Hydrothermal Vents Discovered

Hydrothermal Vents Discovered

On this day in 1977, one of the greatest biological discoveries was made: hydrothermal vents. It forever changed our understanding of the boundaries and potential of life on our planet.

On 8 February 1977, the Galápagos Hydrothermal Expedition set sail from the Panama Canal on the Knorr and began its search for “missing heat,” or underwater hot springs, to explain why an underwater mountain was under tension, rather than compression. By accident, they found a new world teeming with unexpected life, a discovery that rendered many science books obsolete.

Previous underwater expeditions had proved the viability of such a pioneering, and potentially dangerous, mission: Project Famous had proven the ability of submersibles to explore the deep mid-ocean ridges, while the Pleiades and Southtow expeditions had suggested that the Galápagos Rift was a prime location for searching out those elusive hydrothermal vents.

The Knorr carried a team of top scientists out to the Atlantic Ocean and headed towards the Galápagos Rift, a location 330 kilometres northeast of the Galápagos Islands and 640 kilometres west of Ecuador. On 12 February, it arrived at its destination, and on 15 February the crew lowered ANGUS—the Acoustically Navigated Geophysical Underwater System, an unmanned two tonne steel box equipped with lights and cameras—onto the ocean floor.

ANGUS started exploring the depths, and at midnight it recorded a sudden spike in the seawater temperature, suggesting the discovery of a heat source. The next day, a film from ANGUS’s camera was developed with surprising results. Thirteen frames of the film showed hundreds of clams and mussels densely covering the lava flow. Crewmember Robert Ballard described the moment, “This dense accumulation, never seen before in the deep sea, quickly appeared through a cloud of misty blue water and then disappeared from view.”

To get a better look, on 17 February a three-man crew launched ALVIN—the Woods Hole Oceanographic Institution’s deep submergence vehicle—and descended into the Galápagos Rift. Indeed, they found active hydrothermal vents for the very first time. The vents were pumping unexpected chemicals with an astounding exiting temperature of 340 degrees Celsius. But the true discovery was the profusion of wildlife that thrived near the vents. The scientists had found their missing heat, and much more.

In an environment that no one expected could support life, they found a dense biological community of three metre tubeworms, vast beds of a new species of clam with blood-red flesh, blind white crabs, brown mussels, and even a purple octopus that probably saw the vent as a buffet. There were anemones, whelks, limpets, lobsters, and siphonophores, a cousin of the Portuguese man-of-war that resembled dandelions. “Literally every organism that came up was something that was unknown to science up until that time,” said Richard Lutz on a later expedition aimed at studying the animals.

Until this discovery, science dictated that all plants and animals depend on the sun and photosynthesis for survival. Because it is blanketed in darkness, the deep ocean was thought to be like a desert. The Galápagos Hydrothermal Expedition crew found themselves in a new world that defied the known laws of science, with a new food chain that didn’t live off the energy or processes of the rest of life on Earth: the Sun and photosynthesis. A new life cycle was discovered: chemosynthesis. And so our understanding of the ocean, and even life on our planet, was revolutionised.

Photo Credit: NOAA PMEL Vents Program
Photo Caption: An image of a hydrothermal vent, also called a “black smoker.”