its own bacteria. Perhaps the egg comes with a starter set. Scientists also don't know how tube worms and other organisms locate new vents for colonization.
Most vent organisms have a free- swimming larval stage.
Studying the life cycle of vent organisms is difficult. Researchers have visited only a fraction of the ocean's hot spots. They have been able to observe vent life only by shining bright lights on creatures accustomed to inky darkness, and many specimens die quickly when removed from their unique environment. Underwater cameras are helping scientists make less intrusive observations, but diving expeditions are still the most useful way to gather information. The 1993 Alvin expedition to the East Pacific Rise was one in a series of dives to the area.