Nova : The Mysterious Life of Caves.
Time: 1 hour
Pros: multidisciplinary, detailed, in depth exploration of subject
Cons: maybe a bit deep for ninth graders, lots of focus on biology – especially from Nova help
ideas
Story line: Explorers investigate caves created by hydrogen sulfide– Contain life? Darkness?
Acid deadly…carbon monoxide – not expected. How do creatures live in these conditions? Is
cave unique?
 Cave formations – names of
 Guadalupe Mtns of NM –
o Ancient barrier reef of El Capitan, hardened into limestone, lifted.
o Contains Carlsbad caverns
o Formed by rain and underground water eroding and dissolving rock. – theory all
caves are formed this way.
o Mysteries
 Why so big?
 Some rocks full of holes?
 Gypsum – easily dissolved but why still present?
o Nearby cave Lechuguilla- full of gypsum
 Sealed from surface,
 Preserved unique formations, unique origin.
 Sulfuric acid dissolves limestone and leaves gypsum behind.
o Search for source of sulfuric acid.
 Hydrogen sulfide + water = sulfuric acid.
 What is producing Hsufide?
 Life!
 Temperature? Chemical structure protects from heat
 Volcanic cracks spewing gas and minerals – organisms surviving at very
high temperatures, pressures
 Extremophiles – pressure, heat and darkness
o Carlsbad – microbes produce hydrogen sulfide as by product of metabolism of oil.
Combined with water, eroded limestone and left gypsum behind.
o Biological and geological forces working together.
o Research team:
 Wind tunnel due to air pressure changes
 Letchigia – deepest in US, 4th in the world, 100 miles of mapped caves
 S, Manganese, Fe – food, plenty of water Microbes are everywhere we
have looked for them.
 U loops fossilized microbes?
 Dead cave: no longer being eroded, not devoid of life
 Cave walls enlarging? Other microbes might be breaking down material.
Test by placing chemicals that react to living microbes.
 Lake lebarge: over 1 mile in and 1000 feet deep.
o Pristine, almost invisible water.
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o Human threat to caves: skin fragments, hair, camp underground for days.
Organisms not adapted to food sources that humans use.
o Extreme – human perspective – our idea of conditions in which life can exist.
Samples from cave: yes, alive. Microbes, attached to rocks
o How are microbes living in walls?
o Manganese eating bacteria. Shape, leave holes in crystal lattice
 Culture microbes in lab: guess at food, conditions, toxins?
 DNA extraction. Very diverse, dissimilar to other known microorganisms.
 Active, large numbers of them, reproductive.
Younger cave-- microbes? Via Luz
o Hydrogen sulfide combines with water to form hydrogen sulfide – created by
microbes.
o Many poisonous gasses – rise deeper into caves
o More life as go deeper into the cave – what is it driven by??
o Clues:
 Mucousy snotites, like u loops in letchigia, dripping sulfuric acid,
dissolves clothes and caves, leaves behind gypsum. Bacteria inside cave
are producing sulfuric acid. Cave being actively dissolved.
 Microbes’ role: primary food source for mites, worms, spiders,
o Oxygen level drops, expedition ends
Northern Wyoming – lowercane cave.
o Emits hydrogen sulfide, but not as much as Via Luz.
o 3 spring fed pools connected by stream.
o Treasure: rare microbes in stringy formations. Glimpse of early life? No
predators, so microbes dominate.
o Don’t use carbon from sunlight produced things. Don’t use or need any light at
all.
o Droplets of sulfuric acid – dissolving limestone, leaving gypsum behind.
o Bacteria carve or colonize the cave?
 Calcite chips in tubes near microbial mats test
 Evidence suggests bacteria speed up cave formation process. Active
agents of geological change.
o Diverse communities – range of microorganisms in each mat, specific food
sources
o Primitive extremophile similar to those at undersea vents – maybe where life
originated. Glimpse at ancient life, maybe life on other planets. Possibility that
there is more life in the universe than imagined. Active and powerful, we are
dependent on them.
From PBS.org:
TV Program Description
Original PBS Broadcast Date: October 1, 2002
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Deep in the heart of the Guadalupe Mountains in southern New Mexico, rock-eating
microbes are at work. But their appetite is dainty compared to their voracious hunger
millions of years ago, when they carved some of the most impressive caves in the
world. "Mysterious Life of Caves" reports on a revolutionary theory of cave formation
that has startling implications for the development of life on Earth and on other planets.
NOVA's team descends through miles of twisting, plunging caverns, including some of
the most exotic in the world that are off limits to all except researchers. NOVA was
given special permission to film in these fragile, often perilous places, which have
turned the science of speleology on its head.
For all its evident risks, speleology is a science in which women are especially
prominent, including several featured in this program: microbiologist and Mars specialist
Penny Boston, geologist Carol Hill, biologist Diana Northup, and geologist Louise Hose,
among others.
"The first couple of times I went on trips [to Lechuguilla Cave], I kept thinking, all I have
to do is live long enough to get out and then I never have to come back," admits Boston.
"[But then] the beauties of the cave ... really soaked into my soul." And so did the
science. The film crew's first stop is Lechuguilla, along with Carlsbad Caverns, both in
Carlsbad Caverns National Park, New Mexico. Both are home to the most spectacular
and puzzling gypsum formations ever found.
Traditional theories of cave formation could not explain how these vast subterranean
caverns with massive gypsum deposits were formed. Most limestone caves are
dissolved by flowing water that has absorbed carbon dioxide from the atmosphere and
become slightly acidic. However, gypsum is soluble in water and should have been
washed away at Carlsbad and Lechuguilla. Furthermore, there is no sign that flowing
water ever entered or exited the caves.
Whatever process created Carlsbad and Lechuguilla is largely dormant now. So the
team visits a more active and dangerous cavern: Cueva de Villa Luz in Mexico, which
emits the toxic, rotten-egg smell of hydrogen sulfide from its entrance. Inside, explorers
must wear respirators and carry poison-gas monitors to protect themselves from the
hydrogen sulfide that reacts with water in the cave to form caustic sulfuric acid. Deep
within, they discover "snottites," mucous-like stalactites of sulfur-eating bacteria that
also drip sulfuric acid. Oddly enough, the noxious environment teems with microbes,
spiders, insects, crabs, and fish -- all thriving in complete darkness.
As strange as it may seem, sulfuric acid produced by microbial life is the cause of about
five percent of all limestone caves, including Cueva de Villa Luz, Carlsbad, and
Lechuguilla. Sulfuric acid not only dissolves limestone, it leaves a distinctive chemical
residue: gypsum. This process, which is ongoing now in Cueva de Villa Luz, was
completed millions of years ago in Carlsbad and Lechuguilla, where microbial activity
continues today at a very slow pace.
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Sulfuric acid is produced not just by snottites but also deep underground in oil deposits.
Microbes consume oil and release hydrogen sulfide gas, which rises through rock
fissures and combines with groundwater to produce sulfuric acid.
To scientists, the biggest surprise is that this Earth-transforming process is connected to
life -- especially life where no one expected to find it, since caves were long considered
virtually sterile environments. Dubbed "extremophiles," these newfound organisms,
living beyond the margin of what was considered possible, are turning up in more and
more environments, from hot springs at Yellowstone National Park to volcanic vents at
the ocean bottom.
Some scientists believe these bacteria descend directly from the earliest life forms that
emerged on Earth some 3.5 billion years ago. They may even be our best guess of
what life is like on other planets -- buried beneath the surface of Mars, floating in the
oceans of Jupiter's moon Europa, and otherwise thriving in extreme conditions
throughout the cosmos.
Recommends:
Before Watching
1. Ask students what they think it is like to do cave research. How much light might
there be? How hot or cold do they imagine it is? How cramped or open?
2. Researchers in this program find a variety of microbes living in extreme
environments. Have students take notes about where microbes are found and
what role they play in the life of the cave.
After Watching
1. Discuss with students the conditions of working in a cave. What was the
environment like? What seemed like the most difficult part of the expedition?
What kind of precautions did researchers take?
2. Review students' notes about the different kinds of microbes researchers
discovered. Where did researchers find microbes? What processes, if any, did
the microbes perform? What questions do researchers still have about the
microbes?
At http://www.pbs.org/wgbh/nova/caves/ you can see clips the four ways caves are
known to form, and a virtual tour of Lechuguilla Cave.
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Nova Mysterious Life of Caves
Name__________________
Per.______
1. The Guadalupe Mountains were once a different geologic formation called El Capitan. What
was El Capitan 250 million years ago?
2. Coral reefs may become what kind of sedimentary rock?
3. According to one theory of cave formation carbon dioxide + water = carbonic acid.
Where does that carbon dioxide come from?
4. What pieces of evidence led researchers to look for other explanations for the formation of
Carlsbad Caverns?
5. Where did the gypsum in the Carlsbad caves come from?
a. How did researchers determine where the gypsum came form?
6. What produces the hydrogen sulfide under the Guadalupe Montains?
7. How did scientists discover what produced the hydrogen sulfide?
8. What are the THREE extremes that an extremophile can survive?
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9. What causes wind at the entrance to the Lechuguilla Caves?
10. Name two places we have not been able to find microbial life.
11. What do the extermophiles in Lechuguilla Cave eat?
12. True or false: As researchers explore deeper into Cueva de Villa Luz, they find fewer
organisms.
13. Why did scientists put calcite chips in plastic tubes in the water springs at Kane Cave?
a. What were the results of that test?
b. What does that mean in terms of cave formation?
14. What other ways are the discoveries about cave formation applied?
15. (From Internet) What are the four ways caves form?
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