Laboratory Write Up
Your Name: Kelly Douglas
Laboratory Title: We’re in Hot Water Now: Hydrothermal Vents!
Lab Objectives:
Students will:
- Explore the interior of a hot spring and geyser in an online feature
- View and discuss photographs of hydrothermal vents and compare them to land based geysers
- Use a plate tectonics map to hypothesis the regions where hydrothermal vents might be most likely to occur
- Read about and view pictures of four creatures that live near hydrothermal vents
- Create exhibits showcasing these creatures and describing their adaptations
Benchmark(s) Addressed:
Physical Science
CCGMatter: Understand structure and properties of matter.
SC.05.PS.01 Identify substances as they exist in different states of matter
SC.05.PS.01.01Distinguish among solids, liquids, and gases.
CCGMatter: Understand chemical and physical changes.
SC.05.PS.02 Describe the ability of matter to change state by heating and cooling.
SC.05.PS.02.01Recognize that heating and cooling cause changes in states of matter.
Scientific Inquiry
CCG:Forming the Question/Hypothesis: Formulate and express scientific questions or hypotheses to be investigated.
SC.05.SI.01 Make observations. Ask questions or form hypotheses based on those observations, which can be explored through scientific investigations.
Life Science
CCG: Organisms: Understand the characteristics, structure, and functions of organisms
SC.05.LS.03 Describe basic plant and animal structures and their functions
SC.05.LS.03.01Associate specific structures with their functions in the survival of the organism.
CCG: Diversity/Interdependence
Understand the relationships among living things and between living things and their environments
SC.05.LS.05 Describe the relationship between characteristics of specific habitats and the organisms that live there.
SC.05.LS.05.04Explain the relationship between animal behavior and species survival.
SC.05.LS.06 Describe how adaptations help a species survive.
Materials and Costs
Computer with internet access……………………………free at most schools
Construction paper………………………………………….1.19 (50 sheets)
Markers/Crayons (drawing materials)…………………. ~20.00 (purchase a few packs of each)
Scissors (12 for 9.95)……………………………………...... 29.85
Glue……………………………………………………………….10.99 (12 pack)
Pipe cleaners…………………………………………………….0.99 (100 pack)
Estimated, total, one time, start up cost………………...63.02
Estimated total cost each year……………………………...0.00 (simply replenish art supplies when necessary)
Time
Initial prep time: ~1-2 hours to purchase materials/gather information
Preparation time: ~30 minutes
Instruction time: ~20 minutes
Clean-up time: ~30 minutes
Background Information
What is a Geyser?
A geyser is a vent in Earth’s surface that periodically ejects a column of hot water and steam. Even a small geyser is an amazing phenomenon; however some geysers have eruptions that blast thousands of gallons of boiling hot water up to a few hundred feet in the air.
Old Faithful is the world's best known geyser. It is located in Yellowstone National Park (USA). Old Faithful erupts every 60 to 90 minutes and blasts a few thousand gallons of boiling hot water between 100 and 200 feet into the air.
Geysers are extremely rare features. They occur only where there is a coincidence of unusual conditions. Worldwide there are only about 1000 geysers and most of those are located in Yellowstone National Park (USA).
1) hot rocks below
2) an ample ground water source
3) a subsurface water reservoir
4) fissures to deliver water to the surface
Where are Geysers Found?
Most of the world's geysers occur in just five countries: 1) the United States, 2) Russia, 3) Chile, 4) New Zealand and 5) Iceland. All of these locations are where there is geologically recent volcanic activity and a source of hot rock below.
How Do Geysers Work?
To understand how a geyser works, you must first understand the relationship between water and steam. Steam is a gaseous form of water. Steam is produced when water is heated to its boiling point. When water converts into steam at surface conditions it undergoes an enormous expansion because steam occupies 1600 times as much space as the original volume of original water. The eruption of a geyser is powered by a "steam explosion" when boiling hot water suddenly expands into the much more voluminous steam. To summarize: a geyser erupts when superheated ground water, confined at depth, becomes hot enough to blast its way to the surface.
