Transcript who turned out the lights

Who turned out the
Lights?
Life Under the Earth
Scientists have found organisms living in caves that do not exist
anywhere else. These extremophiles have adapted to cold, dark
conditions and in many cases have evolved with no contact with the
outside world.
Weird creatures such as the eyeless spider and worm-sucking leeches
have been discovered.
Where do cave-dwellers get their food? Well, some eat each
other. And there are no plants there, due to the absence of light
(that makes photosynthesis difficult!). But the strangest thing is
that in some the food chain is powered by rock-eating bacteria.
Now that’s extreme.
How do they do it? They stick to the walls and ingest the sulfur
minerals and limestone from the rock.
As microbes eat the cave walls, they help to enlarge the cave and
they produce sulfuric acid. In some caves, bacteria
produce so much sulfur that it is toxic to humans.
In other caves, microbes form a thick gray slime that drips down
the walls and off the ceilings. These are very appropriately called
“snottites.” (EWWW!)
Scientists started to get very curious about what else might live
deep under Earth’s surface. After drilling some holes, they
found rock-eating microbes living more than 3 miles down - in
solid granite!
Rock-eating microbes make different by-products.
Some make minerals or methane gas, while others produce toxins.
Other bacteria eat oil, and have been used to clean up oil
spills.
1. What other uses can you think of for these types of bacteria?
2. Are there any negative possibilities in putting them to work
for us?