In the late 1970's, during a routine study of the Pacific Ocean floor, scientists discovered a landscape of chimneys expelling what seemed to be a strange black smoke. These alien like chimneys were in fact hydrothermal vents 8000 feet below the surface of the ocean.* In geologically active areas along the ocean floor, sea water seeps through fissures in the earth's crust to be heated by magma to astonishing temperatures as high as 360 degrees K. As the hot steam shoots up through the fissures, it strips minerals off the rocks surrounding it, feeding a special type of bacteria that processes these "noxious fumes" as nutrients using chemosynthesis.* The bacteria provide the basis for a nutrient rich ecosystem devoid of sunlight, a concept long believed to be impossible. Creatures such as giant tubeworms, deep sea Pompeii worms, hydrothermal vent crabs, hydrothermal vent squat lobsters, and even hydrothermal vent octopi thrive beside the deep sea hydrothermal vents. The hydrothermal vent ecosystem operates similarly to any other food chain, except that the bacteria do not use photosynthesis in order to produce energy. This discovery is integral as it sheds light unto the fact that life can in fact be sustained on earth without the sun.
The colorful array of organisms that thrive at hydrothermal vents prosper in an area teeming with hydrogen sulfide, a chemical that is toxic to most living creatures. While many of the organisms that inhabit hydrothermal vents filter feed, the giant tube worm (Riftia pachyptila) has developed a system unique to the harsh environment it inhabits. These worms lack mouths and digestive tracts, relying instead on an organ called a trophosome.** The trophosome is home to the bacteria that process hydrogen sulfide, and these bacteria undergo chemosynthesis within the body of the tube worm, giving a majority of the produced nutrients to the worm. However, this is not just a one way relationship. The giant tube worm also has specialized gills that exchange hydrogen sulfide (in addition to carbon dioxide and oxygen) and enable the worm to be protected from the harmful effects of the chemical, as well as pass it along to the bacteria waiting eagerly inside.** Relying on chemosynthesis as opposed to photosynthesis is what keeps this ecosystem alive, allowing hundreds of different organisms and communities to flourish in such a lethal environment.
*1. "Deep Sea Hydrothermal Vents," Sea and Sky, accessed April 10, 2011, http://www.seasky.org/
deep-sea/hydrothermal-vents.html.
**2. Castro, Peter, and Michael E. Huber. "The Ocean Depths" Marine Biology. New York: McGraw-Hill Higher Education, 2005. Print.
Photo: http://www.noc.soton.ac.uk/chess/education/edu_htv.php
