Deep Sea Vents (aka Hydrothermal Vents) -- Final outline/mini-report

This discussion topic submitted by Michele Holland (Michele@nwonline.net) at 9:46 pm on 7/18/99. Additions were last made on Thursday, November 14, 2002.


Deep Sea Hydrothermal Vents

(Please excuse the format, it messed up when I pasted it here, and not being extremely efficient on computers, I can't seem to fix it!) :)

I. What they are

a. Geysers located at an average depth of 2,225 meters on the ocean floor
b. Believed to be 3-4 billion years old
c. Spew out mineral rich water that can reach temperatures of 757°F
d. Support dense bio-communities

II. Formation and location

a. Plate Tectonics Theory
- approximately 20 plates of various sizes make up the earth's lithosphere.
ˇThe plates ride on a hot pliable layer composed of magma, diverging at mid- ocean spreading ridges, converging at subduction zones which lie at the edges of the plates.
ˇThe plates move at different speeds and in different directions. When they move apart, magma rises, forming new crust (a process known as seafloor spreading).
ˇThe continuous movement of these plates causes cracks to form in this new crust "just as cracks eventually develop in asphalt highways and driveways" (Plate Tectonics Theory: Ocean Adventure).
b. Vent formation occurs when cool seawater seeps into these cracks in the earth's crust, becomes superheated by magma, picks up and looses minerals, and is then shot out through holes present on the ocean floor, a process also known as hydrothermal circulation.
c. Vents are thus found near active volcanoes along the mid-ocean ridge and in areas of seafloor spreading.

III. Geological features

a. Some vents topped with chimneys
ˇFormation occurs when hot acidic vent water hits the cool seawater causing minerals to precipitate
ˇPresent in various shapes, sizes and colors (i.e. black smokers which are formed when zinc, iron and copper atoms combine with sulfur present in the surrounding seawater and white smokers, in which barium, calcium and silica elements can be found)
ˇSome chimneys contain radioactive sulfides
ˇChimneys grow incredibly fastÍup to 9 meters (30 feet) in only 18
months!
b. Fauna influence on geological features
ˇNew research indicates worms found near vents may help build templates for black smoker chimneys with the barite molds of their bodies.

IV. Ecosystem

a. A vent ecosystem's bio-mass is estimated to be as high as a rain forest
b. Sulfur bacteria in vent ecosystems serve as the primary producers
c. Vents considered to be an ecotone (a zone where two ecosystems overlap, each supporting its own unique species and species from both ecosystems)
d. Transition zone between hot vent water and cold seawater is only 15 cm
e. Life forms in vent ecosystems are both bizarre and ancient.
f. Vent ecosystems first discovered less than 25 years ago. (1977)

V. Basic hydrothermal vent fauna characteristics

a. Sulfur bacteria
ˇBecause light is not available for photosynthesis, sulfur bacteria, the primary producers of vent ecosystems, harvest the energy stored in the hydrogen sulfide that gushes out of vents, a process known as chemosynthesis.
ˇBacteria covers rocks and surrounds vents in a dense mass.
ˇBacteria abundant in various colors
ˇBacteria are consumed directly or form symbiotic relationships with vent fauna

VI. A few of the species present in vent ecosystems and their characteristics

a. Giant Tube Worm
ˇGrows to lengths of up to 3 meters
ˇLacks a digestive tract; harbors bacteria in the cells of its body in a symbiotic relationship.
ˇIn 1 once of tissue, there are approximately 285 billion bacteria present
ˇThe worm receives high-energy carbon compounds from the bacteria, which, in turn, receives hydrogen sulfide from the worm
ˇWorm contains unique form of hemoglobin that transports hydrogen sulfide to the bacteria while keeping it separate from water to prevent poisoning of the worm. "The bacteria then oxides the sulfide and converts carbon dioxide into nourishment for the worm. The solid sulfur then becomes embedded in the worm as a waste by-product of this digestive process" (Ocean Adventure: Giant Tube Worm).
ˇ"Researchers discovered that Giant Tube Worms have a mouth and a gut for bacteria to enter in their early stages. The mouth disappears and the gut closes during development" (Ocean Adventure: Giant Tube Worm)
ˇFastest growing marine invertebrate--grows more than 33 inches a year
b. Pompeii Worm
ˇ10 cm in length
ˇFound in vent west of Costa Rica
ˇHead survives in water approximately 72°F while tail remains in water 176°F
ˇCraig Cary, researcher from the University of Delaware, believes "bacteria that stream like strands of hair from the worm produce eurythermal enzymes that protect the worm from these extreme temperature ranges" (Pompeii Worm: Vent Fauna)
ˇConsidered the extreme of all extremophiles
c. New domain of life found
ˇNamed Methanococcos jannaschii
ˇUnicellular organism placed in the Archaea domain
ˇ6-millionth of a meter long, looks like a squid
ˇProduces natural methane
d. Vent species provide us a glimpse into the past
ˇTube worms and other organisms found in vents share striking similarities to fossilized creatures that date back 438 million years (during the Silurian period). Scientists believe vents have sustained these ancient life forms because no change in the environment or predators has occurred. This prevented the need for adaptive evolution and natural selection, thus halting evolution.

VII. Theories on the origin of life on earth

a. Scientists believe life on earth began soon after the formation of hydrothermal vents, some 3-4 billion years ago. The discovery of hydrothermal vents may provide proof as to how life on Earth began.
b. Two theories have been made:
ˇLife formed shortly after the formation of hydrothermal vents because of the rich mineral content and high temperatures vents yield (vents provide proof of the presence of a "primordial soup")
ˇBacteria arrived on a meteor from outer space, creating life on earth. This theory is known as the Panspermia Theory.

VIII. Significance

a. Vents provide us with:
ˇHydrothermal circulation--a process vital to the regulation of the chemical and temperature properties of the Earth's oceans (all oceanic water is recycled through hydrothermal vents once every 6-8 million years).
ˇThe ability to investigate the origin of life on earth, and in reference to the Panspermia Theory, life elsewhere in our solar system.
ˇPossible medical and industrial breakthroughs
ˇMining possibilities

The discovery of hydrothermal vents and the bio-communities present in each has generated a new controversy over the ethics of vent exploration, exploitation and protection. Because each vent seems to contain unique properties and some unique organisms, some feel whole species could be destroyed should exploration continue. I, however, feel exploration and exploitation of these newly found resources is extremely important to our growth, both mentally (i.e. knowledge of our origins and the vast bio-diversity of our planet) and physically (i.e. the discovery of medical and industrial breakthroughs), and should not be stopped; rather, continued in a relatively controlled manner.


Works Cited (& References):

Erickson, Jon. "Marine Geology: Undersea Landforms and Lifeforms". Facts on File, NY, 1996.
"Hydrothermal Vent Particle Chemistry" www.pmel.noaa.gov/vents/
"Ocean Adventure" www.library.advanced.org/18828/index.html
Audesirk, Teresa and Gerald. "Biology: Life on Earth, Fifth Edition". Prentice Hall, Upper Saddle River, New Jersey, 1999
Walters, Jon. "Sea Vents: Living Worlds Without Sun


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