Archaea are one of the oldest forms of life on Earth and have adapted to live in some of the harshest places: oil wells, hydrothermal vents, even your digestive system.
The planet Jupiter's moon Europa is probably covered by a huge, ice-capped ocean. Scientists have guessed that Europa's ocean may hide hydrothermal vents . . . and those vents may be the most likely spot for extraterrestrial life in our solar system.
Homer Simpson is Hot
Just like mountains, vents have individual names. Most vents are named by the scientists who discover them. Old Faithful is the name of a vent (geyser) in Yellowstone National Park.
Sometimes undersea hydrothermal vents and vent fields have unusual names:
- Godzilla, Sasquatch, Salty Dawg (North Pacific Ocean)
- Champagne (Caribbean Sea)
- Homer Simpson, Scooby, Tweety (South Pacific Ocean)
- Snake Pit, Lucky Strike (Atlantic Ocean)
- Kairei, Edmond (Indian Ocean)
Vents, such as hot springs and geysers, are cracks in the Earth’s crust that are formed when tectonic plates move apart. Water that seeps through the cracks is heated by molten rocks under the Earth’s surface. Heated by the Earth’s internal energy, the hot water spews from the vents into either the ocean or the air, resulting in a hydrothermal (hot water) vent.
Vents can exist on land, under the ocean, and even in outer space. The geysers at Yellowstone National Park, in the U.S. states of Montana, Wyoming, and Idaho, are a famous example of a hydrothermal vent system.
Underwater Hydrothermal Vents
Underwater hydrothermal vents are places of mystery where primitive life forms exist without light or oxygen. First discovered in the 1970s along the Galapagos Ridge in the Pacific Ocean, underwater vents have been found in the Atlantic and Indian Oceans, as well.
Mid-ocean ridges, where the Earth’s crust is pulling apart, are common places for vents. Cold seawater seeps through cracks along the ridges. Seawater at that depth is about 2° Celsius (about 35° Fahrenheit). That is very close to freezing. Energy from the Earth’s molten interior heats vent fluid to temperatures of up to 400° Celsius. That’s over 700° Fahrenheit—scalding for most animals, including humans. Water boils at 212° Fahrenheit.
Chemicals in water change at very high temperatures. Heat removes oxygen from the water. The remaining hydrogen liquid mixes with minerals such as copper, iron, sulfur, and zinc from the surrounding rock. The fluid also picks up the chemical hydrogen sulfide. Hydrogen sulfide is the smelly gas responsible for the odor of rotten eggs and swamps.
Loaded with minerals and hydrogen sulfide, the vent fluid pushes its way through the ocean’s crust. Some fluids exit through vents, or openings, in the ocean floor. The hot fluid mixes with cold seawater. These cool, slow-moving currents are called diffuse flows.
Vent fluids that do not exit the crust through diffuse flows exit through underwater chimneys. When minerals in the fast-moving fluid mix with seawater, they solidify and form chimneys made from iron, copper, and zinc. As long as they continue to eject fluid, the chimneys will continue to grow. Some chimneys grow 30 centimeters (almost 12 inches) a day and reach 20 meters (65 feet) tall. Tall chimneys don’t last long, though. The mineral structure is fragile. Powerful undersea currents and pressure often lead to their collapse.
Chimneys are classified as either black smokers or white smokers, depending on the color of fluid they emit. Black smokers are larger and eject hotter fluid. The metals in the fluid mix with the oxygen in the seawater to form a black cloud. White smoker fluid does not contain any metals, so its fluid is white.
Many unique organisms are adapted to life in the harsh environment of an underwater hydrothermal vent.
Most organisms rely on the sun for food. Green plants use sunlight, water, and carbon dioxide to manufacture simple sugars and oxygen in a process called photosynthesis. Other plants and animals, including humans, depend on these plants for food.
Organisms near a hydrothermal vent do not always have access to sunlight. The deep ocean floor is so dark that many creatures do not have functioning eyes. These organisms depend on a process called chemosynthesis. In chemosynthesis, microbes convert vent chemicals such as hydrogen sulfide into energy. These chemicals are toxic to most organisms, including humans.
