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Images: The Discovery of Hydrothermal Vents

This vehicle's unassuming appearance belies the fact that it was instrumental in one of the most revolutionary scientific discoveries: finding hydrothermal vents and chemosynthetic deep-sea life. ANGUS (Acoustically Navigated Geophysical Underwater System) was a pioneering deep-sea search-and-survey system developed at WHOI. Equipped with powerful strobe lights and 35-millimeter cameras, it was lowered to the depths on a cable and towed by a ship. ANGUS's 12-foot, 2-ton steel frame was designed to withstand collisions with seafloor rocks. Painted on its side (not visible) was the motto: “Takes a Lickin’ But Keeps on Clickin’.” (WHOI Archives)
The research vessel Knorr towed the deep-sea platform called ANGUS just above the seafloor 8,000 feet (2,500 meters) below the surface. Its lights and camera took photos every 10 seconds. These frames show the moment of discovery—the sudden appearance of a dense accumulation of live white clams. Within hours, the clams led scientists to find hydrothermal vents for the first time. (WHOI Archives)
Even more startling than finding seafloor hydrothermal vents was the completely unexpected discovery of life that thrives in the abyss in the absence of sunlight—like these human-sized tube worms with tulip-looking heads. Instead of living via photosynthesis, communites of microbes live via chemosynthesis. They convert chemicals coming from the vents into organic carbon, the building blocks of life, which sustains higher organisms in the food web. (Jack Donnelly, Woods Hole Oceanographic Institution)
The manipulator arm of the human-occupied submersible Alvin reaches toward a black-smoker chimney, seen through the sub's viewport, at 17°S on the East Pacific Rise. Hot hydrothermal fluids surge through the chimney at velocities of 1 to 5 meters per second. The “black smoke” consists of an abundance of dark, fine-grained, mineral-rich suspended particles. When the hot fluid mixes with cold seawater, they precipitate to form solid chimney structures. (Meg Tivey, Woods Hole Oceanographic Institution)
All living things need energy. People and other animals get their energy from the food they eat. But plants on land and microbes that live around hydrothermal vents manufacture their own food. Plants harness energy from sunlight to make their food, a process called photosynthesis. Vent microbes use chemosyntheses, getting energy from chemicals in hydrothermal fluids to create food. (O. Paul Oberlander)
Hydrothermal vents can sustain lush communities of deep-sea life, including clams, mussels, crabs, and shrimp (though these are not the same types that live in shallower surface waters), as well as fish, octopuses, and other higher organisms. (O. Paul Oberlander)
Giant clams, up to a foot long, reside at a hydrothermal vent site in the Galápagos Rift—fed by vent fluids seeping through cracks in the seafloor. (Tim Shank, Woods Hole Oceanographic Institution)
Since the first vent site was found in 1977, hundreds of vent sites have been discovered along mid-ocean ridges across the global ocean, from Antarctica to the Arctic, along with an estimated eight hundred vent animal species and countless microbial species. The rate of discovery shows no signs of leveling off. (O. Paul Oberlander)
Scientists have used the human-occupied submersible (HOV) Alvin for decades—and still do—to observe vent sites with their own eyes. It enables scientists to make detailed observations, collect specific samples, and place, retrieve, or conduct experiments on the seafloor and in the deep ocean. In addition to the vehicle’s manipulator arm, cameras, sensors, and collection instruments, the HOV also carries another important data-gathering device: the scientists’ own eyes and knowledge of the deep. (Chris Linder, Woods Hole Oceanographic Institution)
The remotely operated vehicle (ROV) Jason has been a workhorse for scientists exploring hydrothermal vents. It has a cable that transmits images and data in real time to scientists aboard ships, allowing researchers to make observations, collect samples, and conduct experiments while controlling the vehicle from the surface. The vehicles can remain below the surface for a day or more at a time, and can hover like a helicopter over a seafloor target or survey a wide area. The cable sends and receives control signals, vehicle sensor data, and images and allows the pilot to control the vehicle’s manipulator arm in real time to carry out targeted surveys and collections, and help carry out detailed experiments in the deep ocean. (CREDIT?)
The most recent technological advance in deep-sea exploration vehicles are autonomous underwater vehicles, or AUVs. They are robotic vehicles that “swim” on pre-programmed missions, mapping the seafloor with sonar and using sensors to find clues to home in on vents. The pioneering AUV, developed at WHOI, was called ABE—the Autonomous Benthic Explorer. (Dan Fornari, Woods Hole Oceanographic Institution)
The autonomous underwater vehicle (AUV) Sentry followed in the wake of its predecessor ABE as a fully autonomous underwater vehicle capable of exploring the ocean down to 19,685 feet (6,000 meters) depth. Sentry builds on ABE's success with improved speed, range, maneuverability, and payload. Sentry produces bathymetric, sidescan, subbottom, and magnetic maps of the seafloor, uses sensors to collect data, and cameras to take photos in a variety of deep-sea terrains. (CREDIT?)
This recently developed instrument for vent exploration is known as Vent-SID, for Vent Submersible Incubation Device. It sucks in vent fluids and enables scientists to incubate microbes and measure their growth rates right at the seafloor in their natural environment. Recent studies show that vent microbes are highly efficient at converting chemicals to produce organic carbon, on which higher organisms feed. (Stefan Sievert, Woods Hole Oceanographic Institution)
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