Here's what happens in the ground...
Cool ground water near the surface percolates down into the earth. As it approaches a heat source below, such as a hot magma chamber, it is steadily heated towards its boiling point. However, at the boiling point the water does not convert into steam. This is because it is deep below the ground and the weight of cooler water above produces a high confining pressure. This condition is know as "superheated" - the water is hot enough to become steam - it wants to become steam - but it unable to expand because of the high confining pressure.
At some point the deep water becomes hot enough, or the confining pressure is reduced, and the frustrated water explodes into steam in an enormous expansion of volume. This "steam explosion" blasts the confining water out of the vent and it erupts out of the vent as geyser.
Explore the Deep Sea
Volcanoes & Vents
Hot facts
- The English word geyser comes from the old Norse word geysa, meaning to rush forth.
- Seafloor vents are often called hydrothermal vents: hydro means water and thermal means hot.
- When it exits the seafloor, vent fluid temperature can beas high as 350°C (675°F) or hotter. But typically it doesn't boil because the pressure at these depths is so great.
- Vent fluid is not only hot, it is often acidic, sometimes as acidic as lemon juice.
Photostories
- Investigating the chemistry and geology of vents, chimneys and smokers
Hydrothermal vents: underwater geysers
What happens when tectonic plates move towards each other: subduction, trenches and mountain building.
Hot fluid jets and wafts from cracks in the seafloor thousands of meters below the ocean surface. The fluid is essentially water that has filtered down into the rock of the Earth's crust through tiny channels and fissures. Surrounding rocks heat the water as it moves downwards, and various minerals dissolve in it. Vents occur where some of the hot fluid finds its way back to the surface. Most areas containing vents are found where the Earth's tectonic plates are moving apart, or in other areas of tectonic activity, such as ocean basins and hotspots.
Plumes of hot fluid
As the hot fluid shoots out of cracks in the rock, it meets the surrounding ocean water, which is cold—just a few degrees above freezing. So the hot fluid begins to cool. The further it moves from the point it came out of the seafloor (the vent), the cooler it gets. But the fluid is so hot when it leaves the seafloor that it can take several hundred meters to cool down to the temperature of the surrounding ocean. Consequently, each vent is marked by a "plume" of warm water that billows into the ocean above. Vents can be tracked down by finding their associated plumes.
Chimneys and smokers
Hot vent fluid has many minerals dissolved in it. When it mixes with seawater and cools, minerals precipitate out of solution, forming a dense cloud of what looks like smoke—so some vents are referred to as "smokers." Depending on the fluid's temperature and what minerals are dissolved in it, the smoke can look black or white. Black smokers emit hot fluids containing iron and sulfide. White smoker fluid is cooler and contains whitish compounds of barium, calcium and silicon. The fluid jetting out of these chimneys can be very hot indeed: hundreds of degrees Celsius.
Some minerals drop out of the water right next to the vent; over time, these can build up to form "chimneys." Some chimneys form very fast—growing several inches per day. Large chimneys can grow to over 150 feet (50 m) high and 90 feet (30 m) diameter. As the chimneys grow, they are colonized by animals and microbes which are able to survive in the extreme conditions. …more about investigating minerals deposited by vents
Diffuse flow
In some areas, seawater seeps into cracks in the seafloor and mixes with the rising vent fluid. So by the time the vent fluid exits the seafloor it is cooler, and has a different chemical make-up, than the fluid that gushes out of chimneys (above): tens, rather than hundreds of degrees Celsius. This is still considerably hotter than the background temperature of the ocean, which is just a few degrees above freezing. …more about investigating the chemical make-up of vent fluid
Just add sulfur
Often, the hot vent fluids contain sulfur-rich chemicals. Sulfur is a yellow mineral that was much prized by mediaeval alchemists, and is one of the ingredients of gunpowder. Sulfur compounds are often very poisonous. However, some microbes have evolved the ability to break down the sulfur-containing chemicals in vent fluids to derive energy. This enables the microbes and many other animals to live in great abundance around vents on the ocean floor, despite the fact that there are no plants in the deep ocean. …more about life in the deep
Next: Life in the deep
© 2008 Venture Deep Ocean
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/ / / / / / / / / / / // / Menagerie at a hydrothermal vent.