These specialized microbes (mostly bacteria and archaea, single-celled organisms similar to bacteria) live everywhere in the vent community. They live on the vent floor. They live inside chimneys. They even live inside animals like tube worms and mussels. These microbes are the basis of the food chain in the underwater hydrothermal vent ecosystem. Tube worms, mussels, and clams use the microbes to produce nutrients. Shrimp eat the microbes. In turn, predators like crabs, fish, jellyfish and octopuses prey on these animals.
Underwater hydrothermal vents are surrounded by seafloor massive sulfide (SMS) deposits. SMS deposits are minerals that harden from the vent fluid interacting with seawater. SMS deposits can be material left over from collapsed chimneys or the chimneys themselves. They contain metals such as copper, iron, zinc, lead, silver, and gold. These metals are valuable for human industry and can be sold for high prices.
Mining companies have studied ways to extract SMS deposits from the deep ocean. Seafloor mining is a complicated and expensive procedure. Mining companies have extracted tons of ore from SMS deposits near vent fields in the South Pacific (near Papua New Guinea and New Zealand).
The environmental impact of SMS mining is enormous. Microbes, animals, and plants are destroyed or displaced as the seafloor is disrupted. Some mining companies work with governments and environmental organizations to ensure that only minimal damage is done to the seafloor.
Term Part of Speech Definition Encyclopedic Entry archaea Plural Noun
(singular: archaeon) a group of tiny organisms often living in extreme environments, such as ocean vents and salt lakes.
bacteria Plural Noun
(singular: bacterium) single-celled organisms found in every ecosystem on Earth.
black smoker Noun
type of ocean vent that ejects black mineral fluid (not smoke) into the surrounding water.
process by which some microbes turn carbon dioxide and water into carbohydrates using energy obtained from inorganic chemical reactions.
tall structure composed of minerals ejected from vents along the ocean floor.
to change from one thing to another.
steady, predictable flow of fluid within a larger body of that fluid.
Encyclopedic Entry: current diffuse flow Noun
an area of the sea floor that forms due to a low-temperature, slow-moving ocean vent.
to get rid of or throw out.
located or formed outside Earth's atmosphere.
food chain Noun
group of organisms linked in order of the food they eat, from producers to consumers, and from prey, predators, scavengers, and decomposers.
Encyclopedic Entry: food chain fragile Noun
delicate or easily broken.
natural hot spring that sometimes erupts with water or steam.
Encyclopedic Entry: geyser hot spring Noun
small flow of water flowing naturally from an underground water source heated by hot or molten rock.
hydrogen sulfide Noun
chemical compound gas responsible for the foul odor of rotten eggs.
related to hot water, especially water heated by the Earth's internal temperature.
tiny organism, usually a bacterium.
mid-ocean ridge Noun
underwater mountain range.
nutrient needed to help cells, organs, and tissues to function.
process of extracting ore from the Earth.
solid material turned to liquid by heat.
aquatic animal with two shells that can open and close for food or defense.
substance an organism needs for energy, growth, and life.
Encyclopedic Entry: nutrient Old Faithful Noun
geyser in Yellowstone National Park in the U.S. state of Wyoming.
process by which plants turn water, sunlight, and carbon dioxide into water, oxygen, and simple sugars.
animal that hunts other animals for food.
animal that is hunted and eaten by other animals.
simple or crude.
seafloor massive sulfide (SMS) deposit Noun
minerals that form from underwater hydrothermal vents.
to slowly flow through a border.
to eject or discharge violently.
land permanently saturated with water and sometimes covered with it.
Encyclopedic Entry: swamp tectonic plate Noun
large, moveable segment of the Earth's crust.
tube worm Noun
type of marine worm that cannot leave its protective tube.
one of a kind.
white smoker Noun
type of ocean vent that ejects white mineral fluid into the surrounding water.