Hydrothermal Vents

Recently, scientists have discovered and recorded the deepest erupting volcano yet found. The eruption occurred in the Pacific Ocean almost 4,000 feet below the surface near the islands of Samoa, Fiji and Tonga.
The scene was extraordinary. Scientists saw “large molten bubbles approximately three feet across bursting into cold seawater.” The sea vents produced massive amounts of red, hot lava, which traveled across the deep-ocean seafloor. Since the water near the eruption is so acidic (between battery acid and stomach acid), Tim Shank, a biologist at WHOI, was surprised to find that shrimp were the only animals living and thriving in this area. Julie Huber, a microbial oceanographer at MBL, was able to sample the fluids around the eruption for microbe life. She found that most of the microbes collected were dominated by bacteria; however she also realized that compared to other vent sites studied, the bacteria diversity was relatively low. This suggests that the microbial community at this specific site (West Mata volcano) could potentially be in the early stages of development. Scientists believe that most (almost 80% of) eruptive activity on Earth occurs in the ocean. Furthermore, most of the volcanoes are in the deep sea.
Living conditions at a hydrothermal vent is very extreme: “Pitch darkness, poison gas, heavy metals, extreme acidity, enormous pressure, water at turns frigid and searing.” One of the most prominent ingredients among the deadly toxicants that come from the vents is hydrogen sulfide. This gas is lethal to most organisms but the creatures and microbes depend on it. Because hydrogen sulfide reacts with oxygen, when the fluids from the vents come in contact with the ocean water, a reaction occurs, which releases energy. The microbes capitalize on this reaction by creating organic compounds with the use of carbon dioxide. Larger creatures then use these organic compounds, which are essential for them to live.

Three of the best understood deep-sea creatures are: tubeworms, clams and mussels. Tubeworms are the most abundant animals. Baby tubeworms can swim; however, the adults are sessile and have no mouth, gut or anus. Thus, they must rely on the bacteria that live within them to provide them with a source of nutrition. They use their tip to take up sulfide and oxygen from the vent water. Then the bacteria convert these chemicals into food for the tubeworms. Like tubeworms, mussels and clams rely on a symbiotic relationship with bacteria. Since mussels are filter feeders, they are able to use more than one bacterial symbiont, and thus, they are able to survive further away from direct source of vent water.

http://www.noaanews.noaa.gov/stories2009/videos/west_mata_eruptionweb.mov

Sources
Primary: http://www.noaanews.noaa.gov/stories2009/20091217_volcano2.html, Scientists Discover and Image Explosive Deep-Ocean Volcano, February 22, 2010.
1. http://www.mbl.edu/news/press_releases/2009/2009_pr_12_21.html, Gina Hebert, MBL Scientist Helps Discover Deep-Ocean Volcano, Finds Thriving Population of Extreme Microbes, February 22, 2010.
2. http://www.pbs.org/wgbh/nova/abyss/life/extremes.html, Peter Tyson, Living at Extrremes, February 22, 2010.
3. http://www.amnh.org/nationalcenter/expeditions/blacksmokers/life_forms.html, Deep Sea Hydrothermal Animals, February 22, 2010.