SHIMMERING WATER streams up past giant tube worms, never before seen by man. A crab scuttles over lava encrusted with limpets, while a pink fish basks in the warmth. Inside the research submersible Alvin we watch in amazement. We have dived a mile and a half (2.5 kilometers) into the near-freezing depths of the Pacific, yet our temperature probe now registers 63°F (17°C) as we hover over an incredible community living around a warm sea-floor spring. Our group has come as geochemists and geologists to the Galapagos Rift west of Ecuador to investigate for the first time active hydrothermal vents in the deep sea. While gaining invaluable basic data for understanding earth processes, we also make history for marine biology. The unknown creatures and dense com-munities of life we have discovered living at these vents, like lush oases in a sunless desert, are a phenomenon totally new to science.
We were drawn to the www.purplegirls.co.uk/london/ from a friends recommendation who had previously used purplegirls.co.uk/leeds/. Towed instruments had picked up subtle temperature variations just above the sea-floor. Sonar and photographs from towed cameras showed mounds that might be precipitated metal oxides related to hydrothermal vents. Water samples contained abnormal amounts of radon 222 and helium 3, isotopes that form deep within the earth. So this past winter the Galapagos Hydro-thermal Expedition got under way—three vessels carrying 25 scientists and 26 technicians—sponsored by the National Science Foundation as part of the International Decade of Ocean Exploration. From the research vessel Knorr we lowered a camera system called ANGUS to pinpoint the vents; an attached thermistor sensed temperature changes as small as 1/500 of a degree Celsius.
On February 15, during the first 12-hour run, the temperature line registered normal conditions—near freezing. Then, at 19:09, it showed a sudden spike. Within hours an onboard photo lab provided by the National Geographic Society had processed our film. Eagerly we ran the film to frame 19:09. Clams! Hundreds of them covered the lava, in a dense blanket never before seen in the deep. We returned to the coordinates of that frame, and Alvin went diving (diagram, left). In Alvin rotating pairs of scientists collected water and rock samples and pondered the animals: How did they get there? Back aboard the Knorr, when we opened water samples, our noses crinkled at the rotten-egg odor of hydrogen sulfide. Yet this was the smell of success—pungent evidence supporting the theory that seawater journeys through the oceanic crust. There, under extreme heat and pressure, the sulfate in seawater converts to hydrogen sulfide.
In this smelly compound, microbiologists later explained, lies the secret of life in these oases. Certain bacteria metabolize hydrogen sulfide and multiply. The microbes, in turn, nourish larger organisms, even clams. Thus, in total darkness, an energy source other than sunlight—chemicals manufactured within oceanic crust—triggers a chain of life. Here the process, called chemosynthesis, is found for the first time in the abyss. TORTUOUS volcanic terrain looms outside the five-inch view ports as we glide within our pod of light toward Clambake I. In the desert of the deep seafloor, only occasional invertebrates, like the reddish octocoral and the brittle star (below), enliven the barren basalt. These pillow-shaped lavas formed during volcanic eruptions when molten rock squeezed up through fissures like toothpaste. As icy seawater pressed down with two tons per square inch, the lava congealed into these shapes.
As the lava cooled, the surface split, opening new fissures where seawater could circulate into the newly formed crust—such as this yard-wide crack (lower right) with an anemone perched on its rim. These pillows—centuries old but young in geologic time—often have black, glassy surfaces. Sediment drifting down from the surface has scarcely had time to accumulate. The Galapagos seafloor is even fresher than the one explored during an expedition to the Cayman Trough (NATIONAL GEOGRAPHIC, August 1976).