Living at Extremes
by Peter Tyson
If there is a harsher place to live than a hydrothermal vent, it hasn't been found yet. Pitch darkness, poison gas, heavy metals, extreme acidity, enormous pressure, water at turns frigid and searing—this seafloor environment seems more like something from deep space than from our own deep sea.
Yet amazing communities of life exist at hydrothermal vents and the so-called "black smoker" chimneys that, given the right conditions, rise above them like erupting stalagmites. Blind shrimp, giant white crabs, and a variety of tubeworms are just some of the more than 300 species of vent life that biologists have identified since scientists first blundered upon this otherworldly community two decades ago. More than 95 percent of these species are new to science.
Sub illuminates smokers adorned with vent life.
It's hard to say which is more remarkable to scientists studying this bizarre world thousands of feet beneath the sea: what these animals have to cope with, or what they have come up with to do that coping.
Dark as night
For starters, it's pitch black at such depths. Sunlight penetrates no farther than a few hundred feet down, leaving the deep-sea floor as dark as the deepest cave. With no sunlight, there are no plants; all vent life belongs to the animal kingdom. And with no plants, there is no photosynthesis. Biologists were flabbergasted when they first learned that creatures lived in total darkness at the seafloor. All other life ever identified, on land or in the sea, derives its energy either directly or indirectly from the sun. How, they wondered, did these animals manage without?
A string of clams winds across a vent.
Through chemosynthesis, it turns out. Vent species rely not on photons from the sun but on chemicals from the Earth's interior. Tiny microbes oxidize the hydrogen sulfide that diffuses out of the vents, providing nutrients for animals higher up the food chain. Some creatures, such as the mollusks known as gastropod snails, feast on the bacteria directly; others, including predatory fish, dine on animals that have eaten or otherwise made use of the microbes; still others, like tubeworms, host the microorganisms in their tissues in exchange for organic compounds that the bacteria fashion from the vent chemicals and seawater. (The only element from above that these microbes require for their artistry is oxygen, which is abundant in seawater and was originally produced, of course, by plants. So when it comes right down to it, even these life forms ultimately rely on sunlight. Which likely made those flabbergasted biologists breathe a little easier.)
Temperature of this Juan de Fuca Smoker: 648°F.
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A toxic brew
As if utter darkness were not enough, vent animals must contend with a witch's cauldron of deadly toxicants. Foremost among them is hydrogen sulfide, one of the principal ingredients of the broiling water spewing from vents and black smokers. While vent microbes thrive on the stuff, this gas is lethal to most other organisms, including the creatures that live within wafting distance. Yet not only do those animals survive it, they depend on it as intrinsically as they do on the microbes. Hydrogen sulfide reacts spontaneously with oxygen, so as soon as vent fluids come into contact with seawater, a swift reaction occurs, releasing energy. All that energy would go to waste if it were it not for the microbes. They harness that reaction and use carbon dioxide to make organic compounds that tubeworms, for example, need to live.
Deep-sea anemone clings to lava outcrop.
Heavy metal and acid rock
Vents and smokers also release a bevy of heavy metals. Besides being toxic substances, these particles can clog mouthparts and gills. Biologists are still trying to figure out exactly how vent animals cope with these. Several animals have metal-binding proteins in their systems, while others, like some polychaete tubeworms, appear to expel these toxics in mucus. Beyond the toxic gas and particles, vent water can also be extremely acidic. The pH of waters coming out of black smokers can be as low as 2.8, making it more acidic than vinegar. Biologists have seen "naked" snails around hydrothermal vents that could not form their calcium carbonate shells because the water was too acidic.
Continue: Pressure's On
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/ / / / / / / / / / / / /
/ / Spider crabs trundle over a lava mound.
Living at Extremes
Part 2 (back to Part 1)
Pressure's on
Another factor these creatures have evolved to live with is the pressure. With every 32.8 feet of descent, the weight of the water above increases by 14.7 pounds per square inch. At 7,500 feet, which is about the depth of the black smokers this expedition will attempt to retrieve, the pressure animals feel over every square inch of their bodies is over 3,350 pounds. At such pressures, any air pockets, such as lungs, would be crushed flat as a deflated balloon. Vent animals have evolved bodies with no such air spaces.
Chimney smoke can be hot enough to melt lead.
Fire and ice
Perhaps the most startling condition these animals cope with is unusual temperatures. For they must deal with both extremes -- icy and scalding, often simultaneously. Water at the bottom of the ocean is about 35°F, while vent fluids released from chimneys can reach 750°F. Tubeworms and other vent creatures often live right on the flanks of black smokers, within mere inches of the scorching brew, which only the pressure keeps from boiling. Currents constantly stir up the hot and cold, meaning tubeworms and the like have to deal with ever changing temperatures. Even without currents, the extremes are sobering. Biologists have determined that the difference in temperature between a tubeworm's plumed tip and its base anchored in the side of a vent can be more than 50°F. Vent microbes themselves can take temperatures up to 230°F.
Tubeworms live dangerously close to chimney plumes.
Location, location, location
To compound problems, the physical environment of the vent itself has limitations. Surprisingly enough considering the vastness of the ocean floor, space is extremely limited. Talk about location, location, location: a tubeworm, for one, must live close enough to a vent to get hydrogen sulfide but not close enough to get burned. To make matters worse, due to geophysical changes taking place beneath them, hydrothermal vents and black smokers can turn off suddenly, choking off the life that depended on them. Even healthy black smokers, though they're made of stone, are fragile structures that eventually crumble beneath their own weight. So vent creatures have to have a means for detecting, traveling to, and colonizing new habitat. Yet vents are spread far and wide throughout the world's seas. How newborn vents acquire new residents is a mystery that continues to keep scientists up at night.
A cascade of tubeworms.
But clearly vent creatures manage to do it. Biologists have discovered these animals at sites right around the mid-ocean ridge that circles the globe. Indeed, they have found that vent animals more closely resemble vent creatures on the other side of the planet than they do animals living even a few feet away from them on the ocean floor.
First life?
The irony of vent communities is that, despite the harshness of their home, they appear to have survived for many millions of years, having apparently changed little in that time. Vent life, for one thing, appears to be more closely related to ancient animals than anything alive today. What's more, even during times when all hell was breaking loose on the surface, such as during
Did life begin at hydrothermal vents?
the periodic mass extinctions that have swept the Earth, vent creatures have calmly gone about their lives, probably little affected. This tenacity, evinced albeit through the most exceptional isolation, bodes well for them in the current mass extinction event.
Some biologists have gone so far as to suggest that a vent-like environment was the place where life on Earth likely got its start. And if such a miracle could have occurred here on Earth, why not on other planets that have the necessary ingredients, including heat, water, and the right mix of chemicals? In the end, there may indeed be a harsher place to live than hydrothermal vents. But again, it hasn't been found ... yet.
Peter Tyson is Online Producer of NOVA.
Living at Extremes | Inside a Tubeworm | Deep-Sea Bestiary
Photos: (1) Visuals Unlimited/©WHOI/D. Foster; (2)IFREMER/Violaine Martin; (3) ©1993 Norbert Wu; (4) NOAA/Pacific Marine Environmental Laboratory ; (5) ROPOS/Urcuyo; (6) ROPOS/Tunnicliffe; (7) V. Tunnicliffe; (8) ©1998 Ken Smith/Mo Yung Productions; (9) ROPOS/Tunnicliffe; (10) IFREMER/Violaine Martin.
The Mission | Life in the Abyss | The Last Frontier | Dispatches
E-mail | Resources | Table of Contents | Abyss Home
Editor's Picks | Previous Sites | Join Us/E-mail | TV/Web Schedule
About NOVA | Teachers | Site Map | Shop | Jobs | Search | To print
PBS Online | NOVA Online | WGBH
© | Updated October 2000
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