Deep-sea hydrothermal vents are home to a thriving diversity of animals, including giant tube worms that can grow longer than 2 meters in length. No sunlight reaches the deep ocean and there is very little organic carbon available, so how is the energy to support this ecosystem generated? The answer is chemosynthesis—a process that, in contrast to photosynthesis, can produce energy from inorganic compounds in the absence of light. The giant tubeworms lack both a gut and a mouth. Instead, they have an organ called a trophosome that is packed full of bacteria. These endosymbiotic bacteria (pictured here) produce energy from hydrogen sulfide and oxygen taken in by the worm from the vent fluids and seawater. The energy generated can then be used to make food for both the bacteria and tube worms. Understanding the ecology of hydrothermal vents provides important clues into the role of animal-microbe symbioses in the colonization and development of ecosystems in extreme environments, and the origin of life on Earth.
For more on giant tube worms watch “How Giant Tube Worms Survive at Hydrothermal Vents”
Trophosome tissue was dissected, processed, and viewed using scanning electron microscopy (SEM) to reveal the densely packed bacteria inside. The grayscale image was colorized using a computer.
Colleen M. Cavanaugh, Ph.D., Dept. of Organismic and Evolutionary Biology, Microbial Sciences Initiative, Harvard University,