1979 - Oases of Exotic Life

Biologists get their first look at the vents

Scientists had hoped to find hydrothermal vents on the 1977 Galápagos Rift expedition. No one had expected to find lush communities of vent life, so there were no deep-sea biologists on the 1977 cruise. Biologists were bursting with eagerness to investigate these extraordinary deep-sea oases for themselves. But it took nearly two years to mount a return expedition.

In 1979, the National Science Foundation sponsored Galápagos expeditions using Woods Hole’s R/V Lulu and Alvin, and R/V Gillis, operated by the University of Miami. The chief scientist was J. Frederick Grassle, then a scientist at Woods Hole Oceanographic Institution, now director of the Institute of Marine and Coastal Sciences at Rutgers University. Grassle organized a team of biologists from many institutions. Their goal was to examine how animals thrive in an environment that seemed so harsh.

For this historic cruise, the scientists built special instruments to collect samples of microorganisms and larger animals at the vents. They made experimental devices to learn how the animals were eating and breathing.

To hold the new equipment, a new basket was installed in the front of Alvin. It also got a second manipulator (it had only one left arm before) to help carry out all the sampling the biologists hoped to do. A new, one-of-a-kind, deep-sea movie camera and special underwater lights were installed for filming by the National Geographic Society. National Geographic created an award-winning documentary called Dive to the Edge of Creation.

“We would subject the newly discovered communities to the full arsenal of techniques available to modern biology,” Grassle wrote in a 1998 article in Oceanus.

A parade of strange creatures

Related mulitimedia

From inside Alvin, pilot Jack Donnelly explains how they captured a “dandelion.”

“Nothing could diminish the excitement of seeing the animals for the first time,” Grassle wrote in Oceanus. And nothing could prepare them for what they found.

On each of its dives, Alvin’s front basket and cameras captured a remarkable variety of animals that never had been seen before: unknown mussels, anemones, whelks, limpets, featherduster worms, snails, lobsters, brittle stars, and blind white crabs. One crustacean seemed to have teeth on the end of eyestalks, which scientists speculated were used to scrape food off rocks. A new species of giant white clams with blood-red flesh was given the scientific name magnifica. The delicate, orange, dandelion-looking creature seen on the 1977 cruise turned out to be called a siphonophore—a cousin of the Portuguese man-of-war. Alvin technicians fashioned a special “dandelion-catching” container, but the siphonophore quickly disintegrated after it was brought to the surface.

At a newly found vent site called “Rose Garden,” scientists found red-tipped tubeworms that were an astonishing 8-feet tall. Aboard ship, they found that the tubeworms had no mouth to take in food and no guts to digest food!

“Literally every organism that came up was something that was unknown to science up until that time,” said Richard Lutz, then a post-doctoral scientist at Yale, now a professor at Rutgers University. “ It made it terribly exciting. Anything that came (up) on that basket was a new discovery.”

Life without light

This rich abundance of animals depended on the warm fluids flowing out of the seafloor.

To live and grow on land, animals use carbon from plants or animals that they eat, and oxygen from the air. At the seafloor, vent animals get their oxygen from seawater. In fact, scientists discovered that the giant clams and tubeworms were such a rich red color because their blood contained hemoglobin—the same molecule that transports oxygen in human blood and makes it red.

So what do the vent animals eat to get the carbon they need to grow? They either eat other vents animals, as the crabs do, or they eat the smaller “life” at the base of the vent food chain—microorganisms.

The 1979 Galápagos expedition collected a huge variety of bacteria in the vent waters. Woods Hole biologist Holger Jannasch proved that these bacteria used hydrogen sulfide from vent fluids to take the carbon from carbon dioxide, a gas dissolved in seawater. They convert this carbon into “organic” carbon, which they can use as food.

Plants do the same thing, using carbon dioxide from air and sunlight as energy, in a process called photosynthesis. In the sunless depths, microorganisms create organic carbon using chemicals for their energy source, a process called chemosynthesis.

The sulfide-rich fluids streaming from the vents nourish an abundant supply of microorganisms, which feed an abundance of animals. Who could have imagined that the dark, cold seafloor would be one of the most fertile places on Earth?

A major discovery of the 20th century

Photosynthesis vs.
Chemosynthesis

creatures slideshow

Woods Hole biologist Holger Jannasch was aboard the 1979 Galápagos expedition and summed it up this way in an article in the Annual Review of Microbiology*:

“In the spring of 1979—after geologists had discovered dense populations of strange new animals clustered around hydrothermal vents in an area north of the Galápagos Islands—a group of biologists took Alvin back to the same site.

“It was an overwhelming experience to ‘fly,’ 2,550 meters deep, over dense beds of large mussels or even larger (up to 30 centimeters long) white clams, or stands of hundreds of snow-white tubeworms (up to two meters long) crowned with feather-like blood-red plumes.

“We were struck by the thought, and its fundamental implications, that here solar energy, which is so prevalent in running life on our planet, appears to be largely replaced by terrestrial energy—chemolithoautotrophic bacteria taking over the role of green plants. This was a powerful new concept and, in my mind, one of the major biological discoveries of the 20th century.”

*Vol. 51 © 1997 by Annual Reviews.

 

Related Video:

Dive to the Edge of Creation

In 1979, the National Science Foundation sponsored a return expedition to the vents at the Galápagos Rift. A film crew from the National Geographic Society participated in the cruise, and produced a documentary about the expedition called “Dive to the Edge of Creation.” At left is part one of from that film. See part two »

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