• ocean vent
    These ocean vents bubble with carbon dioxide, the same gas that carbonates soda.

    Photograph courtesy NOAA

    Ancient Archaea
    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.

    ET?
    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.

    Vent Life

    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.

    Seafloor Mining

    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.

    chemosynthesis Noun

    process by which some microbes turn carbon dioxide and water into carbohydrates using energy obtained from inorganic chemical reactions.

    chimney Noun

    tall structure composed of minerals ejected from vents along the ocean floor.

    convert Verb

    to change from one thing to another.

    current Noun

    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.

    eject Verb

    to get rid of or throw out.

    enormous Adjective

    very large.

    extraterrestrial Adjective

    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.

    geyser Noun

    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.

    hydrothermal Adjective

    related to hot water, especially water heated by the Earth's internal temperature.

    microbe Noun

    tiny organism, usually a bacterium.

    mid-ocean ridge Noun

    underwater mountain range.

    mineral Noun

    nutrient needed to help cells, organs, and tissues to function.

    mining Noun

    process of extracting ore from the Earth.

    molten Adjective

    solid material turned to liquid by heat.

    mussel Noun

    aquatic animal with two shells that can open and close for food or defense.

    nutrient Noun

    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.

    photosynthesis Noun

    process by which plants turn water, sunlight, and carbon dioxide into water, oxygen, and simple sugars.

    predator Noun

    animal that hunts other animals for food.

    prey Noun

    animal that is hunted and eaten by other animals.

    primitive Adjective

    simple or crude.

    seafloor massive sulfide (SMS) deposit Noun

    minerals that form from underwater hydrothermal vents.

    seep Verb

    to slowly flow through a border.

    spew Verb

    to eject or discharge violently.

    swamp Noun

    land permanently saturated with water and sometimes covered with it.

    Encyclopedic Entry: swamp
    tectonic plate Noun

    large, moveable segment of the Earth's crust.

    toxic Adjective

    poisonous.

    tube worm Noun

    type of marine worm that cannot leave its protective tube.

    unique Adjective

    one of a kind.

    white smoker Noun

    type of ocean vent that ejects white mineral fluid into the surrounding water.

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