A Science Odyssey
People and Discoveries

Life is found near deep ocean vents

In 1977 scientists discovered that at the deepest parts of the ocean, which people had long imagined to be dark, cold, and lifeless, was a strange environment teeming with life.

Marine geologist Robert Ballard (b. 1942) and a team of oceanographers and marine geochemists and geologists, took the deep sea submersible Alvin to the Galápagos Rift near the Galápagos Islands in the Pacific Ocean. Their expedition was to look for hydrothermal activity like that found at Yellowstone National Park. Geysers or hot springs of some kind were predicted at the Rift based on the relatively new plate tectonic theory. Remote sensors showed temperature changes and the presence of large clam shells that looked promising. A crew took Alvin down to 2,500 meters below the surface where they were gratified to find what they had been looking for -- and more. The water near the bottom shimmered with the difference in hot and cold, as very hot water spewed out of vents into the 3-degree Centigrade ocean water. A dusting of white lay around the vents, and in some places, had accumulated so high as to look like chimneys on the sea floor, smoking with hot, mineral-rich water. As the water cooled, material that was dissolved in it solidified and settled out.

The crew was happy to have found what they were looking for, but stunned by what else was there: life! Immediately surrounding the hot vents and chimneys were thriving communities of strange species such as giant clams, eyeless shrimp, and colorful tube worms. But no sunlight. How this food chain began was a mystery. It was apparent that the life there was completely dependent upon the vents since only the remains of dead organisms surrounded inactive vents. Scientists collected water from the vents and later found sulfide-eating bacteria, similar to those found in land-based hot springs. These were the initial food source for the larger creatures. The sulfide was in the minerally water coming from the vents, and it was suspected that the heat of the earth itself served as the primary energy source.

Other scientists returned to these life-filled vents and also found similar ones in the Atlantic. Ironically, the original team had included no biologists, since they were looking into theoretical and practical geologic questions. For example, mining interests wanted to know where there might be mineral deposits in the oceans. Deep-ocean study has since been carried out mostly by biologists, whose detailed findings have suggested that life on the young, volatile planet earth may well have started at the bottom of the ocean.